Question about pickups

Happy Face · February 10, 2011, 11:57:32 AM

Hey compadres!

I am confused --- why would a bass with two (single coil) pickups and one tone control be so much noticeably louder when the volume on either pickup is on 10, which seems to turn off the other pickup. When you blend them each below 10, it is much quieter??

I encountered this with a Yamaha BX-1 I recently sold and now the same thing happens on a mash-up bass that just replaced it.

I do not encounter this on my Guild, which has two single coils and two tone pots. When i play it, I leave the tone pots alone and just change the blend between pickups to change the tone. Works well. It only gets slightly louder when the vol on one pup is up all the way, crowding the other off.

I'm wondering if the single tone pot is the isue or if it is something else?

Thanks!

chromium · February 10, 2011, 01:20:50 PM

Nice to "see" you Happy Face!

Making assumptions here, but a single tone control should only be controlling the filter "cutoff" point at which high frequencies are bled off to ground - after the two pickups are mixed together. That said, I wouldn't expect the tone control to account for any sudden jumps in volume.

The taper of the volume pots might be a factor(?) Typically audio taper pots are used for volume (usually designated with an "A" - as in A500K), as the change in resistance throughout their travel better aligns with how our ears respond to changes in volume. If linear pots were used there (these are sometimes designated with a "B" - as in B500K, or without any designation - just 500K) then there would be a jump in volume around the 8-10 position, and very negligible change below that.

Keep in mind thought that in any passive setup - whether it be vol/vol or a blend pot - the pickups are not electrically isolated from one another as they are being mixed, so adjustments to one will affect the other - and this will account for some of the wonkiness when blending the pickups. If an active circuit were used, you could individually buffer the pickup signals before mixing them to get around that issue.

I think I experience this in my basses too. Usually I get the "fullest" sound by having the neck at 10, and bridge pickup at around 8 - or off all-together.

jumbodbassman · February 10, 2011, 01:50:09 PM

are the individual pickups close in volume. If not raise one..

If the volume drop is that dramatic and is it also thin sounding?? if so reverse on of them.

Happy Face · February 10, 2011, 08:08:04 PM

Thanks! And hello to the Chromed One once again. Good to "see" you as well.

I used the bass at practice tonight. Same issue. If I play with both pickups at 8, the volume is noticeably lower than when I crank on or the other pup up to 10. Happens with either pup, so I don't think it's an issue with pickup height?

But it sounds like you gents don't think the tone pot is the issue.

Since I had something similar on the Yammie (Humbuckers with a coil tap), maybe it's just the nature of the beast? Or could the wiring be off?

It's not a horrible thing -- the bass sounds pretty righteous with either pickup up at 10. It has Chisonics. Not as loud as Darkstars (I had to put the input vol higher) but that might be due to pickup placement.

Anyway, thanks again.

exiledarchangel · February 11, 2011, 01:27:32 AM

It's not the tone's fault, as Chromium said its the nature of passive electronics. In a two pickup bass, your loudest settings would be with one pickup on 10 and the other on 7-8. When I aim for fattness, I put my neck pup on 10 and the bridge on 7-8, when I aim for something more clear sounding, I do the opposite.

Happy Face · February 11, 2011, 07:39:44 AM

Thanks Angel in Exile. Sounds like the nature of the beast then.

But, I can blend pickups more subtly on my Guild and Ricky. So I've got into the habit of just setting the tone on each pickup in a sweet spot and then changing the sound by changing the volume balance between pups. I guess with this little guy, a different approach is needed.

Such challenges for an old man to face!

Highlander · February 12, 2011, 07:46:52 AM

[heathen] My answer has always been to junk the tone pots... [/heathen]

(Welcome)

drbassman · February 12, 2011, 11:03:23 AM

Quote from: Kenny's 51st State on February 12, 2011, 07:46:52 AM
[heathen] My answer has always been to junk the tone pots... [/heathen]

(Welcome)

I tried it and it worked!

Happy Face · February 12, 2011, 08:37:18 PM

Please forgive my ignorance... but you just take the tone pot right out of the circuit?

drbassman · February 12, 2011, 08:45:54 PM

Quote from: Happy Face on February 12, 2011, 08:37:18 PM
Please forgive my ignorance... but you just take the tone pot right out of the circuit?

Yes.

Highlander · February 13, 2011, 09:01:13 AM

I just get my "tone" from the way I play - a pick for harder edge and fingers for a softer sound, nearer the neck for more oomph and tinny near the bridge...

I'm not a purist and if you play on a stage controlled by a soundman (hopefully a decent one, not that I've been near one of those since the early 80's) you have little knowledge of what the crowd hears...

My favourite instruments are simple ones - less to screw up...

clankenstein · February 13, 2011, 01:30:48 PM

is the pickup lead soldered to the top of the pot or the wiper(centre tag)-if you wire the pickup lead to the wiper on the pot and take the output from the top of the pot and from there on to top of the other pot, the pickup controls do not turn each other down so to speak.

Dave W · February 13, 2011, 03:18:24 PM

Quote from: tubehead on February 13, 2011, 01:30:48 PM
is the pickup lead soldered to the top of the pot or the wiper(centre tag)-if you wire the pickup lead to the wiper on the pot and take the output from the top of the pot and from there on to top of the other pot, the pickup controls do not turn each other down so to speak.

I.e., standard wiring for a Jazz Bass.

Pilgrim · February 13, 2011, 06:23:02 PM

After many failed attempts to get this pair of humbuckers to work in this '64 BE-0, I managed to sort out the wiring and connect both to the output jack. (The problem was that I had the phase reversed on one pickup.) If both are turned up full, they tend to cancel each other out a bit - if I back one off to 80%, much loudness takes place.

The top one is an early 60's Gibson humbucker - the bottom one is a Dimarzio Model One (mudbucker impersonator). No tone pot - there is no need to reduce the treble signal under ANY circumstances!

Happy Face · February 14, 2011, 06:41:48 AM

Looks nice, Pilgrim. Got you on the treble!

BTW - the bass I am talking about is also a converted EB-O.