[Phil Allison]

Hi,

the signal to noise ratio of Iain Church's cathode follower pre-amp is still
in dispute.

Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

Just as an exercise, I checked the S/N of my own Quad Mk2 power amp using a
1000 times gain mic-pre plus audio band filter followed by a true rms, wide
range voltmeter (over 100kHz bandwidth).

RESULTS:

Input shorted:

The noise residual was mostly hum, 170 uV worth.

Makes the S/N ratio = 96 dB relative to 11 volts output (ie 15 watts).

Take out the hum and the result = 40 uV of random noise.

Makes that ratio = 109 dB.

Now, a Quad Mk2 has a voltage gain of 7.1 times when set to 8 ohms load.

Makes the EIN = 5.6 uV.

Equal to the self noise of a 100kohm resistor.


CONCLUSION:

The two EF86s work as advertised.



........ Phil

[Iain Churches]

"Phil Allison" wrote in message
...

Hi,

the signal to noise ratio of Iain Church's cathode follower pre-amp is
still in dispute.

Hello Phil. First of all, please do me the courtesy of writing my name
correctly. Recently, I decided, as many others have done, to ignore your
posts, but this one seems to require some sort of a response.

Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

I have had plenty of experience of measuring power amps, but this is the
first
time I have measured a preamp. With the info that Patrick gave, and also
some helpful people who have made contact by e-mail, I shall soon have a
low noise measuring 60dB gain OpAmp stage.

It's a pity you cannot bring yourself you behave in a socially acceptable
manner. I get the impression that, despite all the cut-and-paste invective
you do actually sometimes know what you are talking about:-)

Best regards
Iain

[Phil Allison]

"Iain Churches Asinine ****head"


the signal to noise ratio of Iain Church's cathode follower pre-amp is
still in dispute.

Hello Phil.


** Do not "hello" me - you sleazy pile of sub human garbage.



First of all, please do me the courtesy of writing my name
correctly.


** ROTFL !!

Go **** yourself - arsehole.



Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

I have had plenty of experience of measuring power amps,


** Has not got a clue what I just wrote about him - has he ???

What a completely narcissistic prick.


It's a pity you cannot bring yourself you behave in a socially acceptable
manner.


** Pity scum like you are still stealing oxygen.

The sooner that stops, the better.




......... Phil

[Peter Wieck]

On Apr 12, 4:00 am, "Bret Ludwig" wrote:
On Apr 12, 2:18 am, "Phil Allison" wrote:

"Iain Churches Asinine ****head"

Massengill Mouth is going again.

Phil, you are a disturbed lunatic.

And you are merely disturbed.

Peter Wieck
Wyncote, PA

[Patrick Turner]

Phil Allison wrote:

Hi,

the signal to noise ratio of Iain Church's cathode follower pre-amp is still
in dispute.

Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

Just as an exercise, I checked the S/N of my own Quad Mk2 power amp using a
1000 times gain mic-pre plus audio band filter followed by a true rms, wide
range voltmeter (over 100kHz bandwidth).

RESULTS:

Input shorted:

The noise residual was mostly hum, 170 uV worth.

Makes the S/N ratio = 96 dB relative to 11 volts output (ie 15 watts).

Take out the hum and the result = 40 uV of random noise.

Makes that ratio = 109 dB.

Now, a Quad Mk2 has a voltage gain of 7.1 times when set to 8 ohms load.

Makes the EIN = 5.6 uV.

Equal to the self noise of a 100kohm resistor.

CONCLUSION:

The two EF86s work as advertised.

....... Phil

Very good work Phil.

170uV is 0.17mV, and anyone who gets noise low as this with any tube
power
amp is doing very well.

If the noise was measured while you have 11Vrms of signal into a 12.8
ohm load,
would it be 170uV?
Standard Quad-II amps have about the same amount of power supply related
noise
compared to THD using a sine wave. ( Assuming both EF86 are matched, and
KT66 are matched,
if not then 2H,4H can be 15dB above the expected THD of mainly 3H. )

In many a tube power amp, the SNR can decline as power output is
increased,
and most certainly in the case of a class AB amp after it crosses the A
to AB
threshold.

But normal listening with Quad-II may be at a voltage of 0.7Vrms
average,
and there would be the 0.17mV of hiss and hum, spurts, farts and pops
that tubes do, and the SNR is only -72dB, unweighted.
Fact is, its difficult to hear 0.17Vrms of any F being sent to a
speaker of 90dB/W/W from 3 metres away, and when vinyl or radio or tape
were the best sources we had,
-72db was OK, unweighted. If weighted it takes the sting out of 50Hz hum
figures.
100Hz hum is usually a lot worse because harmonics from the rectifying
process
extend upwards and are heard as a buzz, rather than genteel hum.

