Shark Fin treble

[AntKnee]

Finished my Shark Fin. It makes fun stuff!
I don't know exactly how this is intended to sound, but compared to Jon's youtube demo, I think mine is cutting a lot of low and is very bright. I tried for a while to play with the trimpots, but just can't get a fuller sound.
Any thoughts?
Thanks!

[mgwhit]

Despite the complexity of this effect, there is a relatively short path from input to output.  This path contains three high-pass RC filters, all of which should be letting your guitar's full frequency through.  If the low cut/brightness  you described is affecting both modes (filter/S&H), I would concentrate on debugging that very simple input->output path first.

The most obvious reason you may be losing bass would be incorrect component values.  Triple check your resistor color codes and your capacitor codes.  (Concentrate on the components in the top left quadrant of the schematic for now.) What values did you use for C2 and C5?

If you really want to get some help, post some good photos of the board.  Since your board mostly works, voltages might not be necessary, but they never hurt.  Good luck!

[AntKnee]

Here's a pic of the board and wiring.

[AntKnee]

C2 and C5 appear to be correct, .15uF (150n).

Here are my voltages... Is there any trick to measuring voltages on this effect? They seemed a little odd to me, lots of 0's or close to it.

IC1 (LM13700)
1. 7.4 
2. 0     
3. .03
4. .05
5. -.08
6. -8.4
7. .04
8. -1.1
9. .01
10. -.02
11. -.07
12. .01
13. 0
14. 0
15. 0
16. -7.30

IC3 (LM741)
1. -8.95
2. 0
3. 0
4. -8.96
5. -8.95
6. 0.11
7. 9.23
8. 0.01

IC4 (LM741)
1. -8.95
2. -0.01
3. 0
4. -8.96
5. -8.94
6. 0.05
7. 9.23
8. 0

IC5 (LM741)
1. -8.95
2. -0.12
3. -5.00
4. -8.96
5. -8.95
6. -7.50
7. 9.24
8. 0

IC6 (TC1044SCPA)
1. 9.24
2. 5.42
3. 0
4. -3.68
5. -8.96
6. 4.25
7. 4.13
8. 9.16

[mgwhit]

You should be getting somewhere near +8V on IC1 pin 11 (LM13700) and you're only showing -0.07.  I'd reflow that solder joint at minimum.  Test to see if you're getting +8V on the positive leg of C16.  R31 looks good, but test both sides of it, too.

By the way, are you having the brightness problem in both modes?

[AntKnee]

You should be getting somewhere near +8V on IC1 pin 11 (LM13700) and you're only showing -0.07.  I'd reflow that solder joint at minimum.  Test to see if you're getting +8V on the positive leg of C16.  R31 looks good, but test both sides of it, too.

By the way, are you having the brightness problem in both modes?

Thanks, Matt. I will check into those tomorrow and post up.
Its the same in both sides. It sounds like lows are cut, but not overly bright.

[AntKnee]

You should be getting somewhere near +8V on IC1 pin 11 (LM13700) and you're only showing -0.07.  I'd reflow that solder joint at minimum.  Test to see if you're getting +8V on the positive leg of C16.  R31 looks good, but test both sides of it, too.

Reflowed everything that wasn't under a pot. I have 8.8 on pin 11. Not sure if it was a bad reading earlier, or a bad solder joint. C16 and R31 are about 8.8 also.

Does the effect simply cut the low end as part of the sound? Maybe its just supposed to sound like it does? Everything seems to function fine, but the bass disappears, compared to when bypassed.

[AntKnee]

Also, I used 16v electrolytics, but since this has a tc1044, should I have used 25v or 50v caps instead?

[mgwhit]

Reflowed everything that wasn't under a pot. I have 8.8 on pin 11. Not sure if it was a bad reading earlier, or a bad solder joint. C16 and R31 are about 8.8 also.

In retrospect, I'd bet it was a bad reading.  If that joint had been bad I think you would at least notice a difference in sound after reflowing it.  That LM13700 would've been operating in pretty strange conditions with that pin floating.

Does the effect simply cut the low end as part of the sound? Maybe its just supposed to sound like it does? Everything seems to function fine, but the bass disappears, compared to when bypassed.

I can't really answer that, as I've never built it, but it is a filter circuit after all.  Hopefully someone else with direct experience will chime in.  I gave most of your resistors a good looking over Friday night, but I'd still suggest you audit your caps.

Also, I used 16v electrolytics, but since this has a tc1044, should I have used 25v or 50v caps instead?

I don't think the charge pump and power rail caps really get more than 9V apiece because of the way they are stacked -- and if one of them fails I'm guessing the entire effect will stop working.  C6 is in an odd spot where it's charging and discharging to control the envelope.  If it failed, the envelope filter would stop working, but it would not affect the S&H mode.  I would be nervous with 16V electrolytics in there, just because I know the entire effect is running at +/-9V (18V), but I don't think they would cause the problem you're having.

[AntKnee]

I agree. I will probably swap the electrolytics. I did verify my caps are all correct. I am leaning toward the effect just cutting low end. Like you said, it is a filter, after all. I just thought Jon's vid sounded so much fuller. He may have worked his own magic on his build, as he usually does.   
Anyway, thank you for your help. I am open to more comments from anyone else with experience on this build.

[jimilee]

Gives us an audio demo of yours, and also check them out on youtube. I though mine was doing something weird then I looked it up on youtube and had a  nope, that's how it sounds moment.