subosc/harmonic sequencer (iffy response)
2011-05-25 by drryle
I have built a version of the module with revision 2 (8 knobs - 3 switches).
If I understand the module right, is the following description how it should work?
IN BYPASS MODE:
-Channel "A" & "B" are duplicate suboscillators.
-Each channel should output audio through either of the OUTPUTs (normal or inverted).
-Turning up "A/2" will output a sub division one octave down. Turning up "A/4" is four octaves down etc. Volume level blending is with the knobs.
IN PRE-SCALE MODE:
-The divisions switch selects partials for ring modulated outputs. (generally speaking)
-This only works in the MULTIPLIER MODE. (?)
The reason for my query is I suspect there is something wrong with my build.
I get sound out of both outputs through the A channel but not through the B channel. The B channel does affect the sound of the audio signal but only in a strange manner.
The A/2 knob doesn't bring up any audio sound even with high frequency pitches into the channel A. I have to turn up all division knobs before the A/8 or A/16 start out-putting audio. They are definitely suboscillator in nature but there is very little audible divisions happening with A/2 or A/4 knobs. I seemed to hear it very faintly with only A/2 up yet very clearly when all pots including A/8 & A/16 are up.
A similar effect happens with the B channel knobs. I must turn up the lower division knobs (B/2 & B/4) in order for the larger division knobs to have any effect. They do divide the A channel audio further and I was able to get some fun trigger patterns to my envelope generators last night. (Bonus bacon)
All that happens when in BYPASS mode. I'm not hearing any prescale values modifying anything at this point, so I'm not happening with the ring modulation at all yet (I think).
This doesn't seem right and I suspect an IC or something isn't right. I did have a pad lift on one of the 10uF coupling caps but I got that fixed. I didn't detect it until I'd already powered the module once. Is there a possibility I've damaged a chip with improper Vbe inputs?
Some places to check would be handy. I'm rather ignorant of some of these logic chips. I can put together a video tonight to demonstrate the malfunctioning module if that will help.
Here is how I wired up the multi-function 4P switch and "B" knobs.
The resistor bank (47k) out to the middle lug of the pots B/2 - B/16. The right (from the back of the pot) lug goes to the four pole switch middle posts. The switch outer posts are sent to the channel B divisons of the 4024 and to the multiplier inputs (M1-M4) of the 4030. I tried to pay attention to which division knob tied to which place on the PCB. (e.g. A/2 through the switch to "0" on channel B & M1. A/4 through the switch to "1" on channel B & M2, etc.)
If this is wrong I wouldn't be surprised. (you would have to know me)
A new wiring diagram for the revision 2 setup might help old farm boys like me. This was a head-scratcher.
Thanks,
-David
If I understand the module right, is the following description how it should work?
IN BYPASS MODE:
-Channel "A" & "B" are duplicate suboscillators.
-Each channel should output audio through either of the OUTPUTs (normal or inverted).
-Turning up "A/2" will output a sub division one octave down. Turning up "A/4" is four octaves down etc. Volume level blending is with the knobs.
IN PRE-SCALE MODE:
-The divisions switch selects partials for ring modulated outputs. (generally speaking)
-This only works in the MULTIPLIER MODE. (?)
The reason for my query is I suspect there is something wrong with my build.
I get sound out of both outputs through the A channel but not through the B channel. The B channel does affect the sound of the audio signal but only in a strange manner.
The A/2 knob doesn't bring up any audio sound even with high frequency pitches into the channel A. I have to turn up all division knobs before the A/8 or A/16 start out-putting audio. They are definitely suboscillator in nature but there is very little audible divisions happening with A/2 or A/4 knobs. I seemed to hear it very faintly with only A/2 up yet very clearly when all pots including A/8 & A/16 are up.
A similar effect happens with the B channel knobs. I must turn up the lower division knobs (B/2 & B/4) in order for the larger division knobs to have any effect. They do divide the A channel audio further and I was able to get some fun trigger patterns to my envelope generators last night. (Bonus bacon)
All that happens when in BYPASS mode. I'm not hearing any prescale values modifying anything at this point, so I'm not happening with the ring modulation at all yet (I think).
This doesn't seem right and I suspect an IC or something isn't right. I did have a pad lift on one of the 10uF coupling caps but I got that fixed. I didn't detect it until I'd already powered the module once. Is there a possibility I've damaged a chip with improper Vbe inputs?
Some places to check would be handy. I'm rather ignorant of some of these logic chips. I can put together a video tonight to demonstrate the malfunctioning module if that will help.
Here is how I wired up the multi-function 4P switch and "B" knobs.
The resistor bank (47k) out to the middle lug of the pots B/2 - B/16. The right (from the back of the pot) lug goes to the four pole switch middle posts. The switch outer posts are sent to the channel B divisons of the 4024 and to the multiplier inputs (M1-M4) of the 4030. I tried to pay attention to which division knob tied to which place on the PCB. (e.g. A/2 through the switch to "0" on channel B & M1. A/4 through the switch to "1" on channel B & M2, etc.)
If this is wrong I wouldn't be surprised. (you would have to know me)
A new wiring diagram for the revision 2 setup might help old farm boys like me. This was a head-scratcher.
Thanks,
-David