I’ve tried no feedback amps and am dissatisfied with their sound (they were also Class A type).A lot depends on the load impedance and how the speaker is set up. To really get by without using feedback, the speaker has to be in on the idea. If not, tonal aberrations will occur. For more info:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
Hey Koss, measuring and counting is only for the doubters and haters like this guy -
http://www.pspatialaudio.com/LP_performance.htm
Why measure and count when you can simply BELIEVE.
Unfortunately, the article linked is a source of misinformation. The reason is the article lacks a listing of the equipment used. The most we get is a photo of a 70s machine, which maybe might be the same as the 'first class deck' mentioned (one wonders why this obvious omission was made- was he embarrassed by his playback apparatus?); no mention whatsoever of the phono equalizer(!), all of which have an enormous effect on the results, yet the results are construed to seem as if they apply to all LPs and LP reproducers when such obviously can't be the case.
Wouldn't you want to know what is possible, rather than the results of 1960s tech? Here is an example of what I mean:
The standardised groove geometry on an LP record is of a 2 thou* groove on a 5 thou spacing (the latter being based on 200 grooves per inch). As the diagram right illustrates, the absolute maximum modulation of a groove is ±1.5 thou which is equivalent to 76μm pk-pk modulation.The above statement is false- LP reproduction has advanced since the early 60s when this statement was more truthful. Cartridges of the period were horrific and variable groove spacing only arrived in the 1970s (and of course, without variable groove spacing you could simply set the lathe for less than 200 grooves per inch... sheesh!). We use 2 mil modulation as 0VU reference as we are conservative- our 'antiquated' 1980s Technics SL1200 equipped with a lowly Grado Gold (which we use to make sure that a cut we are working on will be playable by the garden variety machine) can manage 3db more than that without complaint; the upper limit is obviously higher than described in the above quote and that's with cheaper gear. Newer arms without engineering bugs like the Techincs arm can do even better.
On the flip side (if you will pardon the expression) it turns out that much of the noise floor in LPs has to do with the pressings, not the lacquers, of which the latter have noise floors that are easily in the high -80s or low -90s (since the phono reproducer itself is actually the noise floor if the cutter head and stylus temperature are optimally set). At least one pressing house (QRP, associated with Acoustic Sounds in Salinas, KS) has found that by eliminating vibration in their pressing machines during cooling, the noise floor of the LP surface is dramatically reduced, approaching that of the lacquer. None of the test recordings for this article were made on such pressing machines, as QRP has only had them working in the last 5 years or so.
I think that getting good measurements is great, but this article is an example of Bad Science- IOW fake news.