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Old 11th August 2012, 11:46 PM   #481
owdeo is offline owdeo  Australia
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I wonder how those that were complaining earlier about keeping the thread on-topic feel about the discussion now moving into generic, boring speculation repeated all over this forum on which opamp is better without reference to the design.

The preamp was designed around low noise, low distortion bipolar opamps with good load driving capability. Substituting FET opamps with much higher noise and distortion will degrade the measured performance but perhaps may result in a more pleasing sound in this particular design depending on individual taste - if so good, please build it and try it and let us know (as Mooly has done ). Otherwise, why ask? The speculation is tedious as is the notion that an opamp on its own can be said to be superior to another type without reference to the specific application (objectively or subjectively).

I am interested in why the design seems to have a certain sonic characteristic. I'm sure it doesn't come down to the particular opamps used and in fact I have tried LM4562 in the output gain control instead of 5532 and liked the result even less. Different brands of 5532 also seem to make a small difference, but the overall character is always there. I don't think changing opamps is the solution. I think it probably comes down to the active gain control configuration but haven't had a chance to try bypassing it etc to find out yet.
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Old 12th August 2012, 12:41 AM   #482
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All it really takes is one flake with a load of bread (claimed) and a few old has-beens with a thirst for the limelight and abracadabra, a perfectly good amp can acquire a totally undeserved bum rep in the space of a few posts.

I know Douglas has got up a few noses for his uncompromising rationality, but how about letting it go now?
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Old 12th August 2012, 08:52 AM   #483
owdeo is offline owdeo  Australia
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Not sure if that was intended in my direction but I have to say I'm probably one of the younger guys posting here, don't require any ego boosting by a bunch of audio nerds thank you, and have never claimed to have any special knowledge beyond the basics of electronics. He certainly didn't get up my nose - I having nothing but respect and admire his stance against audio BS and believed in his hard-line approach - at least until now - hence why I built his preamp design. I'm certainly not bagging the preamp - just to my ears and those of SWMBO and my audio buddies has a particular sonic character - which might be well liked by some, but which surprises me as I had expected that with such excellent specs it would be essentially transparent.

The fact is I've spent quite a bit of money and carefully built a preamp designed to provide uncompromised measured performance as well as really nice features ergononically. I think it is 100% successful in achieving those design goals and am extremely greatful that the designer has been generous enough to share his deep knowledge by publishing this excellent design. I therefore cannot see how it can acquire a bum rep amoung those who share the rationalist approach and I'm quite sure that Mr Self would not be worried about any criticism of the sound quality exactly because of his approach.

This has therefore been a learning experience for me - as an EE I really wanted to believe in that uncompromising rationalism, but I have now learnt that for me it isn't necessarily the path that will lead towards equipment that I will enjoy listening to music through. There's an incredible amount of BS in the audio world and I'm certainly not signing up for the audiophile funny farm yet, but this experience has confirmed for me now that like with so many things in life it comes down to shades of grey and that I sit somewhere in the middle of the two extreme approaches...

My reason for posting my opinions was simply to see if anyone else might have some insight to offer - I really see this as an opportunity to find out more about whether the SQ comes down to the feedback configuration around the opamps or whatever it turns out to be. Seems as though it isn't that interesting to anyone else though?
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Old 12th August 2012, 10:06 PM   #484
kevinkr is offline kevinkr  United States
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Owdeo, I've followed your posts with considerable interest, and suspect your experience to date parallels mine to a certain extent. I too believed and expected that impeccable measurements should lead to equally impeccable realism in reproduction, but found it didn't.

Take a look at some of the stuff Salas or Peter Daniels have done, and the reasoning behind it. Might have a look at some of John Curl's or Nelson Pass's designs as well.

Most of all keep at it, seems relevant to question these things. Ultimately the proof is going to be in the listening experience and not the measurements provided that the engineering is at least competent.
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Old 12th August 2012, 10:54 PM   #485
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Owdeo,
When you talk about the sound of this preamp you say you weren't satisfied with the sound. Can you describe what you don't like in more detail. Was it a frequency response anomaly, noise, distortion. etc. I assume since you are saying you are an EE that you can give us some more scientific detail of what you are hearing. It is hard to take a subjective term such as transparent and know what another person means by this. my definition could be different from yours.

