Which power amp should I build?

[David Rad]

I'm intrigued by the idea of building a SET power amp, and I'm wondering if the GSG is sufficient for my needs.

I have Energy RC-30 speakers, sensitivity 89 dB (anechoic), nominal 8 Ohms, minimum 4 Ohms. I know that this sounds marginal, but: I'm listening at moderate levels, have a powered sufwoofer crossed over at 80 Hz, and plan to connect the GSG to the pre-outs of my Denon receiver. To put things in perspective, the power amp section of my Denon receiver is rated at 75 Watts (RMS per channel), and its volume control is typically at 40 dB below full scale.

Could a GSG work and will it sound good?

[Shannon Parks]

How large is your room and what type of music?

Shannon

[David Rad]

How large is your room and what type of music?

My room is large: 20 ft by 12 ft with a cathedral ceiling and hardwood floor. Music: both classical and rock, i.e. wide and narrow dynamic range.

My thinking is this: If I were to bypass the power amp section of my 75 Watt Denon receiver and use a 3 Watt tube amp instead, then the power drops by a factor of 25, so the peak volume drops by 10*log(25), which is about 14 dB. So the GSG would be 14 dB quieter than my Denon power section. Since I am normally running my Denon at 40 dB below maximum volume, I should be fine. Is this argument correct?

If I'm totally wrong here: what tube amp should I build?

[Geek]

Hrm... you'll need more efficient speakers to go SET

[Shannon Parks]

I think a little push-pull amp like the ST35 would probably work better for you with 14 watts a channel (note: I am planning a ST35 Rev E release in a few weeks). You could also build a Budgie SE which is 4.5W and a cheap build. It would be a dandy headphone amp if it couldn't cut it as the main amp.

Shannon

[David Rad]

Thanks for the feedback.