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Hoffman Amps Forum image Author Topic: Separate power supply chassis/wiring question  (Read 1939 times)

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Offline Diverted

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Separate power supply chassis/wiring question
« on: November 30, 2023, 08:32:10 am »
Hi all,

My brother has asked for a high-ish power amp in a small form factor. I settled on an AB763 circuit with a pair of 6L6s and reverb, no trem. I'm thinking about trying to squeeze it into a Princeton Reverb chassis, but the power and output transformers are large. Between those, the choke and the reverb driver, I think it'll be too tight.
So I was thinking about putting the power transformer and choke, diode rectifier, bias supply and first filter cap in a small chassis at bottom left of cab, and running the wiring up via a harness/octal socket and plug.
My question is about the wiring. As I see it the wiring harness will include the 6.3V heater wires, B+, ground, bias supply voltage, a connection to the primary center tap on the output transformer, and the downstream leg of the choke.
Will bundling all these together cause noise issues? Should I shield the 16g heater wires, and use tht shield as the ground connection between upper and lower chassis? Or is there some other configuration that would be better?

In all, this is what will be in the lower chassis: Power transformer, choke, bias parts and pot, main fuse, HV center tap fuse, first filter cap, power switch and artificial center tap resistors. The choke will go at upper left in the guts shot pic.

Attached are pix of what I've done so far. Not much, need to buy two caps that will fit ... all I've really done so far is wire the heaters to the socket, install the diodes for the rectifier and wire in the fuse and switch. I'm putting the choke in later as it gets in the way when I'm trying to run wires. Thanks for any insight you might have!
« Last Edit: November 30, 2023, 08:44:38 am by Diverted »

Offline shooter

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Re: Separate power supply chassis/wiring question
« Reply #1 on: November 30, 2023, 08:45:42 am »
might find an idea here;


https://sluckeyamps.com/vox/vox.htm
Went Class C for efficiency

Offline Diverted

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Re: Separate power supply chassis/wiring question
« Reply #2 on: November 30, 2023, 09:03:58 am »
Wow, that is one slick build! Very impressive.

Offline Latole

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Re: Separate power supply chassis/wiring question
« Reply #3 on: November 30, 2023, 09:53:31 am »

Offline sluckey

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Re: Separate power supply chassis/wiring question
« Reply #4 on: November 30, 2023, 10:13:59 am »
My Magnatone M10-A has a separate power supply. No need for any shielded cables. I would suggest using ss diodes rather than a tube rectifier.

     http://sluckeyamps.com/magnatone/magnatone.htm
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Diverted

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Re: Separate power supply chassis/wiring question
« Reply #5 on: November 30, 2023, 10:32:38 am »
Thanks. Yep, going with solid state on this. Thanks for the guidance on the wiring!

 


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