Blend pot vs tone pot for tone control

[mikezimmerman]

"Its usually referred to as, "passive tone control on treble pot when in passive mode" "-- it would only be referred to that if it were part of an active circuit that used the same pot for both the active treble and the passive tone control, which is a pretty rare setup. But hey, no one here has been arguing semantics. Have fun!

I've never heard of it as a passive treble roll off. That's what happens when you hook a pickup up to a pot in general. Its usually referred to as, "passive tone control on treble pot when in passive mode" but, whatever man. You get the point. The "tone" doesn't just sap the high end through a capacitor, it alters the frequency spike as well.

 

[fermata]

The other thing worth noting about passive tone controls is that the capacitor doesn't play a role in the circuit until the last bit of the pot's rotation.

For most of the sweep, parallel resistance does all the work bleeding treble to ground and lowering the whole circuit's natural resonant peak.

Then, when the cap comes into play, it does two things: It prevents the entire signal from dumping to ground (the bigger the cap value, the more frequencies go to ground). And when the tone pot is at 0, the capacitor interacts with the rest of the circuit to form a new resonant peak. The circuit's overall capacitance has changed and the pot is now out of the circuit--it's no longer introducing parallel resistance that smooths out the peak (one can hear this happen between about 0 and 1 on a tone control--the peak sounds a bit honky, but a little tweak of the pot smooths it out).

 

[non]

Yes they do. But they do it differently.

ok i suppose they "boost" lower frequencies buy cutting higher frequencies but that is not a "boost" like an active preamp does. by cutting higher frequencies they are just getting rid of them so more of the remaining frequencies are heard better. so that is a "boost" of sorts i guess.

 

[Slater]

…the blend pot becomes the tone control in passive mode.

If the blend pot becomes the tone control, then how do you select the balance between the pickups?

 

[JeezyMcNuggles]

ok i suppose they "boost" lower frequencies buy cutting higher frequencies but that is not a "boost" like an active preamp does. by cutting higher frequencies they are just getting rid of them so more of the remaining frequencies are heard better. so that is a "boost" of sorts i guess.

It boost lower frequencies by altering the frequency hump, and boosting lower frequencies.

 

[JeezyMcNuggles]

If the blend pot becomes the tone control, then how do you select the balance between the pickups?

The "blend" could never become the "tone" otherwise, the capacitor would be on full in the center, left, and right.

 

[Slater]

The "blend" could never become the "tone" otherwise, the capacitor would be on full in the center, left, and right.

That’s the point of the question. The OP @non is using the “blend” to manipulate the tone, but the “blend pot” does not become the “tone”.

 

[JeezyMcNuggles]

That’s the point of the question. The OP @non is using the “blend” to manipulate the tone, but the “blend pot” does not become the “tone”.

Nah, what he's saying is he uses his blend pot instead of a tone pot. He says that his blend pot on his active bass becomes the tone pot in passive mode. Which makes no sense. But, he likes it, and wonders why passive basses don't do this. 1 master, 1 blend, no tone. He wants to do this to his PJ.

 

[Tim Skaggs]

i have a preamp that has a volume push/pull, active/passive pot. i love the sound of the pups in passive mode so much i never use the preamp so i took the battery out long ago. the blend pot becomes the tone control in passive mode.
i love the blend as tone control so i am thinking about converting my p/j bass to this setup. lose the tone knob and use the blend as the tone. the sounds you get from the blend as tone control seem so much more useful than using a tone pot.
why is this set up not more common on basses with two pickups?

If blend pot becomes the tone control in passive mode, how do you select one or the other pickup, or are they both on all the time in passive mode?

 

[LBS-bass]

Blend doesn't alter tone in any way other than a volume does. Its not a tone pot. Tone pots are volume pots. Except, the "pickup" attached to it is a capacitor. You wire it backwards so that when you turn it up, you actually turn the capacitor off. "Tone off" is actually "capacitor on." Passives don't have blends, because they usually have two volumes. It gives far more freedom, and control then a simple blend that brings one down and one up at the same time. You can actually control your blend with two volumes.

Hmmm...

If by "tone" you mean "the way it sounds" then I would argue that it alters it a lot. You just need to know what you're adding and subtracting by favoring one pickup or the other. If you can't figure that out, you probably need a tone knob.

 

[LBS-bass]

If blend pot becomes the tone control in passive mode, how do you select one or the other pickup, or are they both on all the time in passive mode?

On my active/passive basses they are both on all the time. The blend knob just determines the mix. You favor one or the other, by degrees. So I can favor the bridge pickup a little or a lot, or I can dime it to be the only one that's on, and the same with the neck.

