preamp vs amp: relative effect on sound?

Most designers of solid state amplifiers seem to strive for minimal or even zero feedback. Feedback is treated as a negative, something that should be avoided at all cost. Your remark seems to suggest sufficient amounts of feedback are required to reduce distortion. Then why would most solid state designers try to avoid it?

@edgewear  They don't. Solid state amps that eschew feedback are quite rare!

There are too many variables. You can't lump all solid state in the same basket; some are harsh and bright no matter what you do. The brightness and harshness is the result of distortion; the ear assigns a tonality to all forms of distortion. In the case of solid state, the distortion is higher ordered harmonics which the ear uses to sense sound pressure so its keenly sensitive to their presence, even though on paper they appear to be 'negligible'. They are not.


If the amp is able to employ enough feedback and for the record most are not, it will be able to get rid of most of that annoying distortion. But 99% of solid state amps out there have this problem.


Solid state preamps often have this problem as well. Again in a nutshell, if the circuitry in the preamp is discreet, its likely that it will not have enough feedback to control the higher ordered harmonics and so will also sound bright even though its distortion on paper is quite low.

So if you're going to involve tubes to get around this problem you'll want to use a tube preamp, since the brightness of a solid state preamp can be reproduced by any good tube power amp.


There are solid state preamps that are based on opamps. These have the possibility of not being bright if properly designed (i.e. not asking too much gain out of the opamps; 20dB is about the upper limit with most opamps; this leaves enough gain bandwidth product to prevent distortion from causing brightness). If you have a preamp like this then a tube power amp could be used, or a solid state for that matter.

One tip: most amps sound decent at low volumes. Its when you crank it up that the brightness (if its there) becomes unpleasant! The mark of a good system is that it remains relaxed at high volumes such that you can't tell how loud its playing. IOW if it sounds loud that's bad- move on.