Starting a Tweed CHamp

Tele-cat · Post by **Tele-cat** » Tue 04/11/06 6:53 pm

This is my first build. Any sage advice for an aging but still noobie amp builder?

I have soldered pickups, wired an aircraft radio harness so I have some experience with wiring and electricity but this is the most complex task I've taken on.

Trout · Post by **Trout** » Tue 04/11/06 7:20 pm

Tele-cat wrote:This is my first build. Any sage advice for an aging but still noobie amp builder?

I have soldered pickups, wired an aircraft radio harness so I have some experience with wiring and electricity but this is the most complex task I've taken on.

Take up golf

No Really, study the high voltage safety information!!! These amps Can & Will Kill if not approached properly.

Ask Lots of questions as you go, Never second guess If uncertain on polarities, Transformer wiring or parts needed to correctly build your project.

It can be and is very a rewarding hobby.

loverocker · Post by **loverocker** » Wed 04/12/06 3:12 am

Go for it - they're cracking little amps.

I'd suggest adding an extra filtering stage (a 100r power resistor and an extra 16-22uF cap) to the power section to reduce hum a little more than the stock circuit, but that's it. Good luck

Austen · Post by **Austen** » Wed 04/12/06 6:29 am

I am too!

I really want an 18 but I figure a Champ is a fine starting point and as someone said virtually a right of passage for builders.

First I was going to not think, just buy..a kit. The more I read the more i want to understand.

I'd rather do it myself properly and learn.

Can anyone recommend great tutorial sites and/or books for this?

phsyconoodler · Post by **phsyconoodler** » Wed 04/12/06 8:49 am

If you are wiring aircraft harnesses,you will be bored with a champ build.The result will be a nice sounding amp,though.
The champ 5F1 is about as simple as it gets,but the tone is worth the work.Highly recommended for a first build.Simple is best in my book.

MooreCowbelle · Post by **MooreCowbelle** » Wed 04/12/06 11:04 am

Part of the difficulty when first starting out is figuring out where to get all the parts! In this respect, a kit is usually a good deal. Then you can focus on building rather than procurement, shipping from multiple vendors, getting the wrong parts, etc. Takes some of the stress off for the first build.

Certain vendor's kits come with step-by-step instructions, and others don't.

Here are some good kits:
http://www.torresengineering.com/newtweed5f15.html
http://www.ceriatone.com/productSubPage ... ampKit.htm
https://weberspeakerscom.secure.powweb. ... /kit_r.htm

Build one of these, get used to the parts that are required, and then your part sourcing for your next build (yes, there will be a NEXT build) will be easier.

Tele-cat · Post by **Tele-cat** » Wed 04/12/06 3:35 pm

I got a kit from Marsh because he uses American caps and offered a Mercury Magnetics tranny for only a $25 upcharge.

He also let me substitute Mallory 150s for the coupling caps (he normally uses Sprague for those) with no upcharge.

I should have had him skip the tubes because i have bettter tubes for this amp than he normally supplies.

I likethe Ceriatone site because they have a number of very sharp photos of the 5F1 board (though I think it's a Hoffman board) and of course, I snagged them so I have them locally. I have my laptop on the workbench so I can refer to material I have as I go.

I'll start soldering this weekend.

bigsbybender · Post by **bigsbybender** » Wed 04/12/06 3:39 pm

Tele-cat wrote:I likethe Ceriatone site because they have a number of very sharp photos of the 5F1 board (though I think it's a Hoffman board)

Nik uses the turret boards like hoffman but his layouts follow the stock Fender layout rather than Hoffman's. I'm just going by the pics however.

Austen · Post by **Austen** » Wed 04/12/06 4:15 pm

That looks pretty good.

I searched but found very little on the Ceriatone Champ.
Key Question is: how do his tranformers measure up for THIS one? I know people rate his TMB 18 watter.

Mr_dB · Post by **Mr_dB** » Wed 04/12/06 6:50 pm

Tele-cat wrote:I got a kit from Marsh because he uses American caps and offered a Mercury Magnetics tranny for only a $25 upcharge.

He also let me substitute Mallory 150s for the coupling caps (he normally uses Sprague for those) with no upcharge.

I should have had him skip the tubes because i have bettter tubes for this amp than he normally supplies.

I likethe Ceriatone site because they have a number of very sharp photos of the 5F1 board (though I think it's a Hoffman board) and of course, I snagged them so I have them locally. I have my laptop on the workbench so I can refer to material I have as I go.

I'll start soldering this weekend.

Hi stranger!

Does Marsh's kit include instructions, or do you get a bag of parts and are left to sort it all out yourself?

If your eyes are as old as mine, and I believe they are, then don't forget your reading glasses, a strong lamp, and a magnifying glass to check your work. On a 9-pin tube socket, those pins are very close together, so you'll want to make sure you haven't accidentally bridged them with solder.

str82hvn · Post by **str82hvn** » Wed 04/12/06 7:08 pm

MooreCowbelle wrote:Part of the difficulty when first starting out is figuring out where to get all the parts! In this respect, a kit is usually a good deal. Then you can focus on building rather than procurement, shipping from multiple vendors, getting the wrong parts, etc. Takes some of the stress off for the first build.

