John Curl's Blowtorch preamplifier part II

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Joshua,

If a designer can hear the difference and can remove it (to his ears) with some eqalization is he still disqualified? Same goes for fixing an oscillation caused by particular amp/cable/speaker combination.

I would think that if somebody can design an amp that always sounds the same, that wouldn't budge whatever cable is thrown at it, that would be one hell of an amp.
The notion that an amp that changes its sound due to a cable is somehow a good amp is totally alien to me. It would actually make me doubt the competence of its designer.

I do know that there are some cables marketed that have been deliberedly engineered to sound as different from another cable as possible and that the difference in itself is often interpreted by the inexperienced as 'better', but that's another matter entirely.

jd
 
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I should add that in the case of such a cable that has a clear effect on sound (and I have heard often these differences), I could always measure the causes, like a pathologically high capacitance in interlinks coupled with a finite output impedance of the source or preamp.
Even with a source or preamp with very small Zout, you still can have effects on stability with very high capacitance cables that can be audible sometimes. So I admit it is not always easy to design an amp or preamp that is immune to cable effects, but when there IS an effect with a good amp, my experience is that it is measurable, and not subtle.

jd
 
If we then allow the idea of altering the signal as some kind of tonal control, the very idea of transferring a signal from A to B has been violated. The other problem may come about defining which is the "best sounding" cable. In my books, a cable design that alters a signal is a failure as a design or application.

I believe most here will regard good cables as those that have the least influence on a signal. The problem is cables, or any equipment for that matter, can influence certain aspects in sound that are not easy or possible to measure.

Remember, if you can hear a difference between cables, at least one of them is "damaging" the signal. Unacceptable.
-Chris

Do you have any suggestions which cables to use that doesn't "damage" the signal? I would be certainly be glad to finally find a perfect cable. :)
 
What is wrong here? Why are you talking about cables? I haven't mentioned cables recently, on this thread, and 'everybody' knows that it is not rational to talk about differences in cables.
I have been concentrating on phono cartridge loading. Apparently Syn08 has been, as well, as he designed quite an elaborate one with his phono amp project, available for view, just below this thread. In fact, his input loading is even more elaborate than the one that we put into the JC-80, 25 years ago.
Now, I am asking him for his reasons, especially those based on measurement, as to why he would add such elaborate loading to his design.
This is the question. Once this question is answered, THEN we can go forward and talk about cables, if you want.
Off comments so far, about cable, are riddled with subjective opinion that 'holds no water' here.
 
It would appear that I am not going to get further input on MC cartridge loading. I hope that some here, learned something new. It is not immediately obvious that MC cartridge loading has so few measurable effects, but that is the case. It is much the same as connecting wires, even though many here will not believe it to be a similar situation. Perhaps that is because it is difficult for someone to manufacture a special MC load box and make money from it. Not so, with cables.
 
It is not immediately obvious that MC cartridge loading has so few measurable effects, but that is the case.

Do you know where there's any published data on this? I can think of a lot of ways that loading can change the measurements of the MC-preamp combo and would like to see what sort of systems don't show those changes. Certainly, it's less of an issue than the resonant circuit formed by an MM's impedance and the preamp's input impedance, but it's difficult to believe that there's no effect except in special cases.

In my own preamp, I saw a large difference between loading with 68R versus 680R for my 15R source impedance MC, but maybe THAT is the special case, not the sort of preamps that you or syn08 design.
 
Chris and Scott,
Sometimes there are some correlation between how an amp is measured and how it sounds, but most of the time there isn't such a correlation, at least not a direct and obvious one.

One thing is that the human ear (actually, the ear-brain-mind mechanism) usually doesn't notice harmonic distortion of 0.5% or less in the second harmonic and 0.2% or less in the third harmonic, while it is more sensitive to the higher harmonics and extremely sensitive to the 7th harmonic. So, when one amp measures 0.8% THD and another one measures 0.001% THD, by those numbers alone it's impossible to tell which one of them will sound better.

Another thing is that the measurements which are probably most correlated to the way an amp sounds, that is, TIM and its derivates, are seldom taken and almost never published.

All in all, there is no way to tell how any amp sounds by looking at its' published measurements alone. So, only listening tests can tell how any amp, or any other piece of audio gear, sounds.

The impressions of various individuals of the same audio gear and their evaluations of it are varying to enormous degree. For some a certain audio set sounds great, while to others it sounds mediocre, or bad. If it weren’t like this, all would buy the same amps, speakers and other pieces of audio gear.

