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

Showing 2 responses by pani

Thanks everyone for responding on this one.

My source is mostly analog. A Naim Superline phonostage. I am sure it puts out around 3 volts because my cartridge has an output of 0.5 mv fed into full MC gain of the phonostage.

My speakers are Tannoy Turnberry SE which are only 93 db sensitive (not 103 db). Currently I use a Wavac 300B SET which produces only 9 watts. On 70% of the music I do not hear compression in my room (150 sqft). But there is still 30% of the music which I cannot listen at my desired volume levels. The amp I am considering now has parallel 300B and produces 16 watts (conservatively) per channel. I know I will better with more power but if this is going to solve the power issue with say 95% of my music I am still happy because the combination of Tannoy and 300B SET is amazing.

BTW, isnt it true that a power amp should ideally run at full gain (not full power) all the time ? That is how one can get the best dynamics at any given volume level IMO. All studio amps have a gain control which are always kept at max level. My understanding was that the input sensitivity decides the ease with which one can get the amp to full gain.

Secondly there is this concept of voltage gain amplifiers and current gain amplifiers. Does that have anything to do in this discussion ?
Thank Al and Atmasphere. Yes, I am darn serious about keeping the speakers and your suggestion about getting more powerful amps is well taken. My hunt is on. And thanks everyone for the caution about matching passive preamp with the low sensitive power amp. It was an important tip at the right time.