Little wing parallel stages/ Nasty distortion

[chopstuck]

I built Geezer's Little Wing with Hammond AO-44 iron. It's a fun project, small cheap and a little challenging. I dropped the EZ-81 and used SS rectification to get enough heater current to run two additional 12ax7's. I then dropped the incoming DC with resistors to match the EZ-81 internal resistance.

The circuit is basically a plexi pre into a 6BM8 push pull power stage.

Problem is I now have nasty distortion coming from the preamp. It's there even when the MV is turned down to 1 or 2. I have the first two stages parallel on a common 1k5 as in the schematic. I wondering if I need to juggle this stage or if the is a way to tell if the problem lies in stage 2 or 3.

Thanks

[10thTx]

Here is the schematic. I built one also with reverb. It did not have a nasty distortion at all.

with respect, 10thtx

[chopstuck]

Never mind, I fixed it.

This must be the psycho-ampo-therapy forum. Just putting problems onto the net helps me solve it, as if someone had asked me the very same question.

Was just a NFB set up problem.

I really like this amp. So much so I've built two of them. One with reverb and one without.

I can play it for quite a while through a Vox alnico blue with little ear fatigue. Still plenty loud through an efficient speaker though.

Next stop - more amps with 6BM8 outputs.!

[10thTx]

Well, if you're wanting to try another 6BM8 amp. I built this one also & liked it even better than the Little Wing.

With respect, 10thtx

soundclip here: http://www.soundclick.com/player/single ... i&newref=1

[Structo]

You guys ever use the triodes in the 6bm8?

[FYL]

You guys ever use the triodes in the 6bm8?

They are similar to half a 12AT7. Purrfect for a PI or a reverb driver or...

[Structo]

Well that is what I was wondering about, seems a waste to not use them but I wanted to hear if possibly it was a noise issue and that is why they aren't used.

[da Geezer]

You guys ever use the triodes in the 6bm8?

Structo,

If you look closely, you'll see that the 6BM8 triodes are used (in both schems posted by 10thTx) as the LTPI.
As FYL stated, similar specs as a 12AT7.

Geezer

[chopstuck]

Yes, I used the triodes in both my builds. Not terribly noisy that I can tell.
Tell me Jeff, Does your 56T amp use the reverb unit PT ? Is the preamp modeled after anything like a Sunn ?

[Structo]

DOH!

Just ignore me..........

[10thTx]

Does your 56T amp use the reverb unit PT ? Is the preamp modeled after anything like a Sunn ?

The 56T uses a WeberVST Deluxe Reverb PT & OT.

I don't know anything about Sunn amps. The 56T was based on DaGeezer's HoSo56 amp design.

With respect, 10thtx