Derfnofred,
Personally I would have no trouble with DBLT and think it is the only way to truly subjectively compare two systems. Yes a nice looking piece of equipment sitting in your room is nice but that is another story really. I have seen some really nice looking impressive equipment at the Stereophile shows and CES shows I have exhibited at that sounded like dreck, so I give appearance little attention besides just liking someone's attempt at visual design. You can see that every day with the number of purchasers of Apple products, sold on the looks and great marketing, the technical and build quality of some of what they have done in the past is totally ignored.
Personally I would have no trouble with DBLT and think it is the only way to truly subjectively compare two systems. Yes a nice looking piece of equipment sitting in your room is nice but that is another story really. I have seen some really nice looking impressive equipment at the Stereophile shows and CES shows I have exhibited at that sounded like dreck, so I give appearance little attention besides just liking someone's attempt at visual design. You can see that every day with the number of purchasers of Apple products, sold on the looks and great marketing, the technical and build quality of some of what they have done in the past is totally ignored.
I couldn't agree more. If the golden ear brigade would keep things to a personal preference, then I guess nobody would have a problem with that. However, usually it gets to the point to which "I have a secret sauce that makes my designs special", "you don't [know how to] listen", "you don have experience [whatever that is]", etc... Those who don't care on how audio is build have no relationship with a DIY site.
Seems OK to me. Also nicely jives with the rule of thumb that you'd like 1V/us/pk Volt Vout. So for 100W into 8 ohms that would be 40V/uS, which includes a very healthy safety margin.
Jan
It has some interesting perspectives, doesn't it?
I found it as a dissertation and immediately decided it had to be printed and published.
Jan
I got my copy from Linear Audio Press (the publisher). I don't know if it is available elsewhere. ISBN 9789490929091. It's stated that it is based on the author's dissertation ("thesis"); he was awarded a degree in 2010.
The author focuses on low-distortion open loop behavior, but touches on a lot of stuff, some of which is elsewhere, naturally. The 291 references do have repetition as he assigns a new number every time one appears in the text, but that works fine I think.
The author's conclusions are bound to be controversial, but he has done a lot of work including a good deal of experimental stuff. I have only jumped around in it so far.
In particular, I admire his admissions about things that are not proven, despite the temptation to think they support his approaches. Also his frank assessments of the drawbacks of various of his prototypes are refreshing. He mentions that nearly 200 prototype circuits were constructed, some only fragments of overall amplifiers---but that is still a lot of work.
I also like his treatment of thermal distortion. He can hardly be expected to know everything already, so not knowing the origins of certain circuit techniques that predate their application to audio is understandable, and not cringe-worthy.
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NMD (Name Dropping Brigade), nothing relevant to this topic. Nobody said PIM doesn't exist.
John,
Have you personally read Cordell's book which does talk about feedback and the speed at which this is happening? How can feedback cause a time shift in the audio time frame, that just goes against the physics again. You might as well disregard the use of the LTP as a differential circuit if your going to look at feedback as a problem.
Have you personally read Cordell's book which does talk about feedback and the speed at which this is happening? How can feedback cause a time shift in the audio time frame, that just goes against the physics again. You might as well disregard the use of the LTP as a differential circuit if your going to look at feedback as a problem.
Yes, hogwash in its purest form. Feedback chasing its tail, one of the most common misunderstanding of feedback and it's mechanism, your mentor needs a good undergraduate EE course to refresh his knowledge. Essentially a confusion between phase and group delay, why do I suspect you already knew that and asked only to, once again, stir the pot?
My father was self-taught in electronics, beginning with being an amateur radio operator in Idaho. He did a good deal of audio, including speaker designs, as time went on. Late in life he tended to disparage his ability to hear very well, and partly because of a deep-seated conviction that he was disrespected by his children and the audiophilic pretensions of one of them (not me), he tended to discredit any claims made for equipment that could be considered high end. He also suffered from fairly severe tinnitus.
When CDs came into currency he would protest that he wouldn't be able to hear any improvement other than the absence of surface noise. I made some cassettes on a decent Nak deck from CDs before he finally got a player. Some of the source material was from the days before digital audio improved and people began to appreciate what was required for CD mastering. One recording in particular, a CD with Dimitris Sgouros playing the Rachmaninoff 3rd piano concerto, had some disturbing artifacts, although fairly subtle. He detected them immediately, despite wanting not to.
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