Working blend pot with series/parallel switch?

[vin97]

Well, maybe wants go give my 4PDT diagram a try as well.
It requires separate gangs for series and parallel blend, the exact values are of course up for debate.
It's "no-load" in both modes if you cut the resistive traces as indicated.
The B100M gang forms an attenuator with the 250K resistor to balance out volume changes when blending in series mode.

 

[Max3000]

Well, maybe wants go give my 4PDT diagram a try as well.
It requires separate gangs for series and parallel blend, the exact values are of course up for debate.
It's "no-load" in both modes if you cut the resistive traces as indicated.
The B100M gang forms an attenuator with the 250K resistor to balance out volume changes when blending in series mode.

Good point. I’m gonna need to take a bit to wrap my head around it but might as well

 

[Max3000]

@vin97 can I ask what the purpose of the pot to the right of the m/n pot is? It seems it just provides two resistive paths to out, but I’m not sure why? Is this just to keep volume balanced across settings in series mode? If I were ok with a volume hump in the middle position of series mode could I just take this out? Also why do you choose not to use the m/n pot for blending in series?

 

[vin97]

It introduces a symmetric series resistance to the the "pre final output". Combined with the parallel 250K resistor this should in theory attunate the signal to exactly half volume when setting the blend to middle position in series mode.
Yes, you could just leave it out but then a master volume diagram no longer really makes sense.
I'd use a separate gang for series blending because then you can finetune the resistance values independently and it allows for true "no-load" operation, where one pickup can be completely disconnected from the circuit. You also don't have to worry about pots being connected the wrong way or influencing each others tapers or tone loss.

 

[Max3000]

It introduces a symmetric series resistance to the the "pre final output". Combined with the parallel 250K resistor this should in theory attunate the signal to exactly half volume when setting the blend to middle position in series mode.
Yes, you could just leave it out but then a master volume diagram no longer really makes sense.
I'd use a separate gang for series blending because then you can finetune the resistance values independently and it allows for true "no-load" operation, where one pickup can be completely disconnected from the circuit. You also don't have to worry about pots being connected the wrong way or influencing each others tapers or tone loss.

Hmm, interesting. The attenuating resistor makes sense. But I’m still confused why a single potentiometer (the one on the right) is better for blending than the M/N pot. You could def have a no-load scenario in series with the M/N as far as I can tell

 

[vin97]

Because it is essentially "2-in-1" if you cut the trace in the middle.
This should clarify it: Working blend pot with series/parallel switch?
The advantage over M/N is that you don't introduce series resistance to the pickup. It works by shunting only.
Series resistance without a proper L-pad or voltage divider circuit (aka volume trim) will change the impedance and influence tone and taper of everything that comes after it in the circuit (including the amp controls).

 

[Max3000]

Because it is essentially "2-in-1" if you cut the trace in the middle.
This should clarify it: Working blend pot with series/parallel switch?
The advantage over M/N is that you don't introduce series resistance to the pickup. It works by shunting only.
Series resistance without a proper L-pad or voltage divider circuit (aka volume trim) will change the impedance and influence tone and taper of everything that comes after it in the circuit (including the amp controls).

Totally forgot about the cut to the trace. That makes a lot more sense now. So it sort of works like the M/N pot if the “full on” pickup always had infinite resistance in parallel with it. The cut is kind of the whole point I guess.

Thanks a lot, this is def something to think about. Although a quad gang pot with varying tapers is probably something I’d have to implement myself rather than just ordering online lol

 

[vin97]

Of course for testing you can just use separate pots.
Making your own multigang pots seem to be a cheap possibility: How-to: Custom Concentric Pots

 

[Clover3810]

I have been researching this, and I think a gang pot is the answer.

I have a circuit here.

Good luck.

 

[Mr123Clark]

Thanks for your input fig!

I agree: if you don't want the additional three-way switch to quickly go to neck-only or bridge-only and bypass the blender completely, the circuit can be done with a blender + 3pdt.
Actually, I think you still need a 4pdt if you want the blender to be ungrounded in parallel mode, which is what I am looking for.

In my case, however, I would also like to have the 3-way switch to select:

Position 1: neck only (bypass blend)
Position 2: neck + bridge, in parallel or series depending on switch, with blend working in both modes
Position 3: bridge only (bypass blend)

I think the circuit I sent above does work, except for the issue I mentioned: when in series mode (4pdt up) there remains a ground connection to one of the two blend decks (green wire in my figure). The issue with that is that, when selecting positions 1 or 3 with the three-way switch, the blender will be in the way and, will work like a volume.

