Jazz wiring diagram for series/parallel plus blend pot

[thisnameistaken]

While we're on the subject of tone controls, did anyone ever stick a .1uF cap on one? I would like quite a lot of available roll-off, would this be bad in any way that I haven't thought of? Apart from perceived volume loss I suppose?

[Monckyman]

No I used one of Nicks Soviet paper in oil jobs. Sounds great.

[mart]

[quote name='thisnameistaken' post='1235618' date='May 18 2011, 12:57 PM']I did a series/parallel mod on a Jazz earlier this year, now I've got another Jazz and I'd like to add series/parallel switch to that too, plus a blend pot, so the knobs would go...

V (push/pull) - B - T

Does anyone have a diagram for this?

Cheers,

- Kev[/quote]

Ok, finally, here's a diagram for what you want:


I've heard so many people say that you can't have a blend control with a series switch, that I had to try it myself. And it turns out that that's an urban myth: this circuit shows that you can have a blend control with a series configuration. The only problem (as you will discover with this circuit) is that the mid-point - with both pickups on full - is MUCH louder than when the single pickups are soloed.

Incidentally, since the bass I tried this out on has 4 pots with a V/B/T/T config, I also tried adapting this circuit, with individual tone controls for each pickup before the blend control (like Ou7shined mentioned above). This also works, and when you have both pickups on, the two tone controls act cumulatively, just like they do in the original circuit this bass was built with. If you have both pickups on, and one tone control fully anti-clockwise (taking off as much treble as it can), then you will notice a little more treble go when you roll off the other tone control. Here is the V/B/T/T version of the circuit:


Have fun with your soldering iron!

[Ou7shined]

Are you saying that you can chose to make one pup louder that the other while in series?

At first glance it seems this circuit looks very close to what I have done to mine - resulting in each end of the blend (on full extent) offering equal volume from both (obviously as they are in series - a loop if you like) and the middle section boosts the two as a side-effect of my fix to create the two channels for my Schack.

Grrr, I was looking forward to a quiet evening in, now I've got to go and build a whole new bass to try this out... after my tea like.

Edited May 27, 2011 by Ou7shined

[thisnameistaken]

Mart thanks for the diagram that's really good, but I don't want to use Delano pickups - could you do me a diagram for Fender pickups?

[color="#FFFFFF"]j/k![/color]

Also, this business of the blend centre position being much louder, is that true with both series and parallel settings or just one or the other?

Thanks again for the diagram that is boss.

[Monckyman]

Agreed, nice diagram and explanations.
Thanks.

[Ou7shined]

With just one problem.... I don't think it works.
Well it kind of does - it produces similar results to what you'd expect (ie. panning bridge to neck in both switching modes) but there's just something fishy that I can't quite put my finger on.

I bodged together bits and bobs I had lying around to make a test bed. The results were inconclusive (only a noticeable volume drop) so I had to coble together a whole bass to see if I could actually hear the difference in tone. Much noodling later (oops) I still can't hear a distinct series or parallel shift, all I hear is the drop in volume. What you get here is a sort of "quite switch". I think the signal is being bled to earth somewhere but I'm just too tired to work it out tonight.

Think of it in these terms, if you are in series mode (which means they physically share the exact same rail) then you "blend" one pup out to solo the other, [b]what is the remaining pup in series with?[/b]
It's still physically connected with it's buddy but the muted pup's signal is being lost somewhere... presumably to earth.

Seeing as I've spent all night on this, I'll selfishly post some pics.

Unfortunately I don't have a suitable switched pot, so for the purposes of this experiment I've used a separate switch and vol pot.

Test bed


Rat-bass bodge


Not really what me and the Mrs had planned for Friday night ...


... but at least I have a new bass to play about on


Soloed neck pup (in parallel mode ) sounds fantastic on this bass btw.

[mart]

[quote name='thisnameistaken' post='1247751' date='May 27 2011, 11:49 PM']Mart thanks for the diagram that's really good, but I don't want to use Delano pickups - could you do me a diagram for Fender pickups?

