[sdiy] headphone driver for synths

[cheater cheater]

Probably bears saying that the reason the transistor on the output
works well is that headphones are low impedance and so especially with
bass freqs a normal op amp will meet its current capacity, while a
transistor can sink loads more current.

On Wed, Aug 25, 2021 at 12:04 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
>
> I thought Douglas Self covered this in one of his books
>
> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman Sowa
> Sent: 25 August 2021 08:43
> 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
>
> W dniu 2021-08-25 o 01:49, ulfur hansson via Synth-diy pisze:
> > you all are amazing, thanks so much for the info!!
> >
> > sent from outer space
> >
> >> On 24 Aug 2021, at 23:19, Vinicius Brazil via Synth-diy
> >> <synth-diy at synth-diy.org> wrote:
> >>
> >> 
> >> +1 with bd139/140
> >>
> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
> >>      Livre de vírus. www.avast.com
> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>.
> >>
> >>
> >> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
> >>
> >> On Tue, Aug 24, 2021 at 7:29 PM Brian Willoughby
> >> <brianw at audiobanshee.com <mailto:brianw at audiobanshee.com>> wrote:
> >>
> >>     Looking inside gear that I've owned over the years, I have seen
> >>     plenty of purpose-designed headphone amplifier chips. I've never
> >>     designed with them or looked at the pricing, so they might not be
> >>     the best choice for all situations, but they certainly have plenty
> >>     of power and the data sheet example circuits will certainly be
> >>     aimed at driving headphone loads.
> >>
> >>     Brian
> >>
> >>
> >>     On Aug 24, 2021, at 09:49, ulfur hansson via Synth-diy
> >>     <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>> wrote:
> >>     > hello all!
> >>     >
> >>     > i've been getting mixed results for a few yeara using standard
> >>     opamp circuits to drive headphones for my projects. oscillations
> >>     randomly seem to occur, noise issues that disappear if i use nice
> >>     outboard preamp etc...
> >>     >
> >>     > is there a more juicy/capable solution anyone can think of? THAT
> >>     corp line drivers? discrete transistor drivers?
> >>     >
> >>     > any thoughts would be greatly appreciated :)
> >>     > -ulfur
> >>
> >>
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