Isolation for tube amps

Fla, the various Promitheus TVC models are all minimalist designs and none of them have a remote volume control. That's not a problem for me personally, but I understand that many others feel very differently about the importance of remote control.

The Promitheus TVC I am currently using is the Reference model dual-box pure dual-mono unit built around the Promitheus rev 3 EI-core transformers. The Signature TVC that I have ordered is an identical dual-box configuration using much larger double C-core transformers with very fine core laminations. The dual-box TVC design consists of a separate chassis for each channel, such that the right channel signal is completely decoupled from the left channel signal. Each box (i.e., each channel) has its own input selector and volume control.

I lived with the Lamm L2 preamp for years, which also uses a separate volume control for each channel. As long as the volume control knobs have distinct "clicks" as you rotate them, it's not a problem to keep the left and right channels at the same level of attenuation. You just count the clicks as you turn the volume up or down.

As for the Living Voice speakers, I am very pleased with them. They are very musical, non-fatiguing, well integrated two-ways that have paired up very well with my SET 300B monoblocks. The LV speakers render the timbre of acoustic instruments in a very natural, relaxed manner. The speakers also have a big, dynamic, weighty sound that is amazing given their diminutive size. The treble is a bit laid back and very refined - basically, just what you would expect from a first-rate soft dome tweeter (i.e., the ScanSpeak Revelator).

The LV speakers pair very well with tube amplification. Your music preferences, the size of your room and your preferred listening levels will dictate how much power you need to drive them. In most situations, I think you will want at least 10 high quality tube watts per channel to drive the speakers most effectively.

Keithmundy, sorry for hijacking your thread. Fla, if you would like to continue the dialogue, we should probably move the discussion over to my SET virtual system thread:

http://forum.audiogon.com/cgi-bin/fr.pl?vscnd&1187064942

Keithmundy, to revist you initial question re tube amps.......

I enjoy all of the responses folks provide regarding how one deals with vibrations. Most, if not all have some basis in theory but I'm amazed at the disconnect between the theory and pratical application of the theory in audio systems. Especially with amps.

Few ever discusses when the amplitude of the vibration under discussion reaches a level when, and with what equipment, it become an audible problem and when the proposed solution actually reduces the sonic distortions caused by the vibrations.

With airborne vibrations its fairly obvious that at low levels, frequencies even those which might interact with the reasonance points of other components (including room stuff) are not audible to the human ear. At some level they will become audible and the question becomes 'what can reduce that specific problem area' at that level. Something that damps a vibration effectively but only when the vibration is at an inaudible level are IMHO worthless except to 'analites'. I think many products fit into this category.

I'm not trying to start another (endless) war on this subject but I would like to suggest that folks (other than salesmen) apply some critical analysis and engineering principles before spending a lot of money trying to solve non-existant problems with generic 'solutions'. This is truly one of those areas in audio where its based in science, not a what 'it sounds good to me', applies.

BTW, and by way of illustration, IMHO, mass loading of the transformers of any amp, especially tube amps, will help damp the sound of transformer vibrating itself, and it will also change the level and or the frequency of the vibration that actually reaches the tube. To the extent that mass loading actually affects the vibrations of the tube elements I don't know but its at least as good as throwing salt over your sholder. You've can't lose much. Its cheap.

Tube dampers will damp vibrations in the glass that can help damp some tube microphonics (depending on vibration frequencies, resonance points of the glass in the tube and in the elements) but I'm not sure that the dampers will prevent airborne vibrations in a critical frequency from passing thru the glass of the tube. Again, some tube dampers are better than salt and cheap, so why not. But before I bought expensive dampers I spend my money on very low noise tubes tested for microphony.

Just some personal thoughts some folks might like to think about. Maybe I'm just whacked out - no need to tell me though. :-)

FWIW.

As you mentioned, another room is the perfect solution. All else will disappoint. However, building a screen of Tandy ( Leather Stores) 'pound o board' is a cheap and very effective solution. The only more effective is lead wall paper, toxic and expensive.

Wow gentlemen! thank you for your amazing insight. That's a lot of information to chew on. I really appreciate you all taking the time to put together such thoughtful and thought provoking responses! This is one area where I think the industry is coming up short on. I plan to continue expolring this vibration/distortion relationship. Thanks again for all of your input - very good!

Another thought on the subject.....I used a RS dB meter and sampled different frequencies around my room. I found that some areas had much lower sound levels at different frequencies than others. I had to use longer ICs, but placed my rack at the lowest "loudness" position. I also placed the amps on stands nearer the midpoint of the wall behind the speakers because this was the "quietest" place. I then mass loaded the mono amps and used points on the bases through the carpet to the concrete floor. Does it help? I think so, and it cost nothing.