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Jazz mod - Vol-Blend-Tonestyler w/ Para/Series switch

P

phyfe

May 12, 2011
23
0
#1
Finally got it finished. Volume - Blend - Tone mod with parallel/series PU switching. Stock MIJ pickups.

I combined the 2.2 drawing on the ToneStyler website with a parallel/series switch schematic I found here.

Used Bourns 250K volume pot with DPDT push-pull switch, Bourns 500K type M/N blend pot (per ToneStyler schematic) and ToneStyler B-506. Started with #20 size wire. Too big! Went to #22. Much easier job.

I originally did not ground the lugs on the blend pot per some thread I read here. I think some signal loss was talked about.

Described my installation to Don at ToneStyler and he told me how to test to see if the 'de-selected' PU was really dead. It wasn't. So, I grounded the blend pot lugs and that gave a truly soloed PU, no residual signal from the de-selected PU. I did have to increase gain and volume on my amp to get the same sound level I had before grounding the blend pot.

Thought about removing the grounds again, but decided that since everybody else does it that way... I would, too. At least I'm getting a true soloed PU. Evidently the residual signal was strong enough that when I eliminated it, it made a noticeable difference in the output, thus the need to increase amp settings.

Is this making sense?

BTW, Don at Stellartone is VERY knowledgeable and OTT helpful! I asked him some $1 questions and got $10 answers. Loads of good info. Very quick replies to my emails. Can't say enough about him.

Very pleased with the results. Plenty of tone variations for the three bass players in the family. Difference between stock parallel PU sound and series sound is wild! Series seems to turn the two PUs into one humbucker. No hum at all and LOTS of output. Tone is unique, too. Even with a PU soloed, I go through the first 6 or 7 ToneStyler settings before I notice any hum.

Thanks to all who have posted schematics and info about parallel/series switching. This community is a great resource.
 
#2
When you wired up the blend pot, you need to be sure that the correct side is going to ground. If you mix them up, you will lose volume.

You can check with a meter:

blend_pot.jpg


The side that reads highest (almost the full value of the pot) goes to ground. The side that reads almost zero, goes to the output.

When properly wired you should not lose volume.
 
#3
Thanks, David.

In the end, the blend pot was wired per diagram 2.2 for the Bourns blend pot on the Stellartone website. Yes, PU signals are on the center lugs and output on opposite outer lugs with grounds on the OTHER opposite outer lugs. Do I have the grounds and signals on the CORRECT outer lugs? I think that's what you're asking and I will use your diagram to check it out. But wait, if I choose the 'wrong' lugs for output and ground, it will work but rotation will be backwards from what was expected. Correct???

Drawing it out, if no lugs on the blend pot are grounded, all of the PU signal goes to the volume pot through 0-100% of the pot value depending on knob position, i.e. the signal is attenuated, but not drained off. Ground the pot lugs and it seems to me the signal splits. Some or all goes to Volume, some or all goes to ground. Maybe this is the 'loss' that another thread talked about.

Currently, I have no problem. Everything seems normal and works great. I WILL check the wiring just to make sure I'm not losing something.

Thanks again for the diagram. It will go into my files! I'll use it to confirm proper wiring.
 
#4
phyfe said:
Thanks, David.

In the end, the blend pot was wired per diagram 2.2 for the Bourns blend pot on the Stellartone website. Yes, PU signals are on the center lugs and output on opposite outer lugs with grounds on the OTHER opposite outer lugs. Do I have the grounds and signals on the CORRECT outer lugs? I think that's what you're asking and I will use your diagram to check it out. But wait, if I choose the 'wrong' lugs for output and ground, it will work but rotation will be backwards from what was expected. Correct???
Click to expand...

No. If you look at my diagram, from the center to one side reads 514k, and from the center to the other side is 2.8 ohms. If you put the ground on the 2.8 ohm side you will be loading down your signal, and introducing 500k of resistance in the path of the signal. The other deck is the opposite.

You cannot just reverse the direction because they are not linear taper. At the center each side is at full volume.

I haven't looked at the Tonestyler diagram, so I don't know how they have it wired, but my diagram is based on an actual 500k Bourns blend pot.

Drawing it out, if no lugs on the blend pot are grounded, all of the PU signal goes to the volume pot through 0-100% of the pot value depending on knob position, i.e. the signal is attenuated, but not drained off. Ground the pot lugs and it seems to me the signal splits. Some or all goes to Volume, some or all goes to ground. Maybe this is the 'loss' that another thread talked about.
Click to expand...

But once again, if you have the hot going to the wrong side, you have 500k series resistance it its path at the center or on full, instead of 2.8ohms.



Currently, I have no problem. Everything seems normal and works great. I WILL check the wiring just to make sure I'm not losing something.

Thanks again for the diagram. It will go into my files! I'll use it to confirm proper wiring.
Click to expand...

OK, but you mentioned that you have to turn you amp up lower than normal. That's why I posted that diagram.

If the blend is wired backwards you will have a lower output from the bass.
 
#6
OK, David. Checked per your diagram. It's wired properly.

I don't fully understand everything, but I do like the results of these mods.

Thanks for your contributions to this forum. I'm learning much from everybody.

phyfe
 

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