[sdiy] headphone driver for synths

Mike Bryant mbryant at futurehorizons.com
Wed Sep 8 22:23:36 CEST 2021

Yes the OPA1678 has a higher drive current than the 5532, but using both of the pair of a 5532 in parallel works out cheaper than half a OPA1678 per channel provided you don’t mind the 4 times quiescent current (2* per opamp and 2 opamps).
Noise and distortion are very similar, and far below what is audible.

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Martin Klang
Sent: 08 September 2021 17:49
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] headphone driver for synths

What about just using an op amp with higher current capabilities, like

TS922: Rail-to-rail input and output, Low noise: 9 nV/√Hz, High output current: 80 mA (able to drive 32 Ω loads)

or for split rails maybe the OPA2990?

For line level outputs that should also cope with headphones (as opposed to dedicated hp outs) I've been using OPA1678 which I think can output 50mA. Have I been doin' it wrong?


On 08/09/2021 15:07, Mike Bryant wrote:
You can trace that design back to at least Wireless World's around 1974, probably a bit earlier.

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