BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

[Teleplayer]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

This page was interesting to read about the BMP-1.

https://music-electronics-forum.com/showthread.php?t=27195

 

[lotti]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

I also drew up a HSH Auto-split version of this Active/Passive wiring. So the combinations are:
1. Bridge humbucker.
2. Bridge Split + Middle
3. Middle
4. Neck Split + Middle
5. Neck humbucker.
They should all be hum-cancelling except for the Position 3.

This is a bit more complex, so it definitely needs someone to check before its ready for use.

View attachment 98783

Great. So no drawbacks in passive mode.


The only drawback is that we only use one side of the bmp-1 and therefor can not have notch positions in active mode?

Replacing the 2 pole selector switch by a 4 pole mega switch would allow to route 2 pickups at a time to the two “sides” of the Preamp.
Selecting two pickups at once in active mode would therefor be possible.

So two poles on the 4pdt or an additional 2pdt and job done?




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[Teleplayer]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

Great. So no drawbacks in passive mode.


The only drawback is that we only use one side of the bmp-1 and therefor can not have notch positions in active mode?

Replacing the 2 pole selector switch by a 4 pole mega switch would allow to route 2 pickups at a time to the two “sides” of the Preamp.
Selecting two pickups at once in active mode would therefor be possible.

In the notch positions the pickup coils are connected in parallel both in active and passive modes, as the selector switch works the same in both modes. I expect it to work correctly in the notch positions, even though its only using one side of the BMP-1. To me it seems preferable to only use 1 side of the BMP-1 for the notch positions, because you get more brightness out of the pickups when passive pickup coils are wired in parallel. Previously I tried connecting active pickups in parallel and I thought it was a bit too flat sounding and a bit underwhelming for the notch positions. Maybe parallel connection of the coils can make the difference here.

 

[lotti]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

In the notch positions the pickup coils are connected in parallel both in active and passive modes, as the selector switch works the same in both modes. I expect it to work correctly in the notch positions, even though its only using one side of the BMP-1. To me it seems preferable to only use 1 side of the BMP-1 for the notch positions, because you get more brightness out of the pickups when passive pickup coils are wired in parallel. Previously I tried connecting active pickups in parallel and I thought it was a bit too flat sounding and a bit underwhelming for the notch positions. Maybe parallel connection of the coils can make the difference here.

Interesting, I did not consider what you say regarding the brightness.

I tested top coil neck + top coil middle using only one side of the bmp preamp, worked fine, but the volume difference was quite big, guess that’s because the coils are stacked and the top coils are “louder” than the bottom ones.

Do you think in case of stacked humbuckers it could make any sense to connect i.e. top coil neck and bottom coil middle ?



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[Teleplayer]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

I don't think you will get much signal out of the bottom coils, so I'd consider they are only really useful for hum cancelling. The pickup is designed for passive mode, so I would try connecting them in a similar way to the standard wiring where top and bottom coils are wired in series. With my wiring diagram in Post #33, The intention is the sum the coils in the same way by using the BMP-1 Preamp in active mode. The exception is the red and white wires are all are connected together, although it will only affect the tone in the notch positions where two pickups selected at the same time.

Are you happy with the tone of the FURY pickups with the stock wiring scheme in notch pos 2, and pos 4?

 

[lotti]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

Are you happy with the tone of the FURY pickups with the stock wiring scheme in notch pos 2, and pos 4?

They were fine, but I did not use them a lot. Factory for the YJM Strat is a 3-way switch, I played around with coil split and parallel, but since I received the bmp-1 did not have them wired similar to stock. With the top coils wired in series, I did not like neck + middle that much, but really liked middle+bridge.

So I guess bridge and neck in series and middle and neck in parallel could be it for me.

EDIT: I mostly use notch 4 for cleans, I thought that I missed a tad in the top end, but as I also changed my amp, so that was not necessarily due to the pickups.

 

[Teleplayer]

Re: BMP-1 Modular Preamp = 3 Pickups passive AND active in one guitar

By "top coils wired in series", I assume you mean that both middle and bridge were coil-split, then wired in series. It must be a very hot, high output sound, and probably not hum cancelling.