2. amps-preamps
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a solid state amp that is recessed in the treble

i am a reviewer.

i have reviewed all components in a stereo system except a solid state amp.

i have heard some. they remind me of the novel, "dr jekyll and mr hyde".

what i mean to say, is that they do a good job, in the lower frequencies. however, somewhere in the midrange on up, probably above 1000 herz, they sound, hard, shrill, aggressive and unpleasant.

so, for me to consider a solid state amp for review, or even to purchase, as i have noticed, my tube amps warming up my listening room, i seek a solid state amp that sounds like it is attenuated in the treble, or seems to lack some detail in the treble.

i realize that for many audiophiles, i am looking for what may be considered very dark or veiled, but i would probably consider such an amp listenable.

any thoughts.

obviously i could call many manufacturers for advice, however, if there wer an amp that a number of listeners considered a bit lacking in treble extension, i would call the manufacturer and attempt to review it, assuming the amp was not already reviewed too many times.

your input is appreciated.

solid state amps have been a challenge for me , as i have not encountered any that i would want to own.

yes, i realize that a solid state amp will sound different than a classic sounding tube amp.

but, i may get lucky and find a solid state amp i can live with.

my speakers are the quad 57 and magnepan 1.6 .
mrtennis

Showing 2 responses by atmasphere

atmasphere's avatar
atmasphere
11,574 posts
 
The problem has three elements. If you have ever wondered why a tube amp and a transistor amp can have the same bandwidth but the transistor amp sounds bright here's why:

Our ears are tuned to listen for the odd ordered harmonics in order to determine the loudness or volume of the sound. When electronics distort these harmonics it will sound bright to us. BTW, our ears are also tuned to be the most sensitive to **bird song** frequencies, not the human voice!

Now when you add negative feedback to an amplifier you will subtly increase the odd-ordered harmonics. Most transistor amps (not all) use this technique to improve linearity. In addition, nearly all semiconductors have a non-linear capacitance that exists in the junction of their devices. This capacitance is also responsible for adding to the odd-ordered harmonic distortion.

Now the odd orders that we are talking about are very slight, but it happens that the ear is very sensitive to this issue.

Finally, on a speaker like the Quad ESL 57 or ESL 63, the speaker really prefers an amplifier that does not double its power as impedance is halved; both of these designs existed before such was common. So a transistor amplifier, if it is behaving like a voltage source, will be bright on these particular speakers even if no odd-ordered harmonic distortion were present. for more info regarding this phenomena:
http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php
atmasphere's avatar
atmasphere
11,574 posts
 
Another way to keep odd-ordered harmonics down in a transistor amplifier is to increase the impedance of the load.

(This BTW, is why there really is no argument for four-ohm speaker designs, not if the quality of reproduction is your goal- if **sound pressure** is your goal then have at it.)

The Quad is thus unsuitable for although its impedance is high at bass frequencies it is quite low in the upper mids and treble region. This is one of the reasons why ESLs and transistors usually don't play well together.
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