1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

New amp soon: Tweed Champ or Tweed Princeton??

Discussion in 'Shock Brother's DIY Amps' started by richon, May 6, 2009.

  1. richon

    richon Tele-Meister

    Posts:
    268
    Joined:
    Apr 3, 2007
    Location:
    Viña del Mar
    I'm into building a New amp soon: Tweed Champ or Tweed Princeton??

    both are very similar except the Tone control that could be switcheable.

    any reason to avoid the Tone control?

    Besides the circuit I plan to use a Weber 8A125T and a handbuild Pine cabinet.
     
  2. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    40
    Posts:
    6,330
    Joined:
    Dec 3, 2005
    Location:
    CID
    Tweed Princeton, hands down. No more difficult to build than a Champ, just a couple more connections to make, and it's more flexible. Sounds better with the bigger cabinet too, IMO. I love mine!

    - Scott
     
  3. sjhusting

    sjhusting Tele-Afflicted

    Posts:
    1,488
    Joined:
    Jul 8, 2003
    Location:
    Germany
    The tone control causes a certain amount of signal loss, which is why the cathode is bypassed on the first stage on the Princeton, to produce more gain going into the tone circuit. You can make both switchable, the tone control and the bypass, then you have both amps.

    You could also think about putting a switch on the NFB so you can remove it completely. And you could add an extra 47 ohm resistor between the 1.5K on the second stage and ground, and add a (switchable) bypass on the second stage over the 1.5K only. This way you can bypass the second stage (more gain) and still keep your NFB. See the BF champ for an example of this

    You could also add a choke to the power supply. See the 5f2 (no A) schematic.

    steven
     
  4. richon

    richon Tele-Meister

    Posts:
    268
    Joined:
    Apr 3, 2007
    Location:
    Viña del Mar
    I plan not to use a Choke. Use a NFB switch (although i guess I will have it always off). A tone switch... and maybe the bypass cathode switch.

    beside the bigger cabinet... just amp-wise..... both sound the same?
     
  5. bluesfordan

    bluesfordan Friend of Leo's Silver Supporter

    Posts:
    2,777
    Joined:
    Jun 1, 2006
    Location:
    Nashua NH
    not so sure why one wouldn't bother going with a 12" speaker if you're making your own cabinet. One of the things that bothers me the most about these amps (the real deals) are the small speakers. To my ears, single speaker amps sound better with a 12. Two 10s sounds better than one 10 ie Vibrolux. Since it is going to be a homebrew, total vintage authenticity is not crucial. Just my humble opinion.
     
  6. Paulie13

    Paulie13 Tele-Holic

    Posts:
    675
    Joined:
    Feb 16, 2009
    Location:
    Columbia, SC
    I second this.
     
  7. sjhusting

    sjhusting Tele-Afflicted

    Posts:
    1,488
    Joined:
    Jul 8, 2003
    Location:
    Germany
    12" speaker - yes, makes a big difference

    steven
     
  8. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    40
    Posts:
    6,330
    Joined:
    Dec 3, 2005
    Location:
    CID
    I'll third (or fourth) it. A 10" in the Princeton-sized cabinet is a noticeable improvement in sound, and a 12" in a slightly-bigger cabinet should be even better.

    - Scott
     
  9. FiddlinJim

    FiddlinJim Tele-Holic

    Posts:
    890
    Joined:
    Mar 28, 2006
    Location:
    Seee-attle
    I did some experimentation with NFB on the 5F2A Princeton I built a while ago. With no NFB, it felt really uncontrolled (some unexpected oscillations, I suspect) and was just a little too wild for me. I experimented with a few different values and came back to 22K as it sounded the best to me. I guess Leo got it right the first time. Where have I heard that before?

    There was a thread a while back singing the praises of the 8" speaker in that bigger cabinet vs. a 10" or 12". Many people feel that's one of the "magic" things about the Princeton. I experimented to the point of cutting and clothing a new baffle. I liked it OK, but grew to disagree with the "magic-ness" of it and went back to my 10" speaker. I was also comparing an Weber alnico "sig" series 8" with a higher-end Weber 10" alnico, so it may not have been a fair fight.

    Every time I play the Princeton, I think sounds a little better. I'm an edge-of-breakup as opposed to full cranked snarl sort of guy.
     
    dnauheim likes this.
  10. richon

    richon Tele-Meister

    Posts:
    268
    Joined:
    Apr 3, 2007
    Location:
    Viña del Mar
    so you guys thinks building a DIY Tweed Princeton amp is a waste if i don't use a 10" just because I can?

    what if i wan't that boxy nice sound and portability?
     