[color="#FFFFFF"]j/k![/color]

Also, this business of the blend centre position being much louder, is that true with both series and parallel settings or just one or the other?

Thanks again for the diagram that is boss. [/quote]



The centre position is louder ONLY when it's in series mode. In parallel you get a constant volume, but a change in tone as you rotate the blend pot.

[mart]

[quote name='Ou7shined' post='1247410' date='May 27 2011, 06:08 PM']Are you saying that you can chose to make one pup louder that the other while in series? [/quote]
Yes. The idea is to attenuate the volume of one pup before mixing it with the other. That way you get a different proportion of the two pups, whether you're in parallel or in series.

[quote name='Ou7shined' post='1247410' date='May 27 2011, 06:08 PM']At first glance it seems this circuit looks very close to what I have done to mine - resulting in each end of the blend (on full extent) offering equal volume from both (obviously as they are in series - a loop if you like) and the middle section boosts the two as a side-effect of my fix to create the two channels for my Schack.[/quote]

I'm afraid I couldn't understand your comments about your Schack preamp, so I don't know how closely my circuit resembles yours. At each end of the blend, you get the signal from just one pickup. The other pickup has been reduced to zero volume. I'm not sure what you mean by "both". Both pickups? Or both serial and parallel?


[quote name='Ou7shined' post='1247410' date='May 27 2011, 06:08 PM']Grrr, I was looking forward to a quiet evening in, now I've got to go and build a whole new bass to try this out... after my tea like. [/quote]

Hey, I'm really sorry for ruining your evening! Please apologize to your missus on my account

[quote name='Ou7shined' post='1247842' date='May 28 2011, 02:00 AM']With just one problem.... I don't think it works.
Well it kind of does - it produces similar results to what you'd expect (ie. panning bridge to neck in both switching modes) but there's just something fishy that I can't quite put my finger on.[/quote]

I didn't have time to put together some sound samples of how the circuit is working on my bass. From a quick play the sound seemed to be roughly what I expected in each position. In particular, in both series and parallel modes, with the blend pot fully clockwise only the neck pickup was on (checked by tapping the polepieces with a screwdriver - only one pickup produced the tap through the amp), and similarly when fully anti-clockwise only the bridge pup was on.

[quote name='Ou7shined' post='1247842' date='May 28 2011, 02:00 AM']I bodged together bits and bobs I had lying around to make a test bed. The results were inconclusive (only a noticeable volume drop) so I had to coble together a whole bass to see if I could actually hear the difference in tone. Much noodling later (oops) I still can't hear a distinct series or parallel shift, all I hear is the drop in volume. What you get here is a sort of "quite switch". I think the signal is being bled to earth somewhere but I'm just too tired to work it out tonight.[/quote]

I'll be interested to hear what you think the circuit is doing, when you've got time to work it out. But please don't stay up specially for this

[quote name='Ou7shined' post='1247842' date='May 28 2011, 02:00 AM']Think of it in these terms, if you are in series mode (which means they physically share the exact same rail) then you "blend" one pup out to solo the other, [b]what is the remaining pup in series with?[/b]
It's still physically connected with it's buddy but the muted pup's signal is being lost somewhere... presumably to earth.[/quote]

It's being lost somewhere, sure, but it doesn't have to be lost to earth. Put it this way: take your pickup, and join the two wires together. If you pluck a string, it produces a signal in that pup. Where is the signal going to? Well, it's just getting lost in the wire (dissipated as an infinitessimal quantity of heat). It doesn't have to go to earth. And that's essentially what I'm doing with the signal when each pickup is attenuated (by the blend control) before being mixed (in the series/parallel switch).

