More Conversion Amp Projects

[straycat]

So interesting what you can do with this stuff Cyg.
I bet I have a Cyg amp one day.LOL

[Cygnus X1]

Going to post this one backwards.
They always ask for sound clips, I'll do that first, and backwards.
Never apologize for anything (is what they say), but there is a running high frequency noise on the recording that isn't coming form the amp, it's somewhere between the mic and the PC.
Too lazy to look it up, I just wanted to record.
It's in all the clips.

So here is the prototype Cyg-30 (I estimate the wattage).
2x6L6GC, 5U4GB rectifier, 2x12AX7, 12AU7 PI.
Iron is 1950's Masco power and Hammond organ output transformer.

Preamp is nearly the same as the Cygnus-7.
PI section is paraphase, output is cathode biased.

So, all in all, a little vintage, a little modern mixed in together.

High gain first:

http://www.soundclick.com/player/single_player.cfm?q=hi&songID=10488576

Clean:

http://www.soundclick.com/player/single_player.cfm?q=hi&songID=10488577

And dirt:

http://www.soundclick.com/player/single_player.cfm?q=hi&songID=10488575

There is anoise issue in the background beyond that mic problem, just some fine tuning to do.
But I feel the tone is there.
Guitar is Sinster's Gift, his homebrew LP loaded with Stephens Design VL3 Proto bridge and PF Star neck, rolled back to about 70% volume and tone (you'll hear the transitions).
High gain is all VL3 Proto bridge full on.

[Twitch]

So, is this a conversion, or a custom, or a little of both? Anyhow the lead channel sounds killer, is that full distortion? How bout some pics of the build.

[gtrlvr]

You Sir are truly a Wizard, That was pure tone, crystal clear. and you are right. the power is hiding just under the surface. But would it be like the old Marshalls and having to max them out to get a nice growl?

[Cygnus X1]

So, is this a conversion, or a custom, or a little of both? Anyhow the lead channel sounds killer, is that full distortion? How bout some pics of the build.

Thank you man!
Gutted a Univox 1236 50W bass head, so it's not really a conversion of that.
More like a fresh build using vintage iron from another couple of donors.
Power transformer from a 50's Masco PA amp, and output transformer from a Hammond organ.

Preamp is very similar to my Cygnus-7 high gain design (based on AX84 SEL), married to
a paraphase inverter style Fender Tweed Pro-Amp (5E5), cathode biased.
I was looking to duplicate the sound of the Cygnus 7 which is also cathode biased.
The theory is...build for great cleans, then tweak the gains from there.
I like a tight, dry, clear distortion and was concerned that it might come out loose, buzzy, and flabby
due to the fact I had to use a tube rectifier to fit the power transformer on hand.
Tradition tells us tube recto+cathode bias equals sloppy gain.
BUT...Traynor got away with it...why not try?


I think it achieved both goals and now is much quieter with some fine tuning on the grounds.
So what it really is...prototype higher watt version of the Cygnus-7.
"Production" could get pricey but not bad considering what other hand built amps sell for.
I have to shop for fresh transformers to make more.
I'm partial to Magnetic Components and Heyboer.

Will get pix up soon, doing some detailing.

gtrlvr...Thanks!
I'm no wizard, not in the least.
There are a lot of people around doing this kind of building, usually the first step to really learning.
Kit amps are a good way to learn also but I happen to like refreshing old junk too.
Some of my builds are entirely built from new parts (Cygnus-7).
The preamp design gives a lot of great distortion and I spent many sleepless nights getting the
Master Volume circuit just right.
It's three stages cascaded in to a cathode follower tone stack.
Not much loss in the circuit and very efficient.

[Cygnus X1]

Built into what was a Univox 1236 50W bass head.

Pix:





Gut shot of the original 1236 Univox:



And this is what it started as...not really a great sounding amp at all, I decided to gut it out and sent the parts to a Uni fan...

[Twitch]

Looks old school and your tube placement is unique, cool. Really wish I had the time and knowledge to do stuff like this.

[Cygnus X1]

Thanks T.
They had the tubes the same way.
Since I used the old gutted chassis all I needed to do was drill one for the rectifier.

[Cygnus X1]

I realized I never posted a shot of my stash from earlier this year.
(Axegrinder saw this mess and probably still thinks I'm off my rocker).
Check:


And helicopter shot:



Given that...

TIME FOR AN UPDATE!

OK, I'm stoked, really stoked...

One of those old organ amps is really a great stereo power amp.
Ever fall asleep, wake up, and in the "in between foggy time" yields an undeniable thought and destiny?
Well I guess all that great Thanksgiving food did that to me.
(I did something for myself, but it's just for today...)

First, a closeup pic...from upper right of the above.


Now here is what it is.
I don't know!
Apparently a pro grade Baldwin amp because I can't find anything about it amongst the many consumer organ amp forums or sites.
So it's (4) x 6L6, with (2) 12AX7 for the phase inverters.
But EVERYTHING is split, she is true stereo.
One to drive the pedals, the other for the "main".
The only thing that would be needed to make this a true stereo amp is equal output transformers.

As it is...close enough to drive with my stereo tuner, EQ, and the old Teac Model 2 mixer.
SWEET sounding, far better than the SS amp I have, and the separation is simply awesome.
So figure 50 watts per side through the 6L6GC's, into some inefficient but tough and good sounding PA speakers.
I'm in heaven for now.

[Axegrinder87]

I realized I never posted a shot of my stash from earlier this year.
(Axegrinder saw this mess and probably still thinks I'm off my rocker).

Actually, for a moment I thought I was in an adult toy store!!!

Awesome work as always Kevin!!!

[Cygnus X1]

Found a matching output transformer for the power amp.
(!!!)
What are the odds?
Right there in the stash, on another Baldwin.
Towards the upper left, the one with masking tape on the top.

Sounds...OK.
It also let me know I need to update the filter caps, but that's expected.
Other than a very slight underlying hum it sounds fantastic for fidelity and stereo separation.