Two-Stroke w/ Doberman tranny

[Sneakers]

Hi all,
I'm in the process of finishing a Two-Stroke amp as detailed in Dave Hunter's Guitar Amp Handbook. However, I'm substituting a Doberman 20 watt SE OT in place of the Hammond 125 ESE that Hunter recommends. The format of the Doberman wiring schematic (Doberman 20 Watt Single Ended Output Transformer) differs some from the format of the Hammond (http://www.hammondmfg.com/125SEsch.gif) and I'm hoping someone can do a quick check of my work.

Hunter has the Two-Stroke set up with a switch that selects between the white and yellow wires of the Hammond.
He recommends:

White wire:
2-6V6 @ 8 ohms
1-6L6 (EL34) @ 8 ohms

Yellow wire:
1-6V6 @ 8 ohms
2-6V6 @ 4 ohms
1-6L6 (EL34) @ 4 ohms

From this (http://www.hammondmfg.com/125SEsch.gif), I gather 2x 6V6 and 1x 6L6 need to see 2500 ohms, while 1x 6V6 should see 5,000 ohms.

Looking at the Doberman schematic (Doberman 20 Watt Single Ended Output Transformer), it looks like I want to hook up the primary using the brown and brown/yellow wires. Then, the green wire on the Doberman OT will be the equivalent of the white wire on the Hammond (8 ohm secondary @ 2500 ohm primary), and the yellow wire on the Doberman OT will be the equivalent of the yellow wire on the Hammond (4 ohm secondary @ 2500 ohm primary, 8 ohm secondary @ 5000 ohm primary).

Hopefully I'm stating that in a way that makes sense. Basically I just want to know if those wire combinations will get me the closest to the 125ESE.

[soundguruman]

Hi all,
I'm in the process of finishing a Two-Stroke amp as detailed in Dave Hunter's Guitar Amp Handbook. However, I'm substituting a Doberman 20 watt SE OT in place of the Hammond 125 ESE that Hunter recommends. The format of the Doberman wiring schematic (Doberman 20 Watt Single Ended Output Transformer) differs some from the format of the Hammond (http://www.hammondmfg.com/125SEsch.gif) and I'm hoping someone can do a quick check of my work.

Hunter has the Two-Stroke set up with a switch that selects between the white and yellow wires of the Hammond.
He recommends:

White wire:
2-6V6 @ 8 ohms
1-6L6 (EL34) @ 8 ohms

Yellow wire:
1-6V6 @ 8 ohms
2-6V6 @ 4 ohms
1-6L6 (EL34) @ 4 ohms

From this (http://www.hammondmfg.com/125SEsch.gif), I gather 2x 6V6 and 1x 6L6 need to see 2500 ohms, while 1x 6V6 should see 5,000 ohms.

Looking at the Doberman schematic (Doberman 20 Watt Single Ended Output Transformer), it looks like I want to hook up the primary using the brown and brown/yellow wires. Then, the green wire on the Doberman OT will be the equivalent of the white wire on the Hammond (8 ohm secondary @ 2500 ohm primary), and the yellow wire on the Doberman OT will be the equivalent of the yellow wire on the Hammond (4 ohm secondary @ 2500 ohm primary, 8 ohm secondary @ 5000 ohm primary).

Hopefully I'm stating that in a way that makes sense. Basically I just want to know if those wire combinations will get me the closest to the 125ESE.

It doesn't make sense until we see the data sheets. The tranny comes with a sheet or should.
The schematic may not show the actual colors of the tranny, as it is from the box.
and so don't assume, but try to get everything to verify it.
And also you can measure the tranny if that's all you have to go on.
leads can get mixed up when you are dealing with transformers, it's common mistake, so double check.
If you did not get a sheet with the unit, call the manufacturer and cry until they give you one.
just because Dober uses brown yellow on the schematic,
it does not mean that another transformer uses the same color code. Never assume this. Always verify.

[Bruce / Mission Amps]

It looks pretty simple to me.
secondary:
Black is speaker load ground, chassis ground or audio low.
Green is 8 ohms, yellow is 4 ohms.

Primary:
Brown appears to be the main B+ (high voltage DC) wire....
Brown/Yellow to the power tube socket(s) gives you 2500 ohms with either the 4 or 8 ohm tap used
Blue/Yellow to the power tube socket(s) gives you 4000 ohms with either the 4 or 8 ohm tap used.
Blue to the power tube socket(s) gives you 6000 ohms with either the 4 or 8 ohm tap used.

With that info you should be able to get where ever you need to be.... unless you are so inexperienced that you don't understand Hunter's amp or any of this anyhow... in which case maybe you should build a fully prepared kit with full "paint by numbers" instructions.
Now, is there something in your question that we don't understand?

Wiring:

pri Brown=0
brn/yellow=2.5K
blue/yellow=4K
blue= 6K
sec black=0
yellow=4 ohms
green= 8 ohms
orange=16 ohms


** I just reread this and it sounds a little surly.. didn't mean that it should, sorry.

[printer2]

I like when women talk to me surly.


Oh wait a minute, it was sultry that I like, Surly is what I normally get.

[Sneakers]

It looks pretty simple to me.
secondary:
Black is speaker load ground, chassis ground or audio low.
Green is 8 ohms, yellow is 4 ohms.

Primary:
Brown appears to be the main B+ (high voltage DC) wire....
Brown/Yellow to the power tube socket(s) gives you 2500 ohms with either the 4 or 8 ohm tap used
Blue/Yellow to the power tube socket(s) gives you 4000 ohms with either the 4 or 8 ohm tap used.
Blue to the power tube socket(s) gives you 6000 ohms with either the 4 or 8 ohm tap used.

With that info you should be able to get where ever you need to be.... unless you are so inexperienced that you don't understand Hunter's amp or any of this anyhow... in which case maybe you should build a fully prepared kit with full "paint by numbers" instructions.
Now, is there something in your question that we don't understand?

Wiring:

pri Brown=0
brn/yellow=2.5K
blue/yellow=4K
blue= 6K
sec black=0
yellow=4 ohms
green= 8 ohms
orange=16 ohms


** I just reread this and it sounds a little surly.. didn't mean that it should, sorry.

No, I agree that I think I was making this more complicated than it needed to be. I suppose my only confusion came from the fact that Hunter maps different tube combinations and speaker combinations to the same tap. Obviously he's relying on the ratio between the primary and secondary windings, rather than assuming a constant primary impedance and then using the 4 and 8 ohm taps as appropriate. I guess I just wanted to make sure I was understanding that, and the effect that hooking an 8 ohm speaker to the "4 ohm tap".

However, for my purposes here, I don't really need to worry about it. According to the Hammond sheet, the white wire is the 8 ohm tap and the yellow wire is the 4 ohm tap with a 2.5k ohm primary. According to the Doberman sheet, the yellow is the 4 ohm and the green is the 8 ohm, and using the brown and brown/yellow wires give a 2.5k primary. At that point, they're equivalent and everything is good.