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[email protected] jlgotham@gmail.com is offline
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Dear Pat,
I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now.

They suggest wired in series for the stacking....and sent me this link:

http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5

I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency.

Some even says 300B push pull can drive it!!

Gee...are they making a joke with me??

Regards,
JL
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Phil Allison[_3_] Phil Allison[_3_] is offline
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I read your article about Quad ESL and tube amplifier online.
I've discussion recently with my friends about stacking
Quad ESL 57 and some even thinking to stack 4 x ESL 57
in a big room and I'm interested in that since I have 2 in stacking now.

They suggest wired in series for the stacking....and sent me this link:

http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5

I wonder 3 ESL 57 stacking and series wired still ok since the
impedance still 30 ohm range. However, 4 in stacking, no kidding
the impedance will rise to 60 ohm and maximum can go up to 120 ohm
on the low frequency.

Some even says 300B push pull can drive it!!


** As a long time owner of ESL57s and an audio service tech, I can offer
the following advice:

1. The impedance of the speaker is nominally 15 ohms ( 250Hz to 5kHz) -
falling smoothly above 5kHz to around 2ohms at 19kHz. The highest value
reached is 30 ohms at 100Hz. Down at 20 Hz ( no usable sound ) the impedance
is 8 ohms.

2. Normal matching with a hi-fi valve/tube amp is to use the 15 ohm setting
and rely on NFB to keep response flat to within a dB or so across the audio
band.

3. Amplifiers with high output impedance (ie low or no NFB) are not
sensible with ESL57s cos the sound quality will be rather dull. The same is
true with other speakers, for example the AR11 ( 12 inch 3-way) is much
worse than the ESL57 when used with such amps.

4. Series operation has many drawbacks as the impedance gets ridiculously
high and input power will not be shared evenly by non identical speakers.
This could lead to sparking and damage.

5. The ideal way to drive multiple ESL57s is to use multiple tube
amplifiers that use lots of NFB.

6. A good solid state amp can easily drive two ESL57s in parallel - the
Quad 306 is perfect.

7. Stacked ESL57s need to be individually aimed at the listening point, so
NOT mounted so as to make a smooth curve.

8. All the above is based on lots of real experience and testing - NOT
THEORY.


.... Phil





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Jim[_15_] Jim[_15_] is offline
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Dear Phil,
What about 4 pairs of Quad ESL 57 wired in parallel?

Sound Anchor in US might be able to custom made a stand for 4 x Quad ESL 57 in stacking and the design has complete adjustability for time and phase response from all speakers and place for Townshend Maximum supertweeters as well since each ESL 57 has one Townshend supertweeter sitting on top, total 4 of those tweeters. You can see how the Townshend tweeter connect and mount on each Quad ESL 57 thru the link below.

http://imageshack.us/photo/my-images/834/yf5q.jpg/

http://imageshack.us/photo/my-images/211/58d4.jpg/

http://imageshack.us/photo/my-images/12/1m66.jpg/

You know, the 4 x Quad ESL 57 and 4 x Townshend Supertweeter combined impedance has a pretty low impedance on the high frequency if parallel wired all the way.

I did a calculation the minimum impedance of townsend is 11 ohm and Quad is 1.6 ohm at 20KHz for single set, When wired both in parallel as the attachment shown, the impedance is going to be:

(11 x 1.6) / (11 + 1.6) = 1.3968

When wired 4 sets in parallel for stacking, we get 1.3968 / 4 = 0.349 ohm

http://www.townshendaudio.com/supertweeters/

*** a set means the Townshend Maximum Supertweeter parallel to the Quad ESL 57 ***

Therefore, I must put a Zero Autoformer to boost up the impedance 2, 3 or 4 times for compensation like this:

Amplifier -- Zeros Autoformer - Stacked 4 x Quad ESL 57 plus 4 x Townshend Maximum Supertweeter wired in parallel.

http://www.zeroimpedance.com/box.html

Also, I want to have FMOD for 100Hz high pass filter.

http://www.hlabs.com/products/crossovers/

Anything under will be handle by Gradient SW-D. As a result, those 4 x Quad ESL 57 no needed to play anything under 100Hz.

I'll have this processor for bass management and low pass filtering for Gradient SW-D. 2 units, one for each channel.

http://www.dspeaker.com/en/products/20-dual-core.shtml

Any comments I need to pay attention for such a setup??

Thanks!
BR, Jim

On Monday, June 17, 2013 12:55:43 PM UTC+8, Phil Allison wrote:




I read your article about Quad ESL and tube amplifier online.


I've discussion recently with my friends about stacking


Quad ESL 57 and some even thinking to stack 4 x ESL 57


in a big room and I'm interested in that since I have 2 in stacking now..




They suggest wired in series for the stacking....and sent me this link:




http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5




I wonder 3 ESL 57 stacking and series wired still ok since the


impedance still 30 ohm range. However, 4 in stacking, no kidding


the impedance will rise to 60 ohm and maximum can go up to 120 ohm


on the low frequency.




Some even says 300B push pull can drive it!!




** As a long time owner of ESL57s and an audio service tech, I can offer

the following advice:



1. The impedance of the speaker is nominally 15 ohms ( 250Hz to 5kHz) -

falling smoothly above 5kHz to around 2ohms at 19kHz. The highest value

reached is 30 ohms at 100Hz. Down at 20 Hz ( no usable sound ) the impedance

is 8 ohms.



2. Normal matching with a hi-fi valve/tube amp is to use the 15 ohm setting

and rely on NFB to keep response flat to within a dB or so across the audio

band.



3. Amplifiers with high output impedance (ie low or no NFB) are not

sensible with ESL57s cos the sound quality will be rather dull. The same is

true with other speakers, for example the AR11 ( 12 inch 3-way) is much

worse than the ESL57 when used with such amps.



4. Series operation has many drawbacks as the impedance gets ridiculously

high and input power will not be shared evenly by non identical speakers.

This could lead to sparking and damage.



5. The ideal way to drive multiple ESL57s is to use multiple tube

amplifiers that use lots of NFB.



6. A good solid state amp can easily drive two ESL57s in parallel - the

Quad 306 is perfect.



7. Stacked ESL57s need to be individually aimed at the listening point, so

NOT mounted so as to make a smooth curve.



8. All the above is based on lots of real experience and testing - NOT

THEORY.





... Phil

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"Jim"

Dear Phil,

What about 4 pairs of Quad ESL 57 wired in parallel?

** How about you respond to my post, pal ??

Top posting your drivel over my clear advice is no way to impress.



http://www.townshendaudio.com/supertweeters/

** Purest insanity.

http://www.zeroimpedance.com/box.html

** Even worse.

This loopy audiophool must have run out of friends in the USA.



.... Phil










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patrick-turner patrick-turner is offline
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On Monday, 17 June 2013 13:52:32 UTC+10, Jimmy Leung wrote:
Dear Pat, I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now. They suggest wired in series for the stacking....and sent me this link: http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5 I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency. Some even says 300B push pull can drive it!! Gee...are they making a joke with me?? Regards, JL


I agree fully with what Phil said about driving one pair of ESL57.
There is an impedance curve for ESL57 aboubt 1/10 down the page at my website http://www.turneraudio.com.au/quad2powerampmods.htm

Indeed 300B tubes can drive any speaker you could ever possibly imagine.
But you will need to know about how many 300B to use, and how to hook them up, and I suggest you have a very steep learning curve ahead of you. You are the one who wonders if your friends are making a joke with you about 300B, and this implies to me that you may have attrociously inadequate understanding of very basic issues regarding impedance, resistance, capacitance, inductance, load matching, amp design, etc, etc, etc. My knowledge was attrocious once, but gradually I learnt how get fabulous sound while avoid silly un-necessary expense on amps and never having PDEs, ie, "smoke producing events".

I repeat what Phil said....
** As a long time owner of ESL57s and an audio service tech, I can offer
the following advice:

**1. The impedance of the speaker is nominally 15 ohms ( 250Hz to 5kHz) -
falling smoothly above 5kHz to around 2ohms at 19kHz. The highest value
reached is 30 ohms at 100Hz. Down at 20 Hz ( no usable sound ) the impedance
is 8 ohms.

**2. Normal matching with a hi-fi valve/tube amp is to use the 15 ohm setting
and rely on NFB to keep response flat to within a dB or so across the audio
band.

**3. Amplifiers with high output impedance (ie low or no NFB) are not
sensible with ESL57s cos the sound quality will be rather dull. The same is
true with other speakers, for example the AR11 ( 12 inch 3-way) is much
worse than the ESL57 when used with such amps.

**4. Series operation has many drawbacks as the impedance gets ridiculously
high and input power will not be shared evenly by non identical speakers.
This could lead to sparking and damage.

