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Tube vs Solid State - Comparable Output?

I know this is a terribly general question -- and maybe off the wall -- but is there any difference in a tube versus a solid state amplifiers' with comparable power ratings ability to generate high current? This relates to amp selection for current hungry low impedance speakers. Is 200w the same whether its created by tube or solid state? Someone recently told me that a 100w tube amp (Audio Research) was comparable to a 200w solid state amp in this regard. True or no? Thanks in advance.
jim
redkiwi
1,092 posts
 
I understand the theoretical differences which suggest solid state should be better than tubes in the bass, and ditto for low impedence speakers. But, in one of my systems, the best amp for bass, and for the Martin Logans and Thiels they drive is a tube amp. This is despite trotting many solid state amps through the joint (Krell, Classe, Aragon, Ocean, Lewitt, Plinius etc). I suspect the bass is better with tubes because the floor is suspended across spans of about ten feet - meaning it sucks bass somewhat. Using high-damping factor solid state amps the bass sounds almost swallowed. The tube amps (admittedly very good ones) have more realistic bass, with tightness, extension and air. I do not make this point to negate what has been said, only to point out that some situations prove to be the exception to the rule.
jim OP
418 posts
 
Thanks for the input, guys. I've recently purchased a pair of Martin Logan CLS II's (non Z version). Not set up yet due to a recent move. My McCormack DNA 1 Deluxe has done a good job of driving my Apogee hybrids and I'll try it out with the CLS's. Since the CLS's don't go to high Db levels or very low in the bass, my thought was that maybe something like a VT100 might do a better job in the mids and provide more air -- the liquidity of a good tube amp might be a good match for the transparency of these speakers. I guess the only way to find out is to try both. Audio Research is coming out with a MK III version of the VT 100, so there will probably be good deals available soon on MKII's. Yeah, replacing the tubes is a hassle and an expense, but if the sound is right I can live with that (I think). But I still question this amp's ability to deliver the required current to these very difficult to drive speakers (impedance can dip to .5 ohms). Thanks again for all of the information. Jim
albertporter's avatar
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albertporter
4,949 posts
 
There are speakers that present a difficult load at both ends of the (frequency) and impedance range. Soundlab Ultimate Ones are are an example I am familiar with. The are about a 30 ohm load in the deep bass, but only 2.5 ohms in the extreme highs. The power provided by most solid state amps is "halved" at each doubling of the load above 8 ohms. A 400 watt transistor amp at 8 ohms, would (in theory) produce 200 watts at 16 ohms and 100 watts at 32 ohms. This 100 watts of power this transistor amp is reduced to is made worse, as it is in the "power hungry" region of deep bass. In addition to that, the electrostatic panels are capacitive in nature, and have a fair amount of reverse electrical feedback that the amp must tolerate. A good tube amp, OTL or transformer coupled will often out drive even a huge transistor unit in this situation. I am able to play my Ultimates to almost live level in a large listening space, with a 25 watt SET tube unit. My point is the same as Redkiwi was making, there are situations that prove the exception to the rule.
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