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Going from vol-vol to vol- blend?

#21
avocado said:
Glad to come upon this thread, because I've been researching moving my jazz bass from VVT to VBT, and hadn't heard about M/N vs A/C.

I also want to throw a series/parallel switch in there, just to get a few extra chances to mess up the soldering. Would that make any difference with the M/N vs A/C blend pot?
Click to expand...
The way I did my series-parallel switch is the following:
  • it does not matter whether there is a an M/N or A/C pot or a Les Paul switch for pu selection
  • when the series-parallel swithc is in series position, it overrides the M/N or A/C pot or the Les Paul switch. The pu's are connected series, the volume pot can be used. I measured about 6dB extra gain in this case. (compared to the conventional state when both PU's are in parallel at 100% volume).
  • when the series-parallel swithc is in parallel position, the M/N or A/C pot or the Les Paul switch is active as well as the volume pot. This is the conventional way, and you can select/adjust between bridge/both/neck pu's.
I use the series connection as a last resort when the guitar player has activated all his distortion pedals already and I would not have enough volume to hear myself. I am actually glad I did not have to use this so often recently. :)
 
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#24
Jazz Ad said:
It matters very much because to achieve parallel/series if you use a blend pot, you need a 3pdt switch. With 2 volumes or a 3 way pickup switch, you only need a dpdt.
Click to expand...
:) possible, but it is not the solution I found; when I did it with a dpdt, there was a possible (switch position) constellation when there was no output signal, so that was not good. The way that worked for me was with a 3pdt in any case.
 
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#25
If the output of your pickups can be balanced well, by adjusting pickup height, a 3 way switch is nice, no knobs to fiddle with, no trying to find the magic spot, on the one bass I have that setup on it seems to sound better in every way to me. I sometimes think about getting pickups with better output balance for my main bass, (they aren't balanced at all), and using a 3 way instead of VVT. I've used CTS a/c, and Bourns m/n pots for blend, both seemed to do the job to my ears.
 
#26
Jazz Ad said:
It matters very much because to achieve parallel/series if you use a blend pot, you need a 3pdt switch. With 2 volumes or a 3 way pickup switch, you only need a dpdt.
Click to expand...

A DPDT switching scheme is sufficient when using an ungrounded M/N blend pot. It MUST be both ungrounded, and M/N, however, for it to work, as the two inputs of the blend pot are shunted together. If you choose a traditionally grounded blend scheme, and/or an A/C taper blend pot, then you must resort to a 3PDT switching scheme to achieve series/parallel, without the blend behaving as a volume pot when you are in series mode.
 
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#27
radmin said:
Not that I'm an expert but my understanding is:
Audio taper is for the tone control.
Regular pots are for volume.
Click to expand...

With genuine respect, I have to loudly differ. Audio taper pots are for the volume control and ordinary pots are for the tone control. Audio taper is also known as "log taper" which is short for "logarithmic taper". The idea is that as the potentiometer is rotated clockwise the internal resistance is decreased in a logarithmic amount, not a linear amount. THIS IS TO TRY TO COPY THE NORMAL RESPONSE OF THE HUMAN EAR. To explain...ok, imagine the total physical sweep of your bass's volume control - that means the physical distance between all-the-way-off and all-the-way-up....think of it as from "1" to "10". Now...imagine the total physical sweep divided into ten parts...start with volume at "0", then volume at "1", then volume at "2", and so on all the way up to the maximum clockwise rotation. In an audio-taper potentiometer, the total internal electrical resistance is MAXIMUM at "0", or volume off. OK? Now...turn your volume control up to "1". Alright, the electrical resistance across the audio taper potentiometer when the volume is set at "1" is some figure - I don't know the figure, nor do I care, but obviously it is some figure. Now, increase the volume to "2"...how much do you think the difference in internal electrical resistance will be, when you compare the difference between "0" and "1", and "1" and "2". It's not the same amount!! No, the difference is 10 times the amount. As you continue rotating the volume control, EACH step of the way is 10 times greater (or less than, honestly I forget right now) than the previous step. That is the essence of the logarithmic numerical scale - earthquake magnitudes are measured that way, decibels are measured that way, a lot of things are measured that way. It comes from trigonometry which I never did well at in high school, but nevertheless, there you are.

Volume controls need to be audio taper pots (aka logarithmic taper or log taper) so that as you rotate the volume control, the human ear will perceive a smooth increase in volume, not a weird sudden volume increase somewhere in the middle of rotation.

