Contemplateing a Champ 5f1 build

[svstee]

I'm not technically finished with my first "real" amp build (a PCB Firefly) but I have wanted to build a 5f1 for a couple years now and thought I should at least get the ball rolling. After looking around a bit I have decided to go with an eyelet board. I was looking at Watts Tube Audio and I think I'll just take the plunge and buy all the tools and raw materials to make my own. I have a fair idea what all this should cost, with the exception of the transformers; if I'm looking at some of the cheapest (I know) ones, what can I expect to pay?

Also, is this an overly ambitious undertaking? I can read schematics well, have built 30+ effects pedals, a couple SS amps and most of the AX84 Firefly on a PCB. I know a bit about how tubes work (I've incorporated some in effects) but I'm a bit of a stranger to high voltage amps. I would rather not build from a kit. Looking at the schematic and layout at schematic heaven, I think I know how to put it all together. I will also be making my own chassis.

Thanks!

[loudthud]

It's hard to beat the prices at Weber VST.

https://taweber.powweb.com/store/magnetic.htm

I found this on ebay, never purchased from him but his feedback is 100%.

eBay Store - Musical Power Supplies: PP Output Transformers, SE Output Transformers, Tube Power Transformers

One of these might do the job for a PT and the price is good.

Allied Electronics - Catalog

[svstee]

Well, I've been shopping around and I ran into this, any good?
Single Ended Transformer Bundle 5F1 5F2 Tweed Fender Champ Princeton
I haven't heard much about triode electronics, anyone have any experiance with them?

I'm planning to go off these for this build, any thoughts?
Fender Champ Amp 5F1 Layout - KBapps.com
http://www.charlestonarea.com/Fender...s/champ5f1.gif

Thanks.

[loudthud]

I used one of the Triode "Dyna-clone" transformers to replace a damaged power transformer in a Sunn amp. Fit and finish were good. You don't really need the choke for a 5F1. One of the older versions used a choke, maybe a 5C1 ??

Those old Fender layouts are OK but not as good as they could be. One thing is the heater supply grounds one side. The Triode transformer has a center tapped heater winding so it's best to ground the center tap and twist the two sides of the winding and run to each tube socket. This is not too difficult but look for examples.

The grounding in the Fender layouts is what causes the most problems for the novice builder. In an attempt to improve the ground and reduce hum, all kinds of things are tried that many times make things worse. I think if you do a search here for "5F1 hum" you will find many threads an the subject. Some with conflicting solutions. I suggest you keep looking for a better layout that doesn't leave so much to the imagination.

[svstee]

I spent a while looking for a better layout, all I've found so far is this.
http://www.ceriatone.com/images/layo...tra-Layout.jpg
Not the same amp that I'm building, but it is close, and it does fill in the blanks a bit as far as grounding goes. I also read an excellent article on star grounding (R. G. Keen I think) that helped me out a lot.

I think I might get those Triode transformers even though I don't need the choke, they are still cheaper than anything else I've found.

Thanks for all the help!

[loudthud]

Thats a little better. One of the things that causes problems is the chassis connection at input and speaker phone jacks. The Ceriatone layout appears to use the plastic jacks that don't ground to the chassis. Hoffman sells washers that will insulate metal phone jacks from the chassis.

One very important thing to point out. The connection from the line cord to the fuse holder should go the the center terminal (the one farthest from the fuse cap), the side terminal of the fuse holder should go to the switch. This makes it so that you cannot touch the live power line when you are inserting a fuse.

I like how Kevin O'Connor does grounds. I think TUT-3 or TUT-5 has the Champ layout diagram. Because I respect Copyrights, I'm not going to scan his illustrations and post them here (unless by some act of God permission is granted) but his books are some of the best money I ever spent.

[Howlin' Mad Mac]

Go for it! The 5F1 is a very easy build & the schematic & layout you're using are Leo's own. Recomendations I'd add would be 1) use a 3 wire power cord, 2) eliminate the .047mfd "death cap", 3) add a 100 ohm resistor to each 6.3v tap lead, grounding the other end (creates an artificial CT & helps eliminate any 6v winding hum) also twist your heater wires together & run as far away as possible from your tagboard, 4) eliminate the 22K NFB resistor (unless you're wanting a "clean" sound), 5) use shielded wire on pins 2 & 7 from your 12AX7, & finally 5) add a 25mfd/25v cap across the 1.5K cathode resistor from pin 3 of the 12AX7. Do it right & you'll be a pickin' & a grinin' fo sure. Also check Tubes & More (Antique Electronic Supply) for transformer prices... PT's are running about $45-50 & OT's about $20-25 so figure about $75 for the pair. Weber speakers also sell good transformers for about the same plus excellent speakers for a Tweed build.

[svstee]

Well, life put this project on hold for a bit. I found a better layout:
http://www.ceriatone.com/images/layo...-Layout200.jpg

Thoughts?