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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.
..
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,

** Yeah - NOT the AR bloody 9 !!!!!!!!!!!!!!!

( AR1 is an obvious typo)


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.


** OTOH I was enjoying digitally recorded Bartok piano via half speed
mastered LPs from Denon, as early as 1976, played through my Quad ESL57s.

For low processed pop - early Beatles or some live recordings of Jimi
Hendrix were excellent.

Jazz recordings were always pretty natural sounding too.



.... Phil






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On Monday, June 17, 2013 4:52:32 AM UTC+1, 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


Jimmy, that's an interesting idea you have, but it's interesting in the sense of all wrong. First of all, you strike me as an innocent wandering down a rough street with your wallet in one hand and your dick in the other. Normally, in audio this would not matter if you have plenty of money. But in the case of Quad ESL you're intending to dabble dangerously in irreplaceable antiques in very limited supply. This is not a sensitive thing to do.

Secondly, you just don't have the knowledge necessary to do the job right. What you need, if you insist on running with the Joneses, your even more ignorant pals, is to find some local expert who knows what he's doing (those will give a guarantee, and pay to fix what they break) to make and maintain the installation for. I've had ESL, and mine were in no danger, but keeping yours running in this stacking scheme of yours will be about as expensive as maintaining a 68ft yacht, which I found akin to standing under a cold shower tearing up large denomination bills.

Turning from the generalities to the specifics, the QUAD ESL is specifically a speaker for delivering the classics at realistic volumes. One ESL is enough to fill a 270 sq ft room at normal orchestral volume; two just provides stereo and a fractional improvement in sound quality that is far, far below even the threshhold of perception of someone as cultured as me. To use an ESL for some unintended purpose which requires multiple ESL, say playing rock'n'roll very loudly, is barbaric.

In a much larger room, a stack of two ESL per side may be justified, especially if the ceiling is so high that the stacked ESL may be raised about head height and then angled onto the listening chair. But why should you want such a large listening room? ESL give their best to one or two listeners at a time, not crowds. ESL are not showpiece loudspeakers; they're speakers for people who have nothing left to prove.

A stack of four ESL, even abstracting from the horrendous drive problems you've been adequately informed about by the resident experts, will tend to sound much like an array. If you really need (because your listening room is huge) or want an array, there are many vastly cheaper and more efficient and less space-consuming ways of building an array than using ESL. See my article on Bessel Arrays at http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm

So what it comes down to is that if you're not listening to classical music or solo voices or the like, ESL are best left to those who can use them better, and the only time you can use more than two stacked ESL per side is if your listening room is ostentatiously huge.

Now, about driving ESL. The best and least troublesome ESL drivers are the current-dumping QUAD amps. If you insist on tubes, the choice way to spend your money is on sourcing and rebuilding genuine QUAD II and, failing that, get the copies manufactured by QUAD in recent years, which aren't as good but close enough for your purposes.

Yes, you can make a SET amp do the business with ESL, including with stacked ESL, and yes, you can do it with 300Bs. But you really need to know what you're doing, and you can't go buying commercial amps, you're talking about custom amps. Go to http://www.audio-talk.co.uk/fiultra/...0ON%20AMPS.htm and scroll down to T39-KISS-300B-Ultrafi -- this is a ZNFB WE 300B amp run so high and hot to flatten the response curve that the output is only 3.8W. (It's actually the booster or power pre-amp of my 80W ZNFB SET tube amp, but that one is so dangerous, I'm not sharing the plan any more.) Now imagine stacking up five or six of these extremely wasteful 300B amps per side to drive you ESL. Utter madness just about covers it. And the heat all these tubes will give off will be a bitch to handle, probably requiring a locked, air-conditioned room all to themselves.

If you give up the ZNFB idea, you can still have SET and tubes, but it will be pricey because, if you want low NFB, you have to sacrifice power, and very likely you'll be sacrificing tube longevity too. Whichever way you turn, you're looking at serious maintenance issues.

The ESL gets its special sound from three features: that it is a point-source speaker, that it has a large area, and that operates high and hot for a flat transfer curve. There are horn drivers that make an excellent point source if suitably cased. As I write this, I'm listening to a horn of my own devising that started out something like a Lowther Fidelio bicor (this is the KISS 194 T91HWAF3 on the same page on which you've already found the 300B amp I'm using to drive it -- http://www.audio-talk.co.uk/fiultra/...20T91HWAF3.jpg will take you directly to photo of the innards under construction). It makes a good fist of the ESL sound, with a deeper bass. Larger horns, like the Westminster, can fill very large rooms and go much lower.. If you have space for a larger speaker and you want to make a cheap experiment to grasp how much (or little) a point source speaker can sound like an ESL, but louder, you can do it with some wood and a carefully selected but cheap guitar driver. See The Impresario on http://www.audio-talk.co.uk/fiultra/...0ON%20AMPS.htm

In summary then:

If you need multi-stacked ESL, you are misusing the ESL, and you need different speakers.