**5. The ideal way to drive multiple ESL57s is to use multiple tube
amplifiers that use lots of NFB.

6. A good solid state amp can easily drive two ESL57s in parallel - the
**Quad 306 is perfect.

**7. Stacked ESL57s need to be individually aimed at the listening point, so
NOT mounted so as to make a smooth curve.

**8. All the above is based on lots of real experience and testing - NOT
THEORY.

NOW, I cannot see the slightest benefit of using more than 3 stacked pairs of ESL57, but if you had 4 stacked pairs then in theory you can have two pairs in series, then connect these two pairs in parallel and you get the same impedence as ONE ESL57, and described by Phil. I recall my website has an impedance curve for ESL57.

I had a customer with 3 stacked pairs in parallel and who bought an 8585 amp from me and the details are all at http://www.turneraudio.com.au/8585-a...ober-2006.html

The amp was fitted with 8 x KT90 and could give 100W into 4 ohms, with good load tolerance for where the 3 x parallel ESL57 impedance falls to about 0..6 ohms at about 18kHz, where average audio level is very much lower than in the middle of the LF band where most energy is needed, say around 200Hz.

The idea of having 3 of 4 x ESL57 in series creates the problem of having enough voltage available at the amp to give sufficient drive signal.
Quad-II amps capable of about 20 Watts into 16 ohms means that 18Vrms is needed at speakers. If you had 4 in series, you need 72Vrms across the 4, and virtually no amps are made to produce such a voltage unless they are say 1,000Watt rated for PA use. One might use a speaker *step UP* matching transformer but the toridal type at zeroimpedance.com would suffer saturation at a frequency that would be too high.

If you had all 3 or all 4 ESL in parallel, then the use of toriodal *step DOWN* speaker matching tranny with 2:1 TR ratio might be used although the response at HF may suffer because leakage L of the tranny is effectively in series with the very low Z at ESL HF.

The other thing you MUST realize is that with 3 of 4 stacked pairs, the speakers begin to resemble line arrays of dyneamic drivers mounted in vertical lines. The overall efficiency increases, so the POWER needed to make a given SPL for average listening becomes less. With the right sort of wide band speaker matching tranny 2, 3, or 4 pairs of ESL57 in parallel can easily be driven with say 2 x KT88 arranged to give 50W max. With multiple stacked pairs, your need for more power is only slight, to cater for the rare even when you might want more SPL than can be achieved with Quad-II and one pair of ESL57.

The ESL57 Z varies from say 32 ohms down to 2 ohms, and they are designed for a flat response with a constant voltage level. So thus if the amp makes 4Vrms at 50Hz, 32 ohms, it means Po = 0.5Watts, and the same 4Vrms at 18kHz, 2 ohms, Po = 8 Watts. Where you had 4 pairs ESL57 in parallel the Z is 1/4 of ONE ES57, and this may well cook some amps unless they have variable impedance settings allowing nominal speaker Z = 2 ohms for between 200Hz and 1kHz.

Patrick Turner.




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John L Stewart John L Stewart is offline
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Smile

When loudsppeakers are connected in series, each unit becomes the source impedance for the other(s). Not recommended at all, under any circumstance!

Four similar in series/parallel should be OK. Connect the mid points together as well.

Cheers, John
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Phil Allison[_3_] Phil Allison[_3_] is offline
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"Phil Allison"

6. A good solid state amp can easily drive two ESL57s in parallel - the
Quad 306 is perfect.


** FYI: The Quad 306 is a very compact power amp of 50 wpc at 8ohms.

http://www.meridian-audio.info/viewp...7&photoid=3430

http://www.meridian-audio.info/show.php?compid=307

The schem is fascinating - seems to go against every rule most hi-fi amps
follow.

http://www.nasotec.com/acecart/bin/b...ataRoom/25.jpg

It's a "current dumping" design, the PSU has no hard CT and the op-amp is
only for offset correction.

Internal construction is unpretentious, to say the least.

THD is low and hard to measure and there are no vices.

Used examples go for A$300 to A$400.



..... Phil



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patrick-turner patrick-turner is offline
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Phil Allison said.....

6. A good solid state amp can easily drive two ESL57s in parallel - the


Quad 306 is perfect.


** FYI: The Quad 306 is a very compact power amp of 50 wpc at 8ohms.
http://www.meridian-audio.info/viewp...7&photoid=3430
http://www.meridian-audio.info/show.php?compid=307
The schem is fascinating - seems to go against every rule most hi-fi amps
follow.
http://www.nasotec.com/acecart/bin/b...ataRoom/25.jpg
It's a "current dumping" design, the PSU has no hard CT and the op-amp is
only for offset correction.
Internal construction is unpretentious, to say the least.
THD is low and hard to measure and there are no vices.
Used examples go for A$300 to A$400.
..... Phil

Might be interesting, but I don't know anyone who likes Quad SS amps. I figured it wouldn't be hard to make a 5W SET class A amp act with a couple of KT88 in near class B operation to perform "current dumping" duties. One silly Tim De Paravicini said once, "...the worst thing you can do with a current is dump it" Of course this resonated extremely well with audiophiles who hate most logically configured things. There were many dismissive letters to Wireless World about current dumping, but Peter Walker well survived the onslaught.
Patrick Turner.
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"patrick-turner = famous Quad hater "

Might be interesting, but I don't know anyone who likes Quad SS amps.



** A sad comment about YOU - not Quad.


There were many dismissive letters to Wireless World about current
dumping,



** There were equally many that convincingly refuted the ignorati who wrote
the foolish letters.

That you bring such irrelevant crap up *36 years* after it was dead and
buried proves what an utter arsehole you are.

And is why I call you the " Turneriod".




.... Phil




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Jimmy Leung Jimmy Leung is offline
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Dear Pat,
Someone has made a suggestion to my friend by having a pair of GM70 SE amplifier on 4 pairs stacked 57 with series-parallel arrangement, and which has the impedance equivalent to one single ESL 57 as you just described. We all know that SE amplifier is no luck on the Quad ESL 57, is it?

J



On Wednesday, June 19, 2013 2:30:49 PM UTC+8, patrick-turner wrote:
On Monday, 17 June 2013 13:52:32 UTC+10, Jimmy Leung wrote:

Dear Pat, I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now. They suggest wired in series for the stacking....and sent me this link: http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5 I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency. Some even says 300B push pull can drive it!! Gee...are they making a joke with me?? Regards, JL




I agree fully with what Phil said about driving one pair of ESL57.

There is an impedance curve for ESL57 aboubt 1/10 down the page at my website http://www.turneraudio.com.au/quad2powerampmods.htm



Indeed 300B tubes can drive any speaker you could ever possibly imagine.

But you will need to know about how many 300B to use, and how to hook them up, and I suggest you have a very steep learning curve ahead of you. You are the one who wonders if your friends are making a joke with you about 300B, and this implies to me that you may have attrociously inadequate understanding of very basic issues regarding impedance, resistance, capacitance, inductance, load matching, amp design, etc, etc, etc. My knowledge was attrocious once, but gradually I learnt how get fabulous sound while avoid silly un-necessary expense on amps and never having PDEs, ie, "smoke producing events".



I repeat what Phil said....

** As a long time owner of ESL57s and an audio service tech, I can offer

the following advice:



**1. The impedance of the speaker is nominally 15 ohms ( 250Hz to 5kHz) -

falling smoothly above 5kHz to around 2ohms at 19kHz. The highest value

reached is 30 ohms at 100Hz. Down at 20 Hz ( no usable sound ) the impedance

is 8 ohms.



**2. Normal matching with a hi-fi valve/tube amp is to use the 15 ohm setting

and rely on NFB to keep response flat to within a dB or so across the audio

band.



**3. Amplifiers with high output impedance (ie low or no NFB) are not

sensible with ESL57s cos the sound quality will be rather dull. The same is

true with other speakers, for example the AR11 ( 12 inch 3-way) is much

worse than the ESL57 when used with such amps.



**4. Series operation has many drawbacks as the impedance gets ridiculously

high and input power will not be shared evenly by non identical speakers.

This could lead to sparking and damage.



**5. The ideal way to drive multiple ESL57s is to use multiple tube

amplifiers that use lots of NFB.



6. A good solid state amp can easily drive two ESL57s in parallel - the

**Quad 306 is perfect.



**7. Stacked ESL57s need to be individually aimed at the listening point, so

NOT mounted so as to make a smooth curve.



**8. All the above is based on lots of real experience and testing - NOT

THEORY.



NOW, I cannot see the slightest benefit of using more than 3 stacked pairs of ESL57, but if you had 4 stacked pairs then in theory you can have two pairs in series, then connect these two pairs in parallel and you get the same impedence as ONE ESL57, and described by Phil. I recall my website has an impedance curve for ESL57.



I had a customer with 3 stacked pairs in parallel and who bought an 8585 amp from me and the details are all at http://www.turneraudio.com.au/8585-a...ober-2006.html



The amp was fitted with 8 x KT90 and could give 100W into 4 ohms, with good load tolerance for where the 3 x parallel ESL57 impedance falls to about 0.6 ohms at about 18kHz, where average audio level is very much lower than in the middle of the LF band where most energy is needed, say around 200Hz..