Therefore, when I consider purchasing any produced piece of gear for my audio set, whenever it's possible, I listen to it before purchasing, preferably on my own setup. Sometimes it's impossible to do, like in the case of phono cartridges that no merchant will let you try it before you buy. This is also impossible to do on designs which aren't produced. In such cases, I have to rely upon testimonies, or reports of others. Now comes a major question for me: which testimonies or report should I note and which ones should I ignore? As a rule, I don't read reports of audio magazines, whether published, or on-line, for I'm suspicious of possible commercial interests. So I'm left with testimonies and reports of fellow audiophiles. However, there is still the question: which testimonies or report should I note and which ones should I ignore? This question is so much relevant in the light of the enormous differences in appreciations of the same gear. From experience I know that my friends who hear differences between different well engineered cables and me have very similar appreciations of audio gear, while others who don't hear such differences between cables have markedly different appreciations.

Therefore, I'd not consider trying any non-produced design by a designer who confesses that he doesn't hear differences between cables. This is because it's an indication to me that probably his appreciation of the sound of audio gear and mine are most probably markedly different. Of course, not all who claim to hear differences between cables actually hear them. However, I do need a starting point.

I'm absolutely convinced that a designer should have refined listening in order to design and produce great sounding audio gear. A living example for this is my new loudspeakers that came in today. They are Brodmann VC2 (formerly Bosendorfer), designed by Hans Deutsch, who, among other things, was the Tone Master of Herbert von Karajan. These speakers are the best I ever heard and they are ingenious. There is no doubt in my mind that it takes the refined hearing of a man like Hans Deutsch, along with acoustics knowledge and other skills, to design and build such wonderful speakers.

Andre,
Of course the best cables have no influence whatsoever on the sound, in any audio setup, however, such cables are hard to come by.

sawreyrw,
I never measure cables. Moreover, relevant measurements should be done when the cables are hooked to their source and load, something which I'm not sure can be done. Anyhow, this isn't my point at all.

All,
As for MC phone cartridges, many times their recommended load is published.
 
I for one have experienced HUGE sonic differences with different loading on low output MC carts. I'd go as far as to say "night & day".

I happen to prefer 47k loading as it seems to let the cartridge be free and dynamic, but some feel they sound "thin" or "light" with such a loading.

My experience with these situations is that the VTA has been pushed up too high at the arm base to compensate for the dulling of the sound because of the "known" low value of load that "must" be always used with a MC.

I know 5 cartridge makers personally, and when quizzed on what loading they personally use - all have said 47k.

Why someone would fit a complex loading chioce to the preamp is doing it for marketing reasons - the "public" have been told by countless reviewers that it's important to get the loading EXACTLY right.

The only cart that I felt benefitted from a low value of load was my IKEDA, where 68 ohms just makes it sound more coherent and balanced.

But those that use 2 ohms or similar on a Koetsu are very far from my reality...

Regards, Allen (Vacuum State)
 
Allen,
My cartridge is ZYX R1000 Airy3 (MC), whose manufacturer recommended load is 100 Ohm. I use E.A.R. MC4 Step-Up transformer who has inputs which are marked as 3, 6, 12 and 40 Ohm. The combo sounds best when the cartridge is connected to the 3 Ohm input. The VTA seems to be "by the book", it was adjusted when the cartridge was connected initially to the 40 Ohm input and it wasn't touched since.
 
Listening works too, as long as you don't peek.:D

Changing the loading changed level, S/N, and overshoot, with 68R being low enough to have minimal effects on the first two while having a positive effect on the last. All for perfectly logical reasons... You'll be seeing my article on my phono preamp shortly.
 
Sure.
For example: 'HIGH PERFORMANCE REVIEW' Vol. 2, Issue 3, July 1983 p. 30
Regarding the review of the Accuphase AC-2 MC cartridge, 4 ohms impedance, 326uV output. "... Although a variety of loading impedances were used, including 3, 15, 30, and 1000 ohms, the high frequency rise remained."
This is just like I expected, from independent measurements by Mark Levinson and John Meyer and me, in our lab in Switzerland, using B&K test equipment, and Ortofon test records, CBS test records, etc.
High Performance Review used: AA501 distortion analyzer, HP3582A FFT spectrum analyzer, Fluke 8050A multimeter.
 
Soon all HIGH PERFORMANCE parts will be Pb Free, like this SOIC frame for a modern IC (from NASA site):

matte-tin-plated-IC-02.jpg
 
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