Jumping in. Console conversion to (possibly Vibro-)Champazoo

FXBDM 1832

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Hello everyone,

First of all, thanks to everyone for making this forum such a great resource. I have been reading and getting ideas from here ever since I started playing guitar a year ago.

Having been a DIY fan forever, I built a few guitars, one pedal, and now will be attempting a Tube Amp.

I usually learn better by jumping directly into the deep end, so I decided to do what most people here advise against, and build something from an old non-guitar tube amp. This is mostly due to me being pound foolish and penny wise, and also because I like making things complicated.

The donor amp is a Rogers console radio and phonograph. It has a 290-0-290 PT. A dinky little single ended OT, a 4 ohm 8 inch speaker, 5y3, 6v6, and three more tubes.
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Since I already have a Kalamazoo model one that I like, my plan on buying the donor was to follow my amp’s layout and build a ptp Champ. I also noticed that one of the other tubes was a triode with two diodes, so I figured I could use that triode to build a tremolo like the Kalamazoo Model two (which is roughly similar to the vibro-champ, as I understand it).

I don’t plan this to be a conversion job, I will strip out everything but the transformers and sockets and use new components.

So my first realization on starting the strip is that my three other tubes have Loctal sockets, which I will have to swap out most likely. The 6v6 is also probably dead, and the plastic center pin disintegrated in my hands.

So I removed all the big radio parts and now have much more room to play with.
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My reason for posting this thread is that I can be a bit careless with making my builds pretty, and sometimes I rush to make a project work and never complete the job properly. I hope posting updates will keep me honest until the end.
 

vintagelove

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Jesus look at the size of that power transformer...

Should make a nice amp. Lots of room to work too. I did a few of these in tabletop radios that came out really good. I used a choke in mine and they turned out extremely quiet. They were a 5c1 thing with a beefed up psu and star ground.

Have fun!!!
 

Mongo Park

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Looks like a great project, I enjoy a point to point build, many ways to assemble the parts. Killer looking transformer just waiting to power some great guitar playing
Hope you are not planning to use the parts you left in the chassis.
 

FXBDM 1832

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Hope you are not planning to use the parts you left in the chassis.
No, those will be coming out in step two. I might keep a few of the non-electrolytic caps to fool around in other projects, but I think this one I will keep only the transformers and octal tube sockets.
 

FXBDM 1832

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Schematic of the donor, not that I will be keeping any of it.
 

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FXBDM 1832

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And schematic of the Kalamazoo model 2. As you can see, it’s pretty similar to the Champ. Mine is a model one, without the vibrato. My plan now is to work on the schematic, change the relevant parts to make it a Champ (the Kalamazoo amp field guide provides a helpful list), copy my own amp’s layout and make the relevant changes there too.
Current thinking is to get the amp working before trying to add the tremolo.
I am also thinking that that I will have an extra socket just lying there after, so maybe I’ll look at reverb once the rest is working. Maybe not.
 

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FXBDM 1832

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We have a local electronics store (kinda like a big future shop) that has pretty much everything on hand. It’s wonderful.

My other idea would be to order a large set of 1/2 watt resistors on eBay. I already have pretty much all the 1/4 I will ever need, and a bunch of caps too. The high voltage caps might be a bit more expensive, I’ll look at your website, thanks!
 

FXBDM 1832

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Another option would be just to build a straight up AA764 vibro-champ without the Kalamazoo layout. That would give me something a bit more different from what I have now at the cost of (some) simplicity. The 5f1 seems better documented, for sure.
 

FXBDM 1832

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Managed to finish removing components in the chassis. Drilling out the Loctal sockets was a breeze. I am wondering if I won’t change the other sockets too while I am at it. They’re cheap enough to buy and I won’t have to desolder all the pins.
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while I was moving wires around, the insulation on one of the PT leads cracked. They all look pretty brittle. Can I just put some heat shrink tubing on top, or should I be looking at replacing the leads, whether up to the OT or just splice new wire to the stubs of the leads?

i also removed the speaker from the console. It’s more like 7 inch than 8, and I don’t know if it’ll work for guitar, it there’s only one way to know!
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Mongo Park

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The transformer leads have some coating on them. That is old and crispy I put heat shrink on them. If
You want to bend the wires I find if I heat them
with a heat gun, don’t over do it, they becom soft and movable. So I get them in the amp with the heat shrink already installed and then I can heat them individually and bend them to the final position before they cool to much They are also difficult to solder but doable
Good luck, slowly and carefully as they are old and arthritic but cooperate if you are gentle.
 

FXBDM 1832

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Some progress to report. First, I took a picture of my Kalamazoo's layout and marked it from the schematic.
unnamed.jpg


I then created that layout in DIYLC
Kal layout.png


And then converted the relevant parts to 5F1, using RobRob's amazing website as a source. I am still revising things, so if you spot a mistake, please let me know!

KalF1.png


I removed the heater wires for clarity and added a little note about heater wiring for the 6n2p tubes I just ordered. Next step is to measure the existing chassis and move things around so they make sense. I will have to drill the hole for the noval socket, so I have a bit of slack in how I can build things.

All the parts are ordered, but it might take a while, so for now I'll work on the cabinet. I really like the 1940s esthetics, so the rough layout will look like this:

cab.jpg


Unsure yet if I'll go with front controls on the bottom, or rear controls. Probably rear. I have a panel of baltic ply I'll be cutting and kerf-bending, and I am currently thinking about the best way to make the baffle. This will probably be a bare wood cab.
 

printer2

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Managed to finish removing components in the chassis. Drilling out the Loctal sockets was a breeze. I am wondering if I won’t change the other sockets too while I am at it. They’re cheap enough to buy and I won’t have to desolder all the pins. View attachment 943101 View attachment 943102
while I was moving wires around, the insulation on one of the PT leads cracked. They all look pretty brittle. Can I just put some heat shrink tubing on top, or should I be looking at replacing the leads, whether up to the OT or just splice new wire to the stubs of the leads?

i also removed the speaker from the console. It’s more like 7 inch than 8, and I don’t know if it’ll work for guitar, it there’s only one way to know!
I like the idea of heating the leads and to put heat shrink on them. I had one that was a little too brittle and they did not like me taking it out of the chassis. That speaker will give a great period sound being a smooth cone. It looks in good shape. Could you use the grill cloth and the dial plate in the design. I think it would look great together.
 

FXBDM 1832

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I like the idea of heating the leads and to put heat shrink on them. I had one that was a little too brittle and they did not like me taking it out of the chassis. That speaker will give a great period sound being a smooth cone. It looks in good shape. Could you use the grill cloth and the dial plate in the design. I think it would look great together.
The grill cloth I will probably reuse. The baffle was screwed inside the console , so I took it off intact, with the mounting bolts all already in place. Would be a shame to not reuse it.
The dial plate might be a bit trickier, especially if I want the chassis to be easily removable.
 

FXBDM 1832

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Cab Face ideas: the brown highlights are made from some 1/4 strips of oak I have lying around. The paler wood would be solid birch I also have.
TV
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Round
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Narrow panel
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