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Discussion in 'Shock Brother's DIY Amps' started by ArcticWhite, Aug 4, 2019.
A pair of 12AX7A's, one 6AQ5A, and a 5Y3 rectifier. Neato.
What do you mean curb find? Like take me I’m free? Or for sale. It’s cool for sure. But we need details
Free section on Craigslist.
This thing is nuts.
It's a reed organ with an electric fan, and the amplifier simply amplifies the reeds. So it's a loud accordion that you don't have to pump.
The microphone. Naturally, I turned it on and using my best airport intercom voice, I paged my girlfriend - who was watering the front yard - to the nearest courtesy desk.
It seems she lost a big bag of Marijuana and someone turned it in for her.
The microphone tone is something like an AM radio through a vintage telephone. Lofi and I love it.
The volume pedal simultaneously operates the amp volume, and opens the breather valve on the reed box.
I hooked it up without the amp and it works fine. I may put a plug on the Reed and keyboard assembly, and turn it over to my neighbor's kid. He's four.
The amp has a built-in vibrato.
It's almost a guitar amp already.
I need a schematic, bad.
I don't want to gut it, just want to add an input jack, a tone stack and tweak it a bit.
The Amp Chassis number is 157.10000
An Internet search comes up empty..
My family actually bought one of those for us for Christmas 1966. Loved it.
Excellent score. You can take a look at a thread I made also. Silvertone reed organ with a 157.47210 amp inside. Like yours it was a curb find. Mine has a 6v6gt instead of the 6aq5, and a 12dw7 on the first stage. I’m pretty sure I’ve seen info on the one you have here. Just keep looking
Silvertone 4721 Reed Organ Amp, With Real Pitch Shifting Vibrato
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Maybe close to this one? Ground missing on third triode.
An idea to make it more guitar-like.
I am super happy your girl was able to recover her giant bag of weed.
That looks like fun. I'd just play it as an organ and not "mess" with the amp, but that's just me.....it's yours to do with as you wish.
Craigslist is loaded with free organs.
You could fill your house with them once a month. They are WORTHLESS.
This one is basically a toy instrument built in 1966. It makes bad sounds. It is a piece of crap. It has ridiculous keyboard action.
No one is listening to amplified reed organs. It is not a wurlitzer.
Do you want to buy it? Send me 100 bucks, plus shipping and it's yours.
No pitch shifting in this one, unfortunately. Looks like a completely different amp.
Single 6AQ5 power tube. No varistors to be found .
I may try to reverse engineer a schematic this evening.
hey, maybe you can use the reed thingy to make a talkbox.... rocky mtn way....
You have the right transformers tubes (close enough) and probably chassis and speaker to build this....
It’s actually a great sounding amp for guitar. Harmonica players love this one.
I tried to look at the schematics in that thread, but they're not viewable without permission from some image hosting site. I have a diyaudio account already, so that isn't the problem. Applied for permission but never heard back..
Maybe my spam folder. Ah well sooo..
I spent several evenings working out a reverse engineered schematic.
Which was waaaay harder than I thought it would be.
My first draft looked like a plate of spaghetti. Second draft looks like a layout drawn by a third grader, but it allowed me to make some sense of the thing. Third draft ain't too bad.
Note that the first gain stage uses grid leak bias. Also that the tremolo works off of V1b only, which I think is an unusual position. I kept looking for a second tube to get involved.
Is it odd to find there are three gain stages in a low powered toy organ?
At some point, I may tear it all down and build the Kalamazoo 2 that Bender suggested. But for now, I'm curious about the super strange tone stack. One setting is for "Flute" and the other is 'Strings". Flute is bass heavy and muffled, while strings is trebly.
Mods So Far
I've pulled out the microphone and put in a jack with a 39k grid stopper, and a 1 Meg grid leak resistor because that's the biggest one I have right now.
I bypassed the tone stack with a jumper, and the volume doubles and gets super crunchy.
Questions for the board:
Where do I put a jack for a tremolo footswitch?
V1a is grid leak biased. Should I do the same for the next stage (V2a) ?
Sorry, haven't been around.