Need help on making a Fender Champ Amp!

[sir_modulus]

Hey all of you who have been helping out lately (and noobs to my dumb tube help questions)! I have decided what to use the RCA Victrola for: A fender Champ. I swear when i saw the diagram I was seeing the Victrola, as I used almost all the comp. from the baggie of parts that was ripped from the RCA. The tubes matched too (all except the 6V6GT). I got a 5Y3GT (brand new), an RCA 12AX7A and all the components needed. Someone gave me the idea (the name has slipped my mind at the moment) of using the PT from the RCA to make a Fender Ch. as the Champ uses the 300V that my trans. can deliver. The amp is nothing big, but now I need some help. There are quite a few schematics of different models of this amp. Which one should I use?
I'm leaning towards the 5F1 (best one for no vibrato (tremelo), and small part count), but If you see, with only one Volume control, the amp is not stocked too well in the whole tonal variation department.
I've Also thought of the Vibro Champ AA764, as it has reverb, but this is my first tube amp build, and thought it looked a bit difficult. Anyone got any suggestions?

P.S. A little set of questions: When it says it need a 16Uf cap in the power section (450 V) can I use two Ten Uf's in parallel, or go and buy a 16UF (power caps are EXPENSIVE (my Film 350V 1uf cost me $10.00!!!) and do any of the resistors in the 5F1 need to be big? Can all the resistors be 1/2 Watt

Schems are here:
http://www1.korksoft.com/~schem/fenderamps/

Thanks for reading (man your eyes must be sore),

[Dave Z]

Having built a champ 5F1, let me point out it is EXTREMELY easy to add a tone control - check out the Princeton 5F2-A - look familiar? And then you have a great rock n roll monster - the Princeton tone ctrl is like a variable hi-pass (for volume) and tone rolloff, so you can brighten vs. the Champ considerably. And the distortion is great. I make the bypass cap on the first gain stage switchable as it can get a bit nasty with humbuckers with that cap.

As for power caps, you'll need electrolytics...I think I paid only $3US for my 22-mfd caps. Where are you sourcing?! Try Angela, or Hoffmanamps.com.

Let me know (email) if you want to see build pics, I think I have some I could put on my yahoo briefcase

[sir_modulus]

build pics would be great. Two things, can you elaborate on this cap switching thing, and another, What output trans. did you use?

[Dave Z]

OK, check out pics on my briefcase:

http://briefcase.yahoo.com/fenderelectric

folder "V-Champ"

Pics "capswitches" and "board" show how the caps on the cathode leg are switched in or out. Pretty simple. Just break the cnxn, they're out.

I'll put the two schems I mentioned there too. Check out the first preamp stage - one has a bypass cap - one does not. Prince got an extr filter cap on the P.S, and a tone ctrl, else it was the same.

[Lonestarjohnny]

Take a look at all the tweed champs, most of the Schematis are availible on line,I would go with a Bass/Treble tone stack, and keep it simple, the more you do, the more tone suckin goes on,
The output tranny can be had over at Angela music very Cheap, and an old Pre/Rolla speaker and you would be in Bizz, you don't have to use a Multi can filter, you can use the 350 V caps that are availible in your country, if you want good fender tone, use Orange drop Coupling and tone caps,.
I have the Studio version of Layla and other Assorted Love Song's, in the book that covers what went on in the studio, it states, Duane and Eric both used modified Champs off and on during the recording Session, Man that Blew me away, until I read that I had always dreamed of what it would have been like to have been in the studio with them, and this big wall of Fender Super's and Marshall Plexie's, talkin bout burstin my Bubble, LOL !,
It's a great build and worthwhile, Have fun,
JD

[nightingale]

dave z~
i noticed on your champ build, that you used "eyelets" in your board..
i am starting to put together a minimalist 18watter and i just received my board from hoffmanamps.. but i am not certian on how to secure the eyelets into the board.. would you ming pointing me to a link, or explaining the the basics.. i've searched archives in a few amp building forums but i havn't come up with much.. i've read the words"crimping" and "flaring".. but hats about it..

any light you could shed would be appreciated hugely..

