[sdiy] BBD clock bleed

Quincas Moreira quincas at gmail.com
Tue Oct 23 19:16:56 CEST 2018


This is great, thank you!

On Tue, Oct 23, 2018 at 12:11 PM Tom Wiltshire <tom at electricdruid.net>
wrote:

> So, to summarise:
>
> 1) Clock balance trim. 10K to replace R38/R41.This can help a bit, but you
> won’t see a huge effect.
> 2) Proper pre-BBD and post-BBD filtering. Even if the clock noise is
> ultrasonic and can’t be heard, it can cause problems further down your
> audio path. This is the most important. Bonus points for adding tracking
> filters to avoid cutting the bandwidth when not required.
> 3) Keep CP1 and CP2 PCB traces short and neat and away from other
> sensitive lines. I put them on one side of the board and the OUT1 and OUT2
> traces on the other side, and that seemed to work pretty well.
>
> BBDs are noisy in general, and quite a few original 1980’s circuits wrap a
> compander (NE570/SA571 or similar) around them to try and keep it under
> control.
>
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
>
> > On 23 Oct 2018, at 15:36, Quincas Moreira <quincas at gmail.com> wrote:
> >
> > Great info folks, thanks very much! I think for this video I will heed
> Erica's request and keep it as a flanger or slapback. It sounds pretty
> awesome doing that !  I already have two Pico DSP and one Erica digital
> delay for the longer repetitions...
> >
> > Cheers and a great day to all!
> >
> > Q
> >
> >
> >
> > On Tue, Oct 23, 2018 at 9:26 AM <rburnett at richieburnett.co.uk> wrote:
> > I doubt that pursuing any sort of "out-phasing" technique like that to
> > reduce the clock feed-through would ultimately be very fruitful.
> >
> > The amplitude of the clock feed-through likely depends on the
> > instantaneous clock frequency.  The phase shift of the feed-through may
> > also vary with frequency, and your integrator to convert the clock from
> > square to triangle would add 90 degrees worth of phase shift to start
> > with anyway...  It would therefore be hard to achieve any significant
> > degree of cancellation over a range of clock frequencies, in my opinion.
> >
> > I'd be looking at a static LPF or some sort of tracking filter to remove
> > the clock feed-through, once I was happy that the original design was
> > working properly, or at least as good as it can do.
> >
> > -Richie,
> >
> >
> >
> > On 2018-10-23 14:36, Quincas Moreira wrote:
> > > I’ve thought of using na integrator to derive a triangle from the
> > > clock pulse, then an OTA to distort it into a sine, then invert it and
> > > sum it to the BBD output thus cancelling most of the bleed but now
> > > we’re talking a full on daughterboard, lol
> > >
> > > Sent from my iPad
> > >
> > >> On Oct 23, 2018, at 8:12 AM, Tom Bugs <admin at bugbrand.co.uk> wrote:
> > >>
> > >> There appears to be minimal input and output filtering also.
> > >>
> > >>
> > >>> On 23/10/2018 14:07, Vladimir Pantelic wrote:
> > >>> no output balance trimmer between out1 and out2 on this one
> > >>>
> > >>>> On 23.10.2018 14:46, Quincas Moreira wrote:
> > >>>> Sorry Folks, please follow this link
> > >>>> https://drive.google.com/open?id=1O5kKkaJZqom61W8WQKQCfm3gLF83goz0
> > >>>>
> > >>>> Sent from my iPhone
> > >>>>
> > >>>> On Oct 23, 2018, at 06:13, Tom Wiltshire <tom at electricdruid.net
> > >>>> <mailto:tom at electricdruid.net>> wrote:
> > >>>>
> > >>>>> The list strips attachments. Can you post a link?
> > >>>>>
> > >>>>>
> > >>>>>> On 23 Oct 2018, at 08:30, Quincas Moreira <quincas at gmail.com
> > >>>>>> <mailto:quincas at gmail.com>> wrote:
> > >>>>>>
> > >>>>>> thanks folks. It’s a new
> > >>>>>> module, not yet released V3205 based. Strange that you don’t see
> > >>>>>> the
> > >>>>>> pdf attachment, I’ll try again in the morning
