ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

5E3 Filament circuit

:

4/12/2000 3:52 PM

5E3 Filament circuit

Hi:
After 2 years of lurking and reading, I finaly started my first DIY! I'm going to be asking what are probably a lot of simple questions...

I'm trying a 5E3 tweed deluxe. I've decided to change the filament circuit from stock to the one used in later fender amps (SF, maybe some BF?), as described in "Tube Amp Talk..." by Gerald Weber. It's the artifical center tap (two 100 ohm resistors to ground, one on each side, to create an "artificial" center tap) and the filaments for each tube wired in parallel. From what I understand this will be a better circuit (quiter? safer? ?)

I've got the two 6V6 filaments wired up in parallel but am unsure of how to wire the 12Ax7 and 12Ay7 sockets parallel to the 6V6s. Esentially the shared filament pin (pin 9, if I remember correctly) of the 9-pin tubes are causing me confusion. I looked at a schematic for the SR AA568 which apparently has this heater circuit but I couldn't make sense of it. Can anyone help me to wire this up? How do I parallel the 9 pin filament leads (pins 4, 5, and 9 (?)) to the 6v6s (pins 2 & 7)? Do I just tie 4 to 5 and use pin 4 and 9 in parallel like i used pins 2 and 7 on the 6v6?

Thanks to anyone who can help and please feel free to correct me on any and all factual errors (pinouts, circuits, etc.)

mike

4/12/2000 4:11 PM

Mike;

I hope you realize this is probably more addictive than crack. Anyway, you picked a good amp for a first project.

The heater circuit is probably the hardest part of the amp to wire up...physically. You'll probably end up take a few passes at getting it clean and tight.

First off use 18 gauge wire. You can use a thinner gauge but you might as well do it right! Also use two different colors of wire. It'll keep you from going bug-eyed trying to figure out which side is which.

As for the connections you want to connect all the 4/5 connections together and all the 9's together. From here it really doesn't matter which leg you send to the power tubes. Just keep them consistent.
Send 4/5 to pin 2 and send 9 to pin 7

You'll also want as tight a twist as possible on the heater wires to stop the hum. Here's where solid core wire really works like a charm!

That'a about all there is to doing the heaters. That and a little patience.

Hope that helps you out some and don't hesitate to ask questions. We all start somewhere. Wish I had access to someplace like this when I started out!

Carl Z

4/12/2000 4:30 PM
Troy	Speaking of filament wiring. Does anyone know where you can get those ring washers with the lug tabs that you can solder components to? Makes it really easy to solder the 100ohm ground reference resistors from the pilot light (ala Princeton). Mike, I'm in the process of wiring the 5E3 circuit myself, let us know how it turns out. What trannys did you use? Troy

4/12/2000 5:25 PM

Carl Z:

thanks a bunch! Addictive is right! I've already got the transformers lined up for my next project (low power tweed twin). But first things first... I'm using 18 gauge solid core cloth covered wire. Let me just say that it took me an hour and a half to wire up two sockets and the pilot lite! It's hard as hell to bend (as you know)! although both leads are green, I keep track of which side is which by using continuity function of my DMM at the end of each lead in question. Seems to work, although different colors would have been the smart thing (mental note...). I've been religious about keeping the wire pressed to the chassis and twisted tightly. Again, thanks for the explicit description--it is exactly what I needed.

Troy:
I'm using a deluxe reverb OT (not exactly a 5E3 but should work well enough--plus you can't beat the price at $27.50!). For a PT i'm using a Hammond 272EX (hasn't arrived yet) from Angela.com. what trannies did you go with?

mike

4/12/2000 7:07 PM
Mark Knapp	I did my filaments that way and it works very well. I used a Deluxe reverb trannys. With a 5Y3, I get about 375V on the plates. This is my favorite amp now! It gets used every day, practically. Good luck on yours. Mark Knapp

4/12/2000 7:54 PM
rmike	correction: I'm getting a hammond 270EX (not 272) PT....

4/12/2000 8:15 PM

Mike: Looks like we've got the same PT bought from the same place! I'm using a Weber chassis and had to drill new holes and position the standup style Hammond over the original laydown cutout. What chassis are you using?

As far as OT, I'm trying the Hammond 125E universal. It fits in the standard Deluxe OT holes and will allow multiple secondary impedance taps. This amp's going in a 2-10 cab so I can have one jack 8ohms and the other 4ohms.

Page 1 of 3