FS Siemens BV 7105/3 output transformers

For Sale


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I slowly gathered all the parts to build a pair of SE AD1 amplifiers and then never did it. My relationship with music and audio has changed, I probably never will get around to it, so here are the main components for sale.

First is an early pair of Telefunken AD1s with DRP printed on the glass. I purchased these as NOS from a Czech dealer who specialized in pre-war electronics. I can dig up the exact Funke W19 test results if necessary.

Asking $1600 US for these which is much less than I paid. You can buy them and flip them on eBay if you want, I don't care.


And here are a very rare pair of Siemens BV 7105/3 output transformers. They have an interleaved construction which give them a wide bandwidth response of 30 Hz to 18 kHz. Not bad for 1938. They are perfectly suited to loading a single-ended AD1, but also good for RE604, EL12, AL5, F2a11 or other tubes with Ra of 2.2 to 5 kOhm. Power handling of ~8-10 watts with 1:18 transformation ratio. In case you are not familiar with the sonic quality of pre-war German iron, I will simply say it sounds much better to me than the most esoteric and exotic modern transformers.

I can give you a cookie cutter schematic and operating points for an AD1 amplifier using these transformers.

Asking $500 US for the transformers.

Last edited:
the AD1 triodes sold

the transformers are still available. big price drop to $500 US. you will be hard pressed to find pre-war iron of this quality for broad SE applications