You can drive single or stacked ESL with ZNFB SET amps if you can deal with the heat and don't mind keeping your amplifier technician in luxury for the rest of his life. It's smarter to use QUAD current dumping silicon amps, and better to use QUAD II tube amps. Other tube amps that will sound right on ESL will need to be custom built, and require that you first educate yourself because otherwise how will you order them built?

Sorry if this sounds like tough love, but you're walking in a minefield and you're speaking to the survivors who've come out the other side -- and we can't help shuddering at your naiveté.

Good luck.

Andre Jute
http://coolmainpress.com/ajwriting/
http://www.audio-talk.co.uk/fiultra/...0ON%20AMPS.htm
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"Andre Jute"
Jimmy wrote:
Dear Pat,


( ship whole pile of silly nonsense)


Jimmy, that's an interesting idea you have, but it's interesting in the
sense of all wrong. First of all, you strike me as an innocent wandering
down a rough street with your wallet in one hand and your dick in the other.
Normally, in audio this would not matter if you have plenty of money. But in
the case of Quad ESL you're intending to dabble dangerously in irreplaceable
antiques in very limited supply. This is not a sensitive thing to do.

Secondly, you just don't have the knowledge necessary to do the job right.
What you need, if you insist on running with the Joneses, your even more
ignorant pals, is to find some local expert who knows what he's doing (those
will give a guarantee, and pay to fix what they break) to make and maintain
the installation for. I've had ESL, and mine were in no danger, but keeping
yours running in this stacking scheme of yours will be about as expensive as
maintaining a 68ft yacht, which I found akin to standing under a cold shower
tearing up large denomination bills.

Turning from the generalities to the specifics, the QUAD ESL is specifically
a speaker for delivering the classics at realistic volumes. One ESL is
enough to fill a 270 sq ft room at normal orchestral volume; two just
provides stereo and a fractional improvement in sound quality that is far,
far below even the threshhold of perception of someone as cultured as me. To
use an ESL for some unintended purpose which requires multiple ESL, say
playing rock'n'roll very loudly, is barbaric.

In a much larger room, a stack of two ESL per side may be justified,
especially if the ceiling is so high that the stacked ESL may be raised
about head height and then angled onto the listening chair. But why should
you want such a large listening room? ESL give their best to one or two
listeners at a time, not crowds. ESL are not showpiece loudspeakers; they're
speakers for people who have nothing left to prove.

A stack of four ESL, even abstracting from the horrendous drive problems
you've been adequately informed about by the resident experts, will tend to
sound much like an array. If you really need (because your listening room is
huge) or want an array, there are many vastly cheaper and more efficient and
less space-consuming ways of building an array than using ESL. See my
article on Bessel Arrays at
http://www.audio-talk.co.uk/fiultra/...n%20BESSEL.htm

So what it comes down to is that if you're not listening to classical music
or solo voices or the like, ESL are best left to those who can use them
better, and the only time you can use more than two stacked ESL per side is
if your listening room is ostentatiously huge.

Now, about driving ESL. The best and least troublesome ESL drivers are the
current-dumping QUAD amps. If you insist on tubes, the choice way to spend
your money is on sourcing and rebuilding genuine QUAD II and, failing that,
get the copies manufactured by QUAD in recent years, which aren't as good
but close enough for your purposes.

Yes, you can make a SET amp do the business with ESL, including with stacked
ESL, and yes, you can do it with 300Bs. But you really need to know what
you're doing, and you can't go buying commercial amps, you're talking about
custom amps. Go to http://www.audio-talk.co.uk/fiultra/...0ON%20AMPS.htm
and scroll down to T39-KISS-300B-Ultrafi -- this is a ZNFB WE 300B amp run
so high and hot to flatten the response curve that the output is only 3.8W.
(It's actually the booster or power pre-amp of my 80W ZNFB SET tube amp, but
that one is so dangerous, I'm not sharing the plan any more.) Now imagine
stacking up five or six of these extremely wasteful 300B amps per side to
drive you ESL. Utter madness just about covers it. And the heat all these
tubes will give off will be a bitch to handle, probably requiring a locked,
air-conditioned room all to themselves.

