Hi believe he's in his 80 s and not doing anything in audio, he marketed a contact enhancer for the computer industry which he did well with called Stabilant 22 .
I have 5 pairs of various versions of XG 8 and XG 10 in the garage which I thought to refurbish and make a double pair out of , but along with the 289 v8 powered MG next to them it remains undone.
I have 5 pairs of various versions of XG 8 and XG 10 in the garage which I thought to refurbish and make a double pair out of , but along with the 289 v8 powered MG next to them it remains undone.
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It's pretty easy to work out what's right or not. Conventional audio is complex, one sub-circuit chains to the next to the next. So, step one: simplify the circuitry to the absolute minimum to get the job done, so then you know what the recording really sounds like. E.g., eliminate all input selection, and volume control. If you do this intelligently you discover that recordings are generally all quite marvellous, and you have plenty of "meat" to work with. Now, add in the various complexities so that everything can be controlled every which way, and as a result the sound will be flavoured in various directions. Pick the sauce that suits oneself, add big dollops of money if that makes one feel better, and rest content that one has got the "right sound" ... 
Or, just stay simple -- I find that to be preferable, I just like to enjoy the recording, whatever it happens to be ...
Frank
Or, just stay simple -- I find that to be preferable, I just like to enjoy the recording, whatever it happens to be ...
Frank
I've built pre's with the Alps Blue Velvet and a very advanced one using the PGA2320. They both sound very good. The PGA2320 is surprisingly smooth and sweet. Esoteric used it in their top of the line pre (I believe it is still in production) and got great reviews. It is a very good part. In my implementation, I run the PGA in balanced mode, buffering the input signal with an LM4562 and I then buffer the output with a 4562+LM4990 driver. Dual mono layout with separate PSU's per channel, and the digital control is fully isolated via optos. Very quiet - even at mid volume setting without any imput connected. There's a 7" backlit TFT display as well which shows input selection and level setting. I need to box it up.
In the light of recent discussion about brickwall filters, here's one article by late Michael Gerzon:
http://www.audiosignal.co.uk/Resources/Why_do_equalisers_sound_different_A4.pdf
http://www.audiosignal.co.uk/Resources/Why_do_equalisers_sound_different_A4.pdf
That's the key -- conventional volume controls are "rough", add "dirt" to the sound ... just another term for irksome distortion ...
Frank
The Alps is not bad . . . I think pots get a bad name when they are abused - like using high value pots when 10k is quite adequate, or feeding a put directly into an op-amp input that has high input bias currents e.g. 5532/34 for example. Of course, a good stepped attenuator is the ultimate, but a decent one costs about $150-200.
A little thought experiment ... take all the circuit parts that make up an extremely high quality preamp - the name of one escapes me at the moment, - and don't solder them together using your best soldering technique, but to each side of the closed contacts of a sufficient number of "good stepped attenuator"s, so that every link between parts goes via such contacts. Do you reckon such a unit will sound as good as a conventionally assembled unit, ??
Frank
- and don't solder them together using your best soldering technique, but to each side of the closed contacts of a sufficient number of "good stepped attenuator"s, so that every link between parts goes via such contacts. Do you reckon such a unit will sound as good as a conventionally assembled unit, ??Frank
I used in small series production for volume control CMOS DAC in multiplying mode,WM8816, PGA2310, MAS9116. Best from those was CMOS DAC (DAC8043) with good OA, e.g .LM4262. Catalogue data are quite nice, but try to measure e.g. PGA2310 at -6-20dB gain (not 0dB..) and input signal about 2V RMS.
Currently I am using quality signal relay attenuator with constant impedance (1kohm) and 0,5dB step (of course, input buffer is needed), with uP control. "No" distortion, very low own noise, and many other advantages.
... - and don't solder them together using your best soldering technique, but to each side of the closed contacts of a sufficient number of "good stepped attenuator"s, so that every link between parts goes via such contacts. Do you reckon such a unit will sound as good as a conventionally assembled unit,
If one puts together shunt type attenuator with multiple relays, only one contact will be 'on' at a time. Such attenuator won't be cheap, but, so what? We're after the best here, aren't we?
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I have a composite amplifier thread - includes a feedforward sim with one of Cordell's Book circuits as main amp
http://www.diyaudio.com/forums/solid-state/45794-high-loop-gain-composite-op-amp-circuits.html
feedforward sim in post #10, I also give the VanderKooy Lipshitz Error Feedforward paper ref: http://quad405.com/jaes.pdf (looks like archive.org scan is corrupted)
but I've only built high loop gain multiloop op amp composites
100+ dB global loop gain @20Khz is easy with 2 modern op amps in a multiloop
using output CFA DSL driver op amp, specs working alone while driving 25 Ohm load of -100 dB THD <100 kHz, -80 dB @ 1MHz
I don't think there's much chance of measuring distortion rise in upper middle/high (audio) freq everyone talks about - certainly not above noise floor with human hearing scale integration times
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Why be humbled? Just shows you and your two friends aren't deaf like the pseudo Golden Pinnae.
