[solved] Bass Drum BUZZZ

Discuss Nava construction and related issues

Re: Bass Drum BUZZZ

Postby peskado » Jul 29th, '16, 21:15

I'm almost done my tr9090
want check buzz in r9090
maybe it will help
r10 good idea)
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Re: Bass Drum BUZZZ

Postby Grizzlydj » Aug 5th, '16, 00:37

I build earlier tr9090 and bass drum working very good, no buzz... Maybe mistake on the nava board. too bad that it can not see the tracks! possible marriage to some of them.... :|
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Re: Bass Drum BUZZZ

Postby peskado » Aug 5th, '16, 12:27

Grizzlydj wrote:I build earlier tr9090 and bass drum working very good, no buzz... Maybe mistake on the nava board. too bad that it can not see the tracks! possible marriage to some of them.... :|

You are right, hard fix it if you don't see tracks(
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Re: Bass Drum BUZZZ

Postby FUNKflasher » Aug 9th, '16, 22:51

Pescado & Decoder303!!!!

My name is Andy... I'm owner of TR909 and for last 5 years I'm trying to get rid of BD BUZZ noise on my unit... What I've ever tried... Full cap decoupling of voice PCB, sequencer PCB and Power supply and without of success... Changed all semiconductors /transistors, diods/ same thing, no result... But when I disconnect GND from sequencer board ( so called Digital Ground "DGND" from +5V board) all issues like sequncer LED blinking and internal clock sequencer clicks just disappeares away. But instead I have simple humm like 50Hz ground loop on BD ind.out which spoils all main outs of my TR.. I think it's because of +5V trigger IC's which still present on analog voice pcb that creates groundloop effect because of no +5V DGND...

Once again!!! I have same Bass Drum with parasitic noise source (so called digital noise) available only on BD voice section... No matter if POT is up or down LED/CLK noise is still present... I can agree with Pescado that noise source comes from ground lane on pin 3 ML5218l op-amp... Since there were few PCB revisions of TR909 mine have specific to others ground shielding, that's why my noise issue is not so common... But I'm glad that I found you guys so maybe our chances rise up :)

To the point where I'm now I see that Roland made some errors in PCB desighn by puting wrong +5V DGND and +15V AGND separation, where parasitic digital ground noise affect so unimune analog GND of BD voice section... Since NAVA PCB have all digital and analog sections on one place, problem still exists and the possible way of making BD clean is to cut pin3 trace that connects to AGND and find another GND from Snare Drum or other voice section or even directly close to power section, but since NAVA psb traces unvisible have no clue how to do it...

Anyway I've specially registered on this forum in order to gain all our efforts, so I hope to be useful to U ;)

Andrew
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Re: Bass Drum BUZZZ

Postby FUNKflasher » Aug 9th, '16, 22:53

Since 2U TR-9090 have no sequencer and such a variety of logic digital IC's like 909 or NAVA, it explains purity of outs!
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Re: Bass Drum BUZZZ

Postby redstorm » Aug 9th, '16, 23:29

It was interesting to read, and i can advise try to put some inductance between AGND and DGND
( "ferrite bead", or take any ferrite core + wire and do some winding - the shorter is better ).
You can try to desolder ML5218L, bend the pin3, and solder it back with inductance in pcb/pin3.
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Re: Bass Drum BUZZZ

Postby drifter7508 » Aug 10th, '16, 06:09

When I listen to the wav, I also have that buzz. It's low but its there and more prominent when you start to process the BD with EQ and a compressor.
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Re: Bass Drum BUZZZ

Postby drifter7508 » Aug 10th, '16, 18:24

Been testing out my nava some more today and the same buzz is there. Uploaded a link to you on Instagram peskado. (Think it is you).
The machine is really noisy overall... but that we all now by now... and where the noise is coming from.
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Re: Bass Drum BUZZZ

Postby FUNKflasher » Aug 10th, '16, 19:34

Redstorm thank you very much for idea, I'll consider it... But how much "mH" should that coil have... also heared about AGND DGND separation with two opposite Schottky diodes, but haven't tried it yet...

Hi Drifter where I can listen to noise of your Nava... Also can you notice any changes in that buzz/noise while moving Tempo Pot???
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Re: Bass Drum BUZZZ

Postby decoder303 » Aug 10th, '16, 20:57

Thx for sharing this info Funkflasher and also thanks to Redstorm.

Just to add, my Nava is dead silent, it's just the BD for me that has the issue with hum / noise.
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