solved: Little sound problem if touching frontpanel?

[katarakt]

Yeyheey, finished my x0x now and i hear a litte bit distortion in sound if i touch the screws on the frontpanel. Is this normal? Sounds like something is going on with ground signal, maybe those lock-washer are the problem because screwed too deep in the pcb and they have contact with ground?

edit:
I've tested some things now, so it can't be the lock-washers i think. The sound distortion appears even if i touch the frontpanel on the side. The tempo encoder touches the frontpanel a little bit, maybe this has something to do with the tempo encoder? If i move the frontpanel touching the tempo encoder i have some tempo problems too sometimes, the tempo jumps up with a bit sound distortion for half a second.

Before finishing the x0x i've tried desoldering the tempo encoder to solder in a larger one but this was not funny so i leaved the stock encoder as it is. While my desoldtest, the encoder was very very hot, maybe i've destroyed them in some ways? I'm very disappointed ...i hope some can help?

[guest]

does it make the same sound problems
while listening on headphones
it may be a ground loop problem with your mixer

its possible there is a bad connection someplace
try wiggling various parts and see if you can isolate
which one causes the problem

[katarakt]

Yes i have the same problems with headphones.

I've done 3 mods to my x0x, maybe i've placed the switches or cables wrong and this is causing the problem? I don't think so really, but maybe, you can check the pics.

- R46 resonant accent
- R97 variable resonant boost with 5kpot + 4,7k resistor
- Power on/off switch with LED ...i took the LED power from the 7805 5V regulator on the underside from the io-board

Hm, i don't think really there's a bad connection within the parts on the mainboard. I spend a lot of time to every single part do it 100% but i'll check tomorrow evening some things

rear panel mods a.JPG (328.84 KiB) Viewed 2885 times

rear panel mods b.JPG (105.68 KiB) Viewed 2885 times

[charlie_says]

I had a similar sounding issue with my modded x0x.
What I found to the issue to be, and I only noticed it when I pulled the x0x apart and handled it, was that if something (and by something i mean either a finger or a piece wire) touched the mainboard it could cause a very small short (I think the culprit was either the underside of R145 or R135) and it would cause this buzzing noise.
My solution: route the mod wires a different way around, and ensure when I put it all back together that wires weren't sandwiched tightly against PCBs.
Hope that helps.

[katarakt]

It seems this is not the problem. The problem is there if i directly touch the tempo encoder. Hm, the tempo encoder is only for tempo right? If it's damaged somehow, can it affect the sound in this way?
I have also a very little white noise thing but with low volume every time a note is played and only in the beginning from the played note. I hear it best if every pot is turned full counterclockwise. I think this problem has to do with the other problem?...a little bit suspect

[katarakt]

Again i've tested this with R145 or R135, if i touch these resistors there's a buzzing noise you said. Some capacitors have the same problem if i touch the blue side, very strange. I've taken care that no wire or something touches parts. It seems this is not the problem.

The problem is there if i directly touch the tempo encoder and all metal-parts like frontpanel, rearpanel, tempo encoder. Best hearing the problem is take a screw and touching the tempo encoder or frontpanel with the screw. Second problem all the time i've a very low noise in the backround like coming from a ground problem or something. I can't explain this better, the output signal is not 100% clean.

I had some problems first with the power on/off switch, it is too big and i pushed it down in the pactec case on the C48 capacitor...it doesn't look like it's damaged but i want to let you know this.

Strange, i think i'm not able to solve the problem ...are there some easy measuring tests what i can do?

[guest]

the reason why the tempo encoder gives this problem
in comparison to the other knobs
is that it has a metal shaft which is connected to ground

it sounds like a 60hz pickup issue
when you listened via the headphones
did you have the x0x connected to anything else

the low level background noise is always there
its just more noticeable when the notes are quiet
my 303 does this same thing

[katarakt]

Hm, i've not connected the x0x to anything else, just tested it with headphones out or mix out, both the same.

