I'm untrained in electronics, but I'm pretty good with a soldering iron, and I can follow a wiring diagram. That being said, let me explain better what I want to know, because I don't need to know why it does what it does. I need to know this: "Here's what you'll hear with a grounded MN100k. Here's what you'll hear with an ungrounded MN100k." Hopefully, that's a better explanation of what I'm looking for. I can find that out by simply grounding the pot I just installed, but I'm hoping you all can save me the trouble.
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That’s the thing: it’s much easier to solder that cable and listen for yourself. I hope this doesn’t come across as arrogance. You may not notice the loading on the pickups (which dulls the tone by messing with the resonant peak of the pickup) or you may find that your playing reacts better to that setup. Only you will know.
For me, the 100k left my Bass with a smooth transition, without dulling the tone.
MJS80, I absolutely understand what you're saying, and it's correct, so thank you (even though it wasn't what I wanted to hear.) 
This bass came from the factory with an MN250k grounded pot, which reacted like a switch. I mean, the total sweep area was maybe 1/8". Having read this thread, I ordered a couple MN100k pots, proceeded to damage one trying to cut the trace, and installed the other one without cutting the trace and without grounding it. The sweep area has increased, but it's also "different." I don't have the words to describe it. And I don't know if the transition to a 100k pot from a 250k pot is causing that difference, or if the transition to an ungrounded pot from a grounded pot is. Thankfully, the bass still sounds great, as it always has. I will play it like this for a while, and if I get comfortable with it, I won't worry about it. If I don't, I'll try grounding the pot and see what it changes and if that change is for the good or the bad to my ears. Thanks.
This bass came from the factory with an MN250k grounded pot, which reacted like a switch. I mean, the total sweep area was maybe 1/8". Having read this thread, I ordered a couple MN100k pots, proceeded to damage one trying to cut the trace, and installed the other one without cutting the trace and without grounding it. The sweep area has increased, but it's also "different." I don't have the words to describe it. And I don't know if the transition to a 100k pot from a 250k pot is causing that difference, or if the transition to an ungrounded pot from a grounded pot is. Thankfully, the bass still sounds great, as it always has. I will play it like this for a while, and if I get comfortable with it, I won't worry about it. If I don't, I'll try grounding the pot and see what it changes and if that change is for the good or the bad to my ears. Thanks.
A 250K grounded blend pot like you had originally is dulling the resonant peak of your pickups significantly due to its two paths to ground that are always in the circuit (heard as a decrease in treble at any setting), while any ungrounded blend control eliminates these two paths to ground and retains the general treble character of the pickups. With a 100K grounded blend you will likely still feel it work pretty much like a switch (you might get a slightly better taper), but with an overall darker tone as well due to the increased loading (decreased resistance to ground) that it shows the pickups vs the 250k grounded blend. The 100K ungrounded blend should improve both the blending and the treble retention vs your original blend control, but without cutting the internal traces as you attempted before you will never have true isolation of a single pickup at either extreme of the blend (a larger ungrounded blend will give more isolation via added resistance but at the expense of a smaller useable sweep). Cutting the traces on the 100K blend pot is probably the best overall passive compromise.MJS80, I absolutely understand what you're saying, and it's correct, so thank you (even though it wasn't what I wanted to hear.)
The only way to really achieve a “perfect” blend sweep is by using an active/buffered blend control as it eliminates loading effects of the pickups on each-other that make passive blending such a compromise.
That active blend is what I believe I had with the pair of Steinberger Synapse basses I had years ago. I've been chasing that blend ever since. The bass I'm working on, a G&L MJ-4, has a reputation for having poor blend. It was built with an MN250k grounded blend pot installed. It's an active bass, but the blend works in a passive way. The ungrounded MN100k changed the blend, but I need to play it that way for a while to determine how much I like the change. Fortunately for me, the bass sounds great at center detente, and it has a 3-band active EQ, which can compensate for other shortcomings. But I'm a weird guy in that, if you're going to put something in place that acts like a switch, just put in a switch and be done with it.