The idea of having 3 of 4 x ESL57 in series creates the problem of having enough voltage available at the amp to give sufficient drive signal.

Quad-II amps capable of about 20 Watts into 16 ohms means that 18Vrms is needed at speakers. If you had 4 in series, you need 72Vrms across the 4, and virtually no amps are made to produce such a voltage unless they are say 1,000Watt rated for PA use. One might use a speaker *step UP* matching transformer but the toridal type at zeroimpedance.com would suffer saturation at a frequency that would be too high.



If you had all 3 or all 4 ESL in parallel, then the use of toriodal *step DOWN* speaker matching tranny with 2:1 TR ratio might be used although the response at HF may suffer because leakage L of the tranny is effectively in series with the very low Z at ESL HF.



The other thing you MUST realize is that with 3 of 4 stacked pairs, the speakers begin to resemble line arrays of dyneamic drivers mounted in vertical lines. The overall efficiency increases, so the POWER needed to make a given SPL for average listening becomes less. With the right sort of wide band speaker matching tranny 2, 3, or 4 pairs of ESL57 in parallel can easily be driven with say 2 x KT88 arranged to give 50W max. With multiple stacked pairs, your need for more power is only slight, to cater for the rare even when you might want more SPL than can be achieved with Quad-II and one pair of ESL57.



The ESL57 Z varies from say 32 ohms down to 2 ohms, and they are designed for a flat response with a constant voltage level. So thus if the amp makes 4Vrms at 50Hz, 32 ohms, it means Po = 0.5Watts, and the same 4Vrms at 18kHz, 2 ohms, Po = 8 Watts. Where you had 4 pairs ESL57 in parallel the Z is 1/4 of ONE ES57, and this may well cook some amps unless they have variable impedance settings allowing nominal speaker Z = 2 ohms for between 200Hz and 1kHz.



Patrick Turner.



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John,
So don't you think wired pair 57 in series and the other pair 57 in series again and then put 2 series pair in parallel is fine??


On Thursday, June 20, 2013 8:30:02 AM UTC+8, John L Stewart wrote:
When loudsppeakers are connected in series, each unit becomes the source

impedance for the other(s). Not recommended at all, under any

circumstance!



Four similar in series/parallel should be OK. Connect the mid points

together as well.



Cheers, John





+-------------------------------------------------------------------+

|Filename: 150px-Alfred_E__Neumann.jpe |

|Download: http://www.audiobanter.com/attachment.php?attachmentid=351|

+-------------------------------------------------------------------+







--

John L Stewart


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Hi Pat!
I forgot to put this question. Even though 4 ESL in stacked with series-parallel wired achieve the same impedance as a single one, this is no way to have Quad II amplifier driving 4 stacked ESL 57 in series-parallel config, right or wrong?

thx!


On Wednesday, June 19, 2013 2:30:49 PM UTC+8, patrick-turner wrote:
On Monday, 17 June 2013 13:52:32 UTC+10, Jimmy Leung wrote:

Dear Pat, I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now. They suggest wired in series for the stacking....and sent me this link: http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5 I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency. Some even says 300B push pull can drive it!! Gee...are they making a joke with me?? Regards, JL




I agree fully with what Phil said about driving one pair of ESL57.

There is an impedance curve for ESL57 aboubt 1/10 down the page at my website http://www.turneraudio.com.au/quad2powerampmods.htm



Indeed 300B tubes can drive any speaker you could ever possibly imagine.

But you will need to know about how many 300B to use, and how to hook them up, and I suggest you have a very steep learning curve ahead of you. You are the one who wonders if your friends are making a joke with you about 300B, and this implies to me that you may have attrociously inadequate understanding of very basic issues regarding impedance, resistance, capacitance, inductance, load matching, amp design, etc, etc, etc. My knowledge was attrocious once, but gradually I learnt how get fabulous sound while avoid silly un-necessary expense on amps and never having PDEs, ie, "smoke producing events".



I repeat what Phil said....

** As a long time owner of ESL57s and an audio service tech, I can offer

the following advice:



**1. The impedance of the speaker is nominally 15 ohms ( 250Hz to 5kHz) -

falling smoothly above 5kHz to around 2ohms at 19kHz. The highest value

reached is 30 ohms at 100Hz. Down at 20 Hz ( no usable sound ) the impedance

is 8 ohms.



**2. Normal matching with a hi-fi valve/tube amp is to use the 15 ohm setting

and rely on NFB to keep response flat to within a dB or so across the audio

band.



**3. Amplifiers with high output impedance (ie low or no NFB) are not

sensible with ESL57s cos the sound quality will be rather dull. The same is

true with other speakers, for example the AR11 ( 12 inch 3-way) is much

worse than the ESL57 when used with such amps.



**4. Series operation has many drawbacks as the impedance gets ridiculously

high and input power will not be shared evenly by non identical speakers.

This could lead to sparking and damage.



**5. The ideal way to drive multiple ESL57s is to use multiple tube

amplifiers that use lots of NFB.



6. A good solid state amp can easily drive two ESL57s in parallel - the

**Quad 306 is perfect.



**7. Stacked ESL57s need to be individually aimed at the listening point, so

NOT mounted so as to make a smooth curve.



**8. All the above is based on lots of real experience and testing - NOT

THEORY.



NOW, I cannot see the slightest benefit of using more than 3 stacked pairs of ESL57, but if you had 4 stacked pairs then in theory you can have two pairs in series, then connect these two pairs in parallel and you get the same impedence as ONE ESL57, and described by Phil. I recall my website has an impedance curve for ESL57.



I had a customer with 3 stacked pairs in parallel and who bought an 8585 amp from me and the details are all at http://www.turneraudio.com.au/8585-a...ober-2006.html



The amp was fitted with 8 x KT90 and could give 100W into 4 ohms, with good load tolerance for where the 3 x parallel ESL57 impedance falls to about 0.6 ohms at about 18kHz, where average audio level is very much lower than in the middle of the LF band where most energy is needed, say around 200Hz..



The idea of having 3 of 4 x ESL57 in series creates the problem of having enough voltage available at the amp to give sufficient drive signal.

Quad-II amps capable of about 20 Watts into 16 ohms means that 18Vrms is needed at speakers. If you had 4 in series, you need 72Vrms across the 4, and virtually no amps are made to produce such a voltage unless they are say 1,000Watt rated for PA use. One might use a speaker *step UP* matching transformer but the toridal type at zeroimpedance.com would suffer saturation at a frequency that would be too high.



If you had all 3 or all 4 ESL in parallel, then the use of toriodal *step DOWN* speaker matching tranny with 2:1 TR ratio might be used although the response at HF may suffer because leakage L of the tranny is effectively in series with the very low Z at ESL HF.



The other thing you MUST realize is that with 3 of 4 stacked pairs, the speakers begin to resemble line arrays of dyneamic drivers mounted in vertical lines. The overall efficiency increases, so the POWER needed to make a given SPL for average listening becomes less. With the right sort of wide band speaker matching tranny 2, 3, or 4 pairs of ESL57 in parallel can easily be driven with say 2 x KT88 arranged to give 50W max. With multiple stacked pairs, your need for more power is only slight, to cater for the rare even when you might want more SPL than can be achieved with Quad-II and one pair of ESL57.



The ESL57 Z varies from say 32 ohms down to 2 ohms, and they are designed for a flat response with a constant voltage level. So thus if the amp makes 4Vrms at 50Hz, 32 ohms, it means Po = 0.5Watts, and the same 4Vrms at 18kHz, 2 ohms, Po = 8 Watts. Where you had 4 pairs ESL57 in parallel the Z is 1/4 of ONE ES57, and this may well cook some amps unless they have variable impedance settings allowing nominal speaker Z = 2 ohms for between 200Hz and 1kHz.



Patrick Turner.


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John L Stewart John L Stewart is offline
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Quote:
Originally Posted by Jimmy[_8_] View Post
John,
So don't you think wired pair 57 in series and the other pair 57 in series again and then put 2 series pair in parallel is fine??


On Thursday, June 20, 2013 8:30:02 AM UTC+8, John L Stewart wrote:
When loudsppeakers are connected in series, each unit becomes the source

impedance for the other(s). Not recommended at all, under any

circumstance!



Four similar in series/parallel should be OK. Connect the mid points

together as well.



Cheers, John





+-------------------------------------------------------------------+

|Filename: 150px-Alfred_E__Neumann.jpe |

|Download: http://www.audiobanter.com/attachment.php?attachmentid=351|

+-------------------------------------------------------------------+

John L Stewart
Series/Parallel connexion makes the best of a poor situation. Paralleling pairs or groups smooths the Z curve since all will tend to be a little different. If combined say four in a cabinet such as used by rock guitarists helps a bit since they are then to some extent acoustically coupled in the box.

