2. amps-preamps
  3. 1427794264

Input sensitivity, Gain and Preamp matching

Friends,
I am considering to buy an SET amp which has an input sensitivity of 2.5 volts (rather high) and gain is only 14 db (probably low ?). The output power is 16 watts. My choice of preamp was going to be a pure passive using a Dave Slagle autoformer or at most a single stage tube preamp with only 6db gain. But with the specs of the power amp I am not sure if a low gain or zero gain preamp would be a compromise or not. Can anyone throw some light on this subject ?

The input impedance of the power amp is a healthy 47kohms.
pani
arnettpartners
312 posts
 
As I recall the amp's sensitivity needs to be about .5v. I tried a passive line stage with an amp having 1v sensitivity once with a poor result.

Just a guess that you need a higher gain pre as well, but others with weighty authority here can tell you.

I'd just scrap the idea of a passive pre altogether no matter what amp you consider. In the long run, I'm guessing you will not be happy.
mofimadness's avatar
mofimadness
4,933 posts
 
I'm sure Al (Almarg) will see this. He is the master at these type of questions. Whatever he says, listen to his advice.
atmasphere's avatar
atmasphere
11,574 posts
 
One variable in this is the speaker sensitivity. I assume it must be fairly high because it must be able to produce satisfying output by the time the amp has reached about 20-25% of full power or about 4 watts.

So in the average American home that means the speaker is likely about 103 db or so. But we don't know that for sure.

If the speaker is indeed that easy to drive, we are only looking for a fraction of the power of the amp so preamp gain does not need to be high. OTOH if the speaker has less sensitivity more gain will be needed.

So- what speaker is in use, how big is the room and how lively is it?
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