The next one?

[FXBDM 1832]

Ever since the successful completion of my Vibro-Champazoo I have been keeping an eye out for used console radios to build my second amp. The objective was snagging a 2x 6v6 chassis for under 100 bucks with the objective of building something close to a 5e3. I saw a few pass by, but they either were 60 miles away or too expensive. I also spent some time reading and started considering grabbing a Single Ended 6v6 chassis to build something like an AX84 P1 extreme.
This morning I came across an offer for a console for $25 Canadian, 5 minutes off my commute. The offer was first come first serve so I drove and took it. I figured for 25$ if I get a usable speaker out of it I am good.
So I am now the proud owner of an Electrohome PC52-418.

The tube complement is not that interesting, 6k6 power tube, 6sq7 preamp, 6x5 rectifier and two RF octals. Still, there is probably something to do with that.
The Schematic seems to say 285v B+ which is somewhat low for a 6v6 as I understand it.
The speaker looks good though

So the way I see it, I have a few options:

a) harvest the speaker, sockets, OT and whatever else I can scrounge and call it a 25$ experiment, sell the tubes on eBay, wait for a better donor to show up. Pro: less fiddling around, less out of pocket cost. Con: where´s the fun in that?
b) Keep the tube complements and try to make a low cost low power early practice amp. Pro: original, mentally challenging, cheap. Con: uncertain results, I early have a 5f1 type amp and a Kalamazoo, so my Lo-fi practice amp niche is pretty full.
c) keep the octal theme but switch to a 6v6 and 6sl7s or similar for a better documented project. Pros: better documentation, still pretty inexpensive. Con: again, maybe too close to what I have, will the low B+ be a handicap?
d) keep the PT and the OT, move them to another chassis set up for the AX84 Hi Octane. Pro: pretty different from my previous build and other amps (although I do have a black star HT1r that does the hard rock-metal thing). Well documented (although with different transformers). Con: lots more expensive, needs some metalworking.

all in all, I think option d) is the front runner for now, but first things first, let’s open that baby up and see that the parts I want are working.

 

[NTC]

keep the octal theme but switch to a 6v6 and 6sl7s or similar for a better documented project. Pros: better documentation, still pretty inexpensive. Con: again, maybe too close to what I have, will the low B+ be a handicap?

Personally, I think the existing tube complement is IDEAL for a slightly lower power amp. See the 6K6 thread on the other forum. A 6K6 is a legitimate output power tube. The OT might have a bit high of an impedance for a 6V6. Characterize it if you have the equipment.

You could use the other octal sockets for one or two more 6SL7's and create a high gain, all octal amp.

 

[FXBDM 1832]

Personally, I think the existing tube complement is IDEAL for a slightly lower power amp. See the 6K6 thread on the other forum. A 6K6 is a legitimate output power tube. The OT might have a bit high of an impedance for a 6V6. Characterize it if you have the equipment.

You could use the other octal sockets for one or two more 6SL7's and create a high gain, all octal amp.

So something like that AX84 Hi Octane, but with a 6K6 instead of the EL84, and 6SL7s instead of 12AX7s? That sounds interesting. Frugal, low power, documented topology, but some adjustments to be made. intriguing.

 

[Mongo Park]

Yah octal up front, lots of variations on that the am, should be one to suit your tastes.

 

[FXBDM 1832]

Hmmm… you know, a 6g15 reverb unit has a 6k6 at +285.

 

[NTC]

Yes and the circuit can drive a speaker instead of a Reverb tank.

 

[FXBDM 1832]

I was thinking more along the line of building a 6g15 (or a Hoffman ReVibe) in this chassis. Let’s call that option e) for now.

 

[radiocaster]

The Schematic seems to say 285v B+ which is somewhat low for a 6v6 as I understand it.

If your scope is to have maximum headroom and volume, otherwise no.

 

[FXBDM 1832]

If your scope is to have maximum headroom and volume, otherwise no.

Just the opposite, in fact. I play in my living room and get dirty looks if I frighten the baby.

 

[printer2]

Nothing wrong with a 6K6 amp. Rather than use the tube rectifier, use SS diodes and it will get the voltage up a little. I mucked about with Jerry garrcia and we came up with a 6SJ7 as well as a 6SL7 two channel amp. He seems to like it. I still have to try something with the tone control but it is not your standard Champ. I have three chassis with 6K6's, well one chassis and a couple speaker and transformer sets. The 6K6 is not all that bad a tube. The speakers out of these also sound good for guitar in my mind. You could do a BF tone stack and reverb if you want. JG added a Tubetown reverb to his amp and says it works to his taste. It uses LND150 mosfets as the driver and recovery. The kit (no tank) is pretty cheap or if you are inclined you can just do their circuit on a perfboard. They have three mosfets but the first one is if you use it as a stand alone unit, you only use the two sections if you have a tube gain stage before it.

You might be able to use the PT for a SS diode powered 5E3 if you get a P-P output transformer. You got the sockets and use a Hammond universal OT. Use the 6K6 for it, I made one way back.

 

[FXBDM 1832]

The speaker seems nice, and it’s a 10 inch. I probably got my $25 back right there.

gratuitous gut shots.

those sockets are gigantic. They look pretty easy to work on.

 

[radiocaster]

Just the opposite, in fact. I play in my living room and get dirty looks if I frighten the baby.

You could also leave the whole power section intact (after changing the caps), 6K6 and rectifier and all.

Are you sure the speaker is not an 8"? I see an "8" on there. Doesn't really matter if you like the sound.

 

[FXBDM 1832]

You could also leave the whole power section intact (after changing the caps), 6K6 and rectifier and all.

Are you sure the speaker is not an 8"? I see an "8" on there. Doesn't really matter if you like the sound.

I suspect the 8 might be 8 ohms but will measure it to be sure.

 

[FXBDM 1832]

Hmmm. To complicate things a bit, it looks like early Valco 510-11 amps were running ~280v with an octal preamp and a 6v6. So looks like that’s my option C

 

[printer2]

I have two speakers that are 3.2 ohms and one that is 8 ohms. Two have cracks in the radial direction on the surround area. I think I may goop them with something. The other speaker looks like new. Many of these radios came with 10" speakers. I came across one with an 8" though, thought I got my fourth one for a 4x10, oh well. The lower voltages are what the tubes were normally designed to run at, 250V being a common voltage.

 

[FXBDM 1832]

Well, as luck would have it, I did run into a push-pull 6v6 one for $60.
So, now I have two decisions to make!

 

[FXBDM 1832]

12’’ speaker, too, although that magnet is comically small.

 

[FXBDM 1832]

My current thinking is to build a Marshall style amp with the push pull 6v6 (plexi 6v6 or something more like a JTM45) and a reverb unit with the other.
I already have a 5f1 style build, and an EL-84 Kalamazoo model one, so I can get dirty tones at low volume and a 5E3 sorta feels redundant. The Marshall would probably be used clean-ish (or into crunch territory when home alone) The one other thing that’s missing from my palette right now is a clean scooped blackface type, but I have my American Sound for that.

 

[FXBDM 1832]

Subject to me testing the various transformers and confirming impedance and voltage.