Master Tone knob affecting Volume?

MartinBorgen · #1 06-22-2010, 04:44 PM

so, i have a Yamaha BB414, that i re-wired to Volume/volume/tone. (from Volume/tone/switch)

it all works, thouh i bought a cheapo pot (Göldo 250K) that act like an ON/OFF switch after 3/4 turning. replacing with CTS pots soon, hoping for an improvement.

however, the main issue is the Tone knob. if i have both volumes on full, the tone works wonders, but if i have them on half, the tone knob raises the volume as it lets the treble on. also if i have one mic off, and half on the other. but not when one off and one on full.

here is a diagram of how its wired.

**line6man** · #2 06-22-2010, 04:57 PM

First off, you have the tone control backwards.

MartinBorgen · #3 06-22-2010, 05:09 PM

i do? thats odd, because that's how it was wired from yamaha. i havent changed any cabels connected to it.

i assume you dont mean turned 180 degrees wrong?

**line6man** · #4 06-22-2010, 05:11 PM

Quote:

Originally Posted by psykopatsak

i do? thats odd, because that's how it was wired from yamaha. i havent changed any cabels connected to it.

i assume you dont mean turned 180 degrees wrong?

The connections should be to terminals 2 and 3, not 1 and 2.
The way you have it reverses the taper and direction of the rotation.

MartinBorgen · #5 06-22-2010, 05:23 PM

what effect would that have? i'm a little puzzeled here, because it worked fine when there was a 3-way swich. does that change the way the tone pot is supposed to be wired?

**line6man** · #6 06-22-2010, 05:26 PM

Quote:

Originally Posted by psykopatsak

what effect would that have? i'm a little puzzeled here, because it worked fine when there was a 3-way swich. does that change the way the tone pot is supposed to be wired?

The tone control works in reverse, clockwise cuts treble instead of counterclockwise. Also, the taper of the sweep is backwards, if it's a log taper pot.

There is probably little effect at the beginning of the rotation, because that end of the sweep is closer to a linear taper.

MartinBorgen · #7 06-22-2010, 05:33 PM

that's really odd to have it wired that way from factory then. it has always worked like it's supposed to, so i was reluctant to change it, despite what all circuit shematics said.

is there a way i can check if its a strange pot with a meter-tool thing i have?

i might as well take a good listen too.

**line6man** · #8 06-22-2010, 05:49 PM

Quote:

Originally Posted by psykopatsak

that's really odd to have it wired that way from factory then. it has always worked like it's supposed to, so i was reluctant to change it, despite what all circuit shematics said.

is there a way i can check if its a strange pot with a meter-tool thing i have?

i might as well take a good listen too.

You can use an ohm meter to check the actual resistance and the taper, but there isn't much else you can determine with a meter.

MartinBorgen · #9 06-22-2010, 06:22 PM

ok. thanks for your help, i'll try it when i get acces to the tools...

walterw · #10 06-22-2010, 07:43 PM

what line6man is saying is that according to that diagram, turning up the tone knob would make the sound darker. it wouldn't matter what taper the pot is.

as for the original issue, welcome to the drawback of VVT set-ups. the tone has to be connected the output rather than to the pickups, which causes exactly what you're talking about.

it also causes the opposite effect, in that when the tone is backed down some, the volumes get less smooth, having a more severe drop-off from 10.

les paul fanatics make a big deal about "50s wiring", which does exactly the same thing (which is why i don't like it).

a volume-blend-tone arrangement will avoid this issue because the tone pot can be hooked directly to the pickups at the input lug of the single volume pot. (same with your original V-switch-T setup.)

MartinBorgen · #11 06-23-2010, 05:30 AM

oh... there is no workaround i guess? (other than volume, blend tone, and all that)

or i might just get a blend pot. as long as it works good. in that case, should it be 250KOhms or 500KOhms?

MartinBorgen · #12 08-24-2010, 09:04 AM

So BUMP. i've heard something about using double pot value for blendpot or something. i have 250K value Vol and Tpots, so should i get a 250 or 500KOhms blendpot?

**line6man** · #13 08-24-2010, 09:14 AM

Quote:

Originally Posted by psykopatsak

So BUMP. i've heard something about using double pot value for blendpot or something. i have 250K value Vol and Tpots, so should i get a 250 or 500KOhms blendpot?

Well, a 250K blend puts 125K resistance from the signal to ground, and a 500K blend pot puts 250K resistance from the signal to ground.

You can use either, but the 500K will be a bit hotter/brighter.

MartinBorgen · #14 08-24-2010, 10:42 AM

so, as i was told by the guy in the music store, the mics "want" to see 250Kohm resistance to the ground, and therefore i should use a 500K blend pot along with a 500K volume pot. is that correct assuming i want to keep the restistance as close to the manufacturer as possible?

**line6man** · #15 08-24-2010, 11:28 AM

Quote:

Originally Posted by psykopatsak

so, as i was told by the guy in the music store, the mics "want" to see 250Kohm resistance to the ground, and therefore i should use a 500K blend pot along with a 500K volume pot. is that correct assuming i want to keep the restistance as close to the manufacturer as possible?

Mics?

Pot values are personal preference.

A 500K blend is sort of the equivalent of a 250K volume pot in the circuit.

If you're after the traditional 250K VVT Fender type of setup, you can try a 500K blend with a 250K volume pot.

MartinBorgen · #16 08-24-2010, 02:37 PM

one P and one J, both passive.

Quote:

A 500K blend is sort of the equivalent of a 250K volume pot in the circuit.

yes something like that is what i've heard too. pretty confused atm. thou...

good to hear, then i think i'll try with a 250K and a 500K blend. if it sounds strange, i try something else, if it sounds like it did, i'm happy, and if it sounds even better, i won't touch anything inside anymore :P

**line6man** · #17 08-24-2010, 03:16 PM

Quote:

Originally Posted by psykopatsak

yes something like that is what i've heard too. pretty confused atm. thou...

What's confusing about it?

It's a fairly simple formula.
For parallel resistances: R_Total= 1/([1/R₁]+[1/R₂]+...[1/R_n])

-Or-
If there are only two resistances, you can apply: R_Total= (R₁*R₂)/(R₁+R₂)

MartinBorgen · #18 08-24-2010, 04:21 PM

Quote:

Originally Posted by line6man

Mics?

Pot values are personal preference.

A 500K blend is sort of the equivalent of a 250K volume pot in the circuit.

If you're after the traditional 250K VVT Fender type of setup, you can try a 500K blend with a 250K volume pot.

that's the confusing part. how can a 500K pot be the equavilient of a 250K pot? (note i do not know how a blend pot works more than the apperant function of it)

and if i want it to sound pretty much the same way it sounded (basically replace the 3-way with a blend pot) what resistance would i want.

the original wiring was P+Jmick > 3 way switch > 250K Tone > 250K Volume > out, if im not misminded (gotta dig up my shematic of it).

**line6man** · #19 08-24-2010, 04:27 PM

Quote:

Originally Posted by psykopatsak

that's the confusing part. how can a 500K pot be the equavilient of a 250K pot?

Because a blend pot is two pots connected parallel to each other, and parallel resistances decrease to a value determined by the formula I posted above.

If one pot if 500K, and the other pot is 500K, that's:
1/([1/500000]+[1/500000])=
1/(0.000002+0.000002)=
1/0.000004=
250000

Therefore, a blend pot made up of two 500K pots is the equivalent of one 250K pot, as far as the resistance from the signal to ground goes.

MartinBorgen · #20 08-24-2010, 04:32 PM

Aha, that makes it clearer. thanks for clarifying.