> > >>>>>>
> > >>>>>> Sent from my iPhone
> > >>>>>>
> > >>>>>> On Oct 22, 2018, at 23:59, Pete Hartman <pete.hartman at gmail.com
> > >>>>>> <mailto:pete.hartman at gmail.com>> wrote:
> > >>>>>>
> > >>>>>>> As others have said a lot depends on which BBD we're talking
> > >>>>>>> about.
> > >>>>>>>
> > >>>>>>> Most of my BBD experience is with Blacet's Time Machine.  It uses
> > >>>>>>> the MN3005 which has balanced outputs, which can be trimmed to
> > >>>>>>> minimize the clock bleed, and it also uses clock dependent
> > >>>>>>> filtering
> > >>>>>>> and compansion to help reduce the noise further.  I have also
> > >>>>>>> played
> > >>>>>>> some with the Doepfer A-188-2 which uses a tapped BBD, and that
> > >>>>>>> does
> > >>>>>>> *not* have balanced outputs, so the bleed is harder to tame.
> > >>>>>>>
> > >>>>>>> I looked at the Erica site as well, and honestly, I can't tell
> > >>>>>>> which
> > >>>>>>> one you're asking about either.  Let us know/attach the schem,
> > >>>>>>> and
> > >>>>>>> I'm sure someone will have suggestions :)
> > >>>>>>>
> > >>>>>>> Pete
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> On Mon, Oct 22, 2018 at 8:55 PM Quincas Moreira
> > >>>>>>> <quincas at gmail.com
> > >>>>>>> <mailto:quincas at gmail.com>> wrote:
> > >>>>>>> Hey friends! I'm working in a review of the new Erica Synths BBD
> > >>>>>>> module, and I'm getting massive bleed of the clock frequency
> > >>>>>>> (though
> > >>>>>>> it looks sinusoidal rather than square)
> > >>>>>>> Any tips on minimizing this bleed? Anytime the clock steps into
> > >>>>>>> audible range it's super loud
> > >>>>>>>
> > >>>>>>> Schematics included...
> > >>>>>>>
> > >>>>>>> Thanks!!
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> --
> > >>>>>>> Quincas Moreira
> > >>>>>>> Synth Diy Guy
> > >>>>>>> _______________________________________________
> > >>>>>>> Synth-diy mailing list
> > >>>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
> > >>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
> > >>>>>>> _______________________________________________
> > >>>>>>> Synth-diy mailing list
> > >>>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
> > >>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
> > >>>>>> _______________________________________________
> > >>>>>> Synth-diy mailing list
> > >>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
> > >>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
> > >>>>
> > >>>> _______________________________________________
> > >>>> Synth-diy mailing list
> > >>>> Synth-diy at synth-diy.org
> > >>>> http://synth-diy.org/mailman/listinfo/synth-diy
> > >>>>
> > >>> _______________________________________________
> > >>> Synth-diy mailing list
> > >>> Synth-diy at synth-diy.org
> > >>> http://synth-diy.org/mailman/listinfo/synth-diy
> > >>
> > >> --
> > >> BugBrand LTD
> > >> UK company No. 07199808
> > >> VAT No. GB 988 2629 57
> > >> 1 Ninetree Hill
> > >> BRISTOL BS1 3SB
> > >> United Kingdom
> > >> www.bugbrand.co.uk
> > >>
> > >>
> > >> ---
> > >> This email has been checked for viruses by AVG.
> > >> https://www.avg.com
> > >>
> > >> _______________________________________________
> > >> Synth-diy mailing list
> > >> Synth-diy at synth-diy.org
> > >> http://synth-diy.org/mailman/listinfo/synth-diy
> > >
> > > _______________________________________________
> > > Synth-diy mailing list
> > > Synth-diy at synth-diy.org
> > > http://synth-diy.org/mailman/listinfo/synth-diy
> >
> >
> > --
> > Quincas Moreira
> > Synth Diy Guy
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
>

-- 
Quincas Moreira
Synth Diy Guy
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20181023/c2361751/attachment.html>


More information about the Synth-diy mailing list