I've felt that way about every passive blend pot iteration I've ever tried in a bass (and the blending in most basses with active preamps is done passively- active blends are surprisingly rare in production basses). I'm much more of a volume-volume fan for passive blending, as you spread the useable blend range out quite a bit more with dual volume pots (its still a compromise fundamentally though!). You could also add an active blend to your G&L- both EMG and Bartolini make modular active blend options (I'm sure there are others as well). I'd guess your Steinberger had active EMGs that indeed wouldn't have suffered from the same loading issues that make passive blending so fiddly. Then again, I think there is probably a good compromise you'll be able to find with this 100K blend as well- either as it currently is or with the addition of the cut traces to allow full pickup isolation at the ends of the sweep.
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I guess it's always a compromise, especially with a passive blend. While volume-volume is the ultimate blend, I much prefer a bass with a master volume. I have a G&L SB-2, which comes setup volume-volume and nothing else. The way you adjust the tone with it is by adjusting pickup balance. A lot of players have installed tone controls on their SB-2s, and G&L has begun offering that option in their Build to Order basses. But I like the idea of not having a tone control on a bass. I tried blend controls to turn it into a single-volume bass, but they just didn't work. Ultimately, I wired the individual pickup volumes to a concentric pot, then routed that to a master volume. Now I can change volume and still have my tone stay stable.Or change the balance of my pickups and adjust the overall volume of the bass easily when that balance is right.
So I followed MJS80's advice and this afternoon went into my G&L MJ-4 and properly grounded my MN100k blend pot to hear the difference from the ungrounded version. Here are my impressions, but first, keep in mind that this is not a passive V-V bass that I'm converting to V-B. This bass is an active bass with passive pickups, and it already had a grounded MN250k blend pot in the factory circuitry. The leads from the output of the blend pot go directly into the circuit board and not to a volume control.
At first, I replaced it with an ungrounded MN100k blend with the traces not cut. (I tried to cut the traces on my first MN100k blend pot and only succeeded in disabling the pot, so I used my 2nd one without the cuts.) I'd call the results OK. The blend area was slightly but noticeably wider than the MN250k that came from the factory, but then again, the 250k really operated more as a switch than a pot. I went back into the bass today and grounded the MN100k blend in the same manner that the original pot had been grounded. Of course, this turned the opposing pickup off all the way. The blend area seemed to be the same as when ungrounded, but there was a more sudden end to the sweep area. In other words, it dropped off similarly to the 250k, but not as soon as the 250k did with its approximately 1/8" sweep of blend area. The tone of the bass seems to have not been affected. Is the MN100k an improvement? Yes, definitely, but not so much so that I'd try to convert something like a passive jazz bass based on this experience. Again, though, this is an active bass with passive pickups, unlike a jazz bass, so take it for what it's worth.
At first, I replaced it with an ungrounded MN100k blend with the traces not cut. (I tried to cut the traces on my first MN100k blend pot and only succeeded in disabling the pot, so I used my 2nd one without the cuts.) I'd call the results OK. The blend area was slightly but noticeably wider than the MN250k that came from the factory, but then again, the 250k really operated more as a switch than a pot. I went back into the bass today and grounded the MN100k blend in the same manner that the original pot had been grounded. Of course, this turned the opposing pickup off all the way. The blend area seemed to be the same as when ungrounded, but there was a more sudden end to the sweep area. In other words, it dropped off similarly to the 250k, but not as soon as the 250k did with its approximately 1/8" sweep of blend area. The tone of the bass seems to have not been affected. Is the MN100k an improvement? Yes, definitely, but not so much so that I'd try to convert something like a passive jazz bass based on this experience. Again, though, this is an active bass with passive pickups, unlike a jazz bass, so take it for what it's worth.
Bill Lawrence had a cool blend -- but it was only for series wiring. It's on the Wilde pickups website. It uses a regular pot. With no center detent though... it'd be hard to find the 50/50 balance. That guy had some cool wiring.
