Need a pre-amp?

[fresnorich]

I almost bought this on a whim, but I don't really need it:

http://cgi.ebay.com/1993-MUSICMAN-STINGRAY-BASS-PREAMP-WITH-KNOBS_W0QQitemZ120039175636QQihZ002QQcategoryZ4713QQrdZ1QQcmdZViewItem

 

[Rod Trussbroken]

Thanks fresnorich!

I just bought it. Been looking for one for ages.

Ta.

 

[fresnorich]

Cool. I had a feeling someone around here would be interested.

 

[oldbluebassman]

I would like to try and get my Pacific Blue Burst SR5 back to some sense of normality by replacing the OBP-3 that was in there when I bought it with the correct later model MM 3-band SR5 pre-amp. If anyone has one for sale I would be interested. I have a early 2-coil SR5 pick-up and a rectangular 2-band EQ board and pots (not volume) for trade.

 

[dhuffguitars]

I would like to try and get my Pacific Blue Burst SR5 back to some sense of normality by replacing the OBP-3 that was in there when I bought it with the correct later model MM 3-band SR5 pre-amp. If anyone has one for sale I would be interested. I have a early 2-coil SR5 pick-up and a rectangular 2-band EQ board and pots (not volume) for trade.

I have the preamp you are looking for I think. The circuit board is a 3/92 revision. The pots are 1992 as well.

Shoot me a PM if you are interested in the trade.

 

[oldbluebassman]

I have the preamp you are looking for I think. The circuit board is a 3/92 revision. The pots are 1992 as well.

Shoot me a PM if you are interested in the trade.

I need the pre-amp with the dual input pre-amp and associated coil switch. I think that was post 1992. The bass itself was made in 2002/3.

 

[Rod Trussbroken]

Dave..what do you mean by dual input? You've lost me

 

[oldbluebassman]

Dave..what do you mean by dual input? You've lost me

Gav, maybe this much simplified diagram will help explain.

There are two op amp stages in the pre-amp input stage and a further two in the tone circuit.

Looking just at just the input stage, in parallel mode only one op amp is used and the input to the other is grounded.

In series and single coil mode the junction of the two pick-up coils is grounded and the other ends of the coil are fed to the two inputs. The signals are however out of phase and the two stages enable them to be brought back into phase and added togeher. it's a bit like a balanced microphone input circuit in that in helps reduce noise and gives the bass it's excellent signal/noise performance. Hence my comment about 2 inputs.

It is my understanding that the first SR5s used the SR4 3-band pre-amp which only had a single input and used simple coil switching with no phantom coil. I have a copy of the switching circuit and it's a lot simpler than the later SR5. I also have a 2-coil pick-up.

Another feature of the later SR5 pre-amp is the gain switching function to balance the outputs of the three coil configurations. Very neat.

If I've got this wrong then someone form EBMM had better shout.

 

[Rod Trussbroken]

Thanks Dave.