At the moment i can't make a soundfile, haven't a mixer here connecting x0x to recording device but maybe someone of you can make a mp3 or wav with following pattern and without any effects, this would help me to compare it with a 100% x0x from you:

1 C
2 C
3 D
4 F
5 D transpose down
6 C slide
7 C slide
8 G
9 D slide
10 A slide
11 C
12 C accent
13 C
14 C slide
15 C slide
16 A slide

tuning mid, volume full up, all other counterclockwise, mid or slower tempo, no effects ....this would help me very much so i can go for sure that there is something not normal going on.

[guest]

you could try plugging the mixout
into a mixer that is earth grounded
and see what it sounds like

[katarakt]

Ok i'll try this...after testing some things it's better now, i've checked that no cable touching critical parts. Touching screws on frontpanel seems to be nearly gone at the moment, and using the tempo encoder is nearly good now. I'll post a soundfile tomorrow, i have found my special cable but it would be great anyways if someone can post a soundfile too.

Is it normal that the volume overall is not really loud from the x0x and if all potis are counterclockwise it's very low volume?


edit: ok, i'Ve tested some things and took care that no cables are touching caps or resistors as said before and now it seems the problem is gone, i hope so! Cables touching resistors can happen very easy. I'll post pictures in the pics thread asap!

thanks for help at the moment!!

[katarakt]

guest you are right with the earth grounded thing!

While i've put back the boards in the packtec case i tuned my x0x now with g-tune (zelscope is rubbish) i figured out that i haven't these problems with the x0x connected to the line in via 6.3 to cinch adapter -> cinch to 3.5 adapter. The problem is still there if i plug my x0x to my denon avr-1801 hifi amplifier...there seems to be a mysterious ground problem from the denon, is this possible?

Anyways i think i'm sure now and can say that the x0x is well done and everything is working like it should.

[guest]

a lot of audio equiptment uses floating grounds
so that you dont create ground loops
with a bunch of pieces of equiptment plugged in

but if nothing in the system is connected to earth ground
then you get 60hz pickup
i usually use the mixing console as the point to earth ground

[katarakt]

thanks a lot guest!

i've checked it again with my djmixer and it sounds ok too

[katarakt]

I noticed something again, justz want to let you know if you're interested:

As i described i have some earth-problems if the x0x runs directly in my denon 5.1 amplifier. If i'm touching the frontpanel screws the sound gets a little bit distorted, well with this amplifier more than just a little bit. Guilty is the denon amplifier.

Now i plugged the x0x into my djmixer running into an old akai amplifier and thought the problem is gone. Well, the problem is gone to 99% but still there for 1%, you have to listen very very very carefully to notice this! Left hand touching 1 or 2 screws on x0x and with my other hand the earth-cable/contact screw on the back of my mixer, now touch, not touch, touch, not touch ..sound difference, no difference, sound difference, no difference ...so it has to do with the earth/ground thing in the x0x or overall.

If i'm not 100% earthed with my djmixer i noticed an original sounding 303ish muffled, wobbling sound !!! A little bit muffled/wobbling sound like the real 303 i think! Well, maybe i found the mysterious 303ish thing? I don't know. You hear it if resonance,accent, cutoff goes up from down the deep, if it's down deep i don't notice this. I have no real 303 but 18 years listening to acid should do the thing to compare without an original an i THINK there is this 303ish muffling thing.

Guest, if i want a better earth connection within the x0x, especially the frontpanel (and rearpanel too if needed?), how can i do this? Going with a cable from a standoff or from the tempo encoder to which point? Somewhere on the 9v input plug? ...i only want to know, i'm not sure if i really doing this.

Sometime in the future i'll use a real 6,3 to 6,3 cable to my real dod 12ch mixer. Maybe the one what i have here is not good enough, it's an 17 years old cheap selmade 6,3mm to cinch cable...bad cables giving not 100% and i'm a perfectionist wanting 100%...if possible

[guest]

the x0x has no earth ground anywhere on it
so there isnt a good way to ground it without connecting to a mixer
or making some sort of suicide cable that connects to the mains earth ground

you could try connecting the faceplate directly to x0x ground
and see if that helps
if you connect an 1/8th inch cable to cv out
and then touch the sleeve to the faceplate
that should ground it