Can tube amps give true high end bass?

T_bone, as amfibious said, I was talking about damping factor. This has been one of the big discussion themes since the 70's, but apparently it keeps being ignored by most audiophiles. Regardless, it will always be important because it predicts how good is the amp's ability to generate a bass fundamental without the speaker circuit altering its amplitude. Why this happens? The question has to do with the current vectors created in a third order (or bigger) circuit, such as that found in all speakers. It's pure math, but you can measure it and of course listen to it. It manifiests itself as a "boomy" bass at a certain favorite band of frequencies which depends on how the speaker was designed, and how well (or bad) the amp can control it.

Why do I think solid state amplifiers have the advantage? Transistors are low-voltage, high-current devices, whereas tubes are the opposite, i. e. high-voltage, low-current devices. Virtually all speakers in production today are low impedance transducers, varying from 8 ohms down to 1 ohm. THEY NEED CURRENT TO WORK! By nature, they work best with transistors due to their lower output impedances, and better damping factors. Besides, in order to equal a solid-state amplifier current capability, you would need a battery of 30 or 40 tubes in parallel (remember Julius-Futterman OTLs?). That's why most tube design depend on an output transformer in order to compensate for the disparity between tubes and speakers. However, IMHO transformers bring even worst evils than they cure. They introduce even more coloration, hysteresis distortion, they attenuate the lower bass, they introduce phase-shifting, etc. The situation is just hopeless.

I have no doubt that somebody will say "But I like the bass of my tube amplifiers better than a solid-state's. They really kick in ________ recording!". That's OK. It's just a personal preference, a very romantic one... ;)

Regards,

Jmaldonado, thanks for the clarification. I guess I now have an explanation for why I like my tube amps vs others that I have tried on the relatively efficient woofers of my even more efficient speakers. I have thought about powering the woofers with solid state, but have thus far avoided it.

Another question back at you would be... how much tube power (watts vs output impedance) would one need to adequately power an 8ohm 96db woofer? say, the way a 40W solid state amp might...

+++Audiobb, I am surprised the 300B sounded better than the Cambridge consider the fact that you were using B&W 602+++

You shouldn't be.Tubes will give better mids and treble in variety of speakers.Regardless of impedance curves.We tested with few B&W (from 601 to 801D),Tannoy,Focal JM,Dynaudio etc.

+++Had you been using appropriate speakers, you may find your 300B capable of the same (or better) bass than the Cambridge.+++

I agree that,coupled with more tube-friendly speakers(8 ohmstable,93 db+),300B will improve in bass.But,according to our tests,Cambridge gives out more tight and precise bass.In my book,better and more linear bass.This is primarily caused by 2 things:

1.DAMPING FACTOR-Cambridge has couple times higher than SET amps.This can be improved with output trans.
2.PEAK AND RECOVERY TIME-Transistors are better than tubes there.Best are bipolar transistors.This is not my opinion,but plain fact.

For bass output,we have found transistors sonically better.BUT even better result still can be achieved with tubes-but it probably will cost sky high.See the previous post of Jmaldonado.But it still would never catch transistors in Peak and recovery time - which means not enough fast start and stop of bass driver.And for me it is essential.

Damping factor does not play much of a role in the sound of a speaker, previous posts notwithstanding! In fact damping factor is really a spec that gets touted a lot, but would seem to be mythological in its effects.

Damping factor is a means of expressing the output impedance of an amplifier. It is true that as the output impedance of the amp gets closer to the load impedance, that distortion rises, but the idea that the amp 'looses control' of the speaker is a myth, really a sort of chicken and egg thing.

In a conventional speaker, the voice coil requires a certain amount of power in order to displace the speaker. Any amp, regardless of its 'damping factor' that can make the power can displace the cone the same amount. At any and *ALL* cone positions that are possible, the cone will be in that position *because of the power from the amplifier directing it to that position*.

Note also that all bass waveforms (where 'damping factor' is touted as an issue) are real-world mathematical functions, and therefore continuous in nature. The are no worries about 'stopping' and 'starting'- unless you listen to some very weird, amusical stuff that no-body has made up yet :)

Most speakers if heavily damped will in fact not be able to reproduce the bass waveform. This is one of the reasons that high damping factor amplifiers tend to be bass shy, while at the same time having a sort of 'punch' but being otherwise bereft of bass definition and tone. Problematic, as amplifiers with a high output impedance can on some speakers fail to cut power in the frequency band where the speaker/cabinet system develops resonance.

How is this solved? It turns out that there are 2 paradigms of design, test and measurement in competition in the world of audio today. *IF* you mix equipment from one paradigm with that of the other, you will have a mismatch- it will not work right. see:

http://www.atma-sphere.com/papers/paradigm_paper2.html

for a more in-depth explanation of the differences in these paradigms.

BTW there are tube amps with full power to 1Hz and able to reproduce 20Hz square waves with no measurable tilt. This bandwidth has nothing to do with power or output impedance FWIW.

Atma

Most speakers if heavily damped will in fact not be able to reproduce the bass waveform.

A tiny clarification:
"overdamped" could be the result of a combined effect of driver & amp. I.e., if one uses a highly damped Lowther PM4 (x-max 1mm, flux: 24.000 gauss, quoted Fs= ~35Hz) for bass duty and drives this with a low output impedance amp, the audible low frequency result will be... inaudible. The amp-driver combo is over-damped (i.e. the electrical q is approaching 0 :) ).
This is just for the sake of example, no-one to my knowledge uses a PM4 for bass -- but I think it illustrates what atma is referring to.
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