Acetate wrote:As another example, this is what I get on my snare. I think it sounds like a fairly similar issue.

https://vocaroo.com/i/s1OJHCltNJUV

I am probing now as well. I have not figured out the screen capture on my scope. Need to learn that first.

My bass drum and low tom (the only others that I have built thus far) sound great. That leg of C70/C83 really wants to kiss the tab of VR10. Need to ensure a very tight trim on those legs.

Yes, that's exactly how mine sounds too. I went through the whole snare circuit again today and compared it with the original 909 schematics. Everything seems to be correct. Maybe there is again some kind of ground interference like with the bass drum in the first pcb version? Vincent, it would be really cool if you could investigate as well.

I have my component legs always cut very short. But you are right: if you don't do so, there is some risk that the legs of C70/ C83 could touch VR10.

I just compared your ENV scopes with mine once more... assuming that the green horizontal indicates 0V (not the orange) your ENV2&3 look fine!
still it would be interesting to see what's going on at C79/C70

However i'd suspect something goes wrong at Q50/Q51... maybe a faulty series? did you try different 2SC2603 from different series?
you could also check if the transistors are okay with the diode checker on a multimeter.
For NPN:
- red probe on Base (Pin 3)
- black probe on Emitter/Collector (Pin1/Pin2) in both cases a reading of around 600mV is good.
>NAVA has to be turned off, but should also work in-circuit.

Also check if you have 0V at pos./neg. Inputs of IC40B (Pin5/6)
>NAVA turned on

Galaxy3000 wrote:I just compared your ENV scopes with mine once more... assuming that the green horizontal indicates 0V (not the orange) your ENV2&3 look fine!
still it would be interesting to see what's going on at C79/C70

However i'd suspect something goes wrong at Q50/Q51... maybe a faulty series? did you try different 2SC2603 from different series?
you could also check if the transistors are okay with the diode checker on a multimeter.
For NPN:
- red probe on Base (Pin 3)
- black probe on Emitter/Collector (Pin1/Pin2) in both cases a reading of around 600mV is good.
>NAVA has to be turned off, but should also work in-circuit.

Also check if you have 0V at pos./neg. Inputs of IC40B (Pin5/6)
>NAVA turned on

Hi,

thanks again for your time. Those are some good suggestions, but unfortunately I have already tried them out. Voltage readings on IC40 are also correct. I have a few 2SC2603 here from my recent builds that always worked great. I swapped these with the ones that came with v1.02, even though the measurement readings of those were also ok. No difference.

As I am not the only one with this particular issue and both of my new builds show the same behaviour, I am quite sure that it must have something to do with the new board. Unfortunately I couldn't find anything wrong with it yet. I compared all the connections with the 909 schematics and everything is equal.

Really annoying, as I have plenty empty cases laying around that would like to be stuffed...

Any luck with this klang?

I'm just about to start my first build, but I may hold off if it's a v1.02 specific issue.

azander wrote:Any luck with this klang?

I'm just about to start my first build, but I may hold off if it's a v1.02 specific issue.

Right now I gave up on this project. I have spent countless hours trying to find a fix. I am still waiting for others here to report about the same issue with their builds. Hopefully this will get things moving...

Anyone else here with a completed v1.02 and a wrong SD decay? I am unsure whether I should try to build a third v1.02 unit or not...

KlangGenerator wrote:Anyone else here with a completed v1.02 and a wrong SD decay? I am unsure whether I should try to build a third v1.02 unit or not...

Here I am Klang! Just completed the snaredrum after bassdrum and sequencer. Everything is ok except for the infamous sd decay. This is a recording of the snare: https://vocaroo.com/i/s1A2c2dfW0BC . It sounds veeeeery close to the first one you posted. I tell you: I don't dislike the sound as it is, but I don't like that it doesn't sound as it is intended.

So the issue didn't occur on the previous board version ? If so, it has to be viewable on schematics if it is generated with the circuit drawn on eagle.

donzo93 wrote: Here I am Klang! Just completed the snaredrum after bassdrum and sequencer. Everything is ok except for the infamous sd decay. This is a recording of the snare: https://vocaroo.com/i/s1A2c2dfW0BC . It sounds veeeeery close to the first one you posted. I tell you: I don't dislike the sound as it is, but I don't like that it doesn't sound as it is intended.

Thanks for letting us know. So this is definately an issue with the new board!

gihaume wrote:So the issue didn't occur on the previous board version ? If so, it has to be viewable on schematics if it is generated with the circuit drawn on eagle.

I have checked several times, going through the circuit trace by trace and comparing it with the original schematics. I couldn't find anything different, but of course cannot exclude that I overlooked something.