2 volume 2 tone impossibility?

[walterw]

i.e., clipping.

all this is why the 2 volumes, 2 tones thing isn't popular for bass; each tone affects everything, you can't turn one pickup all the way off, or you have to compromise the sweep of the pots or choke down your output with resistors.

gibson uses a switch on their guitars to get around these issues, but in the middle you still get each tone knob affecting everything and one volume shutting everything off at "0".

 

[David Jayne]

I didnt know that, I was just thinking they might work like a check valve keeping the two circuits separate behind them. I didnt know they would distort the signal.

Yes, I assumed that's where you were going. It would work if the signal was DC. Easy to forget that it isn't.

 

[Hopkins]

Yes, I assumed that's where you were going. It would work if the signal was DC. Easy to forget that it isn't.

Makes sense

 

[awilkie84]

To do this properly, you'd need 2 separate outputs from the bass, which you could then merge back into 1 somewhere along your signal path. That would allow you to do the wiring you REALLY want...but it means 2 cables taped together going to an ABY box.

 

[walterw]

To do this properly, you'd need 2 separate outputs from the bass, which you could then merge back into 1 somewhere along your signal path. That would allow you to do the wiring you REALLY want...but it means 2 cables taped together going to an ABY box.

that wouldn't work either, the passive ABY box would be no different than wiring them together inside the bass.

you'd need to run the two outputs into two channels of an active mixer of some sort.

 

[thiocyclist]

So basically to have fully independent controls you need to keep the signals split apart like a Ric or put resistors in series with the outputs like a Yamaha.

 

[frozenbolt]

Just to put a nail in the coffin about the diode idea, a diode also needs about a half volt to even turn on and do its job (rectifying) and the output of a pickup is way below that. I tried that a long time ago in tech school and couldn't figure out why I wasn't getting any signal out, until someone reminded me of that point.

 

[MarkA]

I did not follow all of the arguments here, but I have two basses with two volume and two tone controls (each).

One is a Fender P/J with EMGs. It also has a pickup selector switch (neck/both/bridge). When the switch is on neck or bridge, you only hear that pickup and the volume and tone controls for that pickup work as you'd expect. When the switch is in the middle, turning either pickup down to zero brings the volume of the bass down to zero, even if the other is all the way up. This is handy if I want to do volume knob swells (rare, but I've done it), but otherwise bugs me a bit. Putting the volume of both all the way up yields a scooped sound. Dialing back one or the other a tiny bit yields significant tonal changes, and this is how I usually run it (favoring one or the other slightly, or else using the switch to play exclusively on the P or the J -- rarely with both pups maxed). If each tone control affects both pups in the middle position, I haven't noticed it, and often run the two tone controls in different positions for different sounds (Neck tone wide open and Bridge tone at 50% is noticeably different than vice-versa).

The other bass is a Peavey Grind. Turning one pickup down doesn't affect the overall volume of the bass (which seems to stay at the level of the higher-set pup), just how much of that pup you hear. Again, I usually favor one or the other. Almost always leave both tone controls wide open on that bass, as the pups are a little weak and dark sounding to begin with.

The Fender is my main bass. Despite not having a very big useable sweep with the volume controls with both pickups selected, I am used to the setup and can get pretty much any tone I want out of it. I love the sound of the bass and wouldn't want to do anything to screw it up. But, if I could have the volume controls work the way the Peavey's do, and if that would give me subtler options blending the two pups -- and do it without affecting the tone or output of the bass -- I think I'd go for it. I could still do volume knob swells in the neck or bridge position. (I've noticed the volume tapers differently when both pups are selected vs. one or the other.) I'd still keep the switch.

Sorry for such a long post! And sorry if this isn't the right thread for it, but it's been on my mind for awhile and this issue seemed related. I'll start another thread if that would be better. Can also take pics of the control cavity if that would help.

 

[line6man]

So basically to have fully independent controls you need to keep the signals split apart like a Ric or put resistors in series with the outputs like a Yamaha.

The third option is active buffering.

 

[ShonenCello]

This is the OP.

When I went to pickup the bass, it was a mess.

Both volumes at 0 was like playing at 8. Both volumes varied in loudness (up & down) from 10 to 0.

The tone knobs did nothing that I could hear.

Tomorrow I'm sitting down with him and we will resolve this.

Should I give up the idea of 2 vols & 2 tones?

The discussions here have me wondering.

Any suggestions would be appreciated.

 

[Jeff Bonny]

This is the OP.

When I went to pickup the bass, it was a mess.

Both volumes at 0 was like playing at 8. Both volumes varied in loudness (up & down) from 10 to 0.

The tone knobs did nothing that I could hear.

Tomorrow I'm sitting down with him and we will resolve this.

Should I give up the idea of 2 vols & 2 tones?

The discussions here have me wondering.

Any suggestions would be appreciated.

Don't give up, find a new guy. Cut your losses and get it to someone who will deal with this like the dead simple job it is.

 

[ShonenCello]

Don't give up, find a new guy. Cut your losses and get it to someone who will deal with this like the dead simple job it is.