But best solution is an OPT tapped for multiple speakers.

Hook up your stuff & standby with a fire extinguisher!

Cheers, John
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Dear Pat,
Someone has made a suggestion to my friend by having a pair of GM70 SE amplifier on 4 pairs stacked 57 with series-parallel arrangement, and which has the impedance equivalent to one single ESL 57 as you just described. We all know that SE amplifier is no luck on the Quad ESL 57, is it?

Many ppl like to tell me that if you put one speaker in series with another, and both speaker have the same impedance, then reduce the damping factor because each speaker is being supplied energy through the impedance of the other.

They would like to tell us that using 2 speakers in series, say 8 ohms each, is like having an 8 ohm resistance in series with one speaker, and the 8 ohms adds to the amplifier output resistance which is usually less than 1 ohm. So DF is reduced from say 8 with no 8 ohms to 0.9 with 8 ohms.

Well, having a series resistance is different to having a series resistance.. Speaker makers including myself have often connected 6 ohm midrange speakers in series for a D'Apolito arrangement and this makes the total speaker impedance = 12 ohms, and this makes a much better load match for the amplifier. If the amplifier Rout = 1 ohm, the DF is increased from 6 to 12.

In theory, it is perfectly OK to connect ESL speakers in series reducing the DF, but actually increasing it. Impedance is the frequency dependant resistance, and at 50Hz two ESL57 may total 64 ohms, but at 18kHz the total is 4 ohms. In practice, perhaps the ESL57 have slightly non similar impedances.. Then you find that two seriesed speaker each get a different frequency response of the signal from the amplifier, and the acoustic output becomes different for each speaker. So I don't like having speakers in series which are prone to slight impedance variations. A pair of say SEAS 125mm dynamic drivers bought as a pair will be very close, and be only required to operate from 250Hz to 3kHz, and its safe to series them, but if you measure a pair of ancient ESL57 which may be 50 years old, you may find the impedance of each is slightly different. So when I supplied an amp to drive 3 stacked pairs of ESL57, I put 3 pairs of output terminals on the amp each with 0.6 ohms in series with each output. This make each output mimic the output resistance of a Quad-II amp.
See the schematic of my amp at http://www.turneraudio.com.au/8585-a...ober-2006.html

Using 2 x GM70 could drive any number of ESL57 you wish to use. I would never risk series connection of any ESL speakers. So, if all speakers are to be parallel connected, then All you MUST do is use a correctly configured amplifier OPT or have a following speaker matching transformer.

Let us assume a pair of GM70 can make 30Watts in parallel SET, class A1.
It may be difficult to find a suitable air gapped OPT. But the other alternative is to choke feed the DC to the pair of anodes, and use cap coupling to an easier to find PP OPT, such as a Hammond 60W rated OPT meant for 5k0 : 4,8,16 ohms. ( I am not sure what anode load is needed; YOU need to learn all about load matching and load line analysis ) You could use 4 paralleled ESL57 all connected to the 4 ohm OPT tap. OR two ESL could be connectd to the 8 ohm tap, OR 1 ESL57 connected to the 16 ohm tap.
If any one of the 3 loading options is chosen, the amp loading remains constant, you get the same amount of power from 4, 8 or 16 ohms. What becomes different is that with 4 speaker fed from the 4 ohm terminal, the total power is 30 Watts but each ESL gets only 7.5 Watts. The SPL developed by 4 speakers is much the same as for 1 powered from the 16 ohm tap. ( the 4 stacked ESL produce HIGHER SPL than 1, for the same power, because of increased efficiency due to the close proximity of stacking. )

ESL57 were never known for producing extremely high levels of sound, but designed to accurately reproduce sound heard at a good seat in a large hall with an orchestra with no amplified instruments. If you want ear crunching levels of Dark Metal and other glorified noise that isn't music, then you are wasting my time and your own. But if you persue the use of stacked ESL57, and you manage to find 8 which all are in fine working order ( a real battle, IMHO, ) then the GM70 will be fine to give adequate levels of sound equal to what you'd get from just one pair at least, but with less distortions because each speaker is doing far less work. 30Watts into 4 ohms = 10.95Vrms, and the maximum voltage at the amp 4r0 output without any load would probably be 13Vrms, so you cannot ever apply excessive voltage to the ESL57.. Old ESL57 are prone to arcing in their midrange panels, and I've seen more than one pair cause Quad-II amps to overheat and nearly cause PT failure, after slowly killing KT66.
Patrick Turner.




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"John L Stewart"

When loudsppeakers are connected in series, each unit becomes the source
impedance for the other(s).


** Long as the speakers are near identical - this has NO effect.

The signal voltage divides equally across each speaker at all frequencies.


Not recommended at all, under any circumstance!


** ********.

The Bose 802 has eight identical 1ohm drivers in series.


Four similar in series/parallel should be OK. Connect the mid points
together as well.



** You just contradicted yourself.



.... Phil






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"John L Stewart"


Four similar in series/parallel should be OK. Connect the mid points


Series/Parallel connexion makes the best of a poor situation.
Paralleling pairs or groups smooths the Z curve since all will tend to
be a little different. If combined say four in a cabinet such as used by
rock guitarists helps a bit since they are then to some extent
acoustically coupled in the box.



** However, if one speaker fails open its parallel partner takes 66% of the
power instead of 25%.

Its demise is then guaranteed.


.... Phil





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I've consulted the mfg of the solid state amplifier I have whether it's adequate to handle such load from 4 pairs stacked ESL 57 and wired in parallel with impedance multiplication through autoformer.

http://www.zeroimpedance.com/box.html

This is his response: "The impedance sweet spot is above 4 ohms be the amplifier can drive 2 ohms as long as the load is not to reactive. With an impedance of 0.349 ohms you need a multiplication factor of at least 6 and preferably 10. Regarding the warning about solid state: Since it is has no capacitor in the signal path, there an internal protection against DC offset if output voltage goes above at 4VDC (we were assuming at least 2 ohms for DC). I have seems a few cases where the source to the amplifier has a DC offset and there is a limit to what the internal circuit can do to bring the output voltage less than 100mV DC."

Sounds like ss amplifier is not suitable at all :-(
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"Jimmy"

I've consulted the mfg of the solid state amplifier I have whether it's
adequate to handle such load from 4 pairs stacked ESL 57 and wired in
parallel with impedance multiplication through autoformer.

http://www.zeroimpedance.com/box.html


** This ****head is just NOT listening !!!!!

The Quad ESL57 is a 15ohms or greater load across the audio band up to
5kHz - that means you can treat it as such when using SS amplifier or any
amplifier with low output impedance.


This is his response: "The impedance sweet spot is above 4 ohms be the
amplifier can drive 2 ohms as long as the load is not to reactive.....
blah blah...



** But the ESL57 is NOT a 2 ohm load !!


Sounds like ss amplifier is not suitable at all :-(


** ********.

**** off you bull****ting fool.



.... Phil


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"Jimmy"

Sounds like ss amplifier is not suitable at all :-(

FYI:

The Quad 303 was sold for decades as being ideal for the ESL57.

http://www.dadaelectronics.eu/Images...303%20Back.JPG

It delivered 28 watts at 16ohms, 45 watts at 8ohm, 25 watts at 4 ohms and no
spec given for 2 ohms.

Output impedance is quoted as:

" 0.3 ohms in series with 2000uF and 6uH"

The output current limits at 3.6 amps, hence max power drops into load less
than 8 ohms

IDEAL for the ESL57.

Now **** off.

.... Phil


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Hey man! 4 pairs in parallel is no longer being 15 ohm.

Why ****ed off, I just want to be sure my investment not go to toilet. What the **** about ****head!! Are you feeling comfortable if I say you mother ****er???? Or **** you and your family??

So be nice and civilize!! Treating people how you'd like to be treated yourself.

On Friday, June 21, 2013 1:48:39 PM UTC+8, Phil Allison wrote:




Sounds like ss amplifier is not suitable at all :-(



FYI:



The Quad 303 was sold for decades as being ideal for the ESL57.



http://www.dadaelectronics.eu/Images...303%20Back.JPG



It delivered 28 watts at 16ohms, 45 watts at 8ohm, 25 watts at 4 ohms and no

spec given for 2 ohms.



Output impedance is quoted as:



" 0.3 ohms in series with 2000uF and 6uH"



The output current limits at 3.6 amps, hence max power drops into load less

than 8 ohms



IDEAL for the ESL57.



Now **** off.



... Phil



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Pat, therefore sounds like you have a autoformer for my application, is it?

On Wednesday, June 19, 2013 2:30:49 PM UTC+8, patrick-turner wrote:
On Monday, 17 June 2013 13:52:32 UTC+10, Jimmy Leung wrote:

Dear Pat, I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now. They suggest wired in series for the stacking....and sent me this link: http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5 I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency. Some even says 300B push pull can drive it!! Gee...are they making a joke with me?? Regards, JL




I agree fully with what Phil said about driving one pair of ESL57.

