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I recently built a BMP OP AMP v2. I’d liked to check voltages to make sure all is OK. It seems like a quiet pedal to me with not much clarity, more a muffled sound than I’d expected. I may well be just overthinking this – a list of voltage ranges would really help. I’ve noticed on the schematic that the v2a design that I used does not have reverse polarity protection, not sure if something may have got fried (it has now been added to the current version to the v4 version – 1n5817 added to power side)
Barry, I’ve attached a couple of pictures. Power from an BOSS 9v power supply – reads at 9.4v.
Voltages on IC1 (from 1 to 8) as follows
4.5, 4.51, 4.51, 0, 4.47, 4.50, 4.50, 8.98
on IC2
4.51, 4.51, 4.46, 0, 4.5, 4.51, 4.5, 8.99
Thanks,
Tony
So the capacitors and resistors by value all check out.
I am not sure how much of this is subjective since the BMP opamp version is not really thought of as a bright circuit. There are two individual tones in this video demo, listen to both.
Be sure to test this circuit by itself and not hooked up to anything else. Just two good cables, guitar and amp. Nothing else.
If there is something obviously off to you at a listen however I would re-flow the whole thing to make sure you do not have a cold solder joint. Especially around the tone section of the schematic. Secondly carefully revisit the TONE pads for the potentiometer. I know some of what I see is flux but I would have another strong look there to be sure that not only you have a good connection but that nothing is bridging on either side. Be careful not to overheat those pads.
Good luck.
Barry, Thanks for checking the board – good to know that the components look right. I don’t think the sound is that far off from the YouTube clip. It does come to life more at high tone settings, which makes sense based on the schematic. As I said in my initial post, I wasn’t sure if I was overthinking this. I will reflow – just to be sure. On a separate note, just built the Ratt Deluxe – outstanding pedal with a lot of versatility.
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