Blender + Master Volume = Switch + 2 volumes
- Thread starter stomp
- Start date
line6man
Epic Member
- Messages
- 6,443
They are WAY different!
A blend pot is the equivalent of two volume pots, and into the master makes three parallel resistances, with is a more direct load against the pickups than with two.
Also, when two volumes are used with a pickup selector switch, you can wire the wiper terminals to the output, so that there is a constant load against the pickups that does not change with the volume setting.
A blend pot places a variable resistance load parallel to the pickups as you adjust it.
A blend pot is the equivalent of two volume pots, and into the master makes three parallel resistances, with is a more direct load against the pickups than with two.
Also, when two volumes are used with a pickup selector switch, you can wire the wiper terminals to the output, so that there is a constant load against the pickups that does not change with the volume setting.
A blend pot places a variable resistance load parallel to the pickups as you adjust it.
Blend pots rarely work out as the installer wished, unless they specifically choose pickups to use with it. There's usually enough difference in what pickups are putting out that one of them acts as a load on the other. The same thing happens if you change just one pickup on a guitar - a few million Strat players found out that you can't just dump a humbucker in at the bridge and leave everything else alone. There are combinations that work, accidentally - a loud Tele bridge pickup with a mild PAF-type humbucker at the neck - but having separate volume controls makes everything more workable.
line6man
Epic Member
- Messages
- 6,443
Stub: two Head said:
Personally, I think that blend pots are worthless in a passive setup. You get the additional resistive loading, usually a bad taper, insertion loss in the middle, and just forget about it entirely if you are mixing dissimilar impedances. (FWIW, I've heard good things about leaving the grounds off so that each pot only places a series resistance between the pickup you are attenuating and the output, but I've not yet tried it.)
If I was going to use a blend pot on a guitar or bass, it would be a buffered blend, but the problem with those, aside from requiring a source of DC power, is that the pickups are no longer able to load against each other. The LCR of the pickups does not change when combining them in parallel, which yields a different tone.
Blending pickup volumes is not as useful as you might expect it to be, and especially on guitars. In theory, there are all the issues described above, but in practive, most players find it more useful to quickly switch between sounds than to mix pickups anyways, and that is why things like blend pots are uncommon. Conversely, many bassists find it more useful to mix their pickups to achieve a good tone, and they don't need to change their tone as suddenly and drastically as guitarists, which is why blends are more common on basses.
Every method of wiring a guitar passively presents a compromise, but, personally, I find the pickup selector switch plus one or two volumes setup to be most useful, and best, from an engineering standpoint. That's what I do with my multiple-pickup instruments.
