Another Single Ended High Gainer

[Cygnus X1]

Wanker soundclip through a POS Mr. Microphone:

Arg.

Let me try again.

http://www.soundclick.com/util/getplaye ... 50711&q=lo

[flood]

Hey Cygnus XI, that looks fantastic and it sounds great too... any chance you could give me a tip or two with my own new mad SE build? details are posted in the thread here

nice work. congratulations

[Zippy]

I wired the 6SN7 to run parallel.

Next time I use a 6SN7 as a power tube, I will try a push pull configuration. That amp (and build) is long gone.

This schematic is the basic AX84, shown with a KT88.
I am running a 6550 in it.
I wasn't very clear about that-sorry.
Most all of the tone is in the preamp.
I have all my drawings and notes in Autocad.

Link to the schem:
http://www.ax84.com/static/sel/AX84_SEL_080729.pdf

So your amp is "close" to a Rocket pre - albeit with a 6SN7 in V1... One less cascade gain stage than the AX84 SE?

I'm interested to see your final schematic interpretation if you choose to share it.

[tweedeluxe]

Cygnus, assuming that you are using the OT on the schem - have you tried using 5k for the primary instead of 2k5?

From my calcs it looks like 5k is little high and 2k5 is a little low (for KT88). I would like to get your opinion on the difference in the tone.

[Cygnus X1]

Thanks all.

Again, I am using a 6550. Or a 6V6. Depends on whether I want clean Fender or dirt Marshall. The 6550 delivers the dirt with a better tone, the 6V6 has a better "Tweed" tone
for cleans or slight grind.

The preamps are both 12AX7's.

You guys are getting distracted by the second build-where I used a 6SN7 parallel as the power tube.
I still used 12AX7's for the preamps.
So the first-the prototype-is 12AX7's, and 6550/6V6/KT88/ etc. And so is this one.

I did not depart all that much from the AX84 SEL-just tweaked the values of the tone/couling caps. And a tighter power supply. I am using a full bridge recto setup instead of the half wave.

Schematic is available at the AX84 website, under "Classic Projects". I think.

[Zippy]

You guys are getting distracted by the second build...

No, just confused by the ambiguity.

Thanks for clearing it up. The link to the AX84 website worked for me.

Cheers!

[Cygnus X1]

Yes, Zippy you're right (sorry).

I'll take that as it is, I was a little too detailed in describing something I built before, and not this one.

I'd say go ahead and build it as is, then see if it suits you.
I played around with the coupling caps and tone caps to make it sound more natural, less "fizzy".

The first build sounded like a giant amplified super distortion stomp box to my ears.
I like heavy metal gain, but dang I want some clarity too.

[Structo]

Cygnus X1, what do you think is the biggest contributor of the fizziness in an amp.

I seem to be plagued with it on a couple builds. Done the ceramics across the PI plates, tried low pass filters on outputs of stages etc. with no real improvement.

I have my little 6V6 amp sounding pretty good now but on that amp there is some high frequency oscillation going on. It's very high freq, but enough to fatigue the ears after a while.
No scope here so I'm at a loss to where it is happening.

[Cygnus X1]

Structo,
I upped the bypass values a hair in the second gain stage.
I wanted to pass more signal and decrease the gain so I just went by ear.

I ended up increasing the resistance and dropping the cap value a hair. I would have to look everything up. I have stuck with it ever since. I believe it was something akin to going from an .047 to a .033.

Hard to tell because I broke the number one rule of experimentation-changing more than one thing at a time.
I also played with the cap values on the mid and bass tone stack.

One day after toying with it-it just hit.
It was right.
I was so happy I started to reverse engineer my own build just to see what I had done to make such a positive change in it.
Roight! Life gets in the way.
It's on build three and it still gives that same tone so it isn't just dumb luck.

I owe it to you guys to do my homework and look it up.

Fizziness?
Sometimes just swapping the preamp tubes is the trick.
Try an AT7 where you might run an AX7.
Single ended amps ARE touchy. Feed it the wrong tube, and you'll think something broke.

[Structo]

Thanks but this is on a P/P 6V6 amp bordering on plexi.....

I even changed all the couplers to Mallory 150's just to see if it was the PS orange drops contributing. Nope.

I think it is some kind of parasitic that is riding the signal.

The amp is very cramped with the board over the tubes so lead dress and proximity are not ideal.

[Cygnus X1]

I can't pretend to be the expert, Tom.
I did give it a lot of real estate-to give room for more
gain stages or effects loop, or a PP setup.

I also can state with confidence that my last two builds-conversions-were VERY tight, and it didn't take much to arrange the lead dress and grounding layout to make them sound good even at low volume.

One was a Spitfire, the other a 5C3 Deluxe.
I had a major WTF moment on the 5c3, shot myself in the foot. But in the end I still got away with a star grounding that sounded great.

All that I can suspect is look at grounding schemes, read, reread, and understand Aiken's article, and go for it.
It works, and well, just takes some time to grasp everything.