Resistor summing of pickups

[KR]

On Series instruments, when using either the combined pickup output off the instrument or the DS5 mono out, this yields a lower level from the pickups combined than the level for individual solo pickup. On non-Series two pickup mono instruments using a typical non-panning pickup selector is there also the same resistive summing needed when sending both pickups out together? I know there is a reason for the resistors when stereo, but what about non-panning mono scenarios?

[JimmyJ]

Hey Keith,

Not sure I completely understand the question let me give it a try...  Are you saying the DS5 in mono mode has significantly lower output than the "A" output alone in Stereo mode?  I might need to test that, never really thought about it.

The reason for the summing resistors - as I understand it - is because you don't want to simply run one low-impedance opamp output directly into another or they could effect each other in weird ways.  So with a summing network using 20k resistors for example, the mono "summed" signal is only 20k away from both outputs but those two outputs are 40k away from each other.  Make sense?  I'm sure there's a more scientific explanation but that's my basic understand of it.

In a "standard" mono instrument with 2 pickups obviously those signals are blended together internally.  But if the pickups have already been run through individual opamps then there would be a similar resistor summing network built in.  I think the pan pot setups are designed to have a similar level or overall energy whether centered or panned to one pickup or the other.  That probably takes some trickery.

Any help?  Probably not.   

Jimmy J

[KR]

Jimmy, when you mentioned Rob's stereo WW amp it made me think of how I like the hotter output of my pickups singly when coming out stereo from the DS5. The mono output of the DS5 is a little lower than when each pickup comes out stereo. Taking the mono out jack of the DS5...set the pickup selector to the neck pickup and keep playing as you plug a cable jack into the treble out jack of the DS5. The neck pickup gets louder when you do this. I prefer coming stereo out of the DS5 into my stereo preamp because I like how the output of each pickup raises out of the DS5 and hits my pre harder. I understand that buffered panning stops the pickup loading interaction that occurs in non buffered systems like a Fender. I guess I would like two pickups together to be twice as loud, but combining them isn't quite that easy without artifacts.

[JimmyJ]

Right, ok.  It's a subtle thing though.  And don't be fooled by the slightly hotter level because the TONE of the bass is unaffected.  If you did your experiment and slightly trimmed the neck pickup output when you switched to stereo you'd have exactly the same sound.  On the other hand, if you want to hit your outboard pre or your amp's input harder you could adjust your trim pots to get more gain from the summed mono output...

Running a full stereo rig is a delicious sound (!!) but it gets a little complicated if you need to send a signal to the PA or a studio's DI box. You can always run in stereo and build a little summing box for those occasions.  Or, train the PA person or recording engineer how you want the two pickups balanced.  That takes some explaining... 

Jimmy J

[KR]

Indeed, level is deceiving, but louder is better, right? lol. Definitely not losing any tone, DS5 mono out. When recording I always just get one line input. One of my recording rigs has a dual channel pre that sums into one channel out -allowing me to take the DS5 stereo. Ron W set these up like this, and it's because it's the best way to do it. I do love taking those pickups in stereo when I can.