Yeah I'm pretty much resigned to taking back the instrument tomorrow. I want to hear his B.S. first and then make a decision.

Am I obligated to pay for this mess? I don't want to cheat the guy.

 

[thiocyclist]

He did bad work, I'd try to get a refund.

 

[ShonenCello]

He did bad work, I'd try to get a refund.

I haven't paid yet. Might not get the guitar back without a forceful argument or money.

 

[Stealth]

But you will want to use the wiper terminals as outputs, when using resistors. The resistors prevent the volume pots from dropping the output impedance to zero, so you still have the option to use the wiper terminals as outputs to avoid the variable impedance load on the pickups from the pots.

I didn't even consider that effect. So basically if they're wired Gibson-style (wiper->out), the resistors will keep one pickup from being fully grounded whenever the other's turned down?

Also, wouldn't a treble bypass capacitor or at least a bigger isolating resistor be a better choice in that case, just to avoid loading the pickup with a comparably small parallel resistance?

So basically to have fully independent controls you need to keep the signals split apart like a Ric or put resistors in series with the outputs like a Yamaha.

Just to clarify, that's a modded Yamaha and by no means an original wiring. That came about when someone wanted to go passive because of the (admittedly) low-quality preamp inside an RBX375.

 

[fjadams]

Wouldn't this work?

http://www.talkbass.com/forum/f38/need-2-vol-2-tone-no-switch-diagram-asap-please-683628/

 

[fjadams]

Here's a diagram from line6man from a couple of years ago. I think this is how my luthier wired mine.

 

[uOpt]

This is the OP.

When I went to pickup the bass, it was a mess.

Both volumes at 0 was like playing at 8. Both volumes varied in loudness (up & down) from 10 to 0.

The tone knobs did nothing that I could hear.

Tomorrow I'm sitting down with him and we will resolve this.

Should I give up the idea of 2 vols & 2 tones?

The discussions here have me wondering.

Any suggestions would be appreciated.

It is been explained, but again in more clarity:

if you connect the 2 pickups to 2 volume pots the way that guitars are usually wired, with the slider of the pot to the output (I call that "pot connected forward"), then turning one pot completely down will shut off everything. This is usually combined with a pickup switch.

If you connect the pots "backwards", the hot lead from the pickup going to the slider, then this problem does not apply. This is how a Jazz bass works (blend pot is the same as 2 pots electrically).

The disadvantage of the backwards connected pots is that if any one of the pots is not on either full open or full close then the amplitude of resonance peak of the pickup is suppressed heavily, in fact it is eliminated entirely very quickly.

Jazz bass users with vintage style pickups connected in parallel (in that case) can afford to do without resonance peak, the pickups are pretty much linear frequency response when in parallel and the peak would be so high that there aren't many overtones up there anyway.

Users of pickups that cut off much earlier than parallel connected Jazz bass pickups will generally not be happy, as they rely on the resonance peak to make things sound interesting. The pickup is always a LPF and now you just have a dumb LPF with no resonance peak stealing all your overtones.

This is also the reason why guitarists very rarely connect volume pots backwards. Their higher overtones are cut off by design and they rely on the resonance peak to make the overtones at the cutoff frequency count, give life to the sound. Kill the peak, you make it sound lifeless.

 

[ShonenCello]

Here's a diagram from line6man from a couple of years ago. I think this is how my luthier wired mine.

View attachment 355713

That looks a lot like the "Les Paul" diagram I attached earlier.

I'll bring all these ideas up to him tomorrow.

thanks

 

[ShonenCello]

It is been explained, but again in more clarity:

if you connect the 2 pickups to 2 volume pots the way that guitars are usually wired, with the slider of the pot to the output (I call that "pot connected forward"), then turning one pot completely down will shut off everything. This is usually combined with a pickup switch.

If you connect the pots "backwards", the hot lead from the pickup going to the slider, then this problem does not apply. This is how a Jazz bass works (blend pot is the same as 2 pots electrically).

The disadvantage of the backwards connected pots is that if any one of the pots is not on either full open or full close then the amplitude of resonance peak of the pickup is suppressed heavily, in fact it is eliminated entirely very quickly.

Jazz bass users with vintage style pickups connected in parallel (in that case) can afford to do without resonance peak, the pickups are pretty much linear frequency response when in parallel and the peak would be so high that there aren't many overtones up there anyway.

Users of pickups that cut off much earlier than parallel connected Jazz bass pickups will generally not be happy, as they rely on the resonance peak to make things sound interesting. The pickup is always a LPF and not you just have a dumb LPF with no resonance peak stealing all your overtones.

This is also the reason why guitarists very rarely connect volume pots backwards. Their higher overtones are cut off by design and they rely on the resonance peak to make the overtones at the cutoff frequency count, give life to the sound. Kill the peak, you make it sound lifeless.

Thank you.

I'm not sure what question I asked that prompted this explanation but I do appreciate the information and I'm sure it will help me get to the bottom of this.

Once again thanks.