Low output from Ruby build...

[armstrom]

I built a standard ruby amp and while everything "seems" fine when I attach it to the speaker I chose I get really low output.
I picked up a Jensen MOD 5-30 8Ohm speaker (here's the spec sheet) http://www.tubesandmore.com/scripts/foxweb.dll/moreinfo@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?item=P-A-MOD5-30

So, I tried the amp with a Jensen MOD 8-20 4Ohm speaker I had lying around and it was louder.

I'm not sure what the efficiency of the MOD 8 is (no data is given for the 4 Ohm version, but the 8 Ohm has an efficiency of 93.2dB, I'm not sure how much that can tell me though). So, does a difference of 1.7dB really affect things THAT much? I built the amp with the LM386-1 and am running it at 9V (battery). I have some 386-4 chips on the way. Can I expect any better results?

-Matt

[narov]

I had a Low output Ruby, and couldn't figure out what the hype was about this amp, but then I replaced the FET (same type) and it greatly increased the output level and sounds good.  The first one was somehow lowering the signal levels.
Something to try.

CV

[armstrom]

Thanks, I'll give that a try as I have a number of MPF102 fets. I didn't bother to try that  as the output on the 4Ohm speaker was somewhat decent (not great though). Granted, I'm not expecting to be blown out of my chair by this thing, but with the 8Ohm speaker I couldn't hear the speaker over the strings of the solid body electric guitar without the gain and volume all the way up!