FAT Freebass / MAM MB33 Problems + Midi channel settings

[belzrebuth]

Reviving this thread once again.
New user; first post and seeking for help with my MB33 II.
I have a strange issue with main OUT volume dropping as soon as I turn the distortion pot CW.
The volume drops a LOT as soon as I engage the pot and then goes to zero about 1/3 of the distortion pot's travel.
As I understand from the schematic there's some passive current mixing going on before the signal hits the main OUT opamp which seems like it's only a I-V converter from the sumed current  leaving the OTAs.
So far do good but I don't see any good enough reason for the volume to rapidly drop as soon as the pot is turned.
I get just a little bit of distortion before the signal vanishes.
I have a hunch that it's probably a DC bias issue at play which manages to collapse the whole 13700 but I could be wrong of course.
I haven't actually had a proper look on the circuit but thought to post here in case anyone might have any suggestions.
Possibly help others as well..
Cheers.

[ah-ah]

Reviving this thread once again.
New user; first post and seeking for help with my MB33 II.
I have a strange issue with main OUT volume dropping as soon as I turn the distortion pot CW.
The volume drops a LOT as soon as I engage the pot and then goes to zero about 1/3 of the distortion pot's travel.
As I understand from the schematic there's some passive current mixing going on before the signal hits the main OUT opamp which seems like it's only a I-V converter from the sumed current  leaving the OTAs.
So far do good but I don't see any good enough reason for the volume to rapidly drop as soon as the pot is turned.
I get just a little bit of distortion before the signal vanishes.
I have a hunch that it's probably a DC bias issue at play which manages to collapse the whole 13700 but I could be wrong of course.
I haven't actually had a proper look on the circuit but thought to post here in case anyone might have any suggestions.
Possibly help others as well..
Cheers.

Hello, new user here! Just found an adapter for my MB33 MKII and have the exact same problem, anybody have a solution or suggestions for this?
Here's a video demonstration I found where you can see how it affects the volume and sound:
https://youtu.be/fP7cjYmCjUQ?t=350

Thank you in advance!

[belzrebuth]

I concluded that it's just a bad design and not a fault with my unit.
I noticed the same problem in that YouTube video as well.
It varies a bit so in your unit might be more noticeable than mine and so on but now there are at least three with the same problem which seems weird.
I really don't remember if it ever worked right so I left it at that.
It actually gets better ( you can hear the distorted signal but it's a lot less louder than the original) by replacing a 4053 but don't remember which one as it's been some time, in my case I couldn't hear the distorted signal at all.
At best I don't think you're going to get more than half the pot's travel after the unaffected signal cuts off so either way a bad design regardless if just fails in the field or if it's actually supposed to work this way.
Really hope somebody proves me wrong..

[ah-ah]

Thanks for the input. Might be bad design also since there are units out there which act this way.
I could ask the previous owner of course, if it ever worked on this one, but he hasn't replied to my mail when I asked about the adapter.
I've also read that the different units may sound different when compared side by side, but that's no problem for me.
But I guess I can do without distortion or use a pedal if needed, unless of course somebody figures this out, I'm not much of an electrician myself and don't really know where to start poking.