Dear Lewm: +++++ " many times that if THD had so much "meaning" in relation to lowering audible distortions in our audio system, then amplifier development might have ceased back in the 70s, with the advent of the Phase Linear 700 amplifier. THD was at least down to the 5th decimal place.... " ++++
I agree about and other that that amp design you name it was a very old one with several " faults " ( very old active parts and passive ones too. Deficientes ones. ) against today best SS amp designes there are good reasons why that " meaning " that you said tell almost nothing in reality exist and certainly has a predictable meaning in what we are hearing.
THD and other distortions as IMD or other generated elsewhere the system chain as: electrical impedance non-matched electronics in between or non-matched impedances between speaker and amplifier or between cartridge and tonearm or RIAA eq. deviations or TT unstable speed and several other kind in all cases all those kind of system generated distortions have a real meaning and always affect and degrade the audio signal.
That we can't detected it does not means did not affect the system quality performance level because it does.
Why can we detect easy some kind of generated ditortions as could be a on-matched cartridge/tonearm or TT speed unstabilty? because we all are trained to detect it. We recieve that training through our years of audio experiences, this kind of training was not " on porpose " one, we was not consciente of that training we just learned.
Now, if any one of us receive on-porpose training to detect almost any kind of system link generated distortion/coloration the we could be aware of many " things " that are happening and that we are listening that we can sware came in the LP grooves when in reality are added distortions generated in the system and that did not came in the LP grooves because were not in the recording proccess.
For the last 10-12 years I by my self received ( I'm still learning about. ) on porpose training to detect some kind of distortions that many of you can't do it and not because I'm better than you or because I have " golden ears " ( that I don't have for sure. ) but because I'm trained and I know exactly what to look for in any audio system when some of you do not know what to look for because you do not know how that " what look for " it sounds, you think is part of the LP grooves.
I posted all those in other threads, I have my own training proccess and my own " scientific " evaluation proccess. Each one of you can " invent " yours.
It's a fenomenal experience to be aware with almost 100% precision where are in any system its distortion problems and I don't said that from " out of my mouth " some of you already experienced some of those abilities that I acquired through many training years.
Of course that some of you already had a similar on porpose training to detect and be aware of different kind of distortions and can understand in full what I'm telling here and the ones that does not acquired yet those abilities is obvious that can't understand in deep part of my posts.
I give you one example: I can tell you in a " good " cartridge set up if overhang is on target against what other people could think is VTA/SRA unaccuracies. Both " distortions " are very similar but not excatly the same " sounds ". Btw, I learnede about by " accident " mading mistakes in my cartridges set up and I started to learn and " invented " a trainng/evaluation proccess to detec it easily where you can't do it with out know what to look for.
My, take is that because we can't detect distortions does not means does not exist, ceratinly exist and certainly always degrade the audio signal so lowering any kind of distortions at each system link always will improve our system MUSIC reproduction enjoyment.
Regards and enjoy the music,
R.
