Two Stroke Amp - too quiet !!

[maxfac]

I've built the Two Stroke amp as a head from The Tube Amp Handbook (Dave Hunter) it sounds ok but just lacks volume, I wasn't expecting (or wanting) it to be very loud but comparing it to my Blackheart BH5 head through the same cab its a lot quieter even with 2 x JJ 6v6S running in parallel. On the face of it they would seem to a noob like me fairly similar amps, both 1x 12ax7 preamp and cathode biased, single ended Power amp, I can't get over the difference in volume though. I'd appreciate any thoughts as to why this should be and suggestions as to how I can squeeze some more volume not necessarily gain from the existing layout.

[ampgeek]

Hey Max,
I am not familiar with the two designs that you referenced.
However, if the 2Stroke sounds decent otherwise and the tube voltages are all reasonable, I would take a close look at your OT.

An impedence mismatch might explain low output volume on an otherwise good sounding amp.

Try pulling one of the parallelled output tubes and playing for a short period. Higher or lower output in that condition?

Good luck,
Dave O.

[Phil_S]

Bad wiring job, missed ground, misconnected parts, wrong value (100K vs 1M) etc. Lot's could account for lack of oomph. One more time...get out the schematic, make a photocopy, and trace every part and wire to be sure it matches. Write all over that schematic as you do it to verify where you've been over it. Eventually, you will find the error. This is tedious but necessary. I heard the clips of this amp and it should give you some oomph.

[maxfac]

Hey Max,
I am not familiar with the two designs that you referenced.
However, if the 2Stroke sounds decent otherwise and the tube voltages are all reasonable, I would take a close look at your OT.

An impedence mismatch might explain low output volume on an otherwise good sounding amp.

Try pulling one of the parallelled output tubes and playing for a short period. Higher or lower output in that condition?

Good luck,
Dave O.

Hi Dave
Thanks for pointing me in the right direction, I had soldered a jumper across the two speaker outs in an attempt to make nfb switchable whichever one I decided to using not realising I would also be shorting the taps together, What a dork eh!!! Thanks again. If ever you're in the UK I owe you a pint of our lovely warm beer.

Cheers Andy

[maxfac]

Bad wiring job, missed ground, misconnected parts, wrong value (100K vs 1M) etc. Lot's could account for lack of oomph. One more time...get out the schematic, make a photocopy, and trace every part and wire to be sure it matches. Write all over that schematic as you do it to verify where you've been over it. Eventually, you will find the error. This is tedious but necessary. I heard the clips of this amp and it should give you some oomph.

Hi Phil
Problem sorted, wiring ballsed up as we say over here (see reply to ampgeek) Thanks for encouraging me to look at it again. Another warm beer coming up??

Cheers Andy

[ampgeek]

Great news Andy!

Yum......beer....I will take it at any temperature. Maybe we could chase it down with a small snort of highland single malt while we are at it?!?

Cheers,
Dave O.