I don't know what the EIN of a 6BK8/EF86 is exactly. It has spiral
heaters to make it
as hum free as possible, but remember the complication of
screen partition noise raises its ugly head when pentodes are
considered.
But even trioded, the EF86 could not be expected to be marvellously
quiet because its gm is in ****ant class like a 12AX7, and you'e lucky
to find any 12AX7
that has input noise less than 2uV, or very roughly equal to about 2k.

RDH4 has a lot about noise worth knowing.
And it shows a circuit where the screen of a pentode is used as the
anode,
and anode is grounded, so you have a triode with low but adequate
Pda, and same gain/Ra as a fully trioded pentode.
( Last time I tried this the tube seemed much more sensitive to magnetic
field induced hum )
The shot noise and partition noise are overcome though,
but that still leaves the grid input noise, and
this noise is an equivalant that made by an equivalent resistance that
can be calculated as R = 2.5 / gM where 2.5 is a constant, and gm is in
A/V,
hence 12AX7 with gm = 0.0012 A/V give R = 2,083 ohms.
And rarely do you ever find a triode which conveniently
adheres to this formula; most are worse than what one calculates
because of spurious cathode noises, ion movements, gas, etc.

All such tubes are OK in a power amp and most line stages.
In a serious microphone amp the mic needs to have high output.
So a low output low Z mic is used with step up tranny.

In a preamp with gain, the attenuator should be after the gain tube
for low noise, because the tube noise is attenuated with the amplified
signal.
Trouble is that with gain, the signal from a CD player is high, so
output
after the gain tube is high, several volts, and THD/IMD
is highest with attenator after the gain tube.
So the gain must be minimised, and I normally use
max gain = 12dB which is about 10dB of shunt FB around a typical 6CG7
stage.
OR, one uses a special input R divider to lower the CD input level,
say 22k + 6k8, giving -12.5dB.

Rolls Royce version is to have a deletable gain stage, so that
when a CD player is used, its 1Vrms output at low Z goes straight to a
50k pot,
then a CF buffer lowers the wiper output Z and feeds the cable and power
amp without any problems.
But where a source of only 200mV is used, the gain may be switched in.
Then the gain tube spends most years not being used.....

The old fashioned sources of vinyl were rarely more than 200mV
which could just about be gotten using ONE EF86 with shunt NFB for RIAA,
Quad22 have such a circuit, and Leak and many countless others used this
bean counter special.
Tape and radio signals were always low, and 200mV seemed to be standard
line levels for domestic gear, and preamp stages had a normal
boost of 5x to make enough so 1V would clip a power amp.
CD came along with its much higher output to make the SNR better,
and a preamp without gain was all that is required before a power amp.

Its not hard to make a vinyl preamp even with a an MC cart or FM tuner
with output above 0.5Vrms
and preamp gain can be omitted.

In the bad old days, bean counters hated having to use tubes to get
gain.
But now anyone can buy a tube worth using for the price of a big Mac
with extra cheese and ketchup.

I have yet to sell anything new that i have made using an EF86.


Patrick Turner

[John Byrns]

In article ,
Patrick Turner wrote:

Phil Allison wrote:

Hi,

the signal to noise ratio of Iain Church's cathode follower pre-amp is still
in dispute.

Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

Just as an exercise, I checked the S/N of my own Quad Mk2 power amp using a
1000 times gain mic-pre plus audio band filter followed by a true rms, wide
range voltmeter (over 100kHz bandwidth).

RESULTS:

Input shorted:

The noise residual was mostly hum, 170 uV worth.

Makes the S/N ratio = 96 dB relative to 11 volts output (ie 15 watts).

Take out the hum and the result = 40 uV of random noise.

Makes that ratio = 109 dB.

Now, a Quad Mk2 has a voltage gain of 7.1 times when set to 8 ohms load.

Makes the EIN = 5.6 uV.

Equal to the self noise of a 100kohm resistor.

CONCLUSION:

The two EF86s work as advertised.

....... Phil

Very good work Phil.

170uV is 0.17mV, and anyone who gets noise low as this with any tube
power
amp is doing very well.

I would say it's not so much that they are doing very well, it's more
like they just didn't do anything stupid.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Patrick Turner]

John Byrns wrote:

In article ,
Patrick Turner wrote:

Phil Allison wrote:

Hi,

the signal to noise ratio of Iain Church's cathode follower pre-amp is still
in dispute.

Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

Just as an exercise, I checked the S/N of my own Quad Mk2 power amp using a
1000 times gain mic-pre plus audio band filter followed by a true rms, wide
range voltmeter (over 100kHz bandwidth).

RESULTS:

Input shorted:

The noise residual was mostly hum, 170 uV worth.

Makes the S/N ratio = 96 dB relative to 11 volts output (ie 15 watts).

