| Author |
Message |
hopelessennui
Joined: Mar 23, 2008
Posts: 17
Location: Los Angeles
|
 Posted: Wed Apr 02, 2008 11:38 pm Post subject:
Soundlab not in tune with paia midi2cv
Subject description: 1 octave = 18 notes not 12 |
  |
|
Hello all,
I recently finished building a soundlab which is running great, and I just finished a paia midi2cv which seems to be working correctly (according to the self test mode) However an octave is about 18 notes instead of 12. I cant figure out if this is the soundlab or the paia unit, so im not even sure this post is in the right section.
Anyone encounter simialar problems?
Ive been going crazy wanting to play some music with this bad boy and cant wait to get it up and running. thanks for any help! |
|
|
Back to top
|
|
 |
neandrewthal
Joined: May 11, 2007
Posts: 672
Location: Canada
|
| Posted: Thu Apr 03, 2008 9:40 am Post subject:
|
|
|
Well, the easiest way to test if your MIDI converter is working is to measure it's output. It should put out about .08v per note or 1v per octave. As for the soundlab, I'm afraid I don't have any experience with that. Are you running it stock or did you add the V/Oct trimming mod?
_________________
" I went through quite a few trannies til I found one I liked" - Wild Zebra |
|
|
Back to top
|
|
|
hopelessennui
Joined: Mar 23, 2008
Posts: 17
Location: Los Angeles
|
| Posted: Thu Apr 03, 2008 11:52 am Post subject:
|
|
|
Thanks neandrewthal,
I checked the voltage on the paia and it is indeed .08 per note. So the problem is with the soundlab?
I have installed the 1/v per octave mod and tried adjusting the trimmers but it doesnt seem to change the distance between the notes, maybe only subtly. |
|
|
Back to top
|
|
|
Zodiak
Joined: May 20, 2007
Posts: 249
Location: Gillingham, Kent UK
|
| Posted: Thu Apr 03, 2008 6:19 pm Post subject:
|
|
|
| hopelessennui wrote: | Thanks neandrewthal,
I checked the voltage on the paia and it is indeed .08 per note. So the problem is with the soundlab?
I have installed the 1/v per octave mod and tried adjusting the trimmers but it doesnt seem to change the distance between the notes, maybe only subtly. |
Thats wong, the variable resistor should make quite noticable change. Exactly what type have you used? I suspect that the type you have used are not what the PCB expected and that the lower end of the actual track is not connected to the 475 resistor.
If yo are not sure then I would suggest removing one of the VRs and measuring the resistance between pin 1 and 3 (should be 100ohms)
Then try between pins 1 and 2 to make sure that it changes from 0 to 100 as you adjust it, and again between 2 and three to make sure that varies by the opposite as above.
If that seems to be OK then try measuring the voltage in IC5b pin 7. Not sure what it should start at but it should vary by about 20mv for each octave. If thats not happening then yo have a problem with IC5 or the way it is wired.
_________________
Stephen
www.Rainsbury.Net |
|
|
Back to top
|
|
|
hopelessennui
Joined: Mar 23, 2008
Posts: 17
Location: Los Angeles
|
| Posted: Fri Apr 04, 2008 9:19 pm Post subject:
|
|
|
Well, here is the trimmer i used http://www.bourns.com/PDFs/3362.pdf
It looks like the mod is done correctly, the mod is built into the pcb but i follwed everything and it looks like it does in the schematics.
I measured IC5 and IC6 seperately at pin 7 and an octave going up makes the volts go down by about 4 mV. I socketed all the ICs so i didnt fried them, and its possible but i wouldnt think both ICs were bad to begin with.
So if the voltages are wrong at pin 7 that means i have problems before the v/per octave mod? |
|
|
Back to top
|
|
|
Zodiak
Joined: May 20, 2007
Posts: 249
Location: Gillingham, Kent UK
|
| Posted: Sat Apr 05, 2008 4:49 am Post subject:
|
|
|
| hopelessennui wrote: | Well, here is the trimmer i used http://www.bourns.com/PDFs/3362.pdfI measured IC5 and IC6 seperately at pin 7 and an octave going up makes the volts go down by about 4 mV. I socketed all the ICs so i didnt fried them, and its possible but i wouldnt think both ICs were bad to begin with.
So if the voltages are wrong at pin 7 that means i have problems before the v/per octave mod? |
Ok thats a puzzler.
What happens to the voltage at pin(s) 7 and the frequencies when you turn R55 and R58 from one end to the other? 
_________________
Stephen
www.Rainsbury.Net |
|
|
Back to top
|
|
|
hopelessennui
Joined: Mar 23, 2008
Posts: 17
Location: Los Angeles
|
| Posted: Sat Apr 05, 2008 12:10 pm Post subject:
|
|
|
| Zodiak wrote: | Ok thats a puzzler.
What happens to the voltage at pin(s) 7 and the frequencies when you turn R55 and R58 from one end to the other? |
As the frequency goes up the volts go down, even into the negatives. |
|
|
Back to top
|
|
|
Zodiak
Joined: May 20, 2007
Posts: 249
Location: Gillingham, Kent UK
|
| Posted: Sat Apr 05, 2008 2:34 pm Post subject:
|
|
|
| hopelessennui wrote: | | As the frequency goes up the volts go down, even into the negatives. |
So you turn the knobs and the frequency sweeps from really low to really high pitch cleanly?
If thats the case then the fault has to between the output of the Piaa and pin 6 on IC5 and IC6.
Connect your voltmeter across the actual X1 jack socket itself and make sure thats it is actually swinging +1V for every octave.
If its wrong then its the lead, if its correct then one of the wires from X1/X2 is not connected to the PCB, my first check would be the earth wire.
_________________
Stephen
www.Rainsbury.Net |
|
|
Back to top
|
|
|
hopelessennui
Joined: Mar 23, 2008
Posts: 17
Location: Los Angeles
|
| Posted: Sun Apr 06, 2008 11:41 pm Post subject:
|
|
|
YES, i figured it out. You mentioned measuring at X1 and i realized i wasnt patching the midi2cv into X1. I built the patched out soundlab (i guess i should have mentioned that) And on the patched out schematics there is a CV in at X1 and also at AA/BB but for somer eason there are 220k resistors those instead of the 100k resistor at X1, I guess that was the problem.
Shes up and running! thnks for the help zodiak  |
|
|
Back to top
|
|
|
Zodiak
Joined: May 20, 2007
Posts: 249
Location: Gillingham, Kent UK
|
| Posted: Mon Apr 07, 2008 3:18 am Post subject:
|
|
|
| hopelessennui wrote: | YES, i figured it out. You mentioned measuring at X1 and i realized i wasnt patching the midi2cv into X1. I built the patched out soundlab (i guess i should have mentioned that) And on the patched out schematics there is a CV in at X1 and also at AA/BB but for some reason there are 220k resistors those instead of the 100k resistor at X1, I guess that was the problem.
Shes up and running! thnks for the help zodiak |
Well spotted, glad to hear its working.
_________________
Stephen
www.Rainsbury.Net |
|
|
Back to top
|
|
|
|
Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
FAQ
Calendar
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
Chat Room
