Posted by Matt Rogers on December 20, 2004 at 16:44:48:
In Reply to: Re: Cat JL2 100 watt stereo ... posted by Lew on December 20, 2004 at 11:40:07:
Dear Lew
Disregard Hernando. I did hear and measure the CAT. Using any amps with SL needs big power: forget about the first watt with SL - max power is what we need. No point in meauring the first watt here.
Like anything that we have posted here, they are only our opinions, or more correctly what I post here is my opinion. It is a matter of taking or leaving it. I do not have any intention to cast aspersions on anything or anyone. When something negative is said, inevitably they can be viewed as what you said "cast aspersion." Do you want to hear an honest opinion or not?
The CAT sells for "BIG" dollars. They should be good.
Like I have said. The CAT needs to have NFB to work properly, and I said that it did work well with NFB. Arthur Salvatory said it sounded better without NFB - so I tried it.
In regards to OPT - this is my philosophy: OPT should have wide bandwidth and no unsightly ringing when it is operating. NFB is something that designers use to improve that performance. So to begin with, if the OPT is made well, it should already have wide bandwith and no ringing. And when NFB is appiled, it improves it even further, and it also allows for lowering the output impedance and damping factor. It is possible to make a transformer without the need for NFB to have width bandwidth, low impedance, good damping factor, and no ringing - they are just hard to make and cost lots of money. So in my view, very well made OPT will work without any NFB, and NFB should be optional.
In the last two years I have been convinced that zero NFB is for me. The cicuitry driving the OPT will always cover that 10Hz to 150kHz bandwidth. The limitation has always been the OPT. I have found that NFB destroys the beauty of the music by taking away ambient cues and dimentionality. Yes NFB improves the THD from (let say) 5% to about 1.5% in a typical 200 watt amp, but what is measuring better always sounds worse to my ears in regard to NFB. I threw out the OPTs in my amps that needs about 12dB NFB and started custom winding OPT that produce wide bandwith without NFB and after several big attempts, I have achieved zero NFB in them with no compromise in bandwidth, damping factor, and low impedance. There is no looking back. Unless you have heard well made zero NFB amps you would not know what I am talking about here.
The problem with SL speakers as we all know, is that they need big amps. And big amps are hard to build without NFB. I started understanding the benefits of zero NFB after listening to many SET designs in my friends home. Because SET is easier to do without NFB, I have listened to many without NFB and all of them have that extra magical quality. As soon as feedback is added to improve the bass or impedance, the sound got worse. And for that matter, SET that is designed with NFB always lose that magical quality. I believe the beauty of SET amps that many are raving about is in the very low or zero NFB that could be achieved with them.
Unless you have heard the benefit of zero NFB, you may not understand what I am trying to encapsulate in a few paragraphs. It is best heard than explained.
Cheers