# Choral Reef



## chongmagic (Dec 3, 2019)

Last non-PedalPCB I will post, but I have been wanting to build this for a year or so.

I love the bucket brigade chips.









						New item by Jonathan Freeman
					






					photos.app.goo.gl
				












						New item by Jonathan Freeman
					






					photos.app.goo.gl


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## Funnel (Dec 3, 2019)

Nice! The choral reef has made it on to my ever-growing build list.


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## Chuck D. Bones (Dec 3, 2019)

BBDs do have a great sound.  Love the graphics.


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## zgrav (Dec 3, 2019)

I really like the choral reef.  very versatile with the VFE controls.


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## Barry (Dec 3, 2019)

Nice looking build inside and out!


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## chongmagic (Dec 3, 2019)

Barry said:


> Nice looking build inside and out!



Thank you, it is a little cramped in there for sure.


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## Mourguitars (Dec 5, 2019)

Barry said:


> Nice looking build inside and out!



What Barry said !

Mike


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## dlazzarini (Dec 6, 2019)

chongmagic said:


> Last non-PedalPCB I will post, but I have been wanting to build this for a year or so.
> 
> I love the bucket brigade chips.
> 
> ...


I’ve got a question that you’d be more knowledgeable in answering than I would. I built this same pedal months ago and it works great.  My question is in reference to the 47uF electrolytic mounted to the left of the empty charge pump slot. I wasn’t sure which space it was supposed to go in. I’m not a pro at reading schematics, still learning. From what I thought I was seeing, I decided to mount it in the lower slot. I see that yours is in the top slot. Did I do it wrong or does it not matter which place you put it? The pedal works great but I’d rather have it mounted where it belongs. I’m hoping you could educate me


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## benny_profane (Dec 6, 2019)

dlazzarini said:


> I’ve got a question that you’d be more knowledgeable in answering than I would. I built this same pedal months ago and it works great.  My question is in reference to the 47uF electrolytic mounted to the left of the empty charge pump slot. I wasn’t sure which space it was supposed to go in. I’m not a pro at reading schematics, still learning. From what I thought I was seeing, I decided to mount it in the lower slot. I see that yours is in the top slot. Did I do it wrong or does it not matter which place you put it? The pedal works great but I’d rather have it mounted where it belongs. I’m hoping you could educate me


You have it installed correctly. Reference page 3 of the V2 VFE Switching document. Also, those spots are not interchangeable.


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## chongmagic (Dec 6, 2019)

dlazzarini said:


> I’ve got a question that you’d be more knowledgeable in answering than I would. I built this same pedal months ago and it works great.  My question is in reference to the 47uF electrolytic mounted to the left of the empty charge pump slot. I wasn’t sure which space it was supposed to go in. I’m not a pro at reading schematics, still learning. From what I thought I was seeing, I decided to mount it in the lower slot. I see that yours is in the top slot. Did I do it wrong or does it not matter which place you put it? The pedal works great but I’d rather have it mounted where it belongs. I’m hoping you could educate me



In the switching doc and the build guide for the Choral Reef, Brian indicates that C6 should be inverted to create a separate bias rail for the MN3008.

Your V- pad should measure 5v.

In the Choral Reef  the following exceptions are applied. - - - - R5 (8k2) and R6 (10k) are only  used in the  Choral Reef.  These resistors are left off  in  all other VFE projects. IC2 AND C5  are also  left off in the Choral Reef. C6 is  still used, but it should  be installed backwards. IOW,  the +  side  of the cap goes to the round pad on  the  PCB and the – side  to the square pad on the  PCB. The V- pad on  the switching board is still  wired to the  V- pad on the Choral Reef audio board. But, in this case it carries approximately +5v to the Choral  Reef audio board instead of -9v that we  would have when using the charge pump.  This  is  to give the  CF board a separate  bias rail  it needs to operate  properly.