Take out the hum and the result = 40 uV of random noise.

Makes that ratio = 109 dB.

Now, a Quad Mk2 has a voltage gain of 7.1 times when set to 8 ohms load.

Makes the EIN = 5.6 uV.

Equal to the self noise of a 100kohm resistor.

CONCLUSION:

The two EF86s work as advertised.

....... Phil

Very good work Phil.

170uV is 0.17mV, and anyone who gets noise low as this with any tube
power
amp is doing very well.

I would say it's not so much that they are doing very well, it's more
like they just didn't do anything stupid.

That's where Quad was in 1953, was it not? bean counters had removed
all the fat from the carcass to give us a weak man of an amp,
but one that could actually stand up and do something for the buyer,
as well as something for the Quad Bank Account.

Patrick Turner.



Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Iain Churches]

"Phil Allison" wrote in message
...

** Do not "hello" me - you sleazy pile of sub human garbage.

Hello Phil. Hello Phil. Hello Phil. Hello Phil

Is come as ZERO surprise to see proved that know nothing, knob twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

Had to laugh at the above:-) Everything on my bench was built at least
thirty years after your Quad II. My HP Spectral analyser has a calibration
sticker marked "Control Centre. Houston. Texas" They sent men to
the moon with this test gear, so it is quite adequate for building the
odd tube amp or two:-))


Take care
Iain

[Iain Churches]

"Bret Ludwig" wrote in message
ups.com...


I would argue that the preamp needs to be done away with for most
people, and either stereo amps should have volume controls or CD
players should.

Agreed. At home I feed my CD player straight into the power
amp which has a stepped attenuator. But people sometimes have
more than one CD player and often have more than one audio
source. So a cathode follower with say four switched inputs is
ideal.

Most people either have no turntable or if they do
should have a RIAA stage and a level booster at the table, feeding a
line level to the power amp.

A (very) high end dealer in Stockholm told me recently that he
gets more enquiries for turntables than for CDplayers!

Iain

[west]

"Phil Allison" wrote in message
...

"Iain Churches Asinine ****head"


the signal to noise ratio of Iain Church's cathode follower pre-amp is
still in dispute.

Hello Phil.


** Do not "hello" me - you sleazy pile of sub human garbage.



First of all, please do me the courtesy of writing my name
correctly.


** ROTFL !!

Go **** yourself - arsehole.



Is come as ZERO surprise to see proved that know nothing, knob
twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

I have had plenty of experience of measuring power amps,


** Has not got a clue what I just wrote about him - has he ???

What a completely narcissistic prick.


It's a pity you cannot bring yourself you behave in a socially
acceptable
manner.


** Pity scum like you are still stealing oxygen.

The sooner that stops, the better.




........ Phil

Iain: You took Phil's bait. Actually, I believe you made Phil feel a bit
human for a moment. Your kindness, however, probably embarrassed him,
causing him to immediately lash out, lest you discover that he has a tender
side. Remember, he has a reputation to uphold.
BTW: thanks for the audio connector link. I immediately ordered some black &
red.
west
..

[Phil Allison]

"Iian Cherchs ****ing IDIOT "



Is come as ZERO surprise to see proved that know nothing, knob
twiddling
clown has no clue on the correct use of those wank value, antique boat
anchors he has collected to adorn his test bench.

Had to laugh at the above:-) Everything on my bench was built at least
thirty years after your Quad II.


** The autistic moron has no idea what is being said to him - does he ??


My HP Spectral analyser has a calibration
sticker marked "Control Centre. Houston. Texas"


** No "wank value" in that - is there ??

The autistic moron has no idea what is being said to him - does he ??




........ Phil

[Patrick Turner]

Bret Ludwig wrote:


In many a tube power amp, the SNR can decline as power output is
increased,
and most certainly in the case of a class AB amp after it crosses the A
to AB
threshold.

Yes because the common tube amp has a power supply that is not all
that stout. Even the best consumer tube amp of the old days sonically
and buildwise, the Marantz 5 and 8B, show this. Homebrewers can beat
it by using an outboard power supply of considerable overdesign and
overkill on grounding.

But with Quad-II amps and others, while it works in pure class A the PS
noise
remains low along with THD. CMR is in operation, but once you begin to
move toward AB, the ripple voltage at the CT becomes increasingly in
series with the
anode signal, and in Quad II its about 17Vrms.


But normal listening with Quad-II may be at a voltage of 0.7Vrms
average,
and there would be the 0.17mV of hiss and hum, spurts, farts and pops
that tubes do, and the SNR is only -72dB, unweighted.
Fact is, its difficult to hear 0.17Vrms of any F being sent to a
speaker of 90dB/W/W from 3 metres away, and when vinyl or radio or tape
were the best sources we had,
-72db was OK, unweighted. If weighted it takes the sting out of 50Hz hum
figures.
100Hz hum is usually a lot worse because harmonics from the rectifying
process
extend upwards and are heard as a buzz, rather than genteel hum.

