Dual concentric pots?

[ArtieToo]

Re: Dual concentric pots?

Looks interesting Kent. I'm not sure I understand what you're doing with the bottom of the 4PDT switch. Where is the "common" terminal supposed to go? Is that to adjust the output level if both p'ups are selected?

We'll have to buy a couple transformers, and see how this whole thing works.

[Kent S.]

Re: Dual concentric pots?

Looks interesting Kent. I'm not sure I understand what you're doing with the bottom of the 4PDT switch. Where is the "common" terminal supposed to go? Is that to adjust the output level if both p'ups are selected?

We'll have to buy a couple transformers, and see how this whole thing works.

The upper half of the switch shunts the pup's hot to it's cold side, while at the same time shunting the hot and cold of it's corresponding primary (no signal, signal, no noise, no inductive coupling, no muss, no fuss, no problems ... LOL) when that pup is to be off.
The lower half of the switch (speaking in pairs that is),
grounds the center tap to effectively halve the secondary, since twice the signal is induced with two primaries operating ( a doubling of the voltage ... if assummed linear) ... This bumps it back down. Thing is, transformers aren't my *thing*, so I can't remember off hand the P/S ratio as to which is greater and which should be lesser ... as in step-up or step-down ... the intent was to step down the voltage when both primaries are active; However I may have that backwards. Another problem would be the looming question of what should the primary Z be ... 1 Meg each would be nice, and what should the secondary's Z be (CT and Full). Plus even if you found a transformer that was small enough, and spec'ed, I wonder what it would do to the frequency response ... like you said about the high end.
It does raise some interesting questions ... Things like this are when I would just call the transformer manufacturer and say, hey ... ya got something that will do this?

[ArtieToo]

Re: Dual concentric pots?

Thing is, transformers aren't my *thing . . .

Yeah, me too. Where I work, I have a plethora of electronics catalogs at my fingertips. All the transformers that are listed as "audio-grade" are generally 600 ohm input/output, and, they're designed for communication work. As in voice/modem apps. Even those tend to be in the $35 - $45 range. Too expensive for casual experimentation.

The Jensen transformers will fill the bill, but at $75 - $85, way beyond practical consideration.

It was an interesting academic exercise, but probably not much more than that.

As soon as I get the "bugs" worked out, I'll send you diagram of my upcoming "multi-mode matrix switching system."

[Kent S.]

Re: Dual concentric pots?

Yeah, me too. Where I work, I have a plethora of electronics catalogs at my fingertips. All the transformers that are listed as "audio-grade" are generally 600 ohm input/output, and, they're designed for communication work. As in voice/modem apps. Even those tend to be in the $35 - $45 range. Too expensive for casual experimentation.

The Jensen transformers will fill the bill, but at $75 - $85, way beyond practical consideration.

It was an interesting academic exercise, but probably not much more than that.

As soon as I get the "bugs" worked out, I'll send you diagram of my upcoming "multi-mode matrix switching system."

Oh, and yeah I did leave off the ground for the center tap, as far as the trun ratio that should keep the output the same level ... I think ...
Plus I don't know if the primaries need to be terminated or not. Anyway, here is the corrected schematic, and cool deal on that M. M. S. System, sounds a bit like my series super plus layout ... Anyway here's the corrected schematic ...

[ArtieToo]

Re: Dual concentric pots?

. . . and cool deal on that M. M. S. System, sounds a bit like my series super plus layout ...

Thinking up these names is half the fun!

The "multi-mode" part of my switching system is just that it will be an active switching system, but in the absence of power, automatically reverts back to "ordinary" guitar functionality - so that the guitar could be carried to a friends house to use.

I did find some inexpensive audio transformers that might be worth experimenting with. ($2 or $3 each.) They're available from Mouser under the name HiQ Magnetics. I'm going to order a couple of these later this week, and see how they perform.

[Kent S.]

Re: Dual concentric pots?

Thinking up these names is half the fun!

The "multi-mode" part of my switching system is just that it will be an active switching system, but in the absence of power, automatically reverts back to "ordinary" guitar functionality - so that the guitar could be carried to a friends house to use.

I did find some inexpensive audio transformers that might be worth experimenting with. ($2 or $3 each.) They're available from Mouser under the name HiQ Magnetics. I'm going to order a couple of these later this week, and see how they perform.

Yeah, I'm familiar with the Mouser stuff ( the Hi Q line is very useful for mid notch/varitone controls, and wah Inductor replacements {also if you are planning on using any of them as inductors let me know as I have few of there inductance values on file as pertaining to certain models }), as far as a custom bulit transformer Dale/Vishay has a custom magnetics department that will make any transformer/choke/inductor you want ...( PM me if you want a download of their design/manufacturing/quote sheet). Not exactly the run of the mill stuff, they make it according to your specs. Not something the individual person will find cost effective, but for businesses it's great. Oh, and I forgot to thank you for those part numbers, thanks ...
Yeah, the names are half the fun ... better than saying the *it does this* thing. It's certainly much shorter ...
I still like the active approach, and there is no reason that each pup couldn't have it's output buffered by a JFet ... Don Tillman has a wonderful simple little preamp www.till.com, one of those off each pup feeding a balance control or dual volume would handle the situation nicely I think.

[ArtieToo]

Re: Dual concentric pots?

I've seen Don's website a ways back, and had forgotten about it. I'm glad you reminded me. That little pre-amp looks like it would work great. (I'm gonna build one this weekend.)

If you get a chance, check out the D_Tar Eclipse on-board mixer/buffer. It looks like a slightly more elaborate version of the same thing, with a bit more functionality. I'ld like to experiment with one of those, but I'm not sure what the price is yet.