# First Amp Build! Princeton 5F2-A



## p_wats (Nov 11, 2009)

Hey guys,

I just finished building my first amp. It's basically a Princeton 5F2-A, but I used mostly recycled parts from old radios that my friend/amp guru had. The PT isn't as powerful as an actual Princeton (only about 280V for B+), but it still sounds great! The OT is from musicalpowersupplies.com and I can't stress how happy I was with Matt's service and patience.

Other than that the mods are minimal: SS rectifier and added a switch to toggle the negative feedback in or out.

The chassis is from an old radio and it's pretty small, so space is tight (and wiring is ugly):




























The cab used to be half of a turntable w/speaker combo that I painted (front is all original except for the button I put on to cover a whole where the speaker used to connect to the turntable) and it's loaded with a vintage 8" speaker my friend had (chosen for it's small magnet, so it could all fit nicely in this tight package.





























All in all I'm really happy with it. I learned a hell of a lot building this amp (made a lot of mistakes along the way too). It sounds great, is really small and light, and cranks through an extension cab.

Woo!

Paul


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## greco (Jul 15, 2007)

COGRATULATIONS !....VERY impressive, especially since you recycled most of the components, etc.

I'll bet that you learned a lot (as you mentioned) and approaching the build this way makes it even more impressive to me.

Cheers

Dave


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## p_wats (Nov 11, 2009)

greco said:


> COGRATULATIONS !....VERY impressive, especially since you recycled most of the components, etc.
> 
> I'll bet that you learned a lot (as you mentioned) and approaching the build this way makes it even more impressive to me.
> 
> ...


Thanks, Dave! I learned a ton...but there's still a mountain to climb. I'd love to build something a little bigger with reverb and tremolo.


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## brimc76 (Feb 14, 2008)

Hey Paul, great job. I bet you had a of of fun working on this as well as learning a lot.

Brian


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## starjag (Jan 30, 2008)

Looks great, sounds great... you have a winner here!


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## p_wats (Nov 11, 2009)

starjag said:


> Looks great, sounds great... you have a winner here!


Thanks! I'm itching for the next one now.


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## p_wats (Nov 11, 2009)

brimc76 said:


> Hey Paul, great job. I bet you had a of of fun working on this as well as learning a lot.
> 
> Brian


Thanks! It was a great experience--made a lot of rookie mistakes that I had to troubleshoot, but that just made it more rewarding in the end.


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## Emohawk (Feb 3, 2006)

p_wats said:


> Thanks! I'm itching for the next one now.


Get used to it...I think there's heroin in solder fumes.  I just finished #11 & planning a few more projects.

Nice job, BTW. Cool that you used recycled components & basically scratch built the thing. Makes it extra special & I bet very rewarding.


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## p_wats (Nov 11, 2009)

Emohawk said:


> Get used to it...I think there's heroin in solder fumes.  I just finished #11 & planning a few more projects.
> 
> Nice job, BTW. Cool that you used recycled components & basically scratch built the thing. Makes it extra special & I bet very rewarding.


Yeah, it was a bit difficult at times, as I was always second guessing my parts, but very rewarding when it all fired up. I had a few of the usual mistakes (like layout problems, loose tube socket...), but in the end I was able to customize a bit here and there to craft the perfect tone I was after. 

I'm thinking a push-pull for the next one, though I do still have a smaller power transformer I can use for something else...


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## Wild Bill (May 3, 2006)

Wonderful job! This is the sort of thing that warms an old homebrewer's heart! You had the gumption to dive in and take on the project, ending up with both a neat little amp and a much better understanding of tube electronics!

I will toast a beer in your honour!

WB


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## p_wats (Nov 11, 2009)

Wild Bill said:


> Wonderful job! This is the sort of thing that warms an old homebrewer's heart! You had the gumption to dive in and take on the project, ending up with both a neat little amp and a much better understanding of tube electronics!
> 
> I will toast a beer in your honour!
> 
> WB


Thanks WB (just seeing this reply now...sorry for the delay)! 

This build was challenging, but a lot of fun. I'm sourcing the parts for an Ampeg Rocket now too and have since been able to do some work on one of my vintage Pine amps. Still a lot to learn though.


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## Johnny (Nov 30, 2010)

Nice job Paul! Cool little amp and definitely has your artistic touch! Keep up the great work! Still thinking about all those cool little cookie tin FX pedals I saw at your place. Very creative!


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## mhammer (Nov 30, 2007)

Nice work. I had the good fortune to stumble onto an original in a Hamilton pawn shop in 1976, and it has been my constant companion since then.

I was just about to recommend installing a negative-feedback lift switch, and then read your original post. Good on ya! I've also dickered around with swapping a 6L6 for the 6V6, but with the lower plate voltage that you noted, that might not be such a good idea.

I got rid of the 8" Jensen that came with mine, shortly after purchase, and replaced it with a lovely (and now near-impossible to find) 8" JBL, a move I have never regretted. Plugged into a 10" or 12" in a proper efficient cabinet, you'd be surprised at how loud 5w can be.

I imagine most of these 5W amps come in small in small cabs with small speakers because:
a) the markup on the amps is not going to be that much in real dollars, so they keep the price low by conserving package/cab size, and reducing shipping weight, and warehouse storage requriements;
b) they assume that any serious player will likely have a larger amp, or eventually step up to a bigger amp when the need arrives.


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