Should Amplifiers Be Transparent?

[malvai]

Hi,

You might find this interesting.

The Carver Challenge | Stereophile.com

Regards
Rajiv

This article was certainly a 'ear opener'!

 

[prem]

Hi Kanwar

Nice to have someone from Pro Audio here on this forum. Talking of home audio, you mentioned Bryston 7 as one of the most transparent amps you have heard. Have you had a chance to hear the JC1 amp? To my ears it sounded more transparent than either the Bryston or the Krell. But maybe i do not hear things the way you do. The JC1 amp is incidentally a collaboration between Bob Crump and John Curl.

 

[odyssey]

On the Bob Carver Challenge - not to take away anything there - BUT -

JA from Stereophile posts in response to


Where is that original modified Carver amp today?
--------------
Bob Carver took it back with him when the Challenge was over, where it was used as the prototype for the M1.0t amplifier that was released in 1986. Stereophile reviewed this model in April 1987 (review not yet posted in our archives) and found that it neither measured nor sounded like the C-J tube amp of which it was supposed to be a clone. The null I measured between the production M1.0t and the tube amp using the same methodology as Bob Carver was just 36dB and then only in the midrange.

John Atkinson
Editor, Stereophile

 

[venkatcr]

Stereophile reviewed this model in April 1987 (review not yet posted in our archives) and found that it neither measured nor sounded like the C-J tube amp of which it was supposed to be a clone. The null I measured between the production M1.0t and the tube amp using the same methodology as Bob Carver was just 36dB and then only in the midrange. John Atkinson. Editor, Stereophile

If I had been in Bob Carver's shoes, I would have done the same. If I had released commercial models that duplicated the C-J Tube amp, I would certainly been called a copy-cat and cursed by the industry and, in most probability, by Stereophile itself. Secondly Bob may not have liked the J-C tube sound at all!

But that does not take away the capability of Bob to exactly duplicate the sound signature of any amp.

Cheers

 

[shershah]

regarding the original purpose of this thread - about transparent audio amplification -

here is a link to original research re "memory free" circuits

Lavardin Technologies - Model IT

copy and paste of a section of the legend under "technologies" on the above site-

This discovery at Lavardin Technologies demonstrates that the classic measurements made all over the world for the last decade are meaningless when considering the musical quality of an amplifier.

 

[abhijitnath]

Is that claim backed up by any peer reviewed electronics engineering journal?

 

[Hiten]

Thanks Kanwar.
Good link shershahbhai, Thanks. A new perspective to look at routine things is always exciting. Hope "traces of current flow" concept doesn't remain subjective. A little more explanation in simple language would have been great. but nice link anyway.
Regards

 

[kanwar]

Hi Kanwar

Nice to have someone from Pro Audio here on this forum. Talking of home audio, you mentioned Bryston 7 as one of the most transparent amps you have heard. Have you had a chance to hear the JC1 amp? To my ears it sounded more transparent than either the Bryston or the Krell. But maybe i do not hear things the way you do. The JC1 amp is incidentally a collaboration between Bob Crump and John Curl.

Hi Prem,

Thanxz for the query.

I haven't listened to John Curl's JC1 amp yet, so i can't say about it. Regarding Bryston 7B, i really like the way it maintains the integrity while playing even at high volumes where most of the home audio amps choke to death.
For me Transparency has one more added dimension that is reviewing the amplifier at high volume operation, this thing tells us lot more about the power supply and circuit topology characteristics and alot more.

Cheers,
Kanwar

 

[malvai]

Hi Prem,

Thanxz for the query.

I haven't listened to John Curl's JC1 amp yet, so i can't say about it. Regarding Bryston 7B, i really like the way it maintains the integrity while playing even at high volumes where most of the home audio amps choke to death.
For me Transparency has one more added dimension that is reviewing the amplifier at high volume operation, this thing tells us lot more about the power supply and circuit topology characteristics and alot more.

Cheers,
Kanwar

I agree with you on this. In fact, what impresses me about the Bryston amps is their transparency and the clean and huge soundstaging ability.

Though, they can sound bright with certain loudspeakers...