Post 229 (schematic and wiring diagram) in this thread shows TB member jesterbass's idea for parallel using a regular pot for blending. I mistakenly credited it to Bill Lawrence, but corrected it a few posts later, post 234.
Requires a dpdt switch. Can be push-pull, toggle, whatever player wants. The singular pot for Blend can also be ungrounded and no-load cut, same as standard two-gang blend pot.
The major advantage is using full rotational range of a pot for adjusting one pickup, vice just half a rotation.:
I don't like the standard two-gang Blend Pot, prefer two Volumes. But, if I ever wanted a Blend control again, I'd install the single standard pot version. Screw that half rotation garbage for blend stuff LOL.
Additional benefits not listed here are in post 229.
FWIW, I have some of Bill's ideas for series blending as you mentioned. Very cool stuff he put out.
Requires a dpdt switch. Can be push-pull, toggle, whatever player wants. The singular pot for Blend can also be ungrounded and no-load cut, same as standard two-gang blend pot.
The major advantage is using full rotational range of a pot for adjusting one pickup, vice just half a rotation.:
I don't like the standard two-gang Blend Pot, prefer two Volumes. But, if I ever wanted a Blend control again, I'd install the single standard pot version. Screw that half rotation garbage for blend stuff LOL.
Additional benefits not listed here are in post 229.
FWIW, I have some of Bill's ideas for series blending as you mentioned. Very cool stuff he put out.
Have you seen a single gang pot with a detent at 5? aside from special order I haven't. Perhaps I missed it. a detent at 5 and this wiring would solve a bunch -- least for me. Right now I'm using Audere's preamp because it has a smooth active blending. But it would be nice to one day ditch the active circuit, but it does have it's advantages such as much better blending.
You don't need a center position in this version. Remember, when a two-gang blend pot is centered (detent), both pickup volumes are equal out. In this version, just run the regular pot to full output (full clockwise).
Since the unadjustable pickup was full out anyway, both pickups are now full out.
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Thanks for posting the original diagram to that schematic.
For those passing thru, the first schematic I posted (post 254) is shown with the switch in the Ground position. This makes a Series blend.
Here's the schematic with the switch in the capacitor position. Makes an overall series tone circuit. Think of full cw as treble because only the Bridge pickup is on with all its frequencies. Full ccw is the bass tone as both Bridge and Neck are now on, but the Bridge had its high frequencies removed. Creative stuff with minimal parts:
For those passing thru, the first schematic I posted (post 254) is shown with the switch in the Ground position. This makes a Series blend.
Here's the schematic with the switch in the capacitor position. Makes an overall series tone circuit. Think of full cw as treble because only the Bridge pickup is on with all its frequencies. Full ccw is the bass tone as both Bridge and Neck are now on, but the Bridge had its high frequencies removed. Creative stuff with minimal parts:
What about MN blend knobs with lower values than 100K, I've seen some listings on Ebay and there are MN knobs of 10K, 20K and 50K.
Has anybody here experimented with any of those pots and see if there's a more usable blend area with those? Or why should someone not use such lower values?
Has anybody here experimented with any of those pots and see if there's a more usable blend area with those? Or why should someone not use such lower values?
Sorry. I'm in a rush this morning and don't have time to look for the answer to this question, so here it is. If anybody can jump in with an opinion or answer, please do. My G&L Tribute MJ-4, which I recently bought used, came standard with an MN250k blend pot. It was like having a switch. The bass sounded incredible, so I was happy. Then I swapped out the blend pot for an MN100k ungrounded. It makes the blend smoother and has a bigger blend area, but it cut the balls out of the bass. It now sounds mild and meek instead of snarly and punchy. That blend pot is all I changed. Same pickups, same strings, etc., etc. Any ideas or opinions?
Don't know about the G&L, but that didn't happen with my Highway One. I think a pickup polarity check is a good suggestion.
