Please proof this scheme for me (contains inductor)

R. Laevinus · #2 07-07-2011, 08:57 AM

Your scheme ain't showing, dude.

pig · #3 07-07-2011, 08:59 AM

Your scheme is showing for me though I can't tell if that's right because I don't know what a q filter is

R. Laevinus · #4 07-07-2011, 09:07 AM

Huh. Maybe my browser is too old.

markanini · #5 07-07-2011, 09:34 AM

Here's a direct link to the diagram: http://i.imgur.com/heoIp.png
"Q-filter" is nothing more than an inductor I believe.

SGD Lutherie · #6 07-07-2011, 09:35 AM

The Q filter is wired wrong. I'm not sure why you have two controls for the Q. The Q tone and Vari Q would be doing the same thing.

Here's some schematics from Lawrence:

markanini · #7 07-07-2011, 09:49 AM

Thanks David but as I stated it's an expanded Q-filter scheme and the Vari-Q controls the amount of bass retained by the series cap. I'll admit it's a badly chosen name. Just want to be know if the controls I want to implement have been done so in a good way according to the diagram above.

markanini · #8 07-07-2011, 03:54 PM

Any electronics engineer type that can follow the diagram unlike David? :P I've wired it up and it seems to function as intended but since I sort of hacked the scheme together from two other diagrams I'm not sure I've applied best practices etc.

recnsci · #9 07-07-2011, 04:14 PM

Quote:

Originally Posted by markanini

Any electronics engineer type that can follow the diagram unlike David? :P I've wired it up and it seems to function as intended but since I sort of hacked the scheme together from two other diagrams I'm not sure I've applied best practices etc.

To comply with wiring diagrams David posted, Vari-Q should be 25K. Other than that it should be OK, AFAICT. BTW, EEs don't follow wiring diagrams, we follow schematics. My head allways hurt a bit when I look at wiring diagrams.

eggfart1 · #10 07-07-2011, 04:22 PM

looks great...

markanini · #11 07-07-2011, 04:52 PM

Quote:

Originally Posted by recnsci

To comply with wiring diagrams David posted, Vari-Q should be 25K. Other than that it should be OK, AFAICT. BTW, EEs don't follow wiring diagrams, we follow schematics. My head allways hurt a bit when I look at wiring diagrams.

Thanks but I my diagram is not meant to comply with any other diagram, no matter what David thinks. 100k was the most satisfactory for me as a variable control, out of commonly available values.

Quote:

Originally Posted by eggfart1

looks great...

Maybe that's what I'd get if I tried adding a third control to Davids preamp?

walterw · #12 07-07-2011, 07:23 PM

meh, passive mid controls just siphon off a bunch of signal.

anyway, what's with the second "+ out" coming off the tone pot?

markanini · #13 07-08-2011, 04:06 AM

The second hot out seems required to make the master tone behave like one and not another volume control. I based that part on a diagram by Torres: http://i.imgur.com/jgbBD.png

Here's a demo clip I recorded a while back before the master tone was added: demo.mp3 - File Shared from Box.net - Free Online File Storage

SGD Lutherie · #14 07-08-2011, 06:12 AM

Quote:

Originally Posted by markanini

Thanks David but as I stated it's an expanded Q-filter scheme and the Vari-Q controls the amount of bass retained by the series cap. I'll admit it's a badly chosen name. Just want to be know if the controls I want to implement have been done so in a good way according to the diagram above.

Oh I see what you're doing. Yes, that will work.

Bill Lawrence says to use a 10-25K resistor in that circuit. What you have goes from zero to 100K.

I had a Q-Filter back in the 80s. It's a very mild effect, not at all like a real Varitone.

walterw · #15 07-08-2011, 06:34 PM

Quote:

Originally Posted by markanini

The second hot out seems required to make the master tone behave like one and not another volume control. I based that part on a diagram by Torres: http://i.imgur.com/jgbBD.png

that's not the same at all. in the torres diagram, only the "+out" of the volume goes through the tone pot; you have both lugs of the volume going to the same lug on the tone, shorting them together entirely.

markanini · #16 07-09-2011, 12:22 PM

Thanks fpr pointing that out. Do you reckon this would be better?

SGD Lutherie · #17 07-09-2011, 12:30 PM

Quote:

Originally Posted by markanini

Thanks fpr pointing that out. Do you reckon this would be better?

Yes.

markanini · #18 07-09-2011, 01:53 PM

Thanks David but after wiring to the diagram above the tone control acts like a second volume control again...

SGD Lutherie · #19 07-09-2011, 02:19 PM

Quote:

Originally Posted by markanini

Thanks David but after wiring to the diagram above the tone control acts like a second volume control again...

Does it do that when the volume pot is on 10?

What value is your tone control cap?

Try connecting the tone control to the input side of the volume control.

markanini · #20 07-09-2011, 02:58 PM

Quote:

Originally Posted by SGD Lutherie

Does it do that when the volume pot is on 10?

Yes, behaviour is the same independant of volume setting.

Quote:

Originally Posted by SGD Lutherie

What value is your tone control cap?

.9nf

Quote:

Originally Posted by SGD Lutherie

Try connecting the tone control to the input side of the volume control.

I'll try that right now!