There is an impedance curve for ESL57 aboubt 1/10 down the page at my website http://www.turneraudio.com.au/quad2powerampmods.htm



Indeed 300B tubes can drive any speaker you could ever possibly imagine.

But you will need to know about how many 300B to use, and how to hook them up, and I suggest you have a very steep learning curve ahead of you. You are the one who wonders if your friends are making a joke with you about 300B, and this implies to me that you may have attrociously inadequate understanding of very basic issues regarding impedance, resistance, capacitance, inductance, load matching, amp design, etc, etc, etc. My knowledge was attrocious once, but gradually I learnt how get fabulous sound while avoid silly un-necessary expense on amps and never having PDEs, ie, "smoke producing events".



I repeat what Phil said....

** As a long time owner of ESL57s and an audio service tech, I can offer

the following advice:



**1. The impedance of the speaker is nominally 15 ohms ( 250Hz to 5kHz) -

falling smoothly above 5kHz to around 2ohms at 19kHz. The highest value

reached is 30 ohms at 100Hz. Down at 20 Hz ( no usable sound ) the impedance

is 8 ohms.



**2. Normal matching with a hi-fi valve/tube amp is to use the 15 ohm setting

and rely on NFB to keep response flat to within a dB or so across the audio

band.



**3. Amplifiers with high output impedance (ie low or no NFB) are not

sensible with ESL57s cos the sound quality will be rather dull. The same is

true with other speakers, for example the AR11 ( 12 inch 3-way) is much

worse than the ESL57 when used with such amps.



**4. Series operation has many drawbacks as the impedance gets ridiculously

high and input power will not be shared evenly by non identical speakers.

This could lead to sparking and damage.



**5. The ideal way to drive multiple ESL57s is to use multiple tube

amplifiers that use lots of NFB.



6. A good solid state amp can easily drive two ESL57s in parallel - the

**Quad 306 is perfect.



**7. Stacked ESL57s need to be individually aimed at the listening point, so

NOT mounted so as to make a smooth curve.



**8. All the above is based on lots of real experience and testing - NOT

THEORY.



NOW, I cannot see the slightest benefit of using more than 3 stacked pairs of ESL57, but if you had 4 stacked pairs then in theory you can have two pairs in series, then connect these two pairs in parallel and you get the same impedence as ONE ESL57, and described by Phil. I recall my website has an impedance curve for ESL57.



I had a customer with 3 stacked pairs in parallel and who bought an 8585 amp from me and the details are all at http://www.turneraudio.com.au/8585-a...ober-2006.html



The amp was fitted with 8 x KT90 and could give 100W into 4 ohms, with good load tolerance for where the 3 x parallel ESL57 impedance falls to about 0.6 ohms at about 18kHz, where average audio level is very much lower than in the middle of the LF band where most energy is needed, say around 200Hz..



The idea of having 3 of 4 x ESL57 in series creates the problem of having enough voltage available at the amp to give sufficient drive signal.

Quad-II amps capable of about 20 Watts into 16 ohms means that 18Vrms is needed at speakers. If you had 4 in series, you need 72Vrms across the 4, and virtually no amps are made to produce such a voltage unless they are say 1,000Watt rated for PA use. One might use a speaker *step UP* matching transformer but the toridal type at zeroimpedance.com would suffer saturation at a frequency that would be too high.



If you had all 3 or all 4 ESL in parallel, then the use of toriodal *step DOWN* speaker matching tranny with 2:1 TR ratio might be used although the response at HF may suffer because leakage L of the tranny is effectively in series with the very low Z at ESL HF.



The other thing you MUST realize is that with 3 of 4 stacked pairs, the speakers begin to resemble line arrays of dyneamic drivers mounted in vertical lines. The overall efficiency increases, so the POWER needed to make a given SPL for average listening becomes less. With the right sort of wide band speaker matching tranny 2, 3, or 4 pairs of ESL57 in parallel can easily be driven with say 2 x KT88 arranged to give 50W max. With multiple stacked pairs, your need for more power is only slight, to cater for the rare even when you might want more SPL than can be achieved with Quad-II and one pair of ESL57.



The ESL57 Z varies from say 32 ohms down to 2 ohms, and they are designed for a flat response with a constant voltage level. So thus if the amp makes 4Vrms at 50Hz, 32 ohms, it means Po = 0.5Watts, and the same 4Vrms at 18kHz, 2 ohms, Po = 8 Watts. Where you had 4 pairs ESL57 in parallel the Z is 1/4 of ONE ES57, and this may well cook some amps unless they have variable impedance settings allowing nominal speaker Z = 2 ohms for between 200Hz and 1kHz.



Patrick Turner.


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"Jimmy is getting VERY ANNOYING "

Hey man! 4 pairs in parallel is no longer being 15 ohm.



** HUH ?

So you cannot divide by 4 ???

What an utter ass.


Why ****ed off,



** Cos you are IGNORING the FACTS - ****HEAD

And you THINK you understand amplifiers and load impedances

and YOU DO ****ING NOT !!!!!!!!


So be nice and civilize!!



** How about YOU PAY ATTENTION !!

STOP making WRONG ASSUMPTIONS

And STOP TOP POSTING !!!!!!!!!!!!!!!!

Now **** off to hell.

You are wasting our time with your stupid, audiophool BULL****



... Phil



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"Jimmy is VERY ANNOYING "

Pat, therefore sounds like you have a autoformer for my application, is
it?


** For ****'s SAKE - ****head !!!!!!

Forget the bloody autoformer - it will * NOT * work the way you are
assuming.

You have all your answers right now.

Use multiple tube amps with lots of NFB or a couple of SS amps like the
Quad 306.

Bad ****ing luck you do not LIKE the idea.

If you can afford to buy 8 Quad ESL57s - you can afford it.

BTW:

Only a total ****WIT would use 8 x ESL57s at once OR think an autoformer was
a good idea OR think that ****ing stupid super tweeter was worth a pinch
of ****.

**** off.



.... Phil




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That only show me you're no class!! That's it!! No brainer as well. The answer is useless and I'm seeking an autoformer from PAT so what?? I have money!! From where my business is running the unemployment rate is LOW and everyone made good money!! I made a fortune this year and able to afford whatever I like you just say!!

So?????? :-) Yes I can afford 8 ESL 57 and put a mattress on it and ML with my gf, so what??

On Monday, June 17, 2013 11:52:32 AM UTC+8, Jimmy wrote:
Dear Pat,

I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now.



They suggest wired in series for the stacking....and sent me this link:



http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5



I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency.



Some even says 300B push pull can drive it!!



Gee...are they making a joke with me??



Regards,

JL

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"Jimmy" '''

That only show me you're no class!!


** For ****'s SAKE - ****head !!!!!!

Forget the bloody autoformer - it will * NOT * work the way you are
assuming.

You have all your answers right now.

Use multiple tube amps with lots of NFB or a couple of SS amps like the
Quad 306.

Bad ****ing luck you do not LIKE the idea.

If you can afford to buy 8 Quad ESL57s - you can afford it.

BTW:

Only a total ****WIT would use 8 x ESL57s at once OR think an autoformer was
a good idea OR think that ****ing stupid super tweeter was worth a pinch
of ****.

**** off.



.... Phil





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Quote:
Originally Posted by Phil Allison[_3_] View Post
"John L Stewart"

When loudsppeakers are connected in series, each unit becomes the source
impedance for the other(s).


** Long as the speakers are near identical - this has NO effect.

The signal voltage divides equally across each speaker at all frequencies.


Not recommended at all, under any circumstance!


** ********.

The Bose 802 has eight identical 1ohm drivers in series.


Four similar in series/parallel should be OK. Connect the mid points
together as well.



** You just contradicted yourself.



.... Phil
As often occurs here Phil will debate about nothing.

As in Zero = one

Best approach for the enquiree is to get off his hands & try the various recommendations as in doing something always beats doing nothing.

That is why I recommended the fire extinguisher.

Good for the Bose & its 8R speakers. Who cares?

Cheers to all. Stop talking & do something!!
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"John L Stewort"

'Phil Allison



When loudsppeakers are connected in series, each unit becomes the

source impedance for the other(s).-

** Long as the speakers are near identical - this has NO effect.

The signal voltage divides equally across each speaker at all
frequencies.

-
Not recommended at all, under any circumstance!-



** ********.

The Bose 802 has eight identical 1ohm drivers in series.

-
Four similar in series/parallel should be OK. Connect the mid points
together as well.-



** You just contradicted yourself.


** ****HEAD !!


That is why I recommended the fire extinguisher.



** Certainly - go shove the hose up your arse and push the lever.

Might just get some of the **** out of you.



