6973-powered tweed Princeton-like build

[balcorn80]

http://flic.kr/p/bPZ9eV
http://flic.kr/p/bB5v8E
Here's a new build I started up last night. Should have it finished up tonight. I used the last of some pre-made turret board I had in my stash, and some transfomers from a box of parts i bought at a swapmeet. The turret board is wired up as a Princetion-type circuit, but I modified it to be used with a 6973 power tube(The only amp not built by myself that i own is an Airline version of the Supro 6424 that runs on these tubes, so I have a small handful of them around.) and it will also be SS-rectified. I'm kinda excited to hear this tube run single-ended fashion!

[iambluesman]

Tons of great ideas and great info, thanks. But still in a quandary as to which way to go as I am unsure what these mods would sound like.

I have put a 10" in a champ before and loved the improvement in volume but I would really like to get more of that Mid range punch and round off some of the ice pick highs rather than just boost volume or mod the board to just boost gain.

My 63 Deluxe is punchy and the highs are fat, smooth and chimey, lot's of overtones with just the right amount of break up and sustain, just too loud. I know this is more "player speak" than "tech speak" but I'm sure some of you know what I am trying to achieve. I got sucked into "tube voodoo about 10 years ago and vowed to not go down that path again searching for that "ultimate tone" but I have heard that it is possible without a whole lot of complexity. 

This is a plain ol champ, no vibe and I have an outboard reverb unit so no effect needed internally. one 5y3gt, one 6v6, one 12axy, so let me try to rephrase my initial question, maybe I left it too open ended.

If I upgraded my Champ with a 10" speaker and Princeton O/T and P/T would the amp function correctly and would it give me the "blackface" tone of my 63?

Note: I do like the idea of replacing the can cap with electrolyte typed housed internally, always questioned if the was the most efficient solution. 

Thanks again

Drew 

[DummyLoad]

you can use the 6CZ5 in place of the 6973 which are becoming rare and expensive.

6CM6 would be another good candidate - a derated 6V6 in a 9pin envelope with same pinning as 6973/6CZ5 if you don't use pin 8 as a tie point.

respectfully,

--DL

[balcorn80]

If I upgraded my Champ with a 10" speaker and Princeton O/T and P/T would the amp function correctly and would it give me the "blackface" tone of my 63?

Note: I do like the idea of replacing the can cap with electrolyte typed housed internally, always questioned if the was the most efficient solution. 

It depends on which princeton you are talking about. If you are talking tweed princeton, you COULD just drop those transformers in, but you would have a basically stock champ at that point. If you're talking brown/black/silverface princeton, you can't just drop those transformers in without building a different board.
If you're looking for more midrangey sound, you're not gonna get it(in my opinion) without modding the circuit board and circuitry. Part of the blackface sound is the scooped mids. If you want a more mid-heavy sound, you'll probably be happier with a tweed champ. You can do a lot to curb the icepickiness with speaker selection. Putting a good effecient 10 is defintiely a step up, even with the stock transformers. You may really be better off selling what you have as a project status to fund building what you really want. but only you can make that decision.

Inside my Bronco(vibrochamp) there isn't much room to relocate a cap can into separate electrolytics inside. The only real advantage of doing that would be the option of replacing one cap at a time(instead of the whole can) but for me, if something hit my amp hard enough to make me want to change one cap, I like to change them all(and the associated resistors) anyhow. But everyone builds differently, so thats just my 2 watts.

[balcorn80]

you can use the 6CZ5 in place of the 6973 which are becoming rare and expensive.

6CM6 would be another good candidate - a derated 6V6 in a 9pin envelope with same pinning as 6973/6CZ5 if you don't use pin 8 as a tie point.

Dude. This is good info. I'll have to keep this in mind, as I don't see myself getting rid of my Airline any time soon. Since I am lucky enough to have come across a small handful of 6973s that test good(and sound good) I haven't had to search for any, but have seen the prices they command. Even the new EH(or whoever they are marketed by) ones aren't that cheap. Thanks for the tip!

[balcorn80]

Got this thing wired up last night and fired it up. Fuse blew right off the bat. After upping the fuse to a 1.5a instead of a .75a My PT started getting real hot, and so were the resistors in my power supply. Fter blowing another fuse I disconnected the HV lines from the rectifier and still blew fuses, I came to the conclusion that I had a bad PT. so I pulled one out of my stash, one that came from a Roberts/Akai reel to reel, replaced the caps and resistors in the power supply, and it was good to go.

The Princeton circuit sounds AWESOME with a 6973. Like a mix between a 6v6-powered SE amp and an EL84-powered SE amp. Couldn't be happier. Glad I decided to use the 6973. I was gonna build it with an EL84.

Now to deal with the cabinetry...

[Willabe]

Do you have a light bulb limiter to use on start ups and looking for shorts?

Here's the link to sluckeys web page with instructions on how to build one and use it. This is a must have, must use tool for any amp builder/repairman.

http://home.comcast.net/~seluckey/amps/misc/Amp_Scrapbook.pdf


                       Brad      

[balcorn80]

Dang it... Now I've got something else to build... :-P

Thanks for the tip!

[Willabe]

Dang it... Now I've got something else to build... :-P