At the extremities, in series mode, I've got one pickup with its wires shorted together, joined to the end of the other pickup. Unfortunately, it's not actually quite so simple, because the blend puts an extra 250k resistance in there. That's probably the cause of the volume drop you're hearing. And in the cold light of morning, it doesn't seem a very desirable feature. Originally I had the blend pot wired differently - for each track the 3 tags were wired as: negative, out hot, in hot, instead of -, in, out. In other words each track was acting as a traditional single volume control. But of course that doesn't work well in parallel - when you blend out one pickup you end up shorting out both. (That sounds like something you were describing in your circuit, so maybe this is where the difference is?) So I switched the wiring round to avoid this problem in parallel mode, but perhaps things work better the other way round. That way, in series mode, when one pup is blended out, the other one is in series with nothing.

[quote name='Ou7shined' post='1247842' date='May 28 2011, 02:00 AM']Seeing as I've spent all night on this, I'll selfishly post some pics.
...[/quote]

Well, a pic is worth a thousand words!

[Monckyman]

Thanks Outshined for going "above and beyond the call of duty" on a friday night!
Regards to the Mrs and also Mr Cat.
Also thanks Mart for the contribution, I need to think on this a bit.
Wonder what Thisname is thinking?

[Ou7shined]

[quote name='mart' post='1248102' date='May 28 2011, 11:52 AM']Yes. The idea is to attenuate the volume of one pup before mixing it with the other. That way you get a different proportion of the two pups, whether you're in parallel or in series.[/quote]I want it to work but I'm still struggling with a workable possibility.

[quote name='mart' post='1248102' date='May 28 2011, 11:52 AM']I'm afraid I couldn't understand your comments about your Schack preamp, so I don't know how closely my circuit resembles yours. At each end of the blend, you get the signal from just one pickup. The other pickup has been reduced to zero volume. I'm not sure what you mean by "both". Both pickups? Or both serial and parallel?[/quote]Actually I went on to discover that they look similar but are intrinsically different as you've done away with the traditional crossover blend. I had to... ahem... "reverse engineer" a perfectly good blend pot.

[quote name='mart' post='1248102' date='May 28 2011, 11:52 AM']Hey, I'm really sorry for ruining your evening! Please apologize to your missus on my account [/quote]Don't worry, she's well used to playing second fiddle to matters regarding bass.

[quote name='mart' post='1248102' date='May 28 2011, 11:52 AM']I didn't have time to put together some sound samples of how the circuit is working on my bass. From a quick play the sound seemed to be roughly what I expected in each position. In particular, in both series and parallel modes, with the blend pot fully clockwise only the neck pickup was on (checked by tapping the polepieces with a screwdriver - only one pickup produced the tap through the amp), and similarly when fully anti-clockwise only the bridge pup was on.[/quote]Yep that's how I did my test bed results too and why I subsequently felt it necessary to go for a fully built up bass to try and hear the series punch.

[quote name='mart' post='1248102' date='May 28 2011, 11:52 AM']I'll be interested to hear what you think the circuit is doing, when you've got time to work it out. But please don't stay up specially for this [/quote]Watching the F1 qwallies just now but if I get time later I'll have another pop at it. My eyes are a bit fatigued from staring at schematics too much last night though.

[quote name='mart' post='1248102' date='May 28 2011, 11:52 AM']It's being lost somewhere, sure, but it doesn't have to be lost to earth. Put it this way: take your pickup, and join the two wires together. If you pluck a string, it produces a signal in that pup. Where is the signal going to? Well, it's just getting lost in the wire (dissipated as an infinitessimal quantity of heat). It doesn't have to go to earth. And that's essentially what I'm doing with the signal when each pickup is attenuated (by the blend control) before being mixed (in the series/parallel switch).