Tone pots need to be "standard taper", which means a smooth continuous drop (or increase...again, I forget - sorry) in internal electrical resistance.

Some of the technical guru types can 'splain it all better than I can, but there ya go...that's my lame attempt to put it into modern English.

MORE BASS!!!

...Doug in Arizona
 
#28
cazclocker said:
With genuine respect, I have to loudly differ. Audio taper pots are for the volume control and ordinary pots are for the tone control. Audio taper is also known as "log taper" which is short for "logarithmic taper". The idea is that as the potentiometer is rotated clockwise the internal resistance is decreased in a logarithmic amount, not a linear amount. THIS IS TO TRY TO COPY THE NORMAL RESPONSE OF THE HUMAN EAR. To explain...ok, imagine the total physical sweep of your bass's volume control - that means the physical distance between all-the-way-off and all-the-way-up....think of it as from "1" to "10". Now...imagine the total physical sweep divided into ten parts...start with volume at "0", then volume at "1", then volume at "2", and so on all the way up to the maximum clockwise rotation. In an audio-taper potentiometer, the total internal electrical resistance is MAXIMUM at "0", or volume off. OK? Now...turn your volume control up to "1". Alright, the electrical resistance across the audio taper potentiometer when the volume is set at "1" is some figure - I don't know the figure, nor do I care, but obviously it is some figure. Now, increase the volume to "2"...how much do you think the difference in internal electrical resistance will be, when you compare the difference between "0" and "1", and "1" and "2". It's not the same amount!! No, the difference is 10 times the amount. As you continue rotating the volume control, EACH step of the way is 10 times greater (or less than, honestly I forget right now) than the previous step. That is the essence of the logarithmic numerical scale - earthquake magnitudes are measured that way, decibels are measured that way, a lot of things are measured that way. It comes from trigonometry which I never did well at in high school, but nevertheless, there you are.

Volume controls need to be audio taper pots (aka logarithmic taper or log taper) so that as you rotate the volume control, the human ear will perceive a smooth increase in volume, not a weird sudden volume increase somewhere in the middle of rotation.

Tone pots need to be "standard taper", which means a smooth continuous drop (or increase...again, I forget - sorry) in internal electrical resistance.

Some of the technical guru types can 'splain it all better than I can, but there ya go...that's my lame attempt to put it into modern English.

MORE BASS!!!

...Doug in Arizona
Click to expand...

I don't know what "standard taper" means, but never use a linear taper for a tone control. Linear taper pots do work very well for volumes, however. This comes up about once a week. Do a search.
 
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#29
^^
I like this one, as I've had good results with linear and audio taper on vol pots- factory installs or otherwise.
Could have something to do with active or passive pickups/systems tho, and I don't yet fully understand whether it has to do with that, or pot values, or both combined.
 
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#30
Hi Lineman, ok I better do some more searching! I was quoting from my memory from years ago when I used to like to tinker with electronics - radios & stuff like that. Technology has dramatically changed since then and I suspect I'd better defer to the current crop of experts instead of spouting off my old material!
Thanks, lineman
...Doug in Arizona
 
#31
cazclocker said:
Hi Lineman, ok I better do some more searching! I was quoting from my memory from years ago when I used to like to tinker with electronics - radios & stuff like that. Technology has dramatically changed since then and I suspect I'd better defer to the current crop of experts instead of spouting off my old material!
Thanks, lineman
...Doug in Arizona
Click to expand...
When it comes to pots, there is not much new under the sun.
A linear 500K pot, set to the midway position will have 250K one either side of the wiper.
(Center lug to left lug and center lug to right lug.)
That being said, there are variations of basic pots.
No load pots, blend pots, Fender's TBX pot and others are simply variations of basic pots.
I've even seen reverse taper pots, supposedly used for left handed guitars.
So there are many variations of what are basic potentiometers.

A linear, is a linear, is a linear, but not all Audio Taper pots are created equally.
True log taper pots should all be the same as well.
If they are true log, they operate according to the math of logarithms.
So in theory then, a log, is a log, is a log.
It is common to use the terms Audio Taper and Log Taper interchangeably, but this is not always correct.

All log tapers are audio taper, but not all audio tapers are log taper.
There are different types of tapers available in audio taper pots.
This can add to the confusion when comparing different taper pots and how they function as volume or tone controls.
OGB
 

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