I don't know what the EIN of a 6BK8/EF86 is exactly. It has spiral
heaters to make it
as hum free as possible, but remember the complication of
screen partition noise raises its ugly head when pentodes are
considered.
But even trioded, the EF86 could not be expected to be marvellously
quiet because its gm is in ****ant class like a 12AX7, and you'e lucky
to find any 12AX7
that has input noise less than 2uV, or very roughly equal to about 2k.

RDH4 has a lot about noise worth knowing.
And it shows a circuit where the screen of a pentode is used as the
anode,
and anode is grounded, so you have a triode with low but adequate
Pda, and same gain/Ra as a fully trioded pentode.
( Last time I tried this the tube seemed much more sensitive to magnetic
field induced hum )

No commercial broadcast or recording gear of which I am aware
actually used that circuit, despite it being in several era books. I
am inclined to think that was for a reason.

The shot noise and partition noise are overcome though,
but that still leaves the grid input noise, and
this noise is an equivalant that made by an equivalent resistance that
can be calculated as R = 2.5 / gM where 2.5 is a constant, and gm is in
A/V,
hence 12AX7 with gm = 0.0012 A/V give R = 2,083 ohms.
And rarely do you ever find a triode which conveniently
adheres to this formula; most are worse than what one calculates
because of spurious cathode noises, ion movements, gas, etc.

All such tubes are OK in a power amp and most line stages.
In a serious microphone amp the mic needs to have high output.
So a low output low Z mic is used with step up tranny.

In a preamp with gain, the attenuator should be after the gain tube
for low noise, because the tube noise is attenuated with the amplified
signal.
Trouble is that with gain, the signal from a CD player is high, so
output
after the gain tube is high, several volts, and THD/IMD
is highest with attenator after the gain tube.
So the gain must be minimised, and I normally use
max gain = 12dB which is about 10dB of shunt FB around a typical 6CG7
stage.
OR, one uses a special input R divider to lower the CD input level,
say 22k + 6k8, giving -12.5dB.

Rolls Royce version is to have a deletable gain stage, so that
when a CD player is used, its 1Vrms output at low Z goes straight to a
50k pot,
then a CF buffer lowers the wiper output Z and feeds the cable and power
amp without any problems.
But where a source of only 200mV is used, the gain may be switched in.
Then the gain tube spends most years not being used.....

The old fashioned sources of vinyl were rarely more than 200mV
which could just about be gotten using ONE EF86 with shunt NFB for RIAA,
Quad22 have such a circuit, and Leak and many countless others used this
bean counter special.
Tape and radio signals were always low, and 200mV seemed to be standard
line levels for domestic gear, and preamp stages had a normal
boost of 5x to make enough so 1V would clip a power amp.
CD came along with its much higher output to make the SNR better,
and a preamp without gain was all that is required before a power amp.

I would argue that the preamp needs to be done away with for most
people, and either stereo amps should have volume controls or CD
players should. Most people either have no turntable or if they do
should have a RIAA stage and a level booster at the table, feeding a
line level to the power amp.

Fully integrated power amplifiers address the problem.



The closer the first preamp stage is to the cartridge the better.

It depends. MC Rout is about 12 ohms maybe, so a long line can be run to
an amp.
But it should be balanced, and that means provision for
a balanced input on the amp, not so easy.

So for SE input amps, having cables not too long, under 3M
and well away from magnetic fields is essential.

Patrick Turner.

[Iain Churches]

"west" wrote in message
news:eCyTh.13093$V15.10999@trnddc02...


Iain: You took Phil's bait.

Many would like take his head off with a baseball bat:-)

Actually, I believe you made Phil feel a bit
human for a moment. Your kindness, however, probably embarrassed him,
causing him to immediately lash out, lest you discover that he has a
tender
side. Remember, he has a reputation to uphold.

Unfortunately he is a social outcast. Probably through no fault of his
own he has a condition which prevents him from behaving as normal
people do. This is sad, because, beneath the piles of copy and past
excretia which he posts to this and other groups, one does sometimes
find something from him worth reading.

If he lived in this part of the world, he would be receiving the medical
and psychiatric help he probably needs, or would have been sectioned
years ago.

I feel sorry for him, and have a strong suspicion that something
regrettable may happen to him, maybe quite soon.


BTW: thanks for the audio connector link. I immediately ordered some black &
red.

Excellent:-).
I am sure you will be happy with them. The build quality is good.

