[sdiy] anti pop mosfets in minibrute

[Shalom D Ruben]

That’s embarrassing… first post and it’s an accident. Sorry!

___________________________________________Please excuse the brevity and tpyos as it was sent from my smartphone.
________________________________
From: Shalom D Ruben <shalom at colorado.edu>
Sent: Wednesday, April 24, 2024 6:22:36 PM
To: Chris McDowell <declareupdate at gmail.com>; Mike Bryant <mbryant at futurehorizons.com>
Cc: SDIY List <synth-diy at synth-diy.org>
Subject: Re: [sdiy] anti pop mosfets in minibrute

Can we talk over the phone?

Thanks,
Shalom

___________________________________________Please excuse the brevity and tpyos as it was sent from my smartphone.
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Chris McDowell via Synth-diy <synth-diy at synth-diy.org>
Sent: Wednesday, April 24, 2024 5:59:14 PM
To: Mike Bryant <mbryant at futurehorizons.com>
Cc: SDIY List <synth-diy at synth-diy.org>
Subject: Re: [sdiy] anti pop mosfets in minibrute

[External email - use caution]

good point Mike. And even at 600, the clipping would be barely noticeable at full volume, thus sayeth the spice man

Cheers,
Chris

On Apr 24, 2024, at 6:48 PM, Mike Bryant <mbryant at futurehorizons.com> wrote:


I think the designer assumed the use of consumer 32 Ohm headphones rather than the pro 600 Ohm ones.
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Tom Wiltshire <tom at electricdruid.net>
Sent: 24 April 2024 23:24
To: Chris McDowell <declareupdate at gmail.com>
Cc: SDIY List <synth-diy at synth-diy.org>
Subject: Re: [sdiy] anti pop mosfets in minibrute

Isn't the problem when the output goes *over* the forward voltage of the diodes? Below that limit , they won't conduct, or barely, anyway. In which case, keep the voltage low, but drive the current (it's a low impedance headphone output) and no problem. When the mosfets are on, the output is shorted to ground. When they're not, you're ok up to that (roughly) 2Vpp limit.

Am I just catching up on what you've already worked out? Wouldn't be the first time...;)

Tom


On 24 Apr 2024, at 21:14, Chris McDowell via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:

<https://hackabrute.yusynth.net/MINIBRUTE/digital-board/schematics/MiniBrute-10-OUTPUT.pdf>
<preview.png>
MiniBrute-10-OUTPUT<https://hackabrute.yusynth.net/MINIBRUTE/digital-board/schematics/MiniBrute-10-OUTPUT.pdf>
PDF Document · 339 KB<https://hackabrute.yusynth.net/MINIBRUTE/digital-board/schematics/MiniBrute-10-OUTPUT.pdf>


hello list, I've been looking at minibrute schematics today and I'm puzzled by the anti pop circuitry in the headphone driver. it -seems- like the body diode of the mosfets would conduct when the signal went below 0.6ish volts (something I've run into this using mosfets for dc signal muting).

 From the vca page, that signal can be up to 2Vpp.  https://hackabrute.yusynth.net/MINIBRUTE/analog-board/schematics/MiniBrute-08-VCA.pdf

What am I missing here? Is 2Vpp just fine in this case? Now reading the 2n7002 datasheet I see the forward voltage of the source-drain diode is typ 0.88V, 1.5V max. Did I just answer my own question? 😜

Cheers,
Chris McDowell
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