Certain vendor's kits come with step-by-step instructions, and others don't.

Here are some good kits:
http://www.torresengineering.com/newtweed5f15.html
http://www.ceriatone.com/productSubPage ... ampKit.htm
https://weberspeakerscom.secure.powweb. ... /kit_r.htm

Build one of these, get used to the parts that are required, and then your part sourcing for your next build (yes, there will be a NEXT build) will be easier.

Couple of comments on Torres:

Great Parts
Bad Instructions

I really love my Torres Champ but the direction were REAL terrible. I basically found the original Fender Schematic and Layout and didn't really use the stuff from Torres. He is a low cost supplier with great components just watch out for the details.

str82hvn

jimipage · Post by **jimipage** » Wed 04/12/06 7:11 pm

http://www.stf-electronics.com

Pat Bunn is a swell guy who sells a great product at a great price, as well as offering online tech-support.

Tele-cat · Post by **Tele-cat** » Sat 04/22/06 11:32 pm

ARRRRRRRRRRRRRRRGH!!!!!!!!!!!!!!!!!!

I have voltage everywhere except coming out of the second 100K resistor to the first pin of the 12AX7. I have voltage to one side of the resistor (where it couples with it's twin on the board (258VCD) but nothing on the other side, where it meets up with the second coupling cap. I re-flowed the solder joint where it couples the other resistor, and I have voltage on the north side, but on the south side, I got nothing.

The resistor specs out WRT DC resistance, but something is shunting the voltage elsewhere.

You can see the wiring diagram and the values (circled in red) at http://www.guitarpete.net/champ1.html. All I can figure is a bad resistor.

So it's off to Radio Shack tomorrow for a replacement resistor.

Can any of y'all think if anything that could be shunting that voltage away from the other side of the resistor?

Tele-cat · Post by **Tele-cat** » Tue 04/25/06 9:38 pm

Well kinda. The speaker I had sitting around doesn't cut it, so I have a RI Jensen on the way.

The 5F1 doesn't come with a cathode bypass cap in the preamp. The 5E1 had it, but the original Fender 5F1 diagram doesn't show one. The Weber diagram has it.

This amp needs that. It's quite dark without it. I consulted with Clay Hullett (who built two amps for me) and Curt Emery, the designer of the Superbabyâ„¢ and the tech I've used for the past five years, and both agree, that cathode bypass cap is required. The Diagram for the 5E1 calls for a 25uf cap, but I ended up with a 4.7uf cap because it made the amp brighter.

Given we get almost 130V out of the wall, I don't think it's a bad idea to replace the 100K resistors in the preamp circuit with a higher value. All my voltages across the amp are higher than the specs I see in the paperwork. It'll make the amp less gainy. I haven't replaced them yet, but I may. In the meantime, I'll probably use a 12AY7 or 12AU7 in the preamp, to tame the gain. Sorry, I just don't want it that gainy.

I'll never, again, build an amp that doesn't have a phenolic board with turret lugs. From a build standpoint, it may not make a lot of difference, but from a maintenance standpoint, it's a BIG deal. I look at my other two tweed amps (that Clay Hullett built) and the difference is remarkable.

Do NOT do the cabinet shellacking indoors unless you have LOTS of ventilation and I don't mean just an open door. Denatured alcohol is VERY toxic, even the fumes. Wear safety glasses.

I did mine out on the front porch, using a slab of cardboard to put the cab on, using the screws from the handle and the feet to keep the tweed up off the cardboard.

Do one coat at a time. Some people say 30-60 minutes between coats, but if it's not very warm, 2-3 hours is a better bet. I was doing a coat (three total) very 2.5 hours yesterday. Got it done, but I left the back panels off all night to let the shellac harden more (so it doesn't permanently adhere to the main cab). Make the coats thin. Better to have to do more coats than have it look too blotchy. I have a couple funky spots but you have to look for them. My Bassman (my first time and the tweed was already dirty) doesn't look near as good.

Gotta find the cable for the camera, and I'll put images up.
_________________

jhguitarlab · Post by **jhguitarlab** » Fri 04/28/06 9:01 am

http://www.angela.com/catalog/how-to/single_6v6/

Also some good reading and layout for the simple 6V6 on the Angela Instruments site.

I'm quite glad I started with this information as I still love my first amp build.
JH

Tele-cat · Post by **Tele-cat** » Sat 05/06/06 4:43 pm

Has a Jensen RI P8R in it, a 4.7uf electrolytic on the first (far right) preamp resistor, a Mercury magnetics OT, a NOS Mullard 12AT7, JJ 6V6S and a NOS GE 5Y3. I did the shellac on the tweed myself.

The cap brightened it up some and the RI Jensen did some more. With that Tele, it's a screamin' little amp.

And it completes my screaming Tweed Stack!

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