Aion Blueshift Biasing

[Timko]

I finally finished up my Aion Blueshift last night.  The good news:  It makes sound.  The bad news:  I think something wrong with the chorus path through IC9 (the lower MN3207 on the schematic).  The trim pot didn't do a lot there when moving it like the trim pot for the IC3 path.  There's also some warble in the effect.  Through my time on youtube, the whole thing with the Dimension C was a lack of warble from the two seperate delay paths.  Maybe the sound I'm hearing now is correct (it still sounds massive and lush), but the effect of the trimmer made me think there may be something else at play.

Here's a quick video of the effect I put together this morning.  The order of the effect is switch #2, switch #1, no switch, switch #3.  If you've built this effect, I'd be interested to hear whether or not mine sounds like yours or if something is amiss

[gordo]

I does sound a bit too cyclical (I think that's a word).  I haven't been around mine in ages (I really gotta get me second boards built) but it sounds like there's too much of a standard chorus sound.

[Bio77]

I agree with Gordo.  I think you have identified the problem, there is only chorus path working.  Maybe you can try swapping the position of each 3207 to see if the "no bias" thing happens at the other trim after switching the chips? 

[Timko]

I've taken the entire pedal back apart.  One of the things I was trying to get away with were some jack holes that I drilled not too well.  I also removed all of the switches as they weren't attached the best; I noticed when putting the pedal through a fuzz that there was no noticeable change in sound with the middle and right switches.  I'm going to re-flow all of the switches, and will also try swapping around the chips.  I also think once I solder the switches in place, I'll wire the entire thing outside of the enclosure so I can test it better.  I'm normally a rock before box guy, but this pedal makes that a lot harder .

Thanks for the replies!  I'm glad I wasn't going crazy with thinking the sound wasn't quite right yet.  I have another project in flight right now for a friend for Christmas.  Once I get that knocked out, I'll get back to this.

[Bio77]

Agreed, this one needs to be assembled in the box (at least the top PCB).  Theres no good way to get the switches and the standoff all lined up without doing that. 

[Timko]

Ok, I removed all the switches, removed all the wires, and re etched/painted/drilled/sanded an enclsore that fits the parts much better.  I then took way more time wiring everything up and connecting the toggle switches (I didn't have those 3 nuts to match the length of the offset before; now it's so much easier), and tried it out.

Same deal.  Some sort of pulsed modulation.  No noticeable change in the sound with switches 3 and 4.  Below are the things I have looked at.

*  Audio probe pin 7/8 of IC3 and IC9 (the BBD).  I am getting a strong modulated signal there.
* Swap IC3 and IC9.  No change.
* Audio probe the two test points.  Strong modulated signal, meaning it's making it's way back up to the signal board.

My next steps are to understand what the Compounder chip does, and follow that signal around until I get to the output jacks.  I have all of the voltages from the Clock/BBD board but I'm not quite sure they're useful yet.

[aion]

How are the jumpers set for the bypass mode?

[Timko]

They're set with the standard bypass mode, but I'll verify when I get home this evening.

[Timko]

I had the bypass jumpers on the components part of the board. I think it was wired correctly, but just to be sure, I re did the  them to match the traces on the bottom of the board (so face up). The effect is definitely wired in the stock bypass mode. There's still warble that I think shouldn't be there.

I did a quick video again. This time I used a looper pedal. The order is bypassed, then mode 1, 2, 3, the bypassed again. The good news is that all of the switches seem to behave now!  When I pass a test signal through it, I can definitely hear a difference in the effect.

[Bio77]

Just spitballing here, I'm not an expert.  Since you have one BBD that works and one that doesn't, maybe try measuring the voltages on both to compare.  Might lead you in the right direction. Also, If your DMM had a frequency counter try measuring the clock pins on both BBDs.

[Timko]

I'll have to check my DMM so see if it has a frequency option. I measured voltages from every chip that's part of the clock and delay board. Since this circuit has 2 identical subunits, I wanted to see if there was a chip in particular acting up. Everything that should match did match.

[Timko]

Also, I think at this point, I need to hook it up to a good oscilloscope. I assume that TP1 and TP2, used for biasing, will have inverted copies of the same wave shape. If something appears amiss there, it could explain what's going on.  Also, I assume that the problem is not in the creation of the chorus sound but the way they're combined back together. I'm not quite sure what role the 2nd compounder has in the circuit but I'll read through the data sheet to understand it tomorrow night.

[Timko]

After some delay, here are the voltages off of my ICs.  The voltages on the control board (so the OPA2134s and especially IC2 NE570) look kind of odd to me.

IC1
1. 4.68
2. 4.68
3. 4.29
4. 0
5. 4.67
6. 4.68
7. 4.68
8. 9.37


IC2
1. 1.25
2. 1.86
3. 1.86
4. 0
5. 1.86
6. 1.86
7. 2.97
8. 1.86
9. 1.86
10. 1.86
11. 1.86
12. 1.86
13. 9.37
14. 1.86
15. 1.86
16. 0.76


IC3
1. 0
2. 3.14 - 3.18
3. 3.38
4. 6.12 - 6.14
5. 6.55
6. 3.11 - 3.16
7. 4.69 - 4.70
8. 4.69 - 4.70


IC4
1. 6.56
2. 3.11 - 3.16
3. 0
4. 3.13 - 3.18
5. 4.7 - 5.8
6. 0.7 - 1.7
7. 3.8 - 4.9
8. 6.14


IC5
1. 3.6 - 4.9
2. 1.0 - 1.5
3. 1.2 - 1.9
4. 0
5. 3.3
6. 3.3
7. 2.6 - 3.9
8. 6.34


IC6
1. 2.6 - 3.9
2. 3.36
3. 2.1 - 4.5
4. 0
5. 3.36
6. 1.0 - 1.5
7. 3.8 - 4.9
8. 6.34


IC7
1. 0.5 - 6.0
2. 3.32
3. 2.5 - 4.2
4. 0
5. 3.35
6. 3.36
7. 2.7 - 4.1
8. 6.71


IC8
1. 6.56
2. 3.13
3. 0
4. 3.13
5. 4.3 - 5.8
6. 0.7 - 1.8
7. 3.7 - 5.0
8. 6.1


IC9
1. 0
2. 3.15
3. 3.38
4. 6.12
5. 6.54
6. 3.13
7. 4.80
8. 4.80


IC10
1.
2.
3.
4.
5.
6.
7.
8.


IC11
1. 1.27
2. 1.87
3. 1.87
4. 0
5. 1.87
6. 3.11
7. 3.11
8. 1.87
9. 1.87
10. 3.09
11. 3.09
12. 1.87
13. 9.37
14. 1.87
15. 1.87
16. 1.27


IC12
1. 4.68
2. 4.68
3. 4.68
4. 0
5. 4.68
6. 4.68
7. 4.68
8. 9.37

[tcpoint]

I'm on vacation until Monday.  If you still need some voltages measured, I'll be happy to do that on Tuesday.  A week away from my soldering iron and I'm jonesin' a bit.

[Timko]

I don't own a proper multimeter. I own one of those diy $20 kits. However, I decided to give it a shot with the signal generator from my testing rig from JMK. After some tweaking around with trimpots while watching the scope, I found the oscillation had a notable drop. I then re measured pin 3 of both BBD and the voltage was 4.1V. I plan to hook this up to a proper scope and input the signal from the build doc, but I'm starting to feel that the 3.4V suggested starting voltage must be too low for the parts I sourced. I know the build doc said it may go as high as 3.8V. I feel my parts may be in the higher voltage.