[sdiy] headphone driver for synths

Brian Willoughby brianw at audiobanshee.com
Sat Aug 28 23:05:07 CEST 2021

This is interesting. The National Semiconductor Application Note has absolutely no commentary on the circuit other than the title, "Power Booster."

NS uses the LM108, and the schematic is different from the one Roman shared because it has no negative feedback! Instead, pin 8, the compensation input, is used as a sort of feedback, even though that's not shown anywhere in the Linear Technology data sheet for the LM108.


On Aug 25, 2021, at 16:06, Dave Brown <davebr at modularsynthesis.com> wrote:
> I just built a vintage Buchla 275 reverb module which uses that topology. It works quite nicely. It worked better with a TL071 than with the original vintage MC1456. The module consists of a panel with control circuitry and a separate reverb unit that uses a similar circuit to drive the reverb tank. I have details on my 275 page at https://modularsynthesis.com/mems/275der/275der.htm
> Dave
>> -----Original Message-----
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
>> Roman Sowa
>> Sent: Wednesday, August 25, 2021 12:43 AM
>> To: synth-diy at synth-diy.org
>> Subject: Re: [sdiy] headphone driver for synths
>> Has anyone ever tried to explore this not-so-new idea of using opamp's
>> supply currents to drive boosting transistors?
>> Schematics attached.
>> Roman

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