Good for the Bose & its 8R speakers. Who cares?



** What a ****ing bull****ter.

The Bose 801 uses 1ohm speakers, eight of them, all in series and all
perfectly DAMPED.

You stupid, ****ing septic ****.




..... Phil





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Phil Allison wrote:

"John L Stewort"

'Phil Allison



When loudsppeakers are connected in series, each unit becomes the
source impedance for the other(s).-

** Long as the speakers are near identical - this has NO effect.

The signal voltage divides equally across each speaker at all
frequencies.

-
Not recommended at all, under any circumstance!-


** ********.

The Bose 802 has eight identical 1ohm drivers in series.

-
Four similar in series/parallel should be OK. Connect the mid points
together as well.-


** You just contradicted yourself.


** ****HEAD !!

That is why I recommended the fire extinguisher.


** Certainly - go shove the hose up your arse and push the lever.

Might just get some of the **** out of you.

Good for the Bose & its 8R speakers. Who cares?


** What a ****ing bull****ter.

The Bose 801 uses 1ohm speakers, eight of them, all in series and all
perfectly DAMPED.

You stupid, ****ing septic ****.

.... Phil


....

Back in the day, the 800 series came abour due to
people using 901s for live vocals. The 901s had
nine speakers, 8 in the back side and one in the
front. Musicians turned them around and pointed
the 8 at the audience, but the single (now) rear-
facing driver caused problems with feedback.
Bose brought out the 800 series for live sound
reinforcement use, and they did away with the
problematic ninth driver...but since you must have
a number of drivers that has a square root in
order for the impedance of the cabinet to equal
the impedance of a single driver, they replaced
the missing driver with a 50-watt resistor to keep
the box at 8 ohms. (I seem to remember it wasn't
an 8-ohm resistor, though...11 ohms? Something
like that...) This fix turned one ninth of the applied
power into heat, making the already power-hungry
boxes even more so. Eventually the cabs evolved
into the injection-molded box variety with the 1-ohm
drivers in series; these drivers have plastic frames,
and whenever a box gets knocked over (they're usually
up on sticks) the magnets rip free of the plastic baskets,
necessitating replacement of some or all of them.
The series wiring scheme means that if any of the drivers
packs up by going open, the box will go silent - not a
good thing in a live situation, if you ask me. I realy don't
see why they didn't just go to 16-ohm drivers; two series-
parallel networks of four drivers each (at 16 ohms per network)
placed in parallel would arrive at the desired 8-ohm impedance.

Back in the day - early 70s - my band had the first Bose system
in Colorado, consisting of 8 Bose 800 boxes (four on a side)
driven by two Altec 9440A power amps - 1,600 watts, and
those boxes needed every bit of it. By the standards of the
day, it was a kickass rig. It replaced a pair of Altec A7-500
cabinets driven by a pair of Dynaco MK III amps (built from
kits and modded for higher output by yours truly) but we kept
the old rig as backup; out of doors, the Altecs provided
superior coverage, and in that case we used the Bose
rig for foldback - best monitors I've ever heard, bar none.

Lord Valve




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Quote:
Originally Posted by Phil Allison[_3_] View Post
"John L Stewort"

'Phil Allison



When loudsppeakers are connected in series, each unit becomes the

source impedance for the other(s).-

** Long as the speakers are near identical - this has NO effect.

The signal voltage divides equally across each speaker at all
frequencies.

-
Not recommended at all, under any circumstance!-



** ********.

The Bose 802 has eight identical 1ohm drivers in series.

-
Four similar in series/parallel should be OK. Connect the mid points
together as well.-



** You just contradicted yourself.


** ****HEAD !!


That is why I recommended the fire extinguisher.



** Certainly - go shove the hose up your arse and push the lever.

Might just get some of the **** out of you.



Good for the Bose & its 8R speakers. Who cares?



** What a ****ing bull****ter.

The Bose 801 uses 1ohm speakers, eight of them, all in series and all
perfectly DAMPED.

You stupid, ****ing septic ****.




..... Phil
I will defer to Phil on this one, if all speakers are identical then series connexion is OK. As I’m sure Phil & others are aware as in mathematics & some other areas this is an example of a ‘special case’ as opposed to the ‘general case’. In the general case all combinations are covered while in the special case all the speakers have to be identical. So if the speakers differ the series connexion may not give good results.

I also agree with Phil that Jimmy is dragging his feet & needs to move forward, trying the hookup while observing the many recommendations that have been given.

And thankyou both for again thoroughly reconjugating the verb ‘to copulate’ so well!

Now I gotta go & do some 'real work' with a chain saw. Hope all you amateurs have fun.

Cheers to all, John

Sent from my soft coal burning, steam driven Dell 1737
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On Sunday, June 16, 2013 8:52:32 PM UTC-7, Jimmy wrote:
Dear Pat,

I read your article about Quad ESL and tube amplifier online. I've discussion recently with my friends about stacking Quad ESL 57 and some even thinking to stack 4 x ESL 57 in a big room and I'm interested in that since I have 2 in stacking now.



They suggest wired in series for the stacking....and sent me this link:



http://forum.audiogon.com/cgi-bin/fr...openflup&5&4#5



I wonder 3 ESL 57 stacking and series wired still ok since the impedance still 30 ohm range. However, 4 in stacking, no kidding the impedance will rise to 60 ohm and maximum can go up to 120 ohm on the low frequency.



Some even says 300B push pull can drive it!!



Gee...are they making a joke with me??



Regards,

JL


I have come upon this discussion quite by accident while looking for something else and I enter it only to share some information that I sent to Jimmy by email as he contacted me several weeks ago about my RM-200.

"Using a pair of KT120's I was able to achieve 100 watts on the 1 ohm tap with a 1 ohm load at .15% distortion. At 1% distortion I was able to achieve 144 watts and under those conditions the damping factor was 10 making the output impedance 0.1 ohms. To further prove the low impedance performance of the RM200 I put a 0.5 ohm load on the 1 ohm tap with this load I achieved 100 watts at .15% distortion and 128 watts at 1% distortion. I don't think you'll find another tube amplifier that can do this!"

For those who would like to read about the RM-200 there is a recent review in Stereophile Dec 2011. http://www.stereophile.com/content/m...ower-amplifier

The RM-200 is Michael Fremer's reference tube amp which he has owned since 2000 in the MKI version and now the MKII. For those who want more power we have the more powerful RM-300 monoblocks. http://ramlabs-musicreference.com/




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musref ie JL mentioned......

I have come upon this discussion quite by accident while looking for something else and I enter it only to share some information that I sent to Jimmy by email as he contacted me several weeks ago about my RM-200.

"Using a pair of KT120's I was able to achieve 100 watts on the 1 ohm tap with a 1 ohm load at .15% distortion. At 1% distortion I was able to achieve 144 watts and under those conditions the damping factor was 10 making the output

impedance 0.1 ohms. To further prove the low impedance performance of the RM200

I put a 0.5 ohm load on the 1 ohm tap with this load I achieved 100 watts at .15% distortion and 128 watts at 1% distortion. I don't think you'll find another tube amplifier that can do this!"

For those who would like to read about the RM-200 there is a recent review in Stereophile Dec 2011. http://www.stereophile.com/content/m...ower-amplifier

The RM-200 is Michael Fremer's reference tube amp which he has owned since 2000 in the MKI version and now the MKII. For those who want more power we have the more powerful RM-300 monoblocks. http://ramlabs-musicreference.com/

My reply is :- What has this got to do with the idea of stacked Quad ESL57 for hi-fi?

The use of KT120 sure does allow for more reliable production of high power in class AB1. I found that if Ea AND Eg2 is kept at +500Vdc, even at full Po, then with anode RLa-a = 2k2, then up to 140Watts can be produced with 6550, KT88, KT90 and KT120, but the KT120 is the most reliable because the rated Pda = 60Watts, more than 42W watts for 6550/KT88.

But if the idle current is only 50mA dc in each tube then the classA1 power limit for each tube with 4k4 class A load = 0.5 x 0.05 x 0.05 x 4,400 = 5.5W,
so two tubed give 11W in class A before moving to Class Ab to make the rest of the power up to 140W from anodes, ie, +/- 392pk V swing at each anode. If power losses in OPT are 10%, expect 126Watts.

If one considers stacked Quads, then places a limit for 22 Watts for a pair, it means limiting applied amp voltage to a maximum where the LF impedance is high, or else the step up tranny could saturate or the panels might arc, so 22W into 32 ohms = 26.5Vrms.

If you have an amp with 2 x KT120, set up for 126W for 8 ohms then Vo max could be 32Vrms, and higher for 16 or 32 ohms so DON'T ever use such an amp or you may make the panels arc.

