20 watt Doberman transformer?

[chuckb]

Hey guys, I have a Doberman 20 watt output tranny that I'm using for a 18watt TMB build and I need to clarify the wiring.
The pri =brown-0,
Brn/yellow-2.5k
Blue/yellow-4k
Blue-6K

I'm not to sure which wires go to pin #7's on th El84's? I believe the brown and blue go to pins 7 on the el84's and the blue /yellow is b+?

chuck.

[loudthud]

Where did you get those numbers? It looks like that transformer is single-ended if they are the correct impedance. It may be that there are taps on the speaker side that you select to change the primary impedance. Measure the resistance of all the windings and post results here.

[chuckb]

Where did you get those numbers? It looks like that transformer is single-ended if they are the correct impedance. It may be that there are taps on the speaker side that you select to change the primary impedance. Measure the resistance of all the windings and post results here.

Hey loud thud here is where I got the numbers for this tranny.
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Home > Transformers >

Doberman 20 Watt Single Ended Output Transformer




Our Price: $66.00


Product Code: XFRM-DOB20WSE









Description


It's back! The famous Doberman 20 Watt Single Ended Output Transformer. Made in the USA for Doberman by Heyboer to our specifications. Get that great Heyboer/Doberman sound for your single ended project or amp upgrade, but don't delay. We order these once a year and when they are gone, they are gone until next year.

* Primary winding is rated to 145ma full duty or 180ma for typical audio (15-20 watts)

Wiring:

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

Chuck.

[chuckb]

Where did you get those numbers? It looks like that transformer is single-ended if they are the correct impedance. It may be that there are taps on the speaker side that you select to change the primary impedance. Measure the resistance of all the windings and post results here.

Hey loudthud. This is a single ended output transformer . Can I still use it for the Marshall TMB clone build using two el84's?

If so, can you provide me with the info on how to do this?

Chuck

[chuckb]

Hey loudthud. This is a single ended output transformer . Can I still use it for the Marshall TMB clone build using two el84's?

If so, can you provide me with the info on how to do this?

Chuck

Hey loudthud, Got any suggestions?

[chuckb]

Hey loudthud, Got any suggestions?

So, is there anyone here who can tell me if I can use this single ended transformer for two el84's?

Chuck.

[Steve Conner]

No. It's totally the wrong transformer for an 18 watt Marshall build.

[chuckb]

No. It's totally the wrong transformer for an 18 watt Marshall build.

Hey Steve, thanks for the reply. I kinda figured that it wasn't any good for the 18 watt build. I received this set of transformers from a friend which cosist of a 20 watt Hammond 269ex power tranny and the Doberman 20watt output. Any suggestion where I could use these trannys? An AX84 perhaps?

Charles.

[Steve Conner]

A honking big single-ended OT like that will want something like two parallel 6L6s, or a KT88 or 6550. And, the Hammond 269EX PT doesn't supply enough current on the B+ to power that.

You can always build an AX84. The OT will be oversized for your single EL84 or 6V6 power tube, but that's not necessarily a bad thing. Bigger OT means more volume and bottom end.

[chuckb]

A honking big single-ended OT like that will want something like two parallel 6L6s, or a KT88 or 6550. And, the Hammond 269EX PT doesn't supply enough current on the B+ to power that.

You can always build an AX84. The OT will be oversized for your single EL84 or 6V6 power tube, but that's not necessarily a bad thing. Bigger OT means more volume and bottom end.

Hey steve, so the hammond will be ok for the 18 watt marshall tmb? The doberman isn't that big physically but when you say it will run two 6l6's in parallel, then why wouldn't it work with two el84's. I'm not to sure what you mean when you say 6l6's in parallel?

Chuck.

[Steve Conner]

No no no no, when I said an AX84, I meant one of their single-ended designs. You can't use it for an 18 watter, because that's a push-pull circuit, it requires a centre tap on the OT primary, which your OT doesn't have. It has some taps, but none of them is in the middle.

The PT is a bit short on current even for an 18 watter.

Parallel means what it says, you connect the two tubes directly together and use them like one big tube with twice the current rating. Not like a push-pull where the two tubes are driven with opposite signals and take it in turns to drive the speaker.

[chuckb]

No no no no, when I said an AX84, I meant one of their single-ended designs. You can't use it for an 18 watter, because that's a push-pull circuit, it requires a centre tap on the OT primary, which your OT doesn't have. It has some taps, but none of them is in the middle.

The PT is a bit short on current even for an 18 watter.

Parallel means what it says, you connect the two tubes directly together and use them like one big tube with twice the current rating. Not like a push-pull where the two tubes are driven with opposite signals and take it in turns to drive the speaker.

Hey steve,thanks for the info,much appreciated. So I guess some Mercury Magnetics trannys for the 188 watt TMB are in order. I guess I'll use these trannys for a single ended build somewhere down the road.

Chuck.

[chuckb]

Hey guys, so I have a set of trannys (20 watt Hammond 269ex PT and a Doberman 20 watt OT) that I would like to use. Any suggestions on and ideal amp build for these trannys? Schematics would be great if anyone here has something?

Chuck.