[sir_modulus]

use an eyelet tool. You can get them at a hardwar store. They squish the eyelets into the holes and crimp them in place.

[cd]

Don't bother with film caps for the power supply, use cheap electrolytics (16u @ 500V should be around $2-3.)  I would actually go with a little more capacitance depending on how the power is in your area, my tweed Champ clone hummed badly with 10/10/20 but was OK with 20/20/40.

As for the circuit type, I would go with a 5E1 (that's my favorite sound), but you can always go with the Blackface (I think it's AA764) and mod it later ifi t's not to your liking.  Actually with the BF, you can then add switches to lift the tone controls and increase the FB resistor.

Try posting at www.ampage.org, you're bound to get a lot more replies there.

[The Tone God]

I would recommend the 5F1 schematic. If you want to do the 5E1 I would suggest putting a screen resistor in. In the 5E1 the screen runs at a higher potential then the plate which is not a good idea.

Andrew

[Dave Z]

Bunch of good recommendations...anyway, my power tranny is a hammond 270X. You can see on "NFL_Switch" I also have screen resistors, and a switch for pentode-triode, I'd forget that, not a big deal...let me know if you want a link to the guy who schmeatic'd all the fancy stuff...let's see if I still have it (rummage...) here ya go, see "DIY X-XChamp" also other folders there show step by step build pics...this guy is strack!

http://briefcase.yahoo.com/bc/casey4s/lst?&.dir=/&.src=bc&.begin=9999&.view=l&.order=&.done=http%3a//briefcase.yahoo.com/bc/casey4s/lst%3f%26.dir=/%26.src=bc%26.view=l

I did not build that board, this was a kit I modded, but I have since built a Deluxe Reverb clone from scratch....

Eyelet tool! Ha. I dropped a big carriage bolt into a hole in my bench. You know, the round-head bolts, no slot as they have a square neck?

Then I positioned the board with eyelet, straight side down, over that puppy and used another carriage bolt over the top & whack, smacked it with a hammer. No problemo.

Good fun, enjoy!

[petemoore]

That is a great article, I'd never seen 'how to figure out transformers laid out like that...thank you for providing that link Dave Z. !!!

[sir_modulus]

LOL!! Dave, now thats the way to put in eyelets! Thanks for the link.Thats a nice looking amp. BTW is it okay if my power supply caps are 470/470/100 (as they are comon values I have lots of in high voltage(450))? Thanks for all your help.

P.S. Which Output trans. did you use?

[AL]

Plenty of Fender info here.

http://www.ampwares.com/ffg/

AL

[Dave Z]

Hi Sir_mod - you are quite welcome - that is a great collection he has there.

The output tranny was part of the kit and does not have clear markings on it, but it's a fairly common item sold as a "champ OT", for example from hoffmanamps.com ($25) or angela.com.

Fender part # was 022905, 8 watts, 4 ohm secondary.

As for the power filter caps, you need the third one rated at least 200 V as the voltage on the preamp is 160 at idle on mine, and in fact will swing higher, so use the rated caps if you can get 'em. Else you may burn it up (higher is OK, lower is not). Higher capacitance is OK as well (will get you more bass) You can go up to 40uF but I would not go higher as a tube rectifier cannot handle higher capacitance,you'll burn it up.

[aaronkessman]

http://www.mouser.com/catalog/618/456.pdf

or http://www.mouser.com/catalog/618/458.pdf

radial and axial 450V electrolytic caps for cheaper than i've seen anywhere else. you'd probably be ok with a 10/10/22 configuration instead of 8/8/16.

i'm building a 5C1 champ right now. technically i'm actually replacing all the components in an old amp it's possibly the simplest guitar circuit ever.

if you're experienced with building pedals, i wouldnt worry at all about the complexities of a tube circuit. in my opinion, it's even easier to work with. don't be daunted by the more complex circuits. if it works with your PT and you want to build it, i say go for it!

Aaron

aaron