I've started a new amp build.. tweed Princeton 5F2-A

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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by øøøøøøø » Sat Apr 09, 2022 8:14 am

Add me to the people who have come to believe that coupling capacitor dielectric film material is approaching insignificance in a tube guitar amp.

I didn’t used to feel that way. Some recent experiments have tweaked my thinking a bit.

When removing sources of potential cognitive bias, the differences become incredibly subtle-to-nonexisrent.

To clarify: I’m speaking of the difference between polyester and polypropylene film, and to some extent the difference between metallized films and film-and-foil.

Class 2 ceramics or any electrolytic type are a bit of a different matter, and just might perform differently.

Some metallized types have an inherent inconsistency in their construction and could indeed sound slightly different in theory (more on this if anyone’s interested.)

And I won’t say that all capacitors are created equally—but the difference between a CDE/Sprague “orange drop” and a “boutique” mylar or polypropylene cap is vanishingly small in tube guitar amps (when directly compared)

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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by i love sharin foo » Sun Apr 10, 2022 10:45 am

I’m getting pretty close to having all the chassis parts on hand to actually start building. The final bits are on the way right now.

I was able to repair the old Jensen P10R that I have without a recone, so it’s good to go now, too. I just need to get the rest of the money together for the cabinet.
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by i love sharin foo » Mon Apr 11, 2022 6:20 pm

I've made some progress today. I have almost everything now except for one more package that should arrive tomorrow (except for a cabinet.. that will take a bit more saving).

Here's most of what's onhand now:
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I had an old stock, phenolic fuse holder (on the left) that I really liked. But it needed bigger chassis hole. I have another that fits as-is but I didn't care for it. So, I dug out the drill and went with the phenolic one.
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I also needed to drill a dedicated hole for the power cord ground and two more for a terminal strip which serve a couple purposes. One of which will be to chain a few diodes to drop the B+ if I need to.
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Here, I've run the power cord and grounded it, grounded the center taps, wired up the rectifier, fuse holder, and the power switch.
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The panel is all loaded up. I am changing it to an amber indicator and an old pair of black and brown phenolic chicken heads.
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by JSett » Mon Apr 11, 2022 9:42 pm

Looks good so far, and the transformer looks right at home there. I'm glad the leads are mostly long enough too...looks nice and tidy in there (which is nice as the transformer end of most amps can look kinda messy usually).

Can't wait to see this get more populated.
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by i love sharin foo » Tue Apr 12, 2022 7:04 am

johnnysomersett wrote:
Mon Apr 11, 2022 9:42 pm
Looks good so far, and the transformer looks right at home there. I'm glad the leads are mostly long enough too...looks nice and tidy in there (which is nice as the transformer end of most amps can look kinda messy usually).

Can't wait to see this get more populated.
Thanks! I only had to lengthen a few leads. Everything was mostly already perfect!


I was able to put in a little bit of tie before I had to leave for work. The stock holes in the eyelet board put it closer to the PT than I wanted. Rather than make more holes in the chassis, I instead opted to drill new ones in the boards themselves.
Before:
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After:
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As a tip, it's a good idea to leave the two bolts in the eyelet board as you populate it. That way there are no fitment issues when you go to bolt it down later. I have a few components in the board so far.
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by i love sharin foo » Wed Apr 13, 2022 12:50 pm

The heaters are wired in.
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Connecting the output transformer. The 4 Ohm tap is covered up in case I need it later.
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Backside of the board:
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by i love sharin foo » Wed Apr 13, 2022 12:58 pm

Fully populated board:
Image

And, in the chassis:
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Finished:
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Now I just need to check voltages and test. Ordering a cabinet tonight.
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by JSett » Wed Apr 13, 2022 1:05 pm

Looks great Justin :w00t:

These early Fender circuits are so simple when you see all the components layed out like this...there's barely anything to them. Good work. That lead dress is *chefs kiss*

Hopefully all the numbers line up enough for you, pretty sure you're going to get about 315v out of that PT though so get your diodes ready 😂
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by i love sharin foo » Wed Apr 13, 2022 3:14 pm

Thanks Johnny!

There’s not much to them at all, is there? :D

Everything went together real nicely.

I am hoping to fire it up on the next day or so. You’re probably right about the voltage. I have 4 diodes on hand. Should be good!
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by hulakatt » Thu Apr 14, 2022 5:34 pm

Oh, that's a lovely wiring job! Very nice.

I shoulda checked this thread earlier, I have a 5f2a board and a ClassicTone transformer pair for a 5f2a sitting around from a project I never finished. Abandoning the Two Stroke project, maybe I should build a Princeton too? Anyone know where I can get a 1x8 cabinet cut for a 5f2a chassis but in the 60's Supro cab style?
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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by øøøøøøø » Thu Apr 14, 2022 7:24 pm

Beautiful work, nicely done!

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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by luau » Fri Apr 15, 2022 5:55 am

Looks great! I've got one coming up and I hope it looks half that nice. :D

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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by Fiddy » Fri Apr 15, 2022 7:27 am

luau wrote:
Fri Apr 15, 2022 5:55 am
Looks great! I've got one coming up and I hope it looks half that nice. :D
As in you're building it? :w00t:

Ditto on the comments. This build looks great.

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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by luau » Fri Apr 15, 2022 8:01 am

tribi9 wrote:
Fri Apr 15, 2022 7:27 am
luau wrote:
Fri Apr 15, 2022 5:55 am
Looks great! I've got one coming up and I hope it looks half that nice. :D
As in you're building it? :w00t:

Ditto on the comments. This build looks great.
No, I'm going to build a different tweedy thing, but more on that in its own thread. :ph34r:

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Re: I've started a new amp build.. tweed Princeton 5F2-A

Post by rbrcbr » Fri Apr 15, 2022 9:16 am

Wow, this looks great. Also, amplifier design is so foreign to me that I seeing the board all wired up is basically an abstract image to me. I've been interested in building my own amp for a bit, but have mostly been terrified of frying myself. Maybe one of these days when I've got some spare change I'll convince myself to DIY something, and learn a useful skill or two while i'm at it.

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