Can i use this PT for a 50 watt marshall style 2204 build?

[joesatch]

The 2204 layout only uses the secondary Reds and Green for heaters. I would use a FWB.

[sluckey]

Yes, but it's more suited for a 2203. You'll want to use brown wires for your bias. Slight modification to the layout.

[joesatch]

Yes, but it's more suited for a 2203. You'll want to use brown wires for your bias. Slight modification to the layout.

Which tap would you use for the bias? The 2203 uses like 100v. these browns supply 52V. I'm guessing because the 2204 uses 2 power tubes vs 4 the bias tap can supply half as much?

[sluckey]

Deja vu! Is this the same PT you were gonna use on a twin reverb recently?

[joesatch]

indeed. i've ordered a new PT for my AB763 build for tube rectifier.

[sluckey]

Use the browns. Tape off the brn/yel.

[Willabe]

The 2203 uses like 100v. these browns supply 52V. I'm guessing because the 2204 uses 2 power tubes vs 4 the bias tap can supply half as much?

No.

Negative bias uses the same total -dcv using 2 or 4 or 6 or 8 tubes. And -bias draws no current, except the charging current for the bias cap(s), so no increase in -bias current draw for more than 2 tubes.

[joesatch]

Starting to understand this. For the bias circuit it will be fed with the 50V ac wire from the PT. There are 3 brown wires do i just connect one brown and tape of the other two or does one of the others go to ground?

[sluckey]

We already discussed this. Read your twin reverb thread again.

[joesatch]

thanks sluck as per your own words "you will tape off the BRN/YEL wire and connect one BRN to the bias board and the other BRN to ground. " 

[sluckey]

See joesa, you got this stuff. 

[joesatch]

See joesa, you got this stuff. 

really cant see where on a 2204 this 50v would go. Im gonna have to build a 2203 with 2 power tubes.

[sluckey]

See joesa, you got this stuff. 

really cant see where on a 2204 this 50v would go. Im gonna have to build a 2203 with 2 power tubes.

Show us the layout for your 2204.

[joesatch]

See joesa, you got this stuff. 

really cant see where on a 2204 this 50v would go. Im gonna have to build a 2203 with 2 power tubes.

Show us the layout for your 2204.

The mojo 800 layout for example. It has the High Voltage CT to ground (red/yellow). Nothing coming outta the PT to the bias circuit.

[SILVERGUN]

That one taps into one of the HV legs for the bias supply.


Yours has a separate winding that can be and should be used in your case.

[joesatch]

So i would clip and isolate that 220k resistor and connect the 50V to it?

[SILVERGUN]

So i would clip and isolate that 220k resistor and connect the 50V to it?

From a connection standpoint for the bias supply, yes, that's where it would go.
BUT, you would have to change the value of the 220k resistor....


And, obviously, you are aware that the Mojo layout is not showing a FWB for the HT winding, so you'll have to refer back to what sluckey taught you on your other thread

[joesatch]

So i would clip and isolate that 220k resistor and connect the 50V to it?

From a connection standpoint for the bias supply, yes, that's where it would go.
BUT, you would have to change the value of the 220k resistor....


And, obviously, you are aware that the Mojo layout is not showing a FWB for the HT winding, so you'll have to refer back to what sluckey taught you on your other thread

  Correct i will use a FWB and the 220k resistor here i will swap with a 470 ohm. (i think). Same filter cap setup as mojo

[pdf64]

It seems a beefy PT for a 50 watter, its HT voltage seems likely to be very stiff and up near 500V.
With decent valves, it may end up putting out over 60W clean, 100W overdriven.

[joesatch]

It seems a beefy PT for a 50 watter, its HT voltage seems likely to be very stiff and up near 500V.
With decent valves, it may end up putting out over 60W clean, 100W overdriven.