What I have in mind is modding the 4pdt on-on-on used as 3-way switch (bottom left in my figure) so that the rightmost two colums will only connect the two outer pins when the switch is in center mode. That way, I can use those two columns to disconnect the grounds from the blender in positions 1 and three.
Without the mod, I can only disconnect one of the two, because I need two columns for that (see what happens to the neck - in my circuit diagram).
I ordered a couple on - off - on full-sized toggle switches, I think the mod should be possible on those by bending the internal connectors and adding a couple small springs (still have to find the right ones)..

If anyone can think of a different solution, I'd be more than happy to skip the switch modding fun :-D

Would love to know the outcome of this project, as I too am hoping to have a 3 way selector switch with a blend pot and series/parallel options

 

[Sir_Lysergium]

I'm trying to add a push-pull modification to use either grounded or ungrounded mode in parallel blend mode. But it introduces problems in series mode, and i can only fix either one, with the left over set of poles on the 4pdt switch, using this 3pdt method.

I'm new to designing and solving this level of electrical systems, so either i'm missing some basic, elegant solution, or this is not possible.
Someone mentioned earlier, switching between series, and paralel ungrounded is likely possible, using the aditional poles on 4pdt from this 3pdt method, yet i can't figure it out even with 3 additional pole sets to work with.

I could just wire up what i have, and just have one wonky setting that is series blend, with either the neck or bridge being ignored by the blender. But that's dumb, and requires to always remember what paralel mode you're in, before switching to series, and if in ungrounded paralel mode, then always switch with two actions, which is inconvenient.

 

[fig]

I'm trying to add a push-pull modification to use either grounded or ungrounded mode in parallel blend mode. But it introduces problems in series mode, and i can only fix either one, with the left over set of poles on the 4pdt switch, using this 3pdt method.

I'm new to designing and solving this level of electrical systems, so either i'm missing some basic, elegant solution, or this is not possible.
Someone mentioned earlier, switching between series, and paralel ungrounded is likely possible, using the aditional poles on 4pdt from this 3pdt method, yet i can't figure it out even with 3 additional pole sets to work with.

I could just wire up what i have, and just have one wonky setting that is series blend, with either the neck or bridge being ignored by the blender. But that's dumb, and requires to always remember what paralel mode you're in, before switching to series, and if in ungrounded paralel mode, then always switch with two actions, which is inconvenient.

Yeah, I saw the same as you when I drew that schematic, being the ungrounded parallel blend wouldn't work unless extra switch contacts were used.

The schematic you posted uses 3 sets of contacts. A TB member drew up a version using only 2 sets of contacts (DPDT switch) for series/parallel switching. Like mine, it keeps Vol (and Tone, if desired) controls for each pickup.

Here's the DPDT version using Vol/Vol (not Blend) version. When I draw a DPDT Blend version for my own notes, I'll post it.:

Clean:


Parallel:


Series:


Unfortunately, still can't do ungrounded parallel but this gives you an extra contact to use.

 

[Sir_Lysergium]

Oh wow, incredible, exactly what i needed!!!

I already wired everything up with 4pdt + push-pull dpdt combo, with only compromise being, switching to series from ungrounded paralel configuration, makes only the bridge section of blend pot work, and neck is always on.

Had tons of fun wiring, Incredibly happy with the results, and even happier now, that i can have the series-parallel switch fully ignore ground-unground switch.

I tried messaging you, to avoid bumping this ancient repository of knowledge, but the message system wouldn't let me for some reason.

I'm now considering throwing in seperate tone controls for the pickups, but i'm confused on how the neck tone wouldn't act as master tone in series mode. Need to read up on that more. My Washburn T-24 frankenbass project is slowly reaching its final form, lol.

 

[fig]

...but i'm confused on how the neck tone wouldn't act as master tone in series mode.

Great looking bass and nice cavity work!

My time is limited with the storm heading this way. Finalizing prep stuff today and hopefully won't lose power or have to evacuate tomorrow.

With the Neck Tone control connected to the return (-) of the Neck pickup, as shown in your post #91, the high freqs thru the cap are returned only to the Neck Pickup. Therefore, we have Neck only Tone control (not a Master Tone).

Now, if you removed the Neck Tone control connection from the return (-) of the Neck pickup and grounded it, then it will become a Master Tone for both pickups when in Series because it sends the high freqs of both pickups to the main (system) ground.

Sorry for the short answer right now.

FWIW, I used terms of how we perceive Tone controls to work (sending high freqs to ground). It's easy for me and everyone else in understanding what it does. But 'sending highs to ground' is only partially true. The actual explanation is deeper, so If you're interested, here's an in-depth explanation. And if you've read it already, then I wasted internet space LOL:
https://www.talkbass.com/threads/how-tone-controls-work.1644471/

 

[Sir_Lysergium]

Thank you for the kind words, wiring could be way cleaner, but I intentionally left certain wires long and bunched up, to make future fixes and modifications easier and cleaner. Which helped today. Made the pickups myself as well. They're technically lipstick-tube pickups, as they have a bar magnet core. And bridge is almost a lipstick P-90 hybrid, as it has a very wide and flat coil.

