Princeton reverb micro power circuit

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DSones
Posts: 5
Joined: Mon Jul 29, 2024 12:58 am

Princeton reverb micro power circuit

Post by DSones »

I'm working on modifying a fender princeton reverb amp to use Rob Robinette's princeton micro power circuit. The goal is to have the reverb with the 1 watt power output. I can't find a classictone 40-18027 power transformer so I will use a hammond 270CAX 500v CT 81ma 6.3V@2.5A HV center tap 5V@2A. This is the closet power transformer to the classictone I could find. Not sure what output transfomer to use. The output transformer in the princeton reverb is 15w 8.5k. The micro amp uses a 22.5k 8ohm output transformer. I think I can use the reverb transformer that is in the princeton reverb. I added presence mod and mid/raw mod. I removed the tremelo circuit. Used the princeton reverb wiring for most of the circuit and the princeton micro power circuit. I'm a little fuzzy on where to connect the reverb transformer red wire in the micro circuit. I've attached a pdf and png of my wiring diagram. The diagram is close as I could get with the software I used. If you zoom in you can see the details. Any suggestions or corrections would be greatly appreciated.
Thanks
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Last edited by DSones on Sun Sep 29, 2024 5:03 pm, edited 2 times in total.
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Phil_S
Posts: 6048
Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: Princeton reverb micro power circuit

Post by Phil_S »

That's right...use the reverb transformer. Or you can buy something else, the 2W OT here: https://www.musicalpowersupplies.com/products/
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GAStan
Posts: 456
Joined: Thu Feb 23, 2023 9:35 pm
Location: El Paso, Texas

Re: Princeton reverb micro power circuit

Post by GAStan »

Here is another OT option. This OT works with either a 12AU7 (22k) or 12BH7 (11.5k). Pay attention to speaker impedance if changing between the two types of tubes.

MOJO1580

And here is a schematic of this OT in use.
Studio_One_SCH.pdf
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Glenn

I solder better than I play.
cdemike
Posts: 337
Joined: Tue Apr 04, 2023 5:27 pm
Location: Alabama

Re: Princeton reverb micro power circuit

Post by cdemike »

Agree reverb looks good to me. Inserted in the gain stage before the phase inverter should still work in context of the smaller power section.
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