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Audio output transformer wiring - Printable Version

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Audio output transformer wiring - Mr. Radio-Man - 10-13-2026

I got this OPT a little bit ago to replace the old one that burned out.
Right now I'm just trying to figure out what wires go where (chassis and speaker)
It's a P-TGO-001 Champ Output 2426 from Amplified Parts

RE: Audio output transformer wiring - RodB - 10-13-2026

You should match, as closely as possible, the plate load impedance of the output tube to the primary winding impedance by selecting the right transformer primary tap. Sometimes the secondary also has different taps for different speaker impedance. So if the speaker is 3.2 ohms and the transformer has a 4 ohm tap then use that one. If you don't have access to a transformer chart or schematic then you'll have to use trial and error by sending an audio signal through the amplifier, measure the AC signal at the speaker for one set of connections then reconnect the transformer for a different set, rinse and repeat. Use the set that gives the highest output.

RE: Audio output transformer wiring - Mr. Radio-Man - 10-13-2026

Hello RodB,

I found this diagram for the OPT
I mainly am just wondering where exactly I put the wires cause I don't want to mess it up in any way.
I am still new to everything and even after I read your comment I still have no idea how to do what you are wanting me to do lol.
I think I have an idea on what wires do where.
Red wire connects to pin 4 on the 6F6 tube (Screen Grid/B+ rail)
and the Blue wire connects to pin 3 on the 6F6 (Plate)
and the brown wire is unused.

Secondary (speaker)/

Yellow goes to the small red wire coming out of the speaker cone
and the black wire goes to the small blue wire going into the field coil housing (hum-bucking coil)

I just want to make sure that this is how its going to need to be wired up.

RE: Audio output transformer wiring - radiorich - 10-13-2026

Hello Mr. Radio-Man,
Based on what I read in the tube data sheet, I would use Red and Blue for the primary and Black and Yellow for the secondary.

Yes. For a single-ended 6F6G output stage, the datasheets specify an optimum load of about 7,000 Ω plate-to-voice-coil impedance at typical operating conditions.

An 8,000 Ω primary output transformer is close enough that it will work very well with a 6F6G. In fact, many vintage radios used transformers in the 7 kΩ to 8 kΩ range.

Hope this answers your questions

Richard

RE: Audio output transformer wiring - Mr. Radio-Man - 10-16-2026

The more I look at the schematic and the wires the more confused I am getting.
The Red and Blue wires apparently were White and Green but the other two wires could have also been either green or white with how they are colored which is making me confused on which wires I am actually supposed to connect the new ones to.
The schematic is listed in the previous post.