If you give up the ZNFB idea, you can still have SET and tubes, but it will
be pricey because, if you want low NFB, you have to sacrifice power, and
very likely you'll be sacrificing tube longevity too. Whichever way you
turn, you're looking at serious maintenance issues.

In summary then:

If you need multi-stacked ESL, you are misusing the ESL, and you need
different speakers.

You can drive single or stacked ESL with ZNFB SET amps if you can deal with
the heat and don't mind keeping your amplifier technician in luxury for the
rest of his life. It's smarter to use QUAD current dumping silicon amps, and
better to use QUAD II tube amps. Other tube amps that will sound right on
ESL will need to be custom built, and require that you first educate
yourself because otherwise how will you order them built?

Sorry if this sounds like tough love, but you're walking in a minefield and
you're speaking to the survivors who've come out the other side -- and we
can't help shuddering at your naiveté.

Good luck.

** ROTFL !!

Nice one - Andre.

BTW it is perfectly possible to enjoy rock / pop music with one pair of
ESL57s or ESL63s.

Back in the day, my favourite LPs were by people like Jimi Hendrix, Janis
Joplin, Rory Gallagher, Jeff Beck, Fleetwod Mack and Linda Ronstadt.

Lack of dBs was never an issue.


.... Phil





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On Thursday, July 11, 2013 5:16:25 AM UTC+1, Phil Allison wrote:

BTW it is perfectly possible to enjoy rock / pop music with one pair of

ESL57s or ESL63s.

Back in the day, my favourite LPs were by people like Jimi Hendrix, Janis

Joplin, Rory Gallagher, Jeff Beck, Fleetwod Mack and Linda Ronstadt.

Lack of dBs was never an issue.

... Phil


It's great to see you're still in fine fettle, Phil. -- Andre
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Andre spake to us all with .......


rOn Thursday, July 11, 2013 5:16:25 AM UTC+1, Phil Allison wrote:

BTW it is perfectly possible to enjoy rock / pop music with one pair of

ESL57s or ESL63s.

Back in the day, my favourite LPs were by people like Jimi Hendrix, Janis

Joplin, Rory Gallagher, Jeff Beck, Fleetwod Mack and Linda Ronstadt.

Lack of dBs was never an issue.

... Phil


It's great to see you're still in fine fettle, Phil. -- Andre


Interesting prose from Andre as usual.

But I had a customer with 3 stacked pairs of ESL57 and I sold him an 8585 tube amp to drive them. I'd worked for this fellow for over 10 years to restore his amps. The guy liked a wide variety of music including classical, pop, jazz - whatever. Room wasn't all that large. Anyone could say he "had an unecessary excess of audio gear" but that's just what the man liked, and he had the dough to pay for it, and to maintain it all. Pancreatic cancer claimed his life last year though, and his 4 sons have his gear now. Rather than be predjudiced about Jimmy's capabilities to set up a system with stacked Quads, I tried to point out the technical issues involved. Most often, when I take the time to do this, many if not most readers are quite unable to understand much I have said.

I once was very interested in yachts at age 33, post divorce, and I built a couple of models to explore in detail what I might build on land for launching by say age 40. Not 68 feet. I figured about 50 feet would be fine, but then I realised the bit about tearing up $100 bills abd throwing them overboard, and having to fund the running of the yacht by trafficking drugs or some other nafariousness. Nah, I chickened out, and I kept my house, and I woke up that yacting is mainly for poseurs, and that a bicycle would offer me all the opportunity to get away from the maddening crowd, in addition to living in a ruined sheep paddock, where Canberra is located.

In 1970s, to be social, I was a bit taken in by some of the pop, but I think I failed to really connect mentally with it because the "stars" such as Fleetwood Mac were so drug riddled and such "false people", and their songs spewed forth BS ideas. I considered most pop stars to be ****wits who were useless at doing anything constructive, and just because they gesticulated and screamed around a stage making noise like tomcat with cracker up arse didn't make them appeal to me at all. The syrapy BS of the Beatles was "girly music".
Mick screamed he couldn't get any satisfaction. What the **** was wrong with the little short git?
Anyway, I spent most of my 20s with folk because people sang about stuff that actually mattered sometimes. I quite liked Rye Cooder, and Taj Mahal.
Now, having heard all that stuff more than once, I prefer music without words I am meant to understand so some but not all opera seems OK, but some pure instrumental classical has far more appeal. Of course some classical is just written to antagonise the piano player's abilities, and to assault the listener. I find Bruckner and Mahler a bit over the top. My radio picks up more than one station and has on/off switch, and at times there's nothing on anywhere that I like so I turn off. The radio saves me from collecting music, and the costs of buying stuff I'd later get bored with.