Oh, and they're three-way coil-tapped. But that's getting off topic, i could write many paragraphs about the design of these pickups.

This thread is one of the best resources about this topic on the internet.
I barged in here with questions, and now i can contribute something, never before seen - a working wiring diagram for series-parallel blend control, AND grounded-ungrounded blend pot mode switch, exclusively for parallel blend mode.

Someone here wrote earlier not to worry about loading of the blend pot, but i can say right now, that is not the case. The blend pot modes do indeed have easily perceivable differences in tone. Ungrounded is very slightly clearer and brighter. It's not some ultra-brightness switch, but it is indeed noticeable, the "metallicness" of the string is easier to hear in ungrounded mode, and grounded mode seems a bit warmer. Just as expected, from theory.

I need to get my multimeter, and objectively investigate the difference in tapper between the modes as well.

I love that this thread is over 6 years old, and it's still bearing fruit. Very useful fruit. I love collective intelligence.

Good luck with the storm, Fig. Life in Florida is wild, lol. And don't worry about wasting internet space. All your past posts here have been very useful to me, and will be for future generations. I've seen your profile pic so much over the past few weeks, that i feel like I'm talking with some important historical figure right now, lol. Keep up the good work!

 

[evan_phi]

Hi all,

I've been working on this for a little bit, and I think I may have a solution, using a 5PDT switch. Please see my attached wiring layout made in DIYLC, and the corresponding wiring analysis output. FWIW, the wiring output is the exact same as the output for the previous version of this I had made but it had separate blend knobs, one for the parallel side and one for the series side, as wired as indicated in post here: Working blend pot with series/parallel switch? | Page 2 | TalkBass.com I have run the ungrounded parallel blend as configured on my jazz bass.

I'm planning on testing this in the future, but if anyone gives it a go I'm happy to hear your results.

Feel free to ignore the series/parallel switches for the humbuckers. I'm just planning ahead for my next build.

Wiring Analysis Output:

[HEADING=1]Switch configuration: [Bridge S/P.ON1:Master S/P.ON1:Neck S/P.ON1][/HEADING]


                                             ┌─ BRIDGE.North<- ─┐     
                         ┌─ SM-BRIDGE.2-3 ───┤                  ├─┐   
                         │                   └─ BRIDGE.South<- ─┘ │   
 ┌─ Master Volume.1-2 ───┤                                        ├─┐ 
 │                       │                   ┌─ NECK.North<- ─┐   │ │ 
─┤                       └─── SN-NECK.1-2 ───┤                ├───┘ ├─
 │                                           └─ NECK.South<- ─┘     │ 
 │                                                                  │ 
 ├──────────────────────── TONE.2-3 ─── C1 ─────────────────────────┤ 
 │                                                                  │ 
 └─────────────────────── Master Volume.2-3 ────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with parallel coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in parallel
'NECK' pickup wired in humbucking mode with parallel coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON1:Master S/P.ON1:Neck S/P.ON2][/HEADING]


                                                 ┌─ BRIDGE.North<- ─┐          
                         ┌───── SM-BRIDGE.2-3 ───┤                  ├──────┐   
 ┌─ Master Volume.1-2 ───┤                       └─ BRIDGE.South<- ─┘      ├─┐ 
 │                       │                                                 │ │ 
─┤                       └─ SN-NECK.1-2 ─── NECK.North<- ─── NECK.South<- ─┘ ├─
 │                                                                           │ 
 ├───────────────────────────── TONE.2-3 ─── C1 ─────────────────────────────┤ 
 │                                                                           │ 
 └──────────────────────────── Master Volume.2-3 ────────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with parallel coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in parallel
'NECK' pickup wired in humbucking mode with series coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON1:Master S/P.ON2:Neck S/P.ON1][/HEADING]


                           ┌─ NECK.North<- ─┐       ┌─ BRIDGE.North<- ─┐     
                         ┌─┤                ├─┐   ┌─┤                  ├─┐   
 ┌─ Master Volume.1-2 ───┤ └─ NECK.South<- ─┘ ├───┤ └─ BRIDGE.South<- ─┘ ├─┐ 
 │                       │                    │   │                      │ │ 
─┤                       └─── SN-NECK.1-2 ────┘   └─── SM-BRIDGE.2-3 ────┘ ├─
 │                                                                         │ 
 ├──────────────────────────── TONE.2-3 ─── C1 ────────────────────────────┤ 
 │                                                                         │ 
 └─────────────────────────── Master Volume.2-3 ───────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with parallel coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in series
'NECK' pickup wired in humbucking mode with parallel coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON1:Master S/P.ON2:Neck S/P.ON2][/HEADING]