At the extremities, in series mode, I've got one pickup with its wires shorted together, joined to the end of the other pickup. Unfortunately, it's not actually quite so simple, because the blend puts an extra 250k resistance in there. That's probably the cause of the volume drop you're hearing. And in the cold light of morning, it doesn't seem a very desirable feature. Originally I had the blend pot wired differently - for each track the 3 tags were wired as: negative, out hot, in hot, instead of -, in, out. In other words each track was acting as a traditional single volume control. But of course that doesn't work well in parallel - when you blend out one pickup you end up shorting out both. (That sounds like something you were describing in your circuit, so maybe this is where the difference is?) So I switched the wiring round to avoid this problem in parallel mode, but perhaps things work better the other way round. That way, in series mode, when one pup is blended out, the other one is in series with nothing.[/quote]Haha I thought they were shorting out. I redrew your schematic (and the 4 relevant achievable options (series/parallel/pan left/pan right - neglecting centre indent position) to something that I could visualise better in my mind and each time I traced it to a short I couldn't believe it... I eventually gave up and went back to playing the real life model.

Edited May 28, 2011 by Ou7shined

[Ou7shined]

[quote name='Monckyman' post='1248123' date='May 28 2011, 12:08 PM']Thanks Outshined for going "above and beyond the call of duty" on a friday night!
Regards to the Mrs and also Mr Cat...[/quote]
Haha no worries. It's all for the cause.
It was a bit of a late one for Squiggy... the cat, not the Mrs (she gave up and went to bed early)

[mart]

[quote name='Ou7shined' post='1248180' date='May 28 2011, 12:55 PM']I want it to work but I'm still struggling with a workable possibility.

Actually I went on to discover that they look similar but are intrinsically different as you've done away with the traditional crossover blend. I had to... ahem... "reverse engineer" a perfectly good blend pot. [/quote]
At heart, in series mode, what I wanted was this:

Maybe that schematic will help you grasp what I'm trying to do.

The variable resistors could be individual volume controls for each pickup, or they could be combined into a blend control (but a 6-tag one, not the 3-tag one-track pot that a simple blend control would use; I certainly can't see how you could have a series blend control based on a simple 3-tag pot, except as an asymmetric control that just attenuates one of the pickups). Of course, if you want the series/parallel switch, then you take the four outputs from the two variable resistors (the two sweeps, and the two "earths" from each pickup, but note that only one of those earths is actually connected to earth), and switch them as if they were the outputs from the pickups.

As I mentioned before, if you do that, then in parallel you end up with the problem that if you want to solo one pup you have to short the other, but that shorts both. Which is why I swapped the hot feeds round on the variable resistors.

I've now done a bit more testing, and there really isn't much sound drop between playing a solo pickup in parallel mode or in series mode. So wiring in that 250k resistance isn't causing a massive problem. And if you're switching between a solo pickup and a combination of two pickups in series mode, then you're going to get big volume discrepancies (you can't just add another pickup in in series without the volume jumping up). And I've made a recording of the range of sounds. To clarify what is actually going on, I opted for the screwdriver test rather than just recording my playing. (It was also easier to tap a screwdriver and move the blend control, than to do that while playing a note constantly). In series and parallel mode I tapped away at one of the pickups while I turned the blend control. And it does exactly what it should. Attached is an mp3 recorded from the bass direct into a boss mini-recorder.
[attachment=81157:PUPTEST2.MP3]
There are four sections to the recording:

1) Pickups in series, screwdriver tapped against the bridge pickup. The blend control is steadily rotated from fully clockwise to fully anti-clockwise.

You can hear virtually no sound at first, and then it slowly grows in volume until about half way through (the centre detent on the pot). From then on the volume is constant.

2) Pickups in series, screwdriver tapped against the neck pickup. The blend control is steadily rotated from fully anti-clockwise to fully clockwise.

Again, you hear almost no sound to begin with, then a steady increase in volume until the mid point, then constant.

3) Pickups in parallel, screwdriver tapped against the neck pickup. The blend control is steadily rotated from fully clockwise to fully anti-clockwise.

Now, because I'm tapping the neck pickup, and starting fully clockwise, the volume starts on full. It stays constant until half-way, and then fades steadily to nothing.

4) Pickups in parallel, screwdriver tapped against the bridge pickup. The blend control is steadily rotated from fully anti-clockwise to fully clockwise.

Again, the volume starts full (since I'm now tapping the bridge pickup, and the blend is set to solo this pup), stays constant until half-way, then fades steadily.