Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

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figgypudding18
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Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by figgypudding18 » Thu Mar 25, 2021 12:35 pm

Hi everyone,

I have an AmPro Jazzmaster. It does not have the rhythm circuit. I researched like crazy before I bought it, but didn't realize how I would really like to have the rhythm circuit as a feature as I sometimes prefer the darker/jazzier sound. I did replace the pickups with Lollars and changed the pots to 250k, but I am really wishing I had the rhythm circuit.

Is it possible to install a rhythm circuit and give it the traditional vintage-style wiring? If it is, is this practical?

My instinct would be to sell it and grab an american original at some point, but now that pretty much every guitar on earth is out of stock right now....

Thanks all!

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bodhi
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by bodhi » Thu Mar 25, 2021 1:49 pm

Really depends on if the guitar is routed with the cavities for the controls or not. I think there might be a previous post on this topic or at least for a similar guitar type if you search a bit, where someone ended up routing out the body a bit to fit the stuff. Then you probably need to cut or get a new pickguard for the controls themselves and their screws.

If the guitar plays well, then maybe go for it. If it doesn't, you probably want to try to find a keeper first before considering these kind of mods rather than getting something with those already available.
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HarlowTheFish
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by HarlowTheFish » Thu Mar 25, 2021 2:45 pm

You could go for stacked pots with the right values, and a switch to activate it. It'll probably be a bit of a hunt to find the right values for them, but it shouldn't need any routing and will only need one hole for a switch on the pickguard. Concentric will get you the two separate circuits with separate controls, while a dual-ganged but single-shaft pot will get you both circuits running different pot values but with the same knobs.

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adamrobertt
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by adamrobertt » Thu Mar 25, 2021 3:39 pm

Pretty sure these are not routed for the rhythm circuit. It can definitely be done, of course, but not without modifying the body.

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timtam
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by timtam » Thu Mar 25, 2021 8:46 pm

EDIT: The upper rout on the Am Pro I JM is for the re-located 3 way toggle. Would need enlarging for the rhythm circuit, and a new lower rout for the toggle.
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bodhi
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by bodhi » Thu Mar 25, 2021 10:13 pm

HarlowTheFish wrote:
Thu Mar 25, 2021 2:45 pm
You could go for stacked pots with the right values, and a switch to activate it. It'll probably be a bit of a hunt to find the right values for them, but it shouldn't need any routing and will only need one hole for a switch on the pickguard. Concentric will get you the two separate circuits with separate controls, while a dual-ganged but single-shaft pot will get you both circuits running different pot values but with the same knobs.
Stacked dual audio taper 1M pots are available, I have a few for a build that didn't cost all that much more than a normal pot. If you want 250k pots then it should probably be even easier to find, but mixed sets are more of an anomaly. Depending on the specific target, you could get by with adding extra resistors across the lugs, but that will affect the taper. However, considering that a linear pot gets more of an audio taper with extra resistors, that might be a good thing...
Jazzmaster project (got a body, placeholder neck, some pickups and ideas)
Tokai Telecaster Thinline with Creamery Pickups Filtertron and Tapped Tele
Blake Mills-inspired Strat project w/ Gold Foil and slide pickup

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hexes
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by hexes » Thu Mar 25, 2021 11:08 pm

are you handy with a router? I modified a classic player jaguar for the rhythm circuit with zero issues. if you're not, may be worth finding an accomplished woodworker near you. it took me all of 30 minutes and I went very slow.

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figgypudding18
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Re: Installing Rhythm Circuit into AmPro JM...possible or a fool's errand?

Post by figgypudding18 » Fri Mar 26, 2021 4:11 pm

Nope...but this is starting to sound like more work than I'm up for right now...I think I will sell and grab an American Original or something at some point.

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