Cordially,
Iain

[Phil Allison]

"Ian Cherchs ASD ****ed IDIOT "


** **** OFF - TROLL.




....... Phil

[Patrick Turner]

Iain Churches wrote:

"west" wrote in message
news:eCyTh.13093$V15.10999@trnddc02...


Iain: You took Phil's bait.

Many would like take his head off with a baseball bat:-)

Actually, I believe you made Phil feel a bit
human for a moment. Your kindness, however, probably embarrassed him,
causing him to immediately lash out, lest you discover that he has a
tender
side. Remember, he has a reputation to uphold.

Unfortunately he is a social outcast. Probably through no fault of his
own he has a condition which prevents him from behaving as normal
people do. This is sad, because, beneath the piles of copy and past
excretia which he posts to this and other groups, one does sometimes
find something from him worth reading.

That's right, and he often is the only one who is right about something
technical.
He enjoys this position, but when he gets a little cross with us he just
goes beserko.

We are all grown men who can ignore a barking puppy doggie for 2
seconds, surely?

Patrick Turner.

If he lived in this part of the world, he would be receiving the medical
and psychiatric help he probably needs, or would have been sectioned
years ago.

I feel sorry for him, and have a strong suspicion that something
regrettable may happen to him, maybe quite soon.

BTW: thanks for the audio connector link. I immediately ordered some black &
red.

Excellent:-).
I am sure you will be happy with them. The build quality is good.

Cordially,
Iain

[KeithR]

Iain Churches wrote:

My HP Spectral analyser has a calibration
sticker marked "Control Centre. Houston. Texas" They sent men to
the moon with this test gear, so it is quite adequate for building the
odd tube amp or two:-))


Take care
Iain

Having worked on that particular project, I wouldn't boast about that. NASA
used some awful crap for Apollo. Now if it had a JPL sticker, that would be
far more impressive.

[Ian Iveson]

Bret Ludwig wrote

The Brits had Quad and Leak electronics commercially, and of course
with the publication of DTN Williamson's amp did kick off the
homebrew hi-fi amp craze. Radford was another brand. Philips in
Holland contributed but very little they actually made is really
desireable, besides the tubes, for hi-fi. I can't think of anything
from France, Germany, Italy.

Mainland Europeans insist on speaking foreign languages and for the
last century we only ever saw them from aeroplanes or through
gunsights.

Their pop music is rubbish, but they have a reputation for orchestral
stuff, so their ears must work. I gather from reports that they are
much more likely to learn how to play an acoustic instrument than we
are.

I assumed they must have had audio stuff we don't know about. It seems
unlikely they bought it from us.

What about Japan? Did they have their own hi-fi industry?

cheers, Ian

[Iain Churches]

"Phil Allison" wrote in message
...

"Ian Cherchs ASD ****ed IDIOT "


** **** OFF - TROLL.

Phil. Two mistakes in the spelling of my surname of
two syllables. You are certainly not the brightest lamp
in the street. But you *can* cut and paste:-)

Take care
Iain

[Iain Churches]

"Ian Iveson" wrote in message
k...
Bret Ludwig wrote

The Brits had Quad and Leak electronics commercially, and of course
with the publication of DTN Williamson's amp did kick off the
homebrew hi-fi amp craze. Radford was another brand. Philips in
Holland contributed but very little they actually made is really
desireable, besides the tubes, for hi-fi. I can't think of anything
from France, Germany, Italy.

Had to laugh at the above "Radford was another brand"
Bret probably is unaware that Arthur Radford was a designer
of audio test equipment (used by the BBC and most of the
European record companies) Then someone brought him a
Dynaco amp. AR listened hard, and looked under the hood
and exclaimed "I think I can do a lot better" True
to his word, be produced an amplifier which
although intended for the domestic market became something
of a standard in most studios in the UK. It's power of 25W
gave it an considerable advantage over the Quad II, and
Radford was especially proud of how well his amp drove
the Quad ESL57s.

The KT88 ULPP STA100 was the standard ref
amplifier at the BBC for many years. They are highly
sought after second hand, but hardly if ever on sale.
I am told it is the most highly valued tube amp
of them all, and that nothing that McIntosh or anyone else
has produced is so sought after on this side of the Atlantic.

Think also Bret about analogue tape recorders. The Americans
had a considerable head start with the spoils of war, the
Magnetophon which was captured from the Germans and
taken back to the US.

Ampex with the 300 and 350 series was top of the league
saleswise at least for professioanl machines. There was
little choice. EMI with the TR90 and BTR2 were not far
behind.

Then along came Studer with the C37, and later the J37
tube based machines which wiped the floor with anything
that Ampex were producing. Ampex sounded OK.
But Studer sounded good too, and was much more reliable.

