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Hi all! Small update...

I replaced the V571 ICs with NE570. No change. I double-checked all the component values around compander IC2 (C9 till R28) and also reflowed all the solder joints there. Also no change.

Then I put the regulator back in and measured all the voltages again (see box below).

I found voltages provided by aion himself here: Link

I don't have his voltages on IC2 pins 10 & 11, but I think his values may be off there because on the PCB pins 10, 11 & 12 are connected and he wrote down a different voltage for pin 12. And that side of the compander isn't used anyway.

And on IC1 pin 3 my voltage is a bit low, but I think that's due to the 1M pullup resistor loading down my DMM.

The rest of the voltages all seem pretty much in aion's ballpark, nothing sticks out.

Code Select Expand

IC1
4,54
4,54
2,26
0
4,52
4,54
4,54
9,08

IC2
1,17
1,82
1,82
0
1,84
1,8
2,98
1,83
1,83
1,84
1,84
1,84
9,08
1,8
1,82
0,15

IC3
0
~3,15 fluctuates a bit
3,14
~6,05 fluctuates a bit
~6,50 fluctuates a bit
~3,2 fluctuates a bit
~3,66 fluctuates a bit
~3,66 fluctuates a bit

IC4
~6,5 fluctuates a bit
~3,17 fluctuates a bit
0
~3,15 fluctuates a bit
4,8-5,8 fluctuates
0,6-1,6 fluctuates
3,9-4,9 fluctuates
~6,08 fluctuates a bit

IC5
3,6-4,9 fluctuates
1,05-1,5 fluctuates
1,25-1,9 fluctuates
0
3,3
3,33
2,7-4 fluctuates
6,28

IC6
2,7-4 fluctuates
3,32
3,31
0
1,3-1,9 fluctuates
1,0-1,5 fluctuates
4,0-5,0 fluctuates
6,28

IC7
0,6-6 fluctuates
3,01
2,3-4,3 fluctuates
0
3,3
3,32
2,5-4,1 fluctuates
6,66

IC8
~6,5 fluctuates a bit
~3,13 fluctuates a bit
0
~3,13 fluctuates a bit
4,8-5,8 fluctuates
0,7-1,6 fluctuates
4,0-4,9 fluctuates
~6,08 fluctuates a bit

IC9
0
~3,13 fluctuates a bit
~3,02
~6,08 fluctuates a bit
~3,13 fluctuates a bit
~4,2 fluctuates a bit
4,42
4,42

IC11
1,07
1,83
1,83
0
1,84
3,06
3,06
1,84
1,84
3,05
3,05
1,85
9,08
1,83
1,83
1,08

IC12
4,53
4,54
4,52
0
4,52
4,54
4,54
9,08

OPTO
1,34
0
0
4,54
3,97
4,54

RG1

9,06 0,66 6,66

Qs (E, B, C) or (D, S, G)
#########################

Q2  3,86 4,2 9,08
Q3  3,6 (goes down; due to my DMM?) 3,6 (goes down; DMM?) 0
Q4  3,62 3,17 9,08
Q5  3,84 3,92 9,08
Q6  3,22 3,79 9,08
Q7  6,01 5,45 1,0-1,5 fluctuates
Q8  6,02 5,46 1,0-1,5 fluctuates
Q9  3,21 3,79 9,08
Q10  3,62 3,16 9,08

Hello gordo,

Happy new year!

Below the voltages. Some I had to read from the back, but I think I got it right. Please be aware that the regulator is still out and the input of the regulator on the PCB is shorted to the output of the regulator on the PCB. As mentioned earlier I did that for testing. So the supply voltage on the BBDs is a tad higher.

Brian mentioned earlier he suspects the compander. I audioprobed yesterday and in my opinion the distortion is introduced by the compander like Brian said. You can't really notice it right after the compander, but between R28 and Q5 you can hear the distortion. I think that's just a buffer.

I had to order some items on the internet yesterday, so I added two NE570 chips. I guess they'll arrive tomorrow. I'll swap the Coolaudio V571 chips with these ones, maybe I'll get lucky.

Thanks!

