Jazz Bass Blend Pot Wiring - HELP!

[walterw]

that does matter.

run the tone to the input of the master volume (with the pickups); this will eliminate an annoying interactive thing where turning the tone down makes the volume drop faster, and turning the volume down makes the tone act like another volume for the first half of its rotation.

you can't do this with stock jazz bass wiring, and IMO is one of the key advantages to blend pot setups.

(go ahead, check this on a stock jazz; turn one pot down, and the other will act differently.)

 

[webelo]

I just finished wiring up my jazz with a blend. I left the blend pot ungrounded, but also removed the ground jumper. Do I still need to leave the jumper on there?

Also, my master volume is practically on/off. The volume drops off very quickly after 8 or so. What could be causing this?

 

[walterw]

It's an audio taper pot, isn't it?

Get a linear taper for the volume and it will work smoothly from full to off.

(and yes, that ground jumper gets left off too.)

 

[garfoid]

I have a Bourns Blend Pot on my bass and no matter what connection I make I always have volume loss on center position.

One caveat. Make sure you have the correct type of blend or pan pot. I understand that some will produce only 50% volume at the center detent. Not sure what type or value of these though.

I once had a "blend, volume, tone" on my Jazz and it worked fine. Didn't suffer any perceptible volume loss at center at all. As a matter of fact, I'm thinking of going back with this configuration, as it's so convienient to have a single master volume control.

 

[AlarmClock314]

I have a Bourns Blend Pot on my bass and no matter what connection I make I always have volume loss on center position.

A "MN" taper blend pot should not have volume loss at the center detent if wired properly.

 

[walterw]

assuming the pickups are in polarity and you indeed wired it right (and especially if you did the ungrounded blend thing) there will be no more loss than the normal slight dip due to two pickups being on in parallel;

it would be exactly the same if you used a 3-way switch instead of the blend pot.

 

[96tbird]

I had adverse effects but I had mistakenly brought the hot into the vol pot on the center lug. I swapped it to the end lug and problem gone. Check if you may have that hitch on yours.

 

[nlmcguire91]

Guys, I love this place because of helpful folks like yourselves. Now, perhaps Ivan present a challenge...

I have an Aerodyne Jazz bass, on which I recently installed a DiMarzio matching p/j set of pups. I'm planning on converting the controls to "Master Volume - Blend - Parallel/Series Push/Pull Tone Control".

Now, I have seen plenty of wiring diagrams for adding blend pits, and plenty for adding push/pull pots, but never both on the same diagram. Would any of you fine folks be able to help me out?

Here are the components I will be adding:

Alpha Mini Control Pot - 500k #3477

Alpha Blend Pot - 500k #4138

CTS Push-Pull Pot, DPDT, Split Shaft - 500k #0228


Thanks so much in advance!

 

[line6man]

Guys, I love this place because of helpful folks like yourselves. Now, perhaps Ivan present a challenge...

I have an Aerodyne Jazz bass, on which I recently installed a DiMarzio matching p/j set of pups. I'm planning on converting the controls to "Master Volume - Blend - Parallel/Series Push/Pull Tone Control".

Now, I have seen plenty of wiring diagrams for adding blend pits, and plenty for adding push/pull pots, but never both on the same diagram. Would any of you fine folks be able to help me out?

Here are the components I will be adding:

Alpha Mini Control Pot - 500k #3477

Alpha Blend Pot - 500k #4138

CTS Push-Pull Pot, DPDT, Split Shaft - 500k #0228


Thanks so much in advance!

You have three options.

1. Standard series/parallel switching. This is simplest, but will cause the blend to behave as a volume pot, in series mode.
2. To prevent this, you may opt for an ungrounded M/N taper blend pot, with a modified DPDT based switching scheme, to bypass the blend pot in series mode.
3. If you don't want to use the ungrounded M/N blend, then you can also bypass any standard blend by using a 3PDT based switching scheme. This means that you have to use a mini toggle switch, however, as a push/pull is only DPDT.

 

[nlmcguire91]

You have three options.

