so far: no indicator LED's - one of the ground wires (I'm doing offboard wiring, fragile...) broke off which is probably affecting all of them (?)
But I'm sampling up a storm, grinding away gnarls of my Weird Sound Generator. Overdub works, pitch works, analog controls work...
So I'm going to have to review others' recordings of WTPA. Mine sounds "always bit reduced" - I know its a crunchy box but I can't tell if this is a) malfunction b) how it's supposed to sound c) an effects setting I acc. turned on d) touchy input gain causing crust...
It takes some tweaking to the input gain to get it working right. And by working right I mean, sounding like a gritty 8bit sampler.
I had a bunch of problems with mine due to offboard wiring and the inclusion of a 4-1 mixer circuit, so bleed was a big problem. In the end I cut the traces to the overdub section, and did a bunch of shielding and I'm real happy with the results.
Hey Rodrigo, I read that thread in brief when it was going on and read it in detail now. I don't completely 'get' it.
Questions: - Shielding wire: I have pretty typical connection wire going on. By shielded wire, what sort of shielded wire did you use, and, did you actually *re-do* all your wiring? Or did you some how add shielding to the existing wire? My wire is insulated, but not shielded, much. But it will be crazy trying to pull all the wiring and re do it. if there's a way to add shielding basically to/around the existing wire that would be great.
- perhaps pot grounding is an issue: what did you do?
- I will try to identify the traces to cut and replace with shielded wire- the shielded wire goes from one socket leg to the other, yes?
thanks for this help, I think I have a lot of de-noising to do. The background noise and aliasing are pretty out of control at this point.
For me, the trace cutting that he suggests had a big impact. Your mileage may vary there. For the shielded wire (in that particular mod) I got regular instrument shielded cable (thinner than guitar cable) and the center is the 'hot' and the shield is connected to ground (on one side only, to avoid ground loop).
I didn't use much shielded wire going from/to the board, although I'm sure it would help. Grounding the pots made a massive difference too, particularly to the speed/pitch knob, which was less than an inch from my mixer circuit, and the output jacks. You could really hear the clock bleed otherwise.
Most of the fixes I did dealt with bleed related issues and not grunge so much. The trace cutting did help in my grunge department (I believe it lowers the general noise when recording).
At the moment, what does it sound like if you record silence? (nothing going into the input). Do you get a lot of rumble? Clicks? When you press record, do you hear noise while the button is pressed and the circuit is recording?
For me I got mad noise during all of what I just mentioned, and the trace cutting diminished it quite a bit.
I've noticed that recordings are way noiser the more dynamic the source is. If I try to record a drum machine, synth, or older track with very little to no compression, there's a lot of background noise and very loud aliasing. If I sample a compressed track or compress the synth/track before I sample, I get a much cleaner recording. The WTPA is fairly noisy, and you can hear this when you record some silence - mine crackles and hums a little. I think the severity of this varies from WTPA to WTPA since I've heard cleaner ones in other demos.
This cut traces shielded wire mod is interesting but I find its getting scrambled up with discussions of mods to the add-on mixer cirrcuit that most of us are not doing. Could someone who has done this upload a clear pic and repeat of just the cut and bypass shielded wiring showing it in its completed form please? Maybe an arrow or two etc? Thanks
When I record silence I get clicks, noise, hum, etc. Oscillator bleed too.
I would like to see the break-trace-and-replace-with-shielded mod visually/diagrammatically before I cut. Yikes! I am confused is this the same trace cutting operation as the previously recommended one where the unused overdubbing section is cut off? Where is that on the board? (will review forum past threads for that info)
While I do not have the mixer that made Rodrigo's WTPA noise prone, I have a LOT of off board wiring. And this could be similar in how it is affecting the noise floor.
Thanks everyone for the help I am looking forward to debugging this noise. I know its extra effort but pictorials would be greatly appreciated. - Strategyh
Yeah it's the overdub section trace that I cut. Mine is all put back together and I'm scared to open it as well. He explains it clearly in a thread or two (probably the one that I posted). You have to remove the big IC to cut one of the traces, and you have to wire a jumper to one of the pots too, which I believe I detail what/where in the post too.
I agree that it would be nice to have a clearer guide to it, but it wasn't too difficult to follow.
The bleed and all that other stuff will be helped by grounding pots and shielding stuff, and although mine had a mixer circuit in it that others don't have. All that did was basically act like a noise antenna, so I had to be very careful with everything.
Since it's an 8bit sampler, that means you have much less headroom, which is why compressed/loud things sound great. They are filling the bit depth, or however that works, so you're getting maximum fidelity. With quiet sounds, you're in the shitty range of the bit depth and you'll get more noise/hiss/crap. That's why 24bit recording is so nice, it lets you be quieter without it sounding like shit. And if you use the built in bit reduction effect, when you go down to 1bit you'll notice that you have no dynamic range at all. It's one volume, horribly loud.
First try grounding all your pots and see how that effects the bleed issues. Is your speed control pot right above the rest of the board? Maybe put some grounded metal between the pots and your board. The standard layout keeps clock related things away from audio related things, so there isn't much bleed when you wire it all up on the board, but when you start moving those things about, you are moving the sources of noise.
Oh, as mentioned, I think cutting the traces removes/reduces the noises/clicks when recording silence. As the old overdub traces traverse noisy bits of the board.
Yeah the grit is great and part of the sound. For me I wanted to be super anal about it as it's being setup as the 'hub' of my system, with everything running through it.
I was going to ask a lot more questions about this but, my WTPA has completely stopped working. I was jamming around on it and it gave up the ghost. First, hitting record seemed to only create a millisecond long recording of a little noise blast. Now, it won't record anything. I've checked for shorts and opens but I don't see anything so it's gonna be a long debugging process now.
Thanks everyone for the help, if I can get it up and running again I'll try the audio clean up mods.
I have power, audio, and the oscillator. here's what it does...
if I leave WTPA powered down for 10 min, then hook up the battery and start sampling, it works. But then, as I turn up the pitch (coarse) it dies when I bring the pitch up as high as it will go. Henceforth, it will only sample the micro repeating noise blast.
When I built my first WTPA, it started doing weird stuff like that due to the battery being nearly dead, so I'd definitely a try new battery or a supply. I think I had played with it for less than an hour before the battery died.
So why would the whole LED bank (except the power LED) not work? Any ideas? I fixed the broken wire on that, and still no love from the entire row of LED's. I checked polarity; it's fine. I need to check and make sure I used the correct value resistors in that section, I guess....otherwise, it's a mystery...
If the whole set of LEDs doesn't work, make sure everything is kosher with the driver IC (IC8, the latch near the LEDs). Make sure it isn't upside down. Make sure the Latch Enable pin is toggling and that the Output Control pin is tied to ground (basically the chip select pin for this IC). Pins 11 and 1. See the 373 datasheet: http://www.fairchildsemi.com/ds/MM/MM74HC373.pdf
Make sure it's getting 5v. Make sure the pins didn't get bent badly on insertion if you're using a socket. When in doubt you could just resolder it -- that's what I'd do first.