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Hoffman Amps Forum image Author Topic: Princeton'ish build  (Read 2207 times)

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Offline dmp

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Princeton'ish build
« on: November 30, 2015, 09:50:53 am »
Here is a amp build I completed earlier this year. It is based on a Princeton Reverb circuit using EL84s as the output stage.
I had a salvaged organ chassis and speaker baffle to build around. After getting it going, I upgraded to a new output transformer to get 4,8,16 ohm outputs (and a better sound than the stock Triwec), and more durable speakers (Celestion g10 vintage).
I have a post PI master volume on the back, a switch for fixed or cathode bias, and a three-way switch for feedback: none, princeton (med), or twin (high).
 

Offline dmp

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Re: Princeton'ish build
« Reply #1 on: November 30, 2015, 09:56:07 am »
Pine cabinet made with box joints. Two 10" speakers. I'd like to add tilt back legs when I find something to use that fits the character of the amp.

 

Offline sluckey

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Re: Princeton'ish build
« Reply #2 on: November 30, 2015, 11:06:39 am »
That really looks good! The AO-43 is a very versatile platform for many different 15-20 watt guitar amps. I'm surprised you replaced the Hammond OT. I like that transformer. Just wish it had multiple output taps.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline tubenit

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Re: Princeton'ish build
« Reply #3 on: November 30, 2015, 11:09:51 am »
I am quite impressed with that build!  Thanks for sharing the photos and info.

With respect, Tubenit

Offline dmp

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Re: Princeton'ish build
« Reply #4 on: November 30, 2015, 11:18:36 am »
Thanks guys
I hadn't planned to replace the OT - or the speakers - but the lack of 4 & 16 ohm taps drove me to get the new OT. I did play the amp quite a bit with the original and I do like the new one more.   I pretty sure the original was Triwec, not Hammond. The code on it was 5247105.
I replaced the speakers because they were rattling at high volume (high distortion). I put in the Celestions and I still have the rattle  :BangHead:



Offline shooter

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Re: Princeton'ish build
« Reply #5 on: November 30, 2015, 11:53:44 am »
Quote
still have the rattle
Make sure it's not the chassis doing the rattle, 2 of my homebrew cabs rattled, both turned out to be chassis, not speaker, one still rattles if the screwdriver I have jammed 'tween cab and chassis and comes loose :think1:
Went Class C for efficiency

Offline dmp

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Re: Princeton'ish build
« Reply #6 on: November 30, 2015, 12:00:27 pm »
I think it must be something like that. Shouldn't be too hard to find with a little time to troubleshoot. I just assumed it was a bad speaker.

Offline Ed_Chambley

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Re: Princeton'ish build
« Reply #7 on: December 01, 2015, 04:16:15 pm »
Nice Build.  I have a 2, 10" Princeton'ish build as well.  I tried a single 12, but preferred the 2 10's.

The cab style reminds me of an Ampeg.

 


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