1. Standard series/parallel switching. This is simplest, but will cause the blend to behave as a volume pot, in series mode.
2. To prevent this, you may opt for an ungrounded M/N taper blend pot, with a modified DPDT based switching scheme, to bypass the blend pot in series mode.
3. If you don't want to use the ungrounded M/N blend, then you can also bypass any standard blend by using a 3PDT based switching scheme. This means that you have to use a mini toggle switch, however, as a push/pull is only DPDT.

Thank you Line6man for your insight, and for taking the time to think out and list some options for me.

I do believe I will opt for option 1, as I do not mind the blend acting as a volume pot in series mode. As I understand it, series mode essentially sums the gain of both pups and runs them both in the same circuit, yes? In that case, I would rather run both pups at unity level anyway.

My issue is that, while I'm fairly certain I know what I'm doing, I'd love to get hold of a diagram that's been put together by someone who has done this before. I've invested a lot of time into this bass, and I'd rather like to keep things nice and tidy inside and avoid the messy business of trial and error, soldering and desoldering and whatnot.

Thanks again for your insight

 

[line6man]

Thank you Line6man for your insight, and for taking the time to think out and list some options for me.

I do believe I will opt for option 1, as I do not mind the blend acting as a volume pot in series mode. As I understand it, series mode essentially sums the gain of both pups and runs them both in the same circuit, yes? In that case, I would rather run both pups at unity level anyway.

My issue is that, while I'm fairly certain I know what I'm doing, I'd love to get hold of a diagram that's been put together by someone who has done this before. I've invested a lot of time into this bass, and I'd rather like to keep things nice and tidy inside and avoid the messy business of trial and error, soldering and desoldering and whatnot.

Thanks again for your insight

I'll draw a diagram within a few days.

 

[nlmcguire91]

I'll draw a diagram within a few days.

Very much appreciated. It's folks like you that give amateurs like myself a chance!

 

[line6man]

 

[nlmcguire91]

Great stuff, line6man. Thanks very much! I'll have to figure out how to upload sound files once I get this all assembled

 

[nlmcguire91]

Right, so I've got everything in place, following your instructions to spec, except now I've got a huge volume drop at the middle indent. I have tried reversing the polarity one both sets of pickups, first one, and then the other after testing and reversing the previous set. Could it be that the pot I ordered only runs at half volume when in the middle position?

 

[line6man]

Right, so I've got everything in place, following your instructions to spec, except now I've got a huge volume drop at the middle indent. I have tried reversing the polarity one both sets of pickups, first one, and then the other after testing and reversing the previous set. Could it be that the pot I ordered only runs at half volume when in the middle position?

If you have an A/C taper blend, those are usually no good, as the center detent attenuates both signals, instead of letting them both run straight out. Another factor that can come into play is insertion loss, which is where the impedance of each pickup is at the lowest possible value, causing them to load against each other most greatly. Additionally, one thing that comes up from time to time, is a reversal of output and ground, which throws off the taper.

 

[nlmcguire91]

Well my pot is a CTS MN500K, so I'm assuming that the center detent should be ok. I'm not sure how I would test the other two things you suggested

 

[line6man]

Well my pot is a CTS MN500K, so I'm assuming that the center detent should be ok. I'm not sure how I would test the other two things you suggested

If you had an M/N taper, why not choose the third option that I mentioned earlier? It works much better than the way you are doing it now.

It's probably insertion loss.

 

[nlmcguire91]

If you had an M/N taper, why not choose the third option that I mentioned earlier? It works much better than the way you are doing it now.

It's probably insertion loss.

Conservatism, I suppose.

Mostly, I was trying to avoid altering the outward appearance of the bass too much. It's got three knobs, so I wanted to stay with that theme. However, aesthetics are quickly becoming negligible in my ever changing opinion.

I believe you when you say the third option is best. How would I go about doing that? I apologize for any frustration, and also for kinda hijacking this thread

 

[line6man]

Conservatism, I suppose.

Mostly, I was trying to avoid altering the outward appearance of the bass too much. It's got three knobs, so I wanted to stay with that theme. However, aesthetics are quickly becoming negligible in my ever changing opinion.

I believe you when you say the third option is best. How would I go about doing that? I apologize for any frustration, and also for kinda hijacking this thread

There is zero change in aesthetic.

It's done like this, but with the switch moved over to the tone control, in your case.