I visited a local arts center here today, there was a folk trio there, trinket and clothing sold off tables and harmless old hippies, harmless young ppl, good food, and better than inside a shopping mall with musak.
Patrick Turner.


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On Saturday, July 13, 2013 6:51:14 AM UTC+1, patrick-turner wrote:

But I had a customer with 3 stacked pairs of ESL57 and I sold him an 8585 tube amp to drive them.


Three pairs stacked two, two and two, or two pairs stacked three and three?

Andre Jute
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"Andre Jute"
patrick-turner wrote:

But I had a customer with 3 stacked pairs of ESL57 and I sold him an 8585
tube amp to drive them.


Three pairs stacked two, two and two, or two pairs stacked three and
three?


** Suspect a third option:

The alleged customer had three pairs of ESL57s ( ie 6 speakers) - stacked
in vertical arrays of three per side.

Which ever way, it's tantamount to madness.



..... Phil


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Andre asked me a question......

Andre Jute Jul 13 (18 hours ago)

Other recipients:
On Saturday, July 13, 2013 6:51:14 AM UTC+1, patrick-turner wrote:
But I had a customer with 3 stacked pairs of ESL57 and I sold him an 8585 tube amp to drive them.

Three pairs stacked two, two and two, or two pairs stacked three and three?
Andre Jute

Allow me to explain exactly. The customer had a total of six (6) ESL57 speakers.

For each L and R channel, three were placed vertically on top of each other to make a virtual single panel with height = 3 x height of one speaker, and aligned on the one vertical axis. The guy had timber stands made to do this very easily. The two channels meant two stands maybe 3M apart. He sent me a picture of his system.

One could say that he had a virtual line array of drivers for each channel. Because of the height of the stacked speakers, and most probable large differences in speaker to ear path length then there must have been serious
variations in level for MF and HF due to phase of signals arriving at the ear.

This raises a question about the "rightness" of line arrays regardless of the drivers used, because of timing issues. But where I have been at outside public concerts with line array public address, the music has always been far better to listen to than where old fashioned bins were piled up around the stage and played loud to deafen front rowers, but yet be devoid of HF content, presumably for acoustic FB to mic problems. So, one can reproduce music with amps and speakers and commit huge engineering sins and have ppl find they like it.
Being an old phart, I avoid "gigs" with loud amplified sound - like the plague.

For hi-fi, line arrays and stacked ESLs present special problems, IMHO. The best ESL I heard belonged to a guy Chris Feliefe, a gentleman of Roseville in Sydney, and he built his own ESL after many years of research. He was able to make a very fine sounding system with only 16 Watt SET amps using well designed OPTs and 6C33c tubes. Music was natural, fresh, lively, balanced and warm. Panels were not huge. I could have listened forever. Once I heard Martin Logans, 1.2M high, with subs, and I thought they gave superb sound, even with an SS amp. But two other Quad ESL systems I found to be kind of harsh, and so I've found it impossible to agree Quads are the best. But whatever I think about sound of ESL doesn't matter, I am just a retired amp worker, but I suggest all readers keep an open mind, and be prepared to try things based on applied science rather than applied snake oil.
Patrick Turner.
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On Sunday, July 14, 2013 10:49:07 AM UTC+1, patrick-turner wrote:
Andre asked me a question......



Andre Jute Jul 13 (18 hours ago)



Other recipients:

On Saturday, July 13, 2013 6:51:14 AM UTC+1, patrick-turner wrote:

But I had a customer with 3 stacked pairs of ESL57 and I sold him an 8585 tube amp to drive them.


Three pairs stacked two, two and two, or two pairs stacked three and three?

Andre Jute



Allow me to explain exactly. The customer had a total of six (6) ESL57 speakers.



For each L and R channel, three were placed vertically on top of each other to make a virtual single panel with height = 3 x height of one speaker, and aligned on the one vertical axis. The guy had timber stands made to do this very easily. The two channels meant two stands maybe 3M apart. He sent me a picture of his system.



One could say that he had a virtual line array of drivers for each channel. Because of the height of the stacked speakers, and most probable large differences in speaker to ear path length then there must have been serious

variations in level for MF and HF due to phase of signals arriving at the ear.



This raises a question about the "rightness" of line arrays regardless of the drivers used, because of timing issues. But where I have been at outside public concerts with line array public address, the music has always been far better to listen to than where old fashioned bins were piled up around the stage and played loud to deafen front rowers, but yet be devoid of HF content, presumably for acoustic FB to mic problems. So, one can reproduce music with amps and speakers and commit huge engineering sins and have ppl find they like it.

