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Primer on EL84 to 6v6 conversion wiring?

big mike

Platinum Supporting Member
Messages
12,406
So I'm thinking of either doing an 18 watt TMB, or a 20 watt 2061X, but I want to use 6v6 power tubes., I get the cathode resistor changes to 270 like a tweed deluxe, and the PI tail changes.

Basically..is there some sort of diagram converting the wiring? I'm lost on that.

THanks! Just trying to wrap my head around it before I buy parts.
Was thinking another 50 but I have a 1987 and a JTM45 modded to damn near 1987 specs...so a 20 watt grab abd go would be more to my liking.

Not digging my 5e3 much either. :facepalm
 

WaltC

Member
Messages
2,129
go to duncan's site (http://www.duncanamps.com) and compare the wiring/pinouts for EL-84s and 6V6s at the Tube Data Sheet Locator to see the differences between the pinouts on the two types of tubes and the max voltages, conductance and heater amperage of the two.

You can also compare Fender Deluxe schematic/layout diagrams and the ones for the TMB to see how the two types of tubes are connected.

If you don't have a GE and/or RCA tube manual I'd recommend you get one/both as an ongoing reference, but swapping between EL-84s and 6V6s is overall pretty easy and straight forward as long as you are care with the pinout changes.
 

Blue Strat

Member
Messages
30,067
Compare schematics of amps with both power tube types. One by one, go through the different pins: Plate, cathode, grids, screen grids, heater, etc.
 

Chris Scott

Member
Messages
9,034
Compare schematics of amps with both power tube types. One by one, go through the different pins: Plate, cathode, grids, screen grids, heater, etc.
Tom Mitchell's book has a few good pages regarding this, though any ref. material will work just fine.
 

big mike

Platinum Supporting Member
Messages
12,406
Yeah after looking at the Duncan pages seems it was a bit of a dumb question lol
Was looking for layout but really it's not that bad a conversion when you go to the tube pin outs

Duh

:facepalm
 

big mike

Platinum Supporting Member
Messages
12,406
Not yet. Haven't had the $ to put into the parts.

Not sure I'm going to do it or not.
 

Billm

Member
Messages
574
6V6s like a bigger coupling capacitor than you find in most EL84 circuits. I use .1uF. Also, bigger,non-shared screen resistors.
 

Hacksaw

Time Warped
Platinum Supporting Member
Messages
10,217
Not digging my 5e3 much either. :facepalm
What's the part you don't like on 5e3? I ran into headroom issues and wanted to try 6l6 tubes plus the tranny upgrade but never did it. I always wondered if it would of been more fun.
 

smolder

Platinum Supporting Member
Gold Supporting Member
Messages
14,305
Not yet. Haven't had the $ to put into the parts.

Not sure I'm going to do it or not.
fwiw... I built a Marwatt (two channel 18 watt with one channel voiced to Hiwatt)... with 6V6's. Most of the advice and direction came from the folks over at 18watt... turned out great... One of the sweetest amps I've built.

I'll look to see if I ever made a final layout or schematic.

Edit: no schem or layout... but I did find these notes (titled EL84 to 6V6)

cathode resistors from 100 or 150 to 270
PI tail resistor from 47k to 22k
grid stoppers from 82k to 52k
screen resistors to 470k

It was about 5 years ago... and I have not had the chassis out since... but that's what I have written down.
 
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