That's how balance knobs generally are for stereo stuff, but on most basses, at center the pots are both at 100 percent - no resistance from either side, the 2 inputs are simply shorted together - you can (and I have) verify this with an ohmmeter. The impedances of the 2 sources means that each one is actually down 6 dB (assuming identical pickups), but the pot doesn't cause any of those losses - it's strictly the pickup's impedances at work loading each other.
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Why aren't Jazz basses wired Volume-Balance-Tone?
- Thread starter philthygeezer
- Start date
That's how balance knobs generally are for stereo stuff, but on most basses, at center the pots are both at 100 percent - no resistance from either side, the 2 inputs are simply shorted together - you can (and I have) verify this with an ohmmeter. The impedances of the 2 sources means that each one is actually down 6 dB (assuming identical pickups), but the pot doesn't cause any of those losses - it's strictly the pickup's impedances at work loading each other.
I have a J and 2 PJs that are all VVT. I like it that way.
I also have an Alembic that is Volume, Balance. They seem different to me.
I also have an Alembic that is Volume, Balance. They seem different to me.
The only reason I can think of is that two volumes gives you deeper functionality. If you only have one volume both pickups would always be at the same volume but with their levels blended. It might help with 60 cycle hum. It would be interesting to A/B two basses. I’m a fan of the stacked knobs where each pickup has a volume AND tone for the most variety. I also have hum cancelling pickups in all my J basses.
If you look at the wafers, the carbon on half of each has been replaced with metal - for half of the rotation, each pot (a blend pot is actually 2 pots) has its wiper riding on metal rather than carbon.
....which (most folks don't realize this) isn't one scoop, but a series of scoops - at a different frequency on every string.
I have a question:
What you described would seem to define the "Jazz sound" a lot.
Is doing it any other way (like passive volume/balance/tone) affect that "Jazz sound"?
How much?
OK, here's a reply maybe a bit long. Sorry in advance.
Leo designed "the simplest thing that might work" - it uses 3 pots, one capacitor, and it does something, It has real issues, though, so I do something quite a bit different.
The iconic Jazz sound (with the scoop and a nice, clinky high end) really only occurs when both pickups are on full - every other setting of the controls gives you something...else. The way I have my 2 pickup basses wired, I have a switch, that gives me 2 modes:
1) Neck only (like a P noically), with a tone control that varies the high (and mid) frequency content of that mode.
2) Both pickups, with a tone control that varies the high frequency content of that mode.
I don't have a bridge only mode, as I'd never use that (I play bass, I need all the modes to have decent and consistent low end). That could be done - it'd just take a 3 position switch.
The two tone circuits are different - the one on the second mode has a much lower value capacitor - with the tone "off" it's like I have hotter pickups - the peak is at a lower frequency, but it doesn't roll off all the mids and such like a stock Jazz tone circuit does. As the switch disconnects the tone control that's not in use, it doesn't have the issues that the original stack knob jazz had with control interaction.
This wiring also has a crossover for the bridge pickup - it isn't on at low frequencies, so both modes have the same low end of the neck only mode (a VVT wired jazz loses low end when you turn the bridge pickup volume up) and at mid frequencies, the "scoop" is not as deep as on a regular Jazz - a preference thing. As I'm using hum cancelling pickups, the whole thing is free of hum at any and all settings. While it sounds like this would have less sonic range than a VVT wiring, due to the independent tone controls, it actually has more usable sounds, they are all silent, and I can set up two sounds and switch between them with literally the flick of a switch. On a VVT setup, I'd be trying to turn 3 knobs at the same time, which doesn't happen fast and accurately in the same move.
You can't leave well enough alone, can you?
I can see the tonal flexibility there. I also examined the circuit that is your avatar. Nice.
All in all, do you have a classic "Jazz sound" in all of this if you want it?
I think a schematic is in order!
I have schematics for all my basses (none of them are stock circuits), but the rub is......I design the topology around what I want, and the parameters of the pickups I used (I characterize the pickups electrically, and then do Spice simulations of the circuits to get in the ballpark, then do final tweaking by ear). As I'm aiming at what I want and like, and the pickups I have, if I give you a schematic, and you put in different pickups and you use your ears, the results won't be as good.
I have done wirings like this for local clients (I would never do this long distance) and one of the steps is, after the bass is partly wired, I hook the thing up to a box with big switch knobs, and the person who's bass I'm rewiring plays through all that, and picks what they want to hear, before i wire the last few parts in place. Knowing that this is the level of detail that it takes to provide the correct schematic, I'm not going to try to do that in this context.
That is not the way it works. A blend pot is 100/100 in the center position, not 50/50. You cannot get 75/50 with a blend because the decay of each pickup only occurs beyond the center point. So each pickup is 100% on its side of center as the other pickup is bled off. (You can verify this by unsoldering one pup from the blend…the remaining pickup will be the same volume through its entire throw until you pass center.) As pickups change sound depending on where there volume is set, VVT is able to get sounds impossible with a VBT set up. All that being said, I am perfectly happy with the tones in my active VB-3 band preamp we setup.
Set it to 100:66 blend and set the volume to 75%. That's 75/50. I already conceded in an earlier post that the circuits are different and will have some tonal differences at the same levels. Honestly I can't hear those types on tone differences but other people claim to be able to. In my experience, adjusting down volume on VVT has no noticeable impact on the tone (e.g. turning both pots down together maintaining a fixed ratio).
Do you think this is a good way to represent this type of part on a schematic? It's meant to show that as one pot sweeps along its resistor, the other sweeps along a non-resistive section. Maybe there is a better, standard symbol.
Probably easier just to use the standard VR symbol and specify M/N in the label, e.g. VRn, 500k M/N?
Thanks. I figured for a schematic you need to convey a minimum amount of info to make sure the function can be fully understood. For example, you would not show a multi-pole switch as separate independent switches since they are all controlled by a single physical switch and some combinations are not possible. These linked pots are similar - if you show two independent variable resistors it implies resistor combinations that are not physically possible. But as you suggest, some notes could be added to get the point across.