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## benny_profane (Dec 6, 2019)

chongmagic said:


> In the switching doc and the build guide for the Choral Reef, Brian indicates that C6 should be inverted to create a separate bias rail for the MN3008.
> 
> Your V- pad should measure 5v.
> 
> In the Choral Reef  the following exceptions are applied. - - - - R5 (8k2) and R6 (10k) are only  used in the  Choral Reef.  These resistors are left off  in  all other VFE projects. IC2 AND C5  are also  left off in the Choral Reef. C6 is  still used, but it should  be installed backwards. IOW,  the +  side  of the cap goes to the round pad on  the  PCB and the – side  to the square pad on the  PCB. The V- pad on  the switching board is still  wired to the  V- pad on the Choral Reef audio board. But, in this case it carries approximately +5v to the Choral  Reef audio board instead of -9v that we  would have when using the charge pump.  This  is  to give the  CF board a separate  bias rail  it needs to operate  properly.


Check the schematic. Your build has C5 populated instead of C6.


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## chongmagic (Dec 7, 2019)

benny_profane said:


> Check the schematic. Your build has C5 populated instead of C6.



Yep you're right, but I'm still getting 5v at the V- pad and since the effect is working I am not going to worry about changing it.


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## dlazzarini (Dec 7, 2019)

benny_profane said:


> Check the schematic. Your build has C5 populated instead of C6.





benny_profane said:


> You have it installed correctly. Reference page 3 of the V2 VFE Switching document. Also, those spots are not interchangeable.


Thanks for clearing that up for me. I was pretty baffled. I remember studying that build doc for a couple days straight before I dove in. I’m not real good reading the schems yet but from what I can tell C6 comes off of the #5 pin of the empty charge pump. I did reverse the polarity. C5 looks like it comes off or pins 2 and 4 and that is omitted. I guess I’m making some progress.


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## benny_profane (Dec 7, 2019)

dlazzarini said:


> Thanks for clearing that up for me. I was pretty baffled. I remember studying that build doc for a couple days straight before I dove in. I’m not real good reading the schems yet but from what I can tell C6 comes off of the #5 pin of the empty charge pump. I did reverse the polarity. C5 looks like it comes off or pins 2 and 4 and that is omitted. I guess I’m making some progress.


Yeah, you’ve got it. Compare the schematic to the trace picture and you can see how it translates. Without traces, you have to use the continuity setting on your DMM. Definitely a worthwhile skill to develop.


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## dlazzarini (Dec 7, 2019)

benny_profane said:


> Yeah, you’ve got it. Compare the schematic to the trace picture and you can see how it translates. Without traces, you have to use the continuity setting on your DMM. Definitely a worthwhile skill to develop.


That’s exactly what I did. I just remember sitting on it for a couple days because I didn’t want to do it wrong. I hate desoldering, but it sounds like it works somehow either way.


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## chongmagic (Dec 7, 2019)

I will have to ask Brian what the deal is, I checked all my voltages again today and they are matching up with the build guide.


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## benny_profane (Dec 7, 2019)

chongmagic said:


> I will have to ask Brian what the deal is, I checked all my voltages again today and they are matching up with the build guide.


That capacitor doesn’t affect the voltage: it’s a decoupling capacitor meant to shunt noise from the power supply and isolate it from the circuit. The 8k2 resistor is there to provide the bias voltage (i.e., VB in the choral reef build doc). Both are important parts of the bias voltage circuit block, though.


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## chongmagic (Dec 8, 2019)

benny_profane said:


> That capacitor doesn’t affect the voltage: it’s a decoupling capacitor meant to shunt noise from the power supply and isolate it from the circuit. The 8k2 resistor is there to provide the bias voltage (i.e., VB in the choral reef build doc). Both are important parts of the bias voltage circuit block, though.



Then I guess I should change it, it will make the circuit less noisy. With the jack soldered in it will be a pain.

I guess I could just put in C6 and leave in C5 since they dont seem to be connected without the charge pump.


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