In my younger days I worked at a studio which had Studer
A80 multitrack and an Ampex AG440 (I think it was called)
standing side by side. Both were aligned daily, as was our
custom. The Studer worked day in day out without the
slightest problem. I cannot recall a single session with the
Ampex where a service technician was not called. It was
sold after only two years. We we happy, and very lucky
to get rid of it.


Their pop music is rubbish, but they have a reputation for orchestral
stuff, so their ears must work. I gather from reports that they are much
more likely to learn how to play an acoustic instrument than we are.

Yes. The standard of classical music in most of the EU is very high.
I am always amazed when I visit Prague. Typically 20 classical
concerts on a single weeknight. Every second young person is
carrying a violin case. The music scene in London and Manchester
is also quite remarkable. Stockholm too is well worth a visit.

Best regards
Iain

[west]

"Iain Churches" wrote in message
. fi...

"Ian Iveson" wrote in message
k...
Bret Ludwig wrote

The Brits had Quad and Leak electronics commercially, and of course
with the publication of DTN Williamson's amp did kick off the
homebrew hi-fi amp craze. Radford was another brand. Philips in
Holland contributed but very little they actually made is really
desireable, besides the tubes, for hi-fi. I can't think of anything
from France, Germany, Italy.

Had to laugh at the above "Radford was another brand"
Bret probably is unaware that Arthur Radford was a designer
of audio test equipment (used by the BBC and most of the
European record companies) Then someone brought him a
Dynaco amp. AR listened hard, and looked under the hood
and exclaimed "I think I can do a lot better" True
to his word, be produced an amplifier which
although intended for the domestic market became something
of a standard in most studios in the UK. It's power of 25W
gave it an considerable advantage over the Quad II, and
Radford was especially proud of how well his amp drove
the Quad ESL57s.

The KT88 ULPP STA100 was the standard ref
amplifier at the BBC for many years. They are highly
sought after second hand, but hardly if ever on sale.
I am told it is the most highly valued tube amp
of them all, and that nothing that McIntosh or anyone else
has produced is so sought after on this side of the Atlantic.

Think also Bret about analogue tape recorders. The Americans
had a considerable head start with the spoils of war, the
Magnetophon which was captured from the Germans and
taken back to the US.

Ampex with the 300 and 350 series was top of the league
saleswise at least for professioanl machines. There was
little choice. EMI with the TR90 and BTR2 were not far
behind.

Then along came Studer with the C37, and later the J37
tube based machines which wiped the floor with anything
that Ampex were producing. Ampex sounded OK.
But Studer sounded good too, and was much more reliable.

In my younger days I worked at a studio which had Studer
A80 multitrack and an Ampex AG440 (I think it was called)
standing side by side. Both were aligned daily, as was our
custom. The Studer worked day in day out without the
slightest problem. I cannot recall a single session with the
Ampex where a service technician was not called. It was
sold after only two years. We we happy, and very lucky
to get rid of it.


Their pop music is rubbish, but they have a reputation for orchestral
stuff, so their ears must work. I gather from reports that they are much
more likely to learn how to play an acoustic instrument than we are.

Yes. The standard of classical music in most of the EU is very high.
I am always amazed when I visit Prague. Typically 20 classical
concerts on a single weeknight. Every second young person is
carrying a violin case. The music scene in London and Manchester
is also quite remarkable. Stockholm too is well worth a visit.

Best regards
Iain

Iain: In your opinion, is the Radford STA 100 the best UL/PP amp, in that
power class? If yes, what are some of the reasons that distinguish it from
other well known PP/UL? How does it stand up to a, lets say, Curcio, etc.
modified Dynaco MKIII? Is it worth building something like it? All my
questions are subjective so I only expect your opinions. If you do not know,
no problem. I looked at the schematic for a Radford STA-100 and it doesn't
look too difficult but I don't know what OPTs to use. Thanks in advance my
friend.

Fondly,
west

[Iain Churches]

"west" wrote in message
newsfDUh.960$Qp.456@trnddc07...

Iain: In your opinion, is the Radford STA 100 the best UL/PP amp, in
that
power class?

It stands head and shoulders above the other I have heard.

If yes, what are some of the reasons that distinguish it from
other well known PP/UL?

Probably the quality of the transformers. As mentioned elsewhere
Arthur Radford was an instrument designer - transformer winding
was one of his areas of expertise.

In the BBC technical spec, Radford states, "the amplifier can
run indefinately at full power into open circuit or short circuit
load"


How does it stand up to a, lets say, Curcio, etc.
modified Dynaco MKIII?

It was built as an improvement on the Dynaco.
Curcio is much later, I believe.


Is it worth building something like it?
I looked at the schematic for a Radford STA-100 and it doesn't
look too difficult

Certainly, if you can get the transformers. The schematic
looks deceptively simple:-) Just a cascode, then a pair of
pentodes for the phase inverter driving the KT88s. Easy
and fun.

but I don't know what OPTs to use.

