• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Why Volume/Volume?

#61
Some blends are designed so that both PU's are full on when centered. I've also seen blend pots that are simply a 15A taper and a 15C taper ganged to one pot shaft. This means that when centered, each PU is reduced by 15%. 15A is audio taper and 15C is reverse audio taper. They're out there. They don't work very well, but the exist.
 
#67
I just happened to take a look at this thread today and thought I'd throw in something which could be of interest:

I had it my head to look at the passive blend in order to see if there was some way the performance of the 250k/250k MN taper blend pots, the type that is pretty much standard, could be improved.

I'm quite keen on the buffered electronic blend, as illustrated in my J-Retro design, which is very smooth, but obviously doesn't work in passive. I've started to supply some standard passive blends over the last few years but never been happy with them, and always had this nagging feeling that maybe something could be done to improve them. I had an idea a little while ago and I have recently tried it out.

Having taken the pre out of my 78 maple block inlay Jazz, I took direct feeds from each pickup and hooked up my blend control idea which, although not perfect, seemed to be improved.

Having looked at this post I did a little more on it today.

As Mike rightly pointed out, using the common 250k post, VVT gives you 2 X 250k to control the level and 250k T via the tone capacitor.

Just slapping in a standard blend gives you an additional 250k in the level control which is loading the pickups more, taking the higher frequency output down some more and acts somewhat like a switch.

So my idea, which uses the blend wired in a different way to the current convention, tries to take account of the above:

* Seems smoother than the standard config, but far from totally even.

* Both pickups are at max in the center retaining the important cross-feed interraction, again talked about by Mike.

* The impedance of this blend config remains equivalent to a single pot at 250k, even though it has 2 X 250k elements.

Having said all the above, does it give more control than VVT?

I don't know.

So I'd like to send a few out for some die-hard VVTers to try this config out in practise, to see what they think.

Any takers?

I need to get a little circuit board made, which will take a couple of weeks before they're ready, something I intend to use anyway, which can be configured as the standard or this one I'm experimenting with.

Just to say that I'm very happy to tell anyone what I've come up with, but would like a bit of a trial before I do that, after which, there may be some egg involved, but let's see!
 
#71
Well, I'd love to see a schematic! Sounds really interesting. I've been thinking more along the lines of having a custom taper blend pot made. Slightly non-linear off of center. A permutation of the audio/reverse audio thing but maintaining the 100/100 thing when centered. Kind of expensive at first, but it might be worth it. John, maybe you and I/Fodera should look into it together. It could defray costs a bit. ???
 
#73
Thanks for all the great follow-up from everyone on this discussion! John... that sounds interesting. I unfortunately do not have an instrument that I can use as a tester, but will keep up with yours and others' comments on this interesting idea.

Ken
 
#74
Hey John,

I have your J-Retro in my 77 maple block jazz.
I dig the tone and power on it but did feel I liked it better with my previous vol/vol option(passive wise).

Would love to have a go at your new blend concept, and of cos if schematic is not a problem... would love to know how you did it too.

Count me in too!
 
#79
thepontif said:
Well, I'd love to see a schematic! Sounds really interesting. I've been thinking more along the lines of having a custom taper blend pot made. Slightly non-linear off of center. A permutation of the audio/reverse audio thing but maintaining the 100/100 thing when centered. Kind of expensive at first, but it might be worth it. John, maybe you and I/Fodera should look into it together. It could defray costs a bit. ???
Click to expand...

I'm having a few made as protos so I'll send you one if you like. PM your address.

After I made the sample, I changed it again slighty having realised the impedance at either extreme, for each pickup, was back down to what the normal blend config does, at 125k. So I changed it again! It's really far from perfect but the loading is better and I believe there is a little more control. (Jury out on this one, let's see?)

The big problem is that the M/N tapers are linear, and just as you say, log/reverse log or audio/reverse would seem to be what we need, which is non-standard with zero resistance from centre to end, opposed on each element.

Yes and maybe we could get together on that!

I just played with a reverse log taper simulating control of just one pickup against the other at max, and variation seemed to be much improved, but unable to try with two pickups.

I'll draw a graph of what I think we need and ask a friendly pot supplier for some samples, and see what they say.
 

Latest posts

Top Bottom
Back