  11. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    40
    Posts:
    6,330
    Joined:
    Dec 3, 2005
    Location:
    CID
    Yeah, pentodes and beam power tubes aren't as linear as triodes, so even when it's not clipping, there's going to be a lot of extra harmonic content without negative feedback. When you have a push-pull pair, they'll even out each other's nonlinearity to some degree, so you can get away with using less or no feedback. Leo knew what he was doing. ;)

    Totally! And that's the way I love to play mine -- loud enough to get some hairy cleans, but not to the point where it gets all ratty and buzzy sounding. I dunno if the amp is sounding better, or if I'm adjusting my playing around what sounds best out of it...

    - Scott
     
  12. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    40
    Posts:
    6,330
    Joined:
    Dec 3, 2005
    Location:
    CID
    I don't think it would be a waste -- build an extra baffle and try it both ways! The 5F2A is a little bigger than a Champ, but I'd say they're equally portable. Here's my 5F2A next to a blackface Champ:

    [​IMG]

    - Scott
     
  13. ruger9

    ruger9 Poster Extraordinaire Ad Free Member

    Posts:
    6,627
    Joined:
    Dec 31, 2004
    Location:
    Hackettstown, NJ
    That's what I'd do: build 3 baffles & try them all. Yeah, it's more money if you don't have the extra speakers lying around, but it would be a cool experiemnt, a learning experiment, and in the end you would have the amp you want.

    Or, it could just make the decision harder because they'll both sound good, just different. I've had THAT happen before. Kind of like "boy, I wish I hadn't gone there!" type of thing.

    Personally, I think the 8" rocks. The Valvetrain 205's (%f2A) have the Weber Alnico S in them, and sound awesome. And that's what a 5F2A IS. I might consider bumping up to a 10", but IMHO a 12" makes it no longer the same amp. It's all personal preference tho.
     
  14. richon

    richon Tele-Meister

    Posts:
    268
    Joined:
    Apr 3, 2007
    Location:
    Viña del Mar
    so, a good 8" (like a Weber 8A125T) would sound really good as a Princeton Tweed speaker?

    do any of you have a demo of your tweed princetons to look at? (both 8" and 10" )??
     
  15. premiumplus

    premiumplus TDPRI Member

    Posts:
    29
    Joined:
    Apr 21, 2009
    Location:
    michigan
    It's funny, I've got a 1960 Princeton tweed, and it had a Radio Shack speaker in it when I got it. I put in a top of the line Weber 8" alnico in it and didn't like it. I went to the ceramic Weber and it was okay, I guess, but I still wasn't impressed. A lady at another forum suggested a cheap Jensen MOD 8", the one that used to sell for $16 or $18. I bought it for the heck of it, and lo and behold, it sounds GREAT. I'm going to buy a couple more for my Silverface Champs, it sounds so good. YMMV of course, but I was really blown away at how good that cheap Jensen sounds.
     
  16. ruger9

    ruger9 Poster Extraordinaire Ad Free Member

    Posts:
    6,627
    Joined:
    Dec 31, 2004
    Location:
    Hackettstown, NJ
    yeah, speakers are really a personal thing- there is no "best" or "as good as".

    What did the originals have? Jensens? If so, you might be able to get a Jensen 8" Alnico (?)
     
  17. TNO

    TNO Friend of Leo's

    Posts:
    3,523
    Joined:
    Apr 25, 2003
    Location:
    NC-USA
    Having built the 5f2a and the 5e3 I'd say just go ahead and do the 5e3. Much more useful amp and it would only take about an extra hour to wire up.
     
  18. richon

    richon Tele-Meister

    Posts:
    268
    Joined:
    Apr 3, 2007
    Location:
    Viña del Mar
    I allready have a 5E3 HEAD and 2x12" alnico cabinet...

    so now for good sound, but portability.
     
  19. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

    Posts:
    11,106
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA
    I'd go Princeton... Champs aint bad, but as mentioned you could add a switch or two to make it go Champ or Prince.
     
  20. richon

    richon Tele-Meister

    Posts:
    268
    Joined:
    Apr 3, 2007
    Location:
    Viña del Mar
    JOHNNY , you have a TON of CHAMPs and his rocking brothers..... where to go? 8" o 10"??
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.