Pavel, rather than misquote Sturgeon, I'll ask what system you recommend to investigate if a brickwall filter improves the sound.
Player, preamp, power amp, speakers. A serious enquiry. But please don't specify Blowtorch as I don't think its transparent enough.
In case, its not obvious, I want to see if the State of the Art is such that distortions (in the widest sense) have been reduced sufficiently since 1945. The BBC, Jan's, my tests and some others which I can't remember .. suggest not enough.
There is a serious problem investigating this as most sources today are evil digital and hence severely band-limited. Its now obvious that most SACDs are made from 44.1kHz masters. IIRC, Pavel suggested a few Telarcs but this is still insufficient.
One of the most important tenets of my Double Blind Tests is that the subject chooses the programme material. If he is unfamiliar with the Telarcs and especially if he doesn't listen to them for enjoyment, the test is much less valid to answer the question, "Does it sound better?".
I'm rather disappointed that even in this august company, including aficionados like JC who spurn all evil CDs, there aren't more suggestions for good music with extended supa HF.
It may be we can only test the utility of a brickwall filter on bandlimited programme. So this really only tests how poorly the evil preamp & power amp reacts to supersonic crud from the evil player.
If that's the case, maybe Blowtorch is a suitable candidate for the ancillaries to this test after all.
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It takes a Zobel network at the speaker ... and Yes, it does make for prettier square waves at the speaker terminals if that's your thing.
Great Guru Baxandall would not have agreed with the need ... but he tells you how to do it here Microphone Engineering Handbook Chap 8 and as a bonus, "how to design small audio transformers". Grab this before this knowledge disappears forever.
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Why do EQs sound different?
Thanks for this Electroj. Although I have the greatest respect for Guru Gerzon, (and my pseudo guru status in certain circles is based solely on regurgitating his Word) here, Michael is very naughty in quoting Harwood. What he DOESN'T mention is that Harwood also showed that for the speaker distortions he was looking at, Qs around 0.5 were in fact the MOST audible. Higher Qs were much less of a problem.
Peter Fryer confirmed this in Intermodulation Distortion Listening Tests (this paper is about a lot more than Intermodulation) and I believe so did the false prophet Floyd and his acolytes much later.
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Richard,
it is extremely difficult to recommend anything that is not under own personal control, this especially applies to the audio chain as a whole and not divided into single components.
But I have one non-recommended component, and it is the Behringer active crossover. If this one was used in the test, I cannot take the results serious. This is based on my personal experience.
Regarding the line stage and transparency, my recommendation was expressed in one of my yesterday's posts.
Sincerely,
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jcx, I think the bridge type connection I show does not have the high loop gains of the composite connection because it actually operates in pararallel to the main feedback loop.
Maybe we should split this discussion off into a new thread - I am also thinking about reconfiguring so you get genuine feed forward. Anyway, I would be interested in your thoughts.
I come from the "chain is only as strong as its weakest ..." line of thinking: chain A is made from 99 links of strength 100, 1 link of strength 50; chain B is made from 100 links of strength 50 - which chain is stronger? In the audio world everyone will put up their hand to say chain A is obviously superior; everything in my experience says it works just that real, hard metal "rope" - that single, lesser link sets the standard for everything else.
Not very palatable, but that's how it works, IME ...
Frank
The composite with super high gain is the basis of at least one oscillator for obtaining super low thd. It isnt the same thing as the bridge circuit, of course.
Let go somewhere else and investigate it's potential -- pro and con- further.
[Oh, and zobals are not what i am talking about... group-delay.]
Thx-RNMarsh
If you want to control group-delay at the end of your speaker cable, you will find Zobel networks very useful indeed.
Of course, they have to be matched to the amplifier, speaker & cable on an individual basis. That's what Guru Baxandall's stuff is about. The matching.
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Pavel, could you recommend a complete chain for this purpose? Specifying anything important that I might have left out.
Commercially available if possible.
If nothing is commercially available that is good enough NOT to benefit from Bandwidth Limitation, that's an important piece of info too.
No , but higher level (about 0,007-0,02%) of low order distortions (only 2. and 3. ) , frequency independent. Too much for my taste..No , but higher level (about 0,007-0,02%) of low order distortions (only 2. and 3. ) , frequency independent. Too much for my taste..Higher harmonic burried in noise background (under -120dB)
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