Being an old phart, I avoid "gigs" with loud amplified sound - like the plague.



For hi-fi, line arrays and stacked ESLs present special problems, IMHO. The best ESL I heard belonged to a guy Chris Feliefe, a gentleman of Roseville in Sydney, and he built his own ESL after many years of research. He was able to make a very fine sounding system with only 16 Watt SET amps using well designed OPTs and 6C33c tubes. Music was natural, fresh, lively, balanced and warm. Panels were not huge. I could have listened forever. Once I heard Martin Logans, 1.2M high, with subs, and I thought they gave superb sound, even with an SS amp. But two other Quad ESL systems I found to be kind of harsh, and so I've found it impossible to agree Quads are the best. But whatever I think about sound of ESL doesn't matter, I am just a retired amp worker, but I suggest all readers keep an open mind, and be prepared to try things based on applied science rather than applied snake oil.

Patrick Turner.


Arrays are okay in their place -- outdoors, as you say -- but I have my doubts about the efficacy of large-unit or large-number indoor arrays. Seems a waste of ESL, to put it mildly.

Andre Jute
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Andre said....
Arrays are okay in their place -- outdoors, as you say -- but I have my doubts about the efficacy of large-unit or large-number indoor arrays. Seems a waste of ESL, to put it mildly.
Andre Jute

The owner of the 3 stacked ESL pairs had them all re-membraned by John Hall in Melbourne. Must have cost about $12,000++. I agree its a bit over the top. But old ESL57 are continiually turning up in deceased estates as old owners drop off their perches, or their sons don't want them, and surely most women don't like them. So, there's a constant stream of ESL57 becoming available for those who want them, a small number of ppl I would suggest, and for the well healed, it matters not if they have stuffed membranes because they can be fully restored and made to go for another 50 years.
I see all sorts of ppl spend all sorts of sums on stuff I'd never want. Sure I'd like a mint 1935 Bugatti, but I would not own it, it would own me, and gees, the fuel bill would be horrendous, and probably, I'd not do any better pulling chicks than i do with a bicycle.
Patrick T.


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Hi Pat!
My friend just show me this amplifier recently and this is capable 64 ohm.

http://mcc.berners.ch/power-amplifiers/MC3500.pdf

Is that ok as I come across an used pair with reasonable price?

Regards,
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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Also it's able to deliver 150v at 64 ohm.

JC

On Friday, May 16, 2014 8:20:16 AM UTC+8, wrote:
Hi Pat!

My friend just show me this amplifier recently and this is capable 64 ohm..



http://mcc.berners.ch/power-amplifiers/MC3500.pdf



Is that ok as I come across an used pair with reasonable price?



Regards,

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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Hi Pat!
My friend just show me this amplifier recently and this is capable 64 ohm.

http://mcc.berners.ch/power-amplifiers/MC3500.pdf

Is that ok as I come across an used pair with reasonable price?

I cannot test the amps here and give a health check in writing. That is the work of a serious professional. These amps seem to have much higher power capability than anyone I know would ever need, so I wonder WTF you wish to buy them.
If there is anything wrong, it could be expensive to fix them. The McIntosh were world leaders in OPT construction methods and the MC3500 are able to drive the rated output power into a large number of loads between 1r0 and 64r. Providing you have the correct number of load ohms connected to the outlet labelled for those ohms, or near to that load outlet, all will be well. A 64 ohm speaker can be used on any outlet labelled with lower ohm load, but you MUST NOT use a lower speaker load on the outlet labeled higher. For example, DO NOT use 8 ohms connected to a 64 ohm outlet.

I am not aware if the 3500 has multiple outlets which are taps off the OPT secondary windings or if the secondaries are in fact multiple windings which are strapped to suit many different speaker ohm values.

READ the MC3500 MANUAL. If you get smoke, don't blame me!
Patrick Turner.

Regards,
J

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To Jimmy.
I had a look at the MC3500 schematic. What a beast. It has 8 x 6LQ6 output tubes and complex input driver stages.
But the schema say there's a switch to select any load from 1 to 64 ohms.

So perhaps there's no winding strappings to solder.

6LQ6 is a TV line output pentode, and what I call a KWEER TUBE. Pda is 30W though. AFAIK, the 6LQ6 is no longer made and was noval based tube, like 7868 and a few others, so changing it all to suit 6L6GC or EL34, KT66, KT88 etc, etc, is a huge royal PIA, and then that's ruining American Heritage.
Patrick Turner.
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