The OPT was the key component in the whole design.
I sent one once to European winder to be copied. They
reported back that it was "incredibly complex" A Hammond
might not perform as well.

I have an STA100B which I listen to often. It is
quite stunning. It took me 20 years to find one.
I also have a second amp, stripped down minus
all transformers.

You might be well advised to build something like the
Radford STA25 MkIII. The schematic is on my site
at:
http://www.kolumbus.fi/iain.churches...ford/STA25.gif

These transformers are available to original spec.
I have built a couple of these amps. Now that less input
sensitivity is required for CD sources, a triode can be
used at the front end.

Regards
Iain







Thanks in advance my
friend.



Fondly,
west

[Iain Churches]

"Phil Allison" wrote in message
...

1970s US boat anchors make damn fine offensive weapons.
If dropped from a great enough height.



Hi Phil.

I note your propensity to deride the efforts of others, and yet
I can find no thread or post relating to anything you yourself
have built.

Some pics of your audio system and workshop would be of
great interest.

Cordially,
Iain

[Patrick Turner]

Iain Churches wrote:

"west" wrote in message
newsfDUh.960$Qp.456@trnddc07...

Iain: In your opinion, is the Radford STA 100 the best UL/PP amp, in
that
power class?

It stands head and shoulders above the other I have heard.

If yes, what are some of the reasons that distinguish it from
other well known PP/UL?

Probably the quality of the transformers. As mentioned elsewhere
Arthur Radford was an instrument designer - transformer winding
was one of his areas of expertise.

He may well have had nice trannies.

But the drive amp with ECC88/6DJ8 cascode input and EF184 pentodes in an
LTP
can easily be bettered if the DJ8 is reduced to a simple common cathode
stage with
both halves paralleled, and the LTP built using a CCS and strapped as
triodes.
This will further remove any higher numbered odd order pentode
artifacts.
The STA 100 has 3 nine pin input tube sockets and so a range of
topologies could be tried, and using EL84 in triode instead of the EF184
would make the sound more dynamic IMHO...

Input sensitivity won't be as good, but this doesn't matter because a
preamp is needed,
and 2V sensitivity is OK for a powerful amp.




In the BBC technical spec, Radford states, "the amplifier can
run indefinately at full power into open circuit or short circuit
load"

Hmm, I wouldn't be too blase about this idea.

Clouds of smoke and huge repair costs are usually on the way for those
who manage to design an amplifier
to run at "full power" into a short circuit.

What does full power to a short circuit mean? If there is no voltage
at the load, because the load = 0.0 ohms, there is no power.
But there is a bit of power dissipated in the tubes.
So with NFB, the amp vainly tries to increase its error signal so
a heck of a boost is given to the error signal so the coupling caps
become charged up and bias is effectively increased, and the output
wave into the short circuit is a square wave and the tubes are either
off, or
turned fully on, and most experiments I have done show that
as the load is reduced towards 0.0ohms, pda goes upward and the tubes
will fry,
despite the bias increase due to overload.

Like all old tube amps built before cheap silicon bjts were available,
let alone scrs et all, there was no easy way to provide active shut down
protection for
amps left screaming their heads off to death with a shorted or damaged
speaker or leads.


How does it stand up to a, lets say, Curcio, etc.
modified Dynaco MKIII?

It was built as an improvement on the Dynaco.
Curcio is much later, I believe.

Is it worth building something like it?
I looked at the schematic for a Radford STA-100 and it doesn't
look too difficult

Certainly, if you can get the transformers. The schematic
looks deceptively simple:-) Just a cascode, then a pair of
pentodes for the phase inverter driving the KT88s. Easy
and fun.

but I don't know what OPTs to use.

The OPT was the key component in the whole design.
I sent one once to European winder to be copied. They
reported back that it was "incredibly complex" A Hammond
might not perform as well.

When a tranny winder reports back to a client that something is
"incredibly complex" it is usually total BS.

What it means to be told something is IC is that
perhaps they lack the ability to copy the simple thing thay were asked
to copy,
ie, they are incompetent, or they have not got the time, or they think
you won't pay the re-wind cost for the extra few terminations,
or they cannot figure a way to dumb down the design
and use less turns and random wound windings instead of neat layer
windings
with insulation layers between each layer, and they can't
vacuum impregnate,
and they don't like providing terminations to math
or better the original methods.

The STA 100 circuit diagram showing the OPT layout is
perfectly simple. Nothing is complex. But there are a lot of simple
things in there, and these days it is unprofitable to rewind it.
In 99.99% of instances where I inspect old OPTs from ancient old amps
touted as being marvels, I find they can be easily bettered.

