[sdiy] TB-303 smps interference - LED activity causing buzzing in audio output

[cheater00 .]

Hi Robin,

On Sun, Nov 24, 2013 at 2:13 PM, cheater00 . <cheater00 at gmail.com> wrote:
> On 24 Nov 2013 05:16, "Robin Whittle" <rw at firstpr.com.au> wrote:
>>
>> Hi Damien,
>>
>> In my experience the LED-activity related buzz in the audio out of
>> TB-303s is due to some kind of ground noise.  I fix it by soldering a
>> piece of hookup wire between the ground terminal of the Volume pot and
>> the ground terminal of the Audio Out socket.
>
> I'll try that, thanks. I somehow seem to remember hearing this tip a year or
> two ago, when I couldn't perform the mod.

I've surprised myself today by finding out I'd actually done the mod:

http://imgur.com/a/idtGJ#66

The thing is, even with this there's a nasty buzz. For instance, this
is the headphone jack sleeve referenced to battery -ve:

http://imgur.com/a/idtGJ#67

The buzz is easily audible when listening through a fuzz/compressor
guitar effect.

I've tried adding bypass to the headphone amp:

http://imgur.com/a/idtGJ#68

but this hasn't done anything good, unfortunately.

I've also come up with some newer ideas, I'll post them in the main thread.

Cheers,
D.