But if there is a 4ohm outlet for 126W, then Vo = 22.4Vrms, and someone could use ths to power 5 paralleled ESL57 stacked.
If there is a 2 ohm outlet, Vo = 15.87Vrms, and this is MUCH safer to use with paralleled ESL57, up to 8 paralleled ESL57 could be used.
But having 8 stacked speakers means a tower about 6.4M high. 3 stacked will give 2.4M, and may not suit rooms with standard ceiling height of 8 feet or 2,432mm above floor level. So with standard rooms 2 stacked speakers are enough, and for rooms with 9 feet / 2,736mm, 3 stacked ESL57 can be used.

I cannot see why on earth anyone would want to stack more than 3 x ESL57.
In theory, a 66 Watt amp may be needed, with 10.67 ohm load, ie, 26.Vrms.
But with 3 stacked speakers nobody would need to run right up to 66 Watts and if the amp made 66W into 8 ohms, then Vo max = 22.9Vrms = OK and the same TUBE amp would produce a marginally higher Vo where the 3 x ESL Z becomes 10.7 ohms.
Most tube amps cope well with a reduction of speakewr Z at F above 5kHz because the % of music content is so much lower at HF compared to below 1kHz. Peter Walker knew that the Quad-II "22 Watt" power amp with only 2 x KT66 and when set to suit "16 ohms" at OPT strapping would cope with 1 x ESL57 Z minimum of 1.8 ohms 18kHz, because the signal voltage for all music signals above 5kHz rarely ever exceeds the maximum of 1/4 of the maximum levels for music below 1kHz.

That's quite enough to bamboozle nearly everyone, so have fun making speakers arc and amps smoke if you don't understand.

But where 2 x KT120 can really sing well is when used for class A1. Two can safely be idled at Pda = 40Watts each, and so 80 Watts totalled. If the class A1efficiency is 40% ( allowing for OPT losses ), then expect 32 Watts of PURE Class A1. Of course one might use a quad of 6L6GC/5881/EL34/6CA7 and achieve the same thing with same Ea, and total Pda, same RLa-a or same RLa if the 4 tubes are paralleled for SE power. Methinks 4 x 6L6GC etc would be cheaper and probably better ( for a number of undisclosed reasons ) than 2 x KT120.

Patrick Turner.


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"patrick-turner"

My reply is :- What has this got to do with the idea of stacked Quad ESL57
for hi-fi?


** It's the mad ohms load thing again !!!!!!

No amplifier Quad ever made would "drive" a 1ohm load - or a 2 ohm for
that matter.

But it does not matter.


Joke:
------

Famous US golfer Lee Trevino liked to tell this yarn:

One day a two golfers were out on the fairway when a fierce storm suddenly
sprung up with thunder and lightning - as they ran scurrying for the club
house, one of them held his number one iron high up in the air.

The other, thinking his partner had gone mad and was inviting sudden death
asked what the hell he was doing that for ?

His reply was:

" I doing it because not even God can hit a one iron."



..... Phil














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I said..... My reply is :- What has this got to do with the idea of stacked Quad ESL57
for hi-fi?


Mr Allison replied with ....

** It's the mad ohms load thing again !!!!!!

No amplifier Quad ever made would "drive" a 1ohm load - or a 2 ohm for
that matter.

But it does not matter.

Yes, but many people gat all mixed up and cornfeused because they lack any skills to think about grey. Black is fine, so is white, but grey? No way.
They need to be spoon fed with care. Quad ESL57 do present an amp with Z 2 ohms at HF, but then Z 32 ohms at LF, and Z "average" is between say 32 and 2 ohns and dependant on frequency, In fact, the load value average between 1 mili sec and the next changes depending on the hundreds of harmonics in the music and how they combine to cause a much varying load between one small time period and the next.

If one uses a 1 ohm series R between speaker and an amp with Rout = 0.01 ohm, then the source resistance driving the speaker = 1 ohm.

This is about the same as for Quad-II. If the amp is set for 2Vrms into ESL57,
then power at LF where Z = 32 ohms = 0.125 Watts. At 18kHz, the Z = 2 ohms approx, and Vo has become 1.33Vrms and Po = 0.88 Watts. The Quad-II works OK.
But what does this tell anyone about power and speaker sensitivity?
In the above sampe case, perhaps it takes 0.125W to produce LF SPL = 70dB, ( just guessing ). The same SPL at 18kHz requires 0.88W, ie, 7.1 times the LF power. Luckily, the amount of HF power needed for most music between say 7kHz and 20kHz is far less than for LF, so for those puzzled by what doesn't matter, maybe there's the answer. Many ppl just don't get it though, and never ever will.

Speakers with low Z at LF present a much worse problem for amps than ESL57, which are in fact "easy to drive". Maybe old AR9 were real horrors. They had a pair of 3.4 ohm 11" bass woofers in parallel. These had world's lowest sensitivity and required high power to gety good bass, and very low amp Rout becaise at 120Hz they were less than 2 ohms. I found connection of woofers in series and with totally revised X-over, you could get Z to be less likely to fry amplifiers.

Patrick Turner.
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"patrick-turner"

Mr Allison replied with ....

** It's the mad ohms load thing again !!!!!!

No amplifier Quad ever made would "drive" a 1ohm load - or a 2 ohm for
that matter.

But it does not matter.

** Because any tube amplifier ( and most SS ones) will deliver full current
into a 2ohm load - and that is more than is ever needed at 18kHz when
listening to music. **



Speakers with low Z at LF present a much worse problem for amps than ESL57,
which are in fact "easy to drive". Maybe old AR9 were real horrors. They had
a pair of 3.4 ohm 11" bass woofers in parallel. These had world's lowest
sensitivity and required high power to gety good bass, and very low amp Rout
because at 120Hz they were less than 2 ohms.

** Here is a schem of the AR9 x-over network:

http://www.classicspeakerpages.net/l...schematic.html

The unlabelled inductor in series with the two woofers is 2.9mH.

Looks like AR have gone to a lot of trouble to prevent the low Z problem Pat
alludes to.


..... Phil



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Phil quotes me then replies.....

Speakers with low Z at LF present a much worse problem for amps than ESL57,
which are in fact "easy to drive". Maybe old AR9 were real horrors. They had
a pair of 3.4 ohm 11" bass woofers in parallel. These had world's lowest
sensitivity and required high power to gety good bass, and very low amp Rout

because at 120Hz they were less than 2 ohms.

** Here is a schem of the AR9 x-over network:

http://www.classicspeakerpages.net/l...schematic.html

The unlabelled inductor in series with the two woofers is 2.9mH.

Looks like AR have gone to a lot of trouble to prevent the low Z problem Pat
alludes to.

The schematic you found seems different to what I found in AR9, which I think were 1975 models with 11" woofers, not 12". The AR9 I worked on had adjustable levels for mid-treble units. You have not pointed me to an impedance curve which would validate your assertion that i don't know what I'm talking about. Try harder if you wish to succeed, but the AR9 I worked on were very poor speakers IMHO. I found wrongly labelled capacitors supposed to be 100uF but which were 50uF, and I could not see why on earth anyone would have spent $4,500 they claimed they spent in 1975.

At the bottom of the schematic, we have...
""If God wanted us to go to concerts, He would have given us tickets. AR circa 1980. ""

God sure doesn't mind us going to concerts, and he gave us the means to earn the money for tickets. And that's a hell of a lot cheaper than buying crap from AR.
Patrick Turner.


..... Phil



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I correct a mistake I made in my last previous post about adjustable levels of mids and treble in my last post. The schematic Phil sent us to view DOES HAVE variable level adjustements for mid- treble units. Perhaps the mid-treble parts of schematic do have differences to what i found - some 7? years back, but the owner recently emailed me to say how pleased he was about the sound after I totally rebuilt the speakers using two lower midrange drivers supplied from AR and two Peerless upper mids I supplied. I cannot recall if I replaced the tweeters.

But the bass speaker part of schematic is different to what I found, and because all 4 bass drivers worked OK I retained them, but used them in series..

I well remember how difficult it was to get all drivers to work properly with a total of 6 slightly over damped second order filters and give a flat response at 3 metres, and have an acceptable impedance curve. The trade off was that the overall sensitivity of the bass speakers was determined by the bass acoustic levels at 50-80Hz with all mids&treble set for center switch position.

I concluded that a 4 way speaker is never needed because it can be done better and more easily with 3 way, from 20Hz to 20kHz, and a sub-woofer isn't needed because you pick a decent bass that goes as low as subs do, and then have their cut off at around 250Hz. The mid-treble X-over is then placed at 3kHz, and each driver thus does a decade of frequencies.
Patrick Turner.

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"Phil Allison"


** The AR9 was first sold in 1978 and used two 12 inch woofers, same ones
used in the AR11 released in 1977.


** AR constantly refer to the above woofers as being 12 inch.

But they are closer to 11 inch, in reality.

I remember now there was something odd about the woofers in a friend's
AR11s.

