• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

DIY HIFI using 003-036551 Hammond Organ output transformers

I tried with those but was not really satisfied with the sound. They would saturate pretty quickly with 6v6 outputs.

Be very sure which output coil you are using as there are two secondaries...the second is for feedback to the output tubes.

Try it with the 6bq5 tubes. Its always a learning experience.


Paid Member
2003-06-12 7:04 pm
Maine USA
> 003-036551 Hammond output transformers and the matching 6bq5

Are you sure? The online references I see show this OT# going with the 7591 octal power tubes.

Most organs over $100 had very fine OTs which exceeded the audio band, if only to ensure NFB stability. Specs aside, the older Hammonds were "musical", they just sounded good.
Well I piped a signal generator into it and the result was I could start to hear as low as 25 Hz with less than a 10th of a volt input, Add nice strong output starting about 35 Hz... that being said I just had the base Channel going into a 12 inch guitar speaker. Definitely peaked around three to about 8000 Hz, and there was a nice strong output up to about 14,500 Hz, and an audible outputs up to about 16,500, there’s a good chance that most of the drop off is based on what is in the audio Chain chain.

I’m willing to bet that also I probably can’t hear much above 16,500 Hz…

Well I’m sure these output transformers are not the best, they will certainly get me by for a little while… Although I imagine if I go to a nice pair of Push poll output transformer’s that are “audiophile grade” that I will not really need the bass channel at all. Either way I imagine I can increase their high-end output when I rework the front end