The 'Gilmour' Build Guide (Deluxe Electric Mistress V4 Clone)

[stallik]

OK, honeymoon period is over and there's something annoying me about this pedal. I'm getting hiss as the
LFO sweeps to the top end. I've tried inserting a cap to ground on the output and that gets rid of it but also spoils the sound at that part of the sweep.
Where in this circuit would you attempt to knock out the very top? Or am I just being dumb and this is normal for this pedal? It can hiss like a snake and the guitar has no bearing on it. Seems to be generated in the pedal.

[Govmnt_Lacky]

I'm getting hiss as the LFO sweeps to the top end. I've tried inserting a cap to ground on the output and that gets rid of it but also spoils the sound at that part of the sweep.

Kevin,

This might be an issue with the BBD being clocked beyond its maximum. Do you happen to have an oscope or a meter that can measure frequency? If so, can you measure the clock frequency at the BBD input? Minimum and maximum clock. The RD5106 has a maximum of 1MHz. You just might be getting close to this.

If not, you could try setting the controls until you get this "noise" and ever so slightly adjusting the clock trim until it goes away.

Let us know how you make out 

[stallik]

With the clock set at 40khz, the range measured at the input to the BBD goes from 60 to 360.   The hiss is present from about 150 upward. I tried a second RD5106 and the hiss is lower but still very present and has introduced a second effect which sounds like a crossover filter occurring twice each sweep. There is nothing I can do with any of the trim pots to remove the hiss without completely cutting the signal.
I don't know why but I'm getting more concerned that it's coming from the power supply. I've never had an issue with this ps with any other pedal but I'm going to get hold of an alternative just to make sure

[GGBB]

With the clock set at 40khz, the range measured at the input to the BBD goes from 60 to 360.   The hiss is present from about 150 upward. I tried a second RD5106 and the hiss is lower but still very present and has introduced a second effect which sounds like a crossover filter occurring twice each sweep. There is nothing I can do with any of the trim pots to remove the hiss without completely cutting the signal.
I don't know why but I'm getting more concerned that it's coming from the power supply. I've never had an issue with this ps with any other pedal but I'm going to get hold of an alternative just to make sure

If you want to rule out (or in) the PS, mock up a 12V supply with a 9V and two AA batteries (or 8xAA).

[Govmnt_Lacky]

With the clock set at 40khz, the range measured at the input to the BBD goes from 60 to 360.  

This span seems awfully LOW to me....

1) Why is it that your clock is set to 40KHz and your BBD is seeing 60KHz at minimum?
2) Are you certain that you used a 100KB pot for the Range and NOT a 10KB pot?

[stallik]

GL, yes the range pot is 100k. Matrix mode, range up full, Pin 1 of U6 measures 40KHz and pin 1 of U3 is the same. flange mode, range full, speed 0 the sweep at pin 1 of U3 is 60 to 360 (ish)
Thanks Gord, just tried that and it seems my ps is fine. There's just as much noise with the batteries. Had replaced U2 with an NE5532p. Tried putting the 4558 back, much worse so went back to the 5532.
Finally got a better result raising R17. Perhaps I had the value too low (in my previous attempts to increase volume) and C20 was effectively useless. Everyone asleep so can only test quietly but it's a good improvement. Colour is not working but I'm hoping that's just the feedback adjustment.
Thanks again,will let you know the outcome

[Govmnt_Lacky]

Kevin...

With the pedal in Filter Matrix, can you measure the frequency at the BBD with the Range pot full CCW and full CW?

What minimum and maximum do you have?

[stallik]

40 at max, 510 just above 0 then it drops to .5 at 0
Does that make sense?

[Govmnt_Lacky]

40 at max, 510 just above 0 then it drops to .5 at 0
Does that make sense?

Not really 

I know that it should be 40KHz with the Range pot at full CW

Are you saying that when the Range pot is FULL CCW that the frequency drops to 0.5KHz? That is not a good thing. You should see your highest frequency at full CCW. No dropping to almost 0 

Unfortunately, I do not have my build anymore  So I cannot read it out. You might be able to contact haveyouseenhim as he is the only other person I know of that has built this successfully.

[stallik]

Yup. The pot appears to increase the frequency as it's rotated anti clockwise then the value drops right off at the very end of the travel.  Will check the resistance of the pot tomorrow, see if that sheds any light on it, got to get some sleep now, early start.

[haveyouseenhim]

I'll take some measurements tomorrow.

[stallik]

For info. Should you build this and are disappointed with low effect volume, try increasing the value of R4. 3.6k is standard, I increased to 8.2k which got me back to approx unity gain. Had to adjust R12 slightly to stop distortion when whacking the strings.
So, noise and hiss by adjusting R17/C20, volume with R4
Sure that flies in the face of the circuit design but it really works for me.

[haveyouseenhim]

I'll take some measurements tomorrow.

Holy crap!  I completely forgot to do this.  Do you still need measurements?

[stallik]

Not a problem Mike. Moved on a few stages since my last comments, not least about my expectations and the quality of my ears!

[Fender3D]

...Moved on a few stages since my last comments...

lol
BBD principle indeed

[stallik]

 

[Govmnt_Lacky]

Is there really that much lack of interest in this?

I just dont understand how this is not getting built by more people... 

[mth5044]

Perhaps it just missed that Gilmour wave that has been dieing down over the past four years.

[stallik]

Yup, disappointing given the amount of work you guys put into this project. It was my biggest build to date, took ages because of component supply and even longer to fettle because EH noise is not in my vocabulary though dozy b****r is.
I've ended up with a pedal that's quiet & makes me sound just like Gilmour.... OK maybe not but it does sound awesome and covers so many bases from vibrato through chorus and flange that sweeps forever. It's now welded to my pedalboard so come on everyone, build a great pedal!

[haveyouseenhim]

That is quite the bummer. I highly recommend building this one. The build docs are the best I have ever seen and the final product sounds AMAZING.