 

[Funky Phantom]

I never liked the blend pot. I’d rather have control of my pups.

 

[Tim Skaggs]

On my active/passive basses they are both on all the time. The blend knob just determines the mix. You favor one or the other, by degrees. So I can favor the bridge pickup a little or a lot, or I can dime it to be the only one that's on, and the same with the neck.

As it is on all basses I’ve seen that have a pickup blend knob.

But, the OP said,

the blend pot becomes the tone control in passive mode.

Further reading seems to indicate the blend knob continues to be the blend knob in passive mode and the OP is using the mix between the pickups to change “tone”. No doubt tone changes when pickup mix is changed, as it does with two volume controls also, but it doesn’t read like the OP could solo the bridge pickup and roll off the high end with a tone control when the bass in passive mode.

 

[LBS-bass]

As it is on all basses I’ve seen that have a pickup blend knob.

But, the OP said,

Further reading seems to indicate the blend knob continues to be the blend knob in passive mode and the OP is using the mix between the pickups to change “tone”. No doubt tone changes when pickup mix is changed, as it does with two volume controls also, but it doesn’t read like the OP could solo the bridge pickup and roll off the high end with a tone control when the bass in passive mode.

That is probably true if he does not have a tone control. I would address that by blending in more neck, but maybe that doesn't work for the OPs bass.

 

[JeezyMcNuggles]

On my active/passive basses they are both on all the time. The blend knob just determines the mix. You favor one or the other, by degrees. So I can favor the bridge pickup a little or a lot, or I can dime it to be the only one that's on, and the same with the neck.

If you have a blend pot, they are not on all the time. Only when its in center. It cuts voltage to one pickup as you turn past center.

 

[JeezyMcNuggles]

As it is on all basses I’ve seen that have a pickup blend knob.

But, the OP said,

Further reading seems to indicate the blend knob continues to be the blend knob in passive mode and the OP is using the mix between the pickups to change “tone”. No doubt tone changes when pickup mix is changed, as it does with two volume controls also, but it doesn’t read like the OP could solo the bridge pickup and roll off the high end with a tone control when the bass in passive mode.

Exactly. According to him, there either is no pickup selection in passive mode, or no tone control.

 

[LBS-bass]

If you have a blend pot, they are not on all the time. Only when its in center. It cuts voltage to one pickup as you turn past center.

That's not what mine does. Otherwise you would only need a switch. Blend means 'blend' not on/off. I think you meant to say they are not "full on" all the time. Which is correct.

 

[Tim Skaggs]

That is probably true if he does not have a tone control. I would address that by blending in more neck, but maybe that doesn't work for the OPs bass.

That might work for you, but more neck pickup is miles different in tone from a soloed bridge pickup with the tone rolled off, ESPECIALLY on a fretless.

I have two active basses with a blend knob for selecting pickups. The blend knob remains the blend knob when I switch to passive mode, but I have no tone control whatsoever in passive mode. One of those two is a fretless that I play A LOT with the bridge pickup soloed. In active mode, I roll off the high end and boost the mid (3 band EQ). In passive mode, the soloed bridge pickup is pretty weak as compared to active mode with the highs cut & midrange cranked. There’s nothing the blend knob can help in that situation.....

 

[LBS-bass]

That might work for you, but more neck pickup is miles different in tone from a soloed bridge pickup with the tone rolled off, ESPECIALLY on a fretless.

I have two active basses with a blend knob for selecting pickups. The blend knob remains the blend knob when I switch to passive mode, but I have no tone control whatsoever in passive mode. One of those two is a fretless that I play A LOT with the bridge pickup soloed. In active mode, I roll off the high end and boost the mid (3 band EQ). In passive mode, the soloed bridge pickup is pretty weak as compared to active mode with the highs cut & midrange cranked. There’s nothing the blend knob can help in that situation.....

Yah, it does work for my particular active/passives. I find the tone knobs do very little in comparison to blend, but then again I tend to not run either of them full on. So I get why you might need one.

 

[JeezyMcNuggles]

That's not what mine does. Otherwise you would only need a switch. Blend means 'blend' not on/off. I think you meant to say they are not "full on" all the time. Which is correct.

I mean exactly what I said. When you wire up a blend pot, it's two pots stacked together. It has two sets of nodes. You wire one standard, one in reverse. So as you turn past center, it lowers the voltage to the other side of the knob. At center, it gives equal voltage to both nodes. In other words, it turns one off respectively as you turn the knob. Center, is both on. Its two master volumes, with very limited control, half range, and no ability to adjust individually. One is on, the other is on, both are on. Blending either way only alters one pickup.