A couple of calibration questions and then I'm finished....

So my enclosure has arrived from Elstroumpf and so I'm keen on getting the last few bits of calibration/tuning finished and finally have my Yocto finished, rather than the fragile naked vulnerable board that is currently sat in my studio.

So, from listening to the samples here http://smd-records.com/tr808/?page_id=14 and also couple of other people's finished demos, I've still got a few minor issues..

1: My bass drum seems a bit high pitched, and also seems to have less decay.

2: I can very faintly hear the accent steps triggering the snare, well at least the tuned part when there are no snare steps (you can hear the tone knob affecting this very quiet sound, but not the snappy control). Weirdly, if there is a clap on a step (but with the clap volume turned right the way down) then I don't get this triggered...

3: My clap does not sound quite right - rather than the nice classic 'clak reverb....' sound I have what sounds like a football stadium all clapping at once. This is most likely to do with only being able to turn TM4 down to about 180mv, so seeing as I'll need to desolder bits to get down there I was thinking of doing the noise mods in the service manual:

So am I right in thinking that is:

1)Replace R129 with a jumper
2) Replace R311 (330k) with a 100k? Is this a typo? I can see R131 (300k) replaced with 100k on the diagram above...
3) Replace R 127 with a 10u capacitor
4) Solder a 22p capacitor in parallel to R130

Does anyone have any sound clips of before/after these mods? I'm so close to being finished, and after so many tense sessions of thinking I'd killed my Yocto desoldering etc I'd hate to try to make a last mod and ruin it all at this stage, but of course I want it to be finished and sounding as good as it possibly can before putting it in the case...

In fact, my clap sounds similar to the miami in this video:

https://www.youtube.com/watch?v=cniIkckWtyc[/video]

I use a 68k resistor instead of the 47k resistor for R165 to get a similar pitch for the BD (also used the samples and Nepheton VST from D16 as reference)...because i didn't want to drill a hole in my new enclosure from Elstroumpf...before that i had a 100k pot to alter the pitch.

For the decay i did this mod:

Solder a 390k resistor in parallel with R164 (47k)

I never even noticed the typo (R331 vs. R131) when doing the fix. I followed the schematic and changed R131 to 100k. Your other steps are correct.
The changes nicely get your trimpot in the correct range for calibration of the noise level.

I hear some faint triggering of toms and snare too from trigger pulses. I would like to know a solution to that as well.

So yeah, a the start here is more the classic 808 clap sound, but mine sounds more like at 40 secs in:

https://www.youtube.com/watch?v=2o1iPfn25fA[/video]

If your clap is like at exactly 40 sec of the video, then I think your noise level is too high. In fact, the parameter the guy is changing at this moment is this one I think.

gihaume wrote:If your clap is like at exactly 40 sec of the video, then I think your noise level is too high. In fact, the parameter the guy is changing at this moment is this one I think.

Yep, like I say, currently I can only get down to about 180 mV with the trim. I'm going to do the noise section mods tomorrow and then hopefully be able to set it to 130mV

So I've done the noise section mod, and I'm comparing it to the 808 samples I linked to before.

Weirdly, I can't seem do get a reading from my meter that makes any sense for the noise trimmer, but anything other than fully clockwise is far too noisy.

Other than that, I've noticed a couple of weird things - i seems that the reverb part of my clap does not sound for the first couple of times:

http://4teenth.co.uk/uploads/Yocto_Clap ... Reverb.mp3

Then if I leave it a while without playing, the reverb is gone again, until a few claps have sounded.

Also, compared to the sample, my noise seems kind of scratchy/distorted:

http://4teenth.co.uk/uploads/Yocto_Clap ... _noise.mp3

This might be just that I need to turn the trim a bit further/ swap R127 (I measured it at 90k, even though it is supposed to be 100k)

Also, and possibly related, is the decay on the noise section of the snare is much longer than the examples..

Oh aaaaalso, my snare seems really quiet, and my clap is deafening....

Pretty sure I double checked the pots before I soldered them in, but where would I need to measure to make sure they are correct?

Adjusted TM3, which seems to balance between initial claps and reverb, and now have a much more reasonable level and nice sound from the claps, but the weird no reverb for the first couple of hits problem remains...