However, Hammond may indeed be inferior.
Sowter or Lundahl is where someone should go and be prepared to
pay more than a penny.

Or perhaps see if you can buy OPTs as spare parts for Manley Labs, CJ,
ARC
amplifiers of the same power.

Patrick Turner.



I have an STA100B which I listen to often. It is
quite stunning. It took me 20 years to find one.
I also have a second amp, stripped down minus
all transformers.

You might be well advised to build something like the
Radford STA25 MkIII. The schematic is on my site
at:
http://www.kolumbus.fi/iain.churches...ford/STA25.gif

These transformers are available to original spec.
I have built a couple of these amps. Now that less input
sensitivity is required for CD sources, a triode can be
used at the front end.

Regards
Iain

Thanks in advance my
friend.


Fondly,
west

[Iain Churches]

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"west" wrote in message
newsfDUh.960$Qp.456@trnddc07...

Iain: In your opinion, is the Radford STA 100 the best UL/PP amp, in
that
power class?

It stands head and shoulders above the other I have heard.

If yes, what are some of the reasons that distinguish it from
other well known PP/UL?

Probably the quality of the transformers. As mentioned elsewhere
Arthur Radford was an instrument designer - transformer winding
was one of his areas of expertise.

He may well have had nice trannies.

I think it is generally accepted that he was something of a master
in the art of transformer winding.


But the drive amp with ECC88/6DJ8 cascode input and EF184 pentodes in an
LTP
can easily be bettered if the DJ8 is reduced to a simple common cathode
stage with
both halves paralleled, and the LTP built using a CCS and strapped as
triodes.
This will further remove any higher numbered odd order pentode
artifacts.

Yes indeed. Such a mod has been discussed just recently on
another group. The broadcast version of the amp had sensitivity set
to the standard studio level of 0dBm. These days +8dBm would
be fine.


In the BBC technical spec, Radford states, "the amplifier can
run indefinitely at full power into open circuit or short circuit
load"

Hmm, I wouldn't be too blase about this idea.

People tried it, and it was proved to be true. The last STA100
at Decca was taken out of service after 21 years, which was the
time that Radford gave as MTBF for the OPTs:-) Mine is still
running perfectly (manufactured 1966)

Jim Kerr, who serviced power amps at Decca studios, told me
that he had come across only one failure in a Radford in all the
time he had been there. There must have been dozens of amps.
The fault was in an M15 series II with cathode bias.

Clouds of smoke and huge repair costs are usually on the way for those
who manage to design an amplifier
to run at "full power" into a short circuit.

He guaranteed it could be done, and of course people had
to try it. There was no smoke.

Best regards
Iain

[Patrick Turner]

Iain Churches wrote:

"Patrick Turner" wrote in message
...


Iain Churches wrote:

"west" wrote in message
newsfDUh.960$Qp.456@trnddc07...

Iain: In your opinion, is the Radford STA 100 the best UL/PP amp, in
that
power class?

It stands head and shoulders above the other I have heard.

If yes, what are some of the reasons that distinguish it from
other well known PP/UL?

Probably the quality of the transformers. As mentioned elsewhere
Arthur Radford was an instrument designer - transformer winding
was one of his areas of expertise.

He may well have had nice trannies.

I think it is generally accepted that he was something of a master
in the art of transformer winding.

But its science and trade work, not art.
If wound artistically, its usually very poor engineering.


But the drive amp with ECC88/6DJ8 cascode input and EF184 pentodes in an
LTP
can easily be bettered if the DJ8 is reduced to a simple common cathode
stage with
both halves paralleled, and the LTP built using a CCS and strapped as
triodes.
This will further remove any higher numbered odd order pentode
artifacts.

Yes indeed. Such a mod has been discussed just recently on
another group. The broadcast version of the amp had sensitivity set
to the standard studio level of 0dBm. These days +8dBm would
be fine.

In the BBC technical spec, Radford states, "the amplifier can
run indefinitely at full power into open circuit or short circuit
load"

Hmm, I wouldn't be too blase about this idea.

People tried it, and it was proved to be true. The last STA100
at Decca was taken out of service after 21 years, which was the
time that Radford gave as MTBF for the OPTs:-) Mine is still
running perfectly (manufactured 1966)

Jim Kerr, who serviced power amps at Decca studios, told me
that he had come across only one failure in a Radford in all the
time he had been there. There must have been dozens of amps.
The fault was in an M15 series II with cathode bias.

Clouds of smoke and huge repair costs are usually on the way for those
who manage to design an amplifier
to run at "full power" into a short circuit.

He guaranteed it could be done, and of course people had
to try it. There was no smoke.

Obviously they had too much free time while at work to try such things.

I would have given them a LOT more free time.

Patrick Turner.

Best regards
Iain