                                                                 ┌─ BRIDGE.North<- ─┐     
                         ┌─ NECK.North<- ─── NECK.South<- ─┐   ┌─┤                  ├─┐   
 ┌─ Master Volume.1-2 ───┤                                 ├───┤ └─ BRIDGE.South<- ─┘ ├─┐ 
 │                       └────────── SN-NECK.1-2 ──────────┘   │                      │ │ 
─┤                                                             └─── SM-BRIDGE.2-3 ────┘ ├─
 │                                                                                      │ 
 ├────────────────────────────────── TONE.2-3 ─── C1 ───────────────────────────────────┤ 
 │                                                                                      │ 
 └───────────────────────────────── Master Volume.2-3 ──────────────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with parallel coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in series
'NECK' pickup wired in humbucking mode with series coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON2:Master S/P.ON1:Neck S/P.ON1][/HEADING]


                         ┌─ SM-BRIDGE.2-3 ─── BRIDGE.North<- ─── BRIDGE.South<- ─┐   
                         │                                                       │   
 ┌─ Master Volume.1-2 ───┤                          ┌─ NECK.North<- ─┐           ├─┐ 
 │                       └────────── SN-NECK.1-2 ───┤                ├───────────┘ │ 
─┤                                                  └─ NECK.South<- ─┘             ├─
 │                                                                                 │ 
 ├──────────────────────────────── TONE.2-3 ─── C1 ────────────────────────────────┤ 
 │                                                                                 │ 
 └─────────────────────────────── Master Volume.2-3 ───────────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with series coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in parallel
'NECK' pickup wired in humbucking mode with parallel coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON2:Master S/P.ON1:Neck S/P.ON2][/HEADING]


                         ┌─ SM-BRIDGE.2-3 ─── BRIDGE.North<- ─── BRIDGE.South<- ─┐   
 ┌─ Master Volume.1-2 ───┤                                                       ├─┐ 
 │                       └──── SN-NECK.1-2 ─── NECK.North<- ─── NECK.South<- ────┘ │ 
─┤                                                                                 ├─
 ├──────────────────────────────── TONE.2-3 ─── C1 ────────────────────────────────┤ 
 │                                                                                 │ 
 └─────────────────────────────── Master Volume.2-3 ───────────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with series coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in parallel
'NECK' pickup wired in humbucking mode with series coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON2:Master S/P.ON2:Neck S/P.ON1][/HEADING]


                           ┌─ NECK.North<- ─┐                                               
                         ┌─┤                ├─┐   ┌─ BRIDGE.North<- ─── BRIDGE.South<- ─┐   
 ┌─ Master Volume.1-2 ───┤ └─ NECK.South<- ─┘ ├───┤                                     ├─┐ 
 │                       │                    │   └─────────── SM-BRIDGE.2-3 ───────────┘ │ 
─┤                       └─── SN-NECK.1-2 ────┘                                           ├─
 │                                                                                        │ 
 ├─────────────────────────────────── TONE.2-3 ─── C1 ────────────────────────────────────┤ 
 │                                                                                        │ 
 └────────────────────────────────── Master Volume.2-3 ───────────────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with series coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in series
'NECK' pickup wired in humbucking mode with parallel coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]
[HEADING=1]Switch configuration: [Bridge S/P.ON2:Master S/P.ON2:Neck S/P.ON2][/HEADING]


                         ┌─ NECK.North<- ─── NECK.South<- ─┐   ┌─ BRIDGE.North<- ─── BRIDGE.South<- ─┐   
 ┌─ Master Volume.1-2 ───┤                                 ├───┤                                     ├─┐ 
 │                       └────────── SN-NECK.1-2 ──────────┘   └─────────── SM-BRIDGE.2-3 ───────────┘ │ 
─┤                                                                                                     ├─
 ├────────────────────────────────────────── TONE.2-3 ─── C1 ──────────────────────────────────────────┤ 
 │                                                                                                     │ 
 └───────────────────────────────────────── Master Volume.2-3 ─────────────────────────────────────────┘ 

'BRIDGE' pickup wired in humbucking mode with series coils
'Master Volume' potentiometer acts as a volume control for 'BRIDGE' and 'NECK'
'NECK' and 'BRIDGE' pickups engaged, wired in series
'NECK' pickup wired in humbucking mode with series coils
'TONE' potentiometer acts as a tone control for 'BRIDGE' and 'NECK'
All pickup coils are wired in-phase
This configuration is hum-cancelling

[HR][/HR]