Code Select Expand

IC1
4,54
4,54
2,26
0
4,52
4,54
4,54
9,08

IC2
1,17
1,82
1,82
0
1,84
1,8
2,98
1,83
1,83
1,84
1,84
1,84
9,08
1,8
1,82
0,15

IC3
0
~4.25 fluctuates a bit
4,28
~8,2 fluctuates a bit
~8,8 fluctuates a bit
~4,25 fluctuates a bit
~5,2 fluctuates a bit
~5,2 fluctuates a bit

IC4
~8,8 fluctuates a bit
~4.25 fluctuates a bit
0
~4.25 fluctuates a bit
5-8 fluctuates
0,9-2,8 fluctuates
5,6-7 fluctuates
~8,2 fluctuates a bit

IC5
4,8-7,2 fluctuates
1,3-2,2 fluctuates
1,7-2,7 fluctuates
0
4,52
4,54
3,6-5,5 fluctuates
8,65

IC6
3,6-5,6 fluctuates
4,54
4,52
0
1,7-2,7 fluctuates
1,4-2,2 fluctuates
4,8-7 fluctuates
~8,65 fluctuates a bit

IC7
0,6-8,4 fluctuates
4,11
3-6 fluctuates
0
4,52
4,54
3,3-5,7 fluctuates
9,1

IC8
~8,8 fluctuates a bit
~4,2 fluctuates a bit
0
~4,2 fluctuates a bit
5,6-7,7 fluctuates
1-3 fluctuates
4,8-7 fluctuates
~8,2 fluctuates a bit

IC9
0
~4,2 fluctuates a bit
~4,12
~8,2 fluctuates a bit
~8,8 fluctuates a bit
~4,2 fluctuates a bit
6,42
6,42

IC11
1,16
1,83
1,83
0
1,84
3,06
3,06
1,84
1,84
3,05
3,05
1,85
9,08
1,83
1,83
1,18

IC12
4,53
4,54
4,52
0
4,52
4,54
4,54
9,08

OPTO
1,34
0
0
4,54
3,97
4,54

Qs (E, B, C) or (D, S, G)
#########################

Q2 3,86 4,2 9,08

Q3 3,6 (goes down, dmm?) 3,6 (goes down, dmm?) 0

Q4 3,62 3,17 9,08

Q5 3,84 3,92 9,08

Q6 3,22 3,79 9,08

Q7 8,1 7,51 1,4-2,2 fluctuates

Q8 8,1 7,49 1,4-2,2 fluctuates

Q9 3,21 3,799,08

Q10 3,62 3,16 9,08

Thanks Brian! I pulled the companders and the signal stays clean when on.

I don't have 220n to try your idea #1 right now. And #2 seems awkward as you say. I'll ponder these ideas, though.

I tried one other thing. I pulled the regulator and shorted in and out. But it didn't make a difference.

Thanks!

I'd think somebody with over 11k posts wouldn't even blink building this pedal 

Hi all,

Happy new year!

I built a Blueshift over the holidays from a kit. I like the modulation a lot actually, sounds great. But I'm running into a headroom issue: when I dig in it clips.

I've made a recording with my mobile. It's not a good recording, sorry for that. I don't have a microphone. And also my amp isn't 100% clean either (Marshall), so it may sound like there's clipping with or without Blueshift engaged.

But when I connect headphones to the Blueshift's output I can hear no clipping when it's in bypass, but it's audible when it's switched on.

I've read on the internet already a couple of times that the Dimension C had some headroom issues. But not owning the original I don't have a possibility for an A/B comparison, sadly. So I'm not sure if my Blueshift works as expected or if there's a problem that can be fixed somehow.

My guitar from the recording is an Epi 1958 Explorer (2022/23 model) with stock Gibson Burstbucker pickups. So not particularly hot pickups I'd imagine, but humbuckers nonetheless. In the recording I used the bridge pickup. With the neck pickup the clipping is less. I have also a Dean 79 ML (Korea) with stock pickups. They are hotter in my opinion, which makes the Blueshift clipping worse.

I also have an Aion Azure (like a CE-2), where I used the same 3207 BBD I have in the Blueshift and that doesn't clip. I biased both pedals with the same scope.

I used the opamps suggested in the build doc, OPA2134, TL072 and TL022. I also replaced the OPAs with TL072s I had, but no difference.

Sorry for the long text, but it's driving me nuts a little bit, because I like the modulation a lot so I really want to use the Blueshift, but the clipping is a turnoff.

I read here on the forum that R9 influences the volume, so maybe I try changing the resistor to see if that helps.

Can anybody with a Blueshift tell me if their pedal is also not doing so great in the headroom department?

Kind regards,
Seb