 

[kanwar]

Shershah,

I don't agree with that link posted by you containing the Memory Distortion Claim by a company, is there any journal or white paper or research paper linked to that very so called amazing discovery?

the article from Lavardin Technologies - distorsion de memoire says


Tube technology allows electrons to travel through a vacuum which leaves no storage or memory effect, but solid-state amplifiers use silicon components which keep a trace of current flow that has gone through . New electron flow is continuously affected by the pattern of the immediately preceding electron flow.

No one would agree on this who has basic understanding of Semiconductor physics. Electron Flow never leave any traces. Lavardin is not giving any scientific proof of it.


Cheers,
Kanwar

 

[square_wave]

This story about John Curls ability to duplicate the SOUND SIGNATUE of any amplifier is very well known and discussed/dissected by many. It is true that a solid state amp can be made to duplicate the sound signature of any type of amp out there. After all it is all mathematics.

The sound signature of an amp is just one aspect of sound reproduction. I am sure if you give this tuned amp to the owner of the tube amp it was trying to replicate and let him live with it for some six months, he will surely return the amp. An expensive Yamaha synthesizer can replicate the sound signature of an actual piano. Try getting a Steinway player / owner to live with one !

There are many aspects of an amplifier which endears the amp to a very acute and critical listener. You come to know this only after you live with one for a long time. If the John curl technique is a fool proof one, all tube amps would have vanished from this planet.

 

[kanwar]

If the John curl technique is a fool proof one, all tube amps would have vanished from this planet.

There is a catch, people love to listen to euphonics [coloration] in the sound which is coming from Tube amps.

Its a matter of Taste. let it be.

 

[shershah]

Shershah,

I don't agree with that link posted by you containing the Memory Distortion Claim by a company, is there any journal or white paper or research paper linked to that very so called amazing discovery?

the article from Lavardin Technologies - distorsion de memoire says


Tube technology allows electrons to travel through a vacuum which leaves no storage or memory effect, but solid-state amplifiers use silicon components which keep a trace of current flow that has gone through . New electron flow is continuously affected by the pattern of the immediately preceding electron flow.

No one would agree on this who has basic understanding of Semiconductor physics. Electron Flow never leave any traces. Lavardin is not giving any scientific proof of it.


Cheers,
Kanwar

i (too) do not believe in that sort of meaningless drivel -

but, as far as home-audio enthusiasts are concerned, such drivel adds to the aura and desirability of such equipment.

the longest that an audiophile can live with a piece of equipment (does not matter if it is a transparent amplifier, great loudspeakers, or expensive cabling) is, probably,two years - especially if he/she has some disposable cash lying around-

the ides of march are over, the taxes have been paid, and in the subsequent months till september, home audiophiles will be making changes to their gear.

and such changes are always aspirational, and therefore, the more the meaningless drivel attached as copy describing the equipment, the more desirable it becomes.

and this mind-set is CRUCIAL if the listener is to enjoy his (high-end) "memory-free" circuit amplifier.

96.3% of audiophile life is lived in the abstract domain, where state of the mind holds the key

sorry to go OT, Kanwar

 

[square_wave]

There is a catch, people love to listen to euphonics [coloration] in the sound which is coming from Tube amps.

Its a matter of Taste. let it be.

This is an often discussed / debated point.

My opinion is that there are musical tube amps as well as solid state amplifiers. Some solid state amps which apparently measure well in the usual mainstream parameters sound dry and non-musical to me. Some tube amps which are purveyed as musical sound euphonic. There are good and bad examples in both camps.

The moot point is that live music is never dry, non-musical or euphonic.

Really good designs sound extremely musical!

Anyways, let it be. And there is no catch

 

[square_wave]

Just couple of quick questions to you Kanwar:

How do you evaluate the musical ability of your amplifiers? I know they measure well.

1.What is your reference loudspeaker system on which you test the amp ?
2.What parameters do you test to know the amplifier is musically sound ?
3.The process ?

It will be interesting for rest of us in home audio.

Thanks.

 

[kanwar]

Just couple of quick questions to you Kanwar:

How do you evaluate the musical ability of your amplifiers? I know they measure well.

1.What is your reference loudspeaker system on which you test the amp ?
2.What parameters do you test to know the amplifier is musically sound ?
3.The process ?

It will be interesting for rest of us in home audio.

Thanks.

Since i am into pro-audio, my ways and procedures might be new to you guys.

