Multi-capacitor tone control

[kurosawa]

Originally Posted by BassLife77

Don't pay $14 for the switch, thats ridiculous. It's on ebay much cheaper. they probably get them from the same manufacturer and mark up the price http://www.ebay.com/itm/1pcs-Chrome-...item43a9295bbb

Thanks man, they were $2.42 so I bought 2 (last of the big time spenders).

[GODSBASSMAN]

Ditto. 2 . Thanks.

[scotch]

I've been experimenting with different cap values & am running into distortion with the inductor in series with large value caps (say .2 or higher). I know this is 'normal', but would using a different transformer allow me to go with bigger caps without distortion?

I'm using a TL021-R

[SGD Lutherie]

Originally Posted by scotch

I've been experimenting with different cap values & am running into distortion with the inductor in series with large value caps (say .2 or higher). I know this is 'normal', but would using a different transformer allow me to go with bigger caps without distortion?

I'm using a TL021-R

You may need to include a series resistor (R1) like this:



Inductors do distort a little at times. A different inductor might help.

[scotch]

Originally Posted by SGD Lutherie

You may need to include a series resistor (R1) like this:



Inductors do distort a little at times. A different inductor might help.

So the resistor is limiting signal hitting the inductor? Wouldn't this also limit the bypassed (raw) signal a little?

[SGD Lutherie]

Originally Posted by scotch

So the resistor is limiting signal hitting the inductor? Wouldn't this also limit the bypassed (raw) signal a little?

A little. This is how the Gibson Varitone is too. You can probably wire it up to bypass that resistor when you bypass the Varitone. It's a passive tone control, so there is always a little insertion loss involved.

[T-34]

What R1 does too, it isolates the Varitone circuit from the inductance of the pickup. Without R1, the pickup will form its own LC filter with the C1-C5 capacitors which could mess up with varitone function...

[T-34]

Originally Posted by Jazz Ad

It lets you try different setups of cap+resistor so you get different low pass and resonant frequencies.THis is not my work, it is Dolganoff's from Onlybass.
He slowly improves on his concept and sells some readymade units.
Here's a link to the main thread but it's all in french.
http://forum.onlybass.com/index.php?...st-passif-diy/

By the way, that's me (I have different nickname on Talkbass )

By now the "thing" has evolved into its 4th version after many tests and comments from onlybass.com french community. We call it "Megatone" there.
Many people considered 12 and even 10 notches as too much to fiddle with. Other complaints were about loosing the traditional tones (like tone pot rolled-off to the middle). I had an idea of combining both requirements in one design: it is based on an inexpensive 2x6 rotary switch (two independent sections on one shaft, 6 positions).

The "boost" section has 6 "always full on" capacitors from 1000pf to 0.047 mF.
The "classic" section has one 0.1 mF capacitor and 4 resistors simulating 5 discrete positions of a classic tone pot plus a bypass.
Other resistors are there to discharge the caps and don't participate in tone shaping.



Computer simulations of this circuit give the following frequency curves (the simulation is made for an average PB pickup - inductance 4H, parasitic capacitance 100 pF)

Boost mode


Classic mode


It can be made compact enough to fit in almost any instrument if small enough caps are used. The last prototype looks like that:



This one is made with point-to-point soldering and doesn't require any particular tools but tweezers and soldering iron, and some patience I believe almost any electronics enthusiast DIY-er should be able to build one

[Doner Designs]

This has evolved into a nice mad scientist thread!

[T-34]

"Nice Mad Scientist". I take that

[sixway]

Originally Posted by T-34

By the way, that's me (I have different nickname on Talkbass )

By now the "thing" has evolved into its 4th version after many tests and comments from onlybass.com french community. We call it "Megatone" there.
Many people considered 12 and even 10 notches as too much to fiddle with. Other complaints were about loosing the traditional tones (like tone pot rolled-off to the middle). I had an idea of combining both requirements in one design: it is based on an inexpensive 2x6 rotary switch (two independent sections on one shaft, 6 positions).

The "boost" section has 6 "always full on" capacitors from 1000pf to 0.047 mF.
The "classic" section has one 0.1 mF capacitor and 4 resistors simulating 5 discrete positions of a classic tone pot plus a bypass.
Other resistors are there to discharge the caps and don't participate in tone shaping.



Computer simulations of this circuit give the following frequency curves (the simulation is made for an average PB pickup - inductance 4H, parasitic capacitance 100 pF)

Boost mode


Classic mode


It can be made compact enough to fit in almost any instrument if small enough caps are used. The last prototype looks like that:



This one is made with point-to-point soldering and doesn't require any particular tools but tweezers and soldering iron, and some patience I believe almost any electronics enthusiast DIY-er should be able to build one

This looks like something I could do, but I'm a visual guy... would you mind posting some close-ups of the bottom of the pot showing the soldering points? Is the bottom of the pot numbered? Just trying to make it easier on myself when I attempt this. Thanks for your time in making this pot up!

Have you tried it in your bass yet, and if so, what are your thoughts on how it works?

[Clark Dark]

Is this varitone example close to the BC Rich Mockingbird design?

[T-34]

Sixway, I am on holidays till January 7, will post more photos then!

[sixway]

Originally Posted by T-34

Sixway, I am on holidays till January 7, will post more photos then!

Thanks T!

[Angel LaHash]

Any way C1 and C4 1000pF and 0.001uF .. are they the same thing

Im building the MegaTone36 at the moment
but i will also build this one as i think i have the parts and put it in another bass i got

[T-34]

Angel, it's really a typo, well spotted: C4 value should be a 0.01.
Cannot change the pic right now being on holidays w/o my PC...

[NorCal Dog]

Originally Posted by T-34

It can be made compact enough to fit in almost any instrument if small enough caps are used. The last prototype looks like that:



This one is made with point-to-point soldering and doesn't require any particular tools but tweezers and soldering iron, and some patience I believe almost any electronics enthusiast DIY-er should be able to build one

that's badass

i have a bass that could totally use some different flavors of MegaTone

will be sourcing parts after the new year, thanks for sharing

[T-34]