The impedance curve of the AR11 was so wild I drew it out and kept a copy -
here is a listing:

DC = 4.2 ohms
10Hz = 5 ohms
32Hz = 30 ohms
100Hz = 4 ohms
500Hz = 10 ohms
1kHz = 4 ohms
2kHz = 2.5 ohms
5kHz = 2 ohms
10kHz = 2 ohms
12kHz = 2 ohms
20kHz = 3 ohms
50kHz = 8 ohms

BTW:

The low figures above 2kHz are because the 4ohm dome mid and 4ohm dome
tweeter are operating in parallel.

The owner was originally using twin wire he got from Tandy / Radio Shack (
14x0.14 stuff ) - so each run was about 1.5 ohms resistance, plus about 2.5
ohms of inductance at 15kHz.

So I made him up some leads using "Tocord" ( aka Mogami cable) with near
zero inductance and about 0.2 ohms resistance.

His mouth dropped open when he heard the difference.



.... Phil




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Phil mentioned....

** The AR9 was first sold in 1978 and used two 12 inch woofers, same ones
used in the AR11 released in 1977.

** AR constantly refer to the above woofers as being 12 inch.
But they are closer to 11 inch, in reality.
I remember now there was something odd about the woofers in a friend's
AR11s.
The impedance curve of the AR11 was so wild I drew it out and kept a copy -
here is a listing:

DC = 4.2 ohms
10Hz = 5 ohms
32Hz = 30 ohms
100Hz = 4 ohms
500Hz = 10 ohms
1kHz = 4 ohms
2kHz = 2.5 ohms
5kHz = 2 ohms
10kHz = 2 ohms
12kHz = 2 ohms
20kHz = 3 ohms
50kHz = 8 ohms

BTW:
The low figures above 2kHz are because the 4ohm dome mid and 4ohm dome
tweeter are operating in parallel.
The owner was originally using twin wire he got from Tandy / Radio Shack (
14x0.14 stuff ) - so each run was about 1.5 ohms resistance, plus about 2.5
ohms of inductance at 15kHz.
So I made him up some leads using "Tocord" ( aka Mogami cable) with near
zero inductance and about 0.2 ohms resistance.
His mouth dropped open when he heard the difference.
... Phil

Before completely re-forming the pair of AR9 I was given to fix, I did manage to get one working as it may have worked when new by swapping out working mid/HF drivers so that enough working drivers were in the same box. I found the acoustic response response using the middle position of mid-HF level switches was anything but flat and extremely poor by my standards. I don't recall any HF dips to 2 ohms as you state exists above 2kHz, but I do recall the 3.6 ohm woofers were connected in parallel and had a second order filter so that the current through L&C plus current speakers summed to Z 2 ohms, and potential amp killers.

I didn't like the switches, or the wire wrap type of connections typical of cheap junk. I figured prevention of future problems was needed, and they could be made to have a minimum Z of just over 4 ohms, and thus be drivable by the customers 200W ARC monoblocs. So the bass speakers were connected in series to raise Z, and a damped second order LC filter used with a bar cored L to avoid Rw losses in the L. Bass speakers were atrociously insensitive, and the acoustic levels above 150Hz had to be all tailored to be flat, and equal to the level of bass at 80Hz, so this allowed resistance networks to drive the mid/treble units. The owner had given me a pair of supposed replacement lower midrange drivers from AR, and I thought they looked badly made, like a cheap Chinese POS, and these were remarkably sensitive. Considerable series R was used. The new X-over networks were mounted on new boards with all soldered joints and losses in speaker cables due to their resistance or inductance ceased to be a problem - any cable could be used OK, as long at it was at least dual core mains flex rated for 5Amps, and say 3M long, max. I've also made speaker cables using two cat5 blue covered cables to form a twisted pair and the 8 conductors in each cable are all soldered to a banana plug on each end. I made 3 pairs, each 6M long to get from a power amp to 3 stacked pairs of ESL57, each had been fully re-membraned by John Hall in Melbourne. I didn't bother measuring those cables, but I thought they'd be fine, and sound OK.

I've got all the info on what I did to those AR9 speakers buried in a pile of papers a foot high which I doubt I'll ever get around to publishing. IMHO, it is very easy to make a better pair of speakers than the AR9.
Patrick Turner.
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"patrick-turner"
Phil mentioned...

** The AR9 was first sold in 1978 and used two 12 inch woofers, same ones
used in the AR11 released in 1977.

** AR constantly refer to the above woofers as being 12 inch.
But they are closer to 11 inch, in reality.
I remember now there was something odd about the woofers in a friend's
AR11s.
The impedance curve of the AR11 was so wild I drew it out and kept a copy -
here is a listing:

DC = 4.2 ohms
10Hz = 5 ohms
32Hz = 30 ohms
100Hz = 4 ohms
500Hz = 10 ohms
1kHz = 4 ohms
2kHz = 2.5 ohms
5kHz = 2 ohms
10kHz = 2 ohms
12kHz = 2 ohms
20kHz = 3 ohms
50kHz = 8 ohms

BTW:
The low figures above 2kHz are because the 4ohm dome mid and 4ohm dome
tweeter are operating in parallel.
The owner was originally using twin wire he got from Tandy / Radio Shack (
14x0.14 stuff ) - so each run was about 1.5 ohms resistance, plus about 2.5
ohms of inductance at 15kHz.
So I made him up some leads using "Tocord" ( aka Mogami cable) with near
zero inductance and about 0.2 ohms resistance.
His mouth dropped open when he heard the difference.
... Phil

Before completely re-forming the pair of AR9 I was given to fix, I did
manage to get one working as it may have worked when new by swapping out
working mid/HF drivers so that enough working drivers were in the same box.
I found the acoustic response response using the middle position of mid-HF
level switches was anything but flat and extremely poor by my standards. I
don't recall any HF dips to 2 ohms as you state exists above 2kHz,


** Please, read my post more carefully - it's the *AR1 * that has absurdly
low impedance above 2 kHz.

IMHO, it is very easy to make a better pair of speakers than the AR9.



** The various AR speakers I have seen and tested were riddled with unholy
compromises and evil Yankee dodges - plus built as cheaply as possible.

Their Aussie built models were even worse, with plastic veneer - yuck.

But still better than Bose by a mile.



.... Phil



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"patrick-turner"
Phil mentioned...

- show quoted text -

** The AR9 was first sold in 1978 and used two 12 inch woofers, same ones
used in the AR11 released in 1977.

** AR constantly refer to the above woofers as being 12 inch.
But they are closer to 11 inch, in reality.
I remember now there was something odd about the woofers in a friend's
AR11s.
The impedance curve of the AR11 was so wild I drew it out and kept a copy -
here is a listing:

DC = 4.2 ohms
10Hz = 5 ohms
32Hz = 30 ohms
100Hz = 4 ohms
500Hz = 10 ohms
1kHz = 4 ohms
2kHz = 2.5 ohms
5kHz = 2 ohms
10kHz = 2 ohms
12kHz = 2 ohms
20kHz = 3 ohms
50kHz = 8 ohms

BTW:
The low figures above 2kHz are because the 4ohm dome mid and 4ohm dome
tweeter are operating in parallel.
The owner was originally using twin wire he got from Tandy / Radio Shack (
14x0.14 stuff ) - so each run was about 1.5 ohms resistance, plus about 2.5
ohms of inductance at 15kHz.
So I made him up some leads using "Tocord" ( aka Mogami cable) with near
zero inductance and about 0.2 ohms resistance.
His mouth dropped open when he heard the difference.
... Phil

Before completely re-forming the pair of AR9 I was given to fix, I did
manage to get one working as it may have worked when new by swapping out
working mid/HF drivers so that enough working drivers were in the same box.
I found the acoustic response response using the middle position of mid-HF
level switches was anything but flat and extremely poor by my standards. I
don't recall any HF dips to 2 ohms as you state exists above 2kHz,



** Please, read my post more carefully - it's the *AR1 * that has absurdly
low impedance above 2 kHz.

But your post said AR11, see above, re-quoted.


IMHO, it is very easy to make a better pair of speakers than the AR9.




** The various AR speakers I have seen and tested were riddled with unholy
compromises and evil Yankee dodges - plus built as cheaply as possible.

Their Aussie built models were even worse, with plastic veneer - yuck.

But still better than Bose by a mile.

I'd certainly agree with you on that.

Ah, the un-glorious 1970s, full of Krapp from all directions. Hardly anyone knew what hi-fi was about, and hardly anyone attended concerts with unamplified music to calibrate their ears. Mostly ppl experienced music when boozed up, smoking and talking with ppl mostly liking highly processed pop music.

I cringe when I listen to some old records I have.

But now I much prefer the Brandenburg Orchestra. I think my mind grew to become bored with the peurile efforts of dysfunctional pop stars full of cocaine, and it now demands each bar of music be different to the others, and to be the product of cleverness, not stupidity.

See http://brandenburg.com.au/site/2013-sydney-season/

Patrick Turner.



.... Phil



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