Wednesday, April 27, 2016
Blackout Effectors Mantra Overdrive
Here's a great sounding overdrive from Blackout Effectors. It features a 2-band EQ and the standard drive and volume controls. The topology of the circuit is reminiscent of the classic Big Muff, (input amplifier, gain stage, gain stage, EQ, gan recovery stage) but the components are completely different. Here's the schematic for reference. Adjust the trimmers to around 6.2v, then fine tune by ear if necessary.
I built the project and have a few questions.
ReplyDeleteThe pedal works relatively well, the tone controls work but the volume control and distortion is wrong. It produces distortion but very low volume and distortion is like an amplifier with worn tubes (mini explosions).
I working in the voltages of the j201's found that with a 200k in Q3 trimpot could not reach 6,2v. (I used trimpots 200k instead of 150k)
in Q3 I used the 200k trimpot and I think goes well (0,5v to 9v). In Q4 I used the largest potentiometer that I found 1M and came to 0v to 5v but I think that is not enough, apparently I have to reach a minimum 4.5V to work the fet in good shape.
how I can reach 4.5V? what I can change?
Thank you
I built this and the treble control is pretty much useless, and the bass control adds a lot of volume. Looking at the FSB forum on this it looks like the original schematic had an error where the 470k should come immediately after lug 2 of the treble control instead of after the 100k which goes to the bass control. They have an updated schematic on the thread. I'm wondering if this could be fixed with the existing layout by removing the 470k resistor and connecting it to the same hole as the 100k resistor and connecting it to the 10n cap below it?
ReplyDeleteOk yes this is the fix. Disconnect the 470k resistor from the 100k right after lug 2 of the treble control and connect it to lug 2 of the treble control or the same lead of the 100k resistor and that will fix the treble control issue. The treble control will have more impact on the tone and the will not have such an impact on the volume anymore.
DeleteThanks for figuring that out, Raif. The layout has been corrected.
DeleteSure, no worries, thanks for all the layouts!
DeleteHello, is this layout verified? Thank you very much !
ReplyDeleteI built the first version of the layout, which was based on an old version of the schematic which didn't have the correct tone stack. I was able to get it working with a few changes. The new version looks correct to me. You should go for it. I've had this thing on my pedal board ever since.
ReplyDelete