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how close in sound can a tube and ss amp sound ?

i have observed threads requesting advice regarding tube sounding solid state amps, within a price point.

i wonder how to confirm such a request.

in addition to recommendations, what about comparing a particular ss amp to a particular tube amp using an experimental design where bias, or preconception has been eliminated ?

has anyone tested the hypothesis that he/she cannot detect the difference between a tube and a ss amp, within the same power range, price point and minimizing interaction problems, such as impedeance mismatches ?

on the other hand if someone is seeking a tube-like sound out of a solid state amp, i would assume that one would use a "classic" sounding tube amp, e.g., cj mv 45, cj 75, cj 100, or cj mv125 as the tube amp and try to find a ss amp that is indistinguishable from the sound of the classic tube amp.

i have found that many ss amps differ with respect to bass and treble response from many tube amps.

in my own case, i would love to find a 120 watt ss amp which sounds like my vtl tube amp. unfortunately, i am not optimistic.

in other threads, some people have stated that it is impossible to find a ss amp that is "tube-like", in the classic sense.
mrtennis
timlub
1,649 posts
 
Hi Orpheus 10, If you ran your tubes into speakers that had phase angle dips, you'd find out real quick about the load. MOST tubes if on the right tap have no problems driving lower impedances, but I haven't seem tubes handle speakers that have deep phase angle dips and the combination of impedances and phase angles ends it. I'm sure some out there can tell you of a tubed amp or two that can handle it, but I haven't seen it.
orpheus10
5,988 posts
 
Unsound, the tube amp has a 4ohm out; which is what I am using, while the SS has no such option. Maybe that is what you are referring to.
mapman's avatar
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mapman
15,679 posts
 
I think Unsound, Timlub and I are hitting on the same point that there are many difficult load speakers as Timlub describes that few if any tube amps can handle properly. The result is tonal imbalance and often weak bass regardless of volume/loudness/watts.

Tube amps and SS amps tend to each mesh best with different speaker designs, so it is not possible to equate them based on watts delivered alone, even though a tube amp will likely remain listenable at louder volumes than a similar watt SS amp due to soft clipping and other aspects of how these amps perform.
unsound
6,115 posts
 
Orpheus10, if the load has a higher than typical numerical impedance (15 Ohms?) a ss amp would typically reduce power, while the tube amp would maintain power. Conversely if the load has lower than typical numerical impedance (2 Ohms?) a tube amp would typically reduce power, and the ss amp would typically increase power. That coupled with the phase angles mentioned above all have an influence on the amount of power an amplifier is able to provide. Don't let your experience with small sampling lead to blanket conclusions. It's possible your lower power rated tube amp is providing more power than your higher rated power ss amp into the load you provide them, but it's just as possible that with a different load the outcome might be reversed. Just to further complicate things, there are other design considerations that might subjectively lead you to believe one amp is more powerful than an other in a given system, but objectively wont neccesarilly measure that way. The numbers used in ratings taken out context, can lose context.
timlub
1,649 posts
 
Orpheus10,
I'm no tube expert, but I've built a whole bunch of speakers. When you look at impedance charts, you will many time see phase charts also. When you see phase dips, these are going into capacitive loads, when you see phase rise, these are going into reactive loads. Tubes like reactive loads. When a phase dips very capacitive, many tubed amps can handle it when the impedance stays reasonable, but when you have the combination of low impedance and a capacitive phase dip, most tubed amps don't stand a chance of driving this. No different in looking what happens to a solid states power output driving 16 ohms, where a tubed amp is typically quite happy. I know there are some hard core tube guys around that could answer this more thoroughly as far as how tubes react to phasing, but I would consider this one subject of major importance for any tube fan when selecting and amp and speakers.
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