Steven
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Old 12th August 2012, 10:58 PM   #486
kevinkr is offline kevinkr  United States
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counter culture comments like the one I just deleted are unwarranted, and borders on what I consider a personal attack. I recommend you desist before I feel compelled to take further action. You have been warned.
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Old 12th August 2012, 11:47 PM   #487
owdeo is offline owdeo  Australia
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Thanks kevinkr, appreciate that.
Quote:
Originally Posted by kevinkr View Post
Take a look at some of the stuff Salas or Peter Daniels have done, and the reasoning behind it. Might have a look at some of John Curl's or Nelson Pass's designs as well.
Would like to do that. I'm aware of the Pass stuff, and have seen there's a John Curl Blowtorch preamp thread but it looks a bit long to wade through - is there a working deisgn in there somewhere?
I'm not familiar with the other names though - could you point me in the right direction?
Cheers,
Owdeo
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Old 13th August 2012, 12:04 AM   #488
kevinkr is offline kevinkr  United States
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Hi Owdeo,
Search here on the forum for threads authored by Salas, our head moderator - you'll find solid state shunt regulators, solid state and tube phono and line stages..

Peter Daniels is the author of the shigaclone thread and is noted for his audiosector designs which he shares freely. (There is a commercial forum here where he sells kits)

Avoid the BT thread unless you want to be perpetually bogged down and never build anything again.. I was referring to his published designs which are all over the net, and here as well.

Have a look at Morgan Jones if curious about the world of tubes.
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Old 13th August 2012, 12:17 AM   #489
sandyK is offline sandyK  Australia
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owdeo
You could always look a little closer to home, for designs by David Tilbrook from Au. who designed many well received projects such as the AEM 6000,and ETI 5000 PAs, as well as some other designs such as the Ultra Fidelity preamp. One of those from close to 30 years ago also used NE5534s !
DIYAudio member, and C.S.I.R.O engineer Suzy J even got to update one of those amplifiers using modern surface mount components, and was even ripped off by an ebhay clone of her hard work. Perhaps you even got to meet David Tilbrook in person at Jaycar's Gore Hill store many years ago ?
Of course, that was back in the days when you had an interest in high quality audio reproduction, and studied to become an E.E.

SandyK
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Old 13th August 2012, 12:19 AM   #490
owdeo is offline owdeo  Australia
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Quote:
Originally Posted by Kindhornman View Post
Owdeo,
When you talk about the sound of this preamp you say you weren't satisfied with the sound. Can you describe what you don't like in more detail. Was it a frequency response anomaly, noise, distortion. etc. I assume since you are saying you are an EE that you can give us some more scientific detail of what you are hearing. It is hard to take a subjective term such as transparent and know what another person means by this. my definition could be different from yours.

Steven
Hi Steven,

I agree with you but as you probably know I can't give you scientific description of the sound quality since it is subjective. I have however tried to remove as much bias as possible by conducting blind AB testing myself and with my wife and friends (seperately) and the conclusion was the same each time. How to interpret descriptions of what I hear is of course tricky - for me I was a musician, a hobbyist building amps and speakers, listening to friends' high-end audio systems and involved with recording live concerts at an early age, long before I did my engineering degree, and I think for anyone else with a lot of experience in listening it is not so hard to interpret these descriptions. But many of my EE colleagues would not understand what the descriptions mean - interestingly they would still think they can deisgn a good amplifier though

Standard measurements such as THD, noise etc do not seem to correlate at all with any of the aspects of SQ I'm not happy with - and I think this is the point really. This experience has removed any doubt I previously had about bias and the fallability of our hearing - I'm now much more happy to trust my ears but would still like my equipment to perform well objectively.

I have described my impressions earlier on in the thread, but basically it seems a little too "tightly gripped" for want of a better description. The sense of the music flowing freely is diminished a bit somehow. Tonally it's excellent - instrument timbre is realistic and the bass is very full albeit very slightly "blurred". The "soundstage" seems a little more confined to each speaker and doesn't seem to spead out as wide. Audiophile friends have told me these are classic symptoms of high levels of feedback, and I was very skeptical at the time but now I'm lost for a better explanation and would like to explore this idea further.
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