Tube vs Tran

Here's a link about damping factors:

See http://en.wikipedia.org/wiki/Damping_factor

Measured square waves are not relevant to damping because of the interaction of the speaker and cable is also part of the equation.

Dave

Back to the original question of why would anyone ever buy SS when tube "sound so good". Many speakers benefit from the extremely low impedance at SS amps which causes a high damping factor.

Basically the damping factor rates the amps ability to control the physical ringing of speakers after a note has sounded. If you switch out amps while listening to a passage with lots of bass content, it'll be very obvious as you move from a low damping factor to a high damping factor or vice versa.

Vienna Acoustics, DALI and Sonus Faber are examples of speakers that are really designed to work best with a high damping factor and relatively high power.

Tube amps are sometimes described as having "woolly bass." This is probably because they were paired with a speaker that needed a much higher damping factor. Relative to tubes, SS amps tend to have higher damping factors, but they're not all equal. The Jeff Rowland 501 monoblocks have a damping factor of like 1000 into an 8 ohm speaker. That's very high (and you hear it) but a damping factor of 100 or 50 isn't unusual for SS amps.

Generally, if you hear a speaker with a woolly, ringing bass, it'll very likely benefit from being driven by a SS amp with a high damping factor.

Dave

03-26-08: Rwwear said:
"I agree that damping factor has some effect on the poor bass of most tube amps. But wooly bass can mostly attributed to the hundeds of feet of wire in the output transformer. This is not always the case but the main reason."

"Wooly bass" isn't just a tube vs. SS thing. Last week I heard a Primare integrated driving the DALI Helicon 400Mk.2 sounding unacceptably wooly. It came under control when we put in a Rowland Capri/102 combination, but it really started to shine when the Rowland 501 monoblocks were switched in.

I think it's a combination of damping factor and watts. You can have a relatively high damping factor, but if it's combined with low wattage and big drivers in the speakers, then it can still get "wooly."

Bi-amping a big speaker is a great way to get control of the woofer(s) while optimizing the "liquidity" of the mids and treble. You can combine high watts and damping on the bottom, separate the signals so they don't muddy each other and free yourself to maximize the euphonic character of the mids and highs with tubes.

Dave

03-26-08: David12 wondered:
"I just wonder how many people go from SS to tube, or tube to SS. My suspicion is, once you have tried tubes, for most of us, there is no way back. Nor are tube amps wooly and soft, my tube integrated is lightening fast, quiet, uncoloured with deep base. It is more than $3000 though. If I was going for an integrated in that price range,..."

As with any component I suspect the answer will vary widely depending on associated equipment, particularly speakers. I can't imagine using tubes with Vienna Acoustic Mahlers after hearing them driven by Rowland 501s or a Rowland 312. However, there are speakers that are going to sound just peachy with tubes, even low powered tubes.

BTW, I LOVE tubes with my headphones. My single-ended, class A Woo Audio WA6 with GZ34 rectifier tube is magic with all my cans. There's an example of a perfect application for tubes.

Dave