I do understand that there is a real audible benefit of vacuum tube amps. And I think there is a real reason for it, even though it sort of flies in the face of Ohm's law. But my belief is that vacuum tubes, which are voltage-based devices are just more suited to audio signals than transistors, which are current-based devices. And in the case of double-sided (push-pull or push-push) solid state amps, there's that nasty business of the barrier voltage in the zero crossing area. Of course, the other side of the problem was building (and later lifting) output transformers with enough iron in the cores to efficiently couple the low frequencies.

I agree with you concerning the psychoacoustics of audio perception. In fact, if you go the site I referenced, I’ve said exactly the same things about dynamic range, loudspeaker efficiency and power requirements. That’s why I believe in efficient loudspeakers and amps with plenty of reserve power. That’s why I don’t endorse low power SET amps unless you’re driving headphones. I also generally agree with your comments on distortion - certain types of distortion are more audiable than others. My tube type amps are rated at full power at 1% THD/IM - a figure that is terrible compared to the best solid state amps (but they “sound” better.).

Like you, when I played LPs and cassettes, I unapologetically used extensive signal processing to overcome the deficiencies of the media. I used a dbx 3BX expander (to my knowledge, the best expander ever made) to increase dynamic range. I used a Carver “sonic hologram generator” to increase channel separation and broaden the soundstage. To combat noise, I was scrupulous in keeping my LPs pristine - a cleaning machine, Polonium based anti static brush, and even a Burwen pop and click remover on occasion. And when I transferred LPs to cassette to minimize wear on the LPs, only using them for critical listening and cassettes for casual use, a used dbx (2:1 compression) on the cassettes.

I don’t do any of that any more. I sold all the signal processing paraphernalia and listen to CDs, which I can play any number of times without degradation, and they are DEAD QUIET - I can place my ear in the speaker cone with the amp gain wide open, and it is completely silent. The system end-to-end S/N is close to 90 dB, the frequency response is dead flat and the channel separation is probably close to 60db - the result is an ultra-wide soundstage.

Regarding room equalization, I used to do that also, but I don’t anymore. Why? Because once you get past the basics of a fairly linear mid and high frequency response by perhaps changing the listening room furnishings or speaker placement, you are left with the issue of standing waves at bass frequencies, and no amount of equalization can address that. I build loudspeakers at are flat within 3db from 20Hz to 20KHz, tested in an anechoic environment with the best Bruel and Kjaer Mike you can buy. What I can do is change my seating position within the listening room, which can certainly make a difference in perceived bass. In short, straight from the CD player to the amp. No preamp, just a passive remote controlled level control for loudness.

Now, thanks for the interesting discussion, and let’s get back to the OP’s original topic!

OMG Trix, I know I said I would stop, but wow! I have either owned or are familiar with every piece of sound modifying equipment that you mentioned. A friend of mine owned the Burwen, and used judicially it worked really well. I still use my dbx compander to enhance the dynamic range of vinyl and tapes. My speakers are equalized to match my room characteristics and my listening position is just inside the standing wave intersect. But, because, the position of where that standing wave would be at maximum, my room is open to a stairway and to two other side rooms, it really doesn't develop the amplitude that it would in a standard rectangular room. Okay, thanks for the discussion, now I'm done!

Thanks. I kept one 3BX expander and a dbx 224 encoder/decoder for those occasions where I listen to (dbx encoded) cassettes copied from LPs, and I have found one really good use for the Carver. With headphone listening, it moves the soundstage in front of the listener, rather than in the middle of the head, which I find more pleasant. I don’t listen to headphones much. I have a pair of the original Koss electrostatics which are heavy and uncomfortably tight, but the come with an individuals tested frequency response curve printout for each earphone, and they are remarkable transducers (from the 60s) that are dead flat across the audiable range. Too bad they are not more comfortable. The Burwen (which was also sold under the KLH label) as a TNE 7000 could do remarkable things with large defects, such as a scratch, but not a lot of help with low-level noise. It would detect a very fast transient, such as a scratch, and mute that channel, filling in the missing space from content before or after the scratch. You can actually run a knife across an LP, and the Burwen will make the deep scratch almost inaudiable. Obviously, audiophiles don’t intentionally subject their prized possessions to such abuse, but for a scratched vintage LP, they’re useful at some expense of intentional fast transients such as percussion.

Cheers,
Chris