1: 4 X Trapezoidal Bass reflex enclosures tuned at 80hz comprising of Dual 15 inch Selenium 15PW6 600W Woofers , HF transducer is Horn loaded compression driver from P.Audio 750M 150W, Mids are tackled by 12inch 12MBP3 300W selenium midrange. 4 X Subwoofers use 2X 1200W Selenium Drivers in Dual opposing manner in horn loaded.[Already posted its pics.]
18mm Russian Birch Plywood is used throughout in the construction.
The enclosure is designed by my friend exclusively for testing purpose. It has been engineered and developed and measured using world renowned loudspeaker measurement system known as CLIO Audiomatica.

2: For evaluating an amplifier i usually do the following tests:
THD at 1dB below Clipping
SMTPE IMD 60hz+7kHz Dual tone test
Phase Response test is performed to check phase shift at HF.
TIM test for checking out transient mode of distortions we usually hear as smearing effect such as while playing notes of kick drums.
Step Response is another test we usually do to check the stability of amplifier in real world loads like so called difficult speakers.
Slew Rate test to check slew limiting of an amplifier, that is slew induced distortion.
Clip recovery test is also done to check how fast and how smooth the clip recovery takes place in the amplifier.
Damping factor measurement is also done by injecting a pure sinusoidal current inthe output of amplifier in order to check the output impedance and current drive capability of the amplifier.
Full power bandwidth test is also performed by sweeping sinewave from 10hz to 50khz.
Another test which no one does is Full power bandwidth Triangular and Square wave test which we do, it tells us alot about the power supply capability of an amplifier, mainly in peak domain.

Apart from these there are many other reliability oriented tests which include burn-in test, line under/over-voltage test, High temperature test etc.

3 From the above mentioned test TIM, SLEW RATE, CLIP RECOVERY and DAMPING FACTOR are the most prominent of the all tests which gives us clear indication of how the amplifier is going to sound. I am saying this because we usually test the amplifier in the large open space with a near full blast output and check for any deviations in sound clarity. If measurements show TIM and Slew Rate are suffering then the amplifier would show up definitely in the high volume listening test. We usually play piece of Snare drums, Cymbals, Kick Drums, Trumpet and live audio recording using FLAC format and many more in order to carry out listening tests. We also perform a linearity test which includes testing/listening the amplifier first at moderate volume for some hours and then for continuous high volume listening, which is both evaluated by our measurement system. If there is difference it speaks out itself in the listening and measurement simultaneously.



Cheers,
Kanwar

 

[square_wave]

@kanwar,

Wow ! Would love to be a spectator to one of these test sessions ! I guess the pro-audio world is a completely different animal altogether. Most of our typical audiophile aspirations will be blown to smithereens during the blast !

We usually sit at the tip of an equilateral triangle formed by the speakers and the listener and evaluate if a piano sounds exactly like a piano. Just an example.

 

[kanwar]

@kanwar,

Wow ! Would love to be a spectator to one of these test sessions ! I guess the pro-audio world is a completely different animal altogether. Most of our typical audiophile aspirations will be blown to smithereens during the blast !

We usually sit at the tip of an equilateral triangle formed by the speakers and the listener and evaluate if a piano sounds exactly like a piano. Just an example.

You are welcome, Yes Pro-audio is completely different world which pushes the amplifier to its limits and sometimes beyond it. If you hear distortion at very loud volume playing it means the amplifier has a serious flaw and going to sound very worse. Try it with your home audio amps.



Cheers,
Kanwar

 

[venkatcr]

The sound signature of an amp is just one aspect of sound reproduction. I am sure if you give this tuned amp to the owner of the tube amp it was trying to replicate and let him live with it for some six months, he will surely return the amp. An expensive Yamaha synthesizer can replicate the sound signature of an actual piano. Try getting a Steinway player / owner to live with one !

The objective of this thread was to discuss whether or not amplifiers should be transparent. As part of the discussion we veered into discussing whether it is possible to design an amplifier that will behave exactly as you want it. Bob Carver proved (long ago) that it can be done.

That is it.

Cheers

 

[prem]

Hi Kanwar


Most of the studios where the recording and mastering happens typically have standard amplifiers. I mean the likes of Mcintosh, Krell and even tube amps like Wavac. Even mastering experts like Steve Hoffman use a Wavac when mastering. If according to you these amps are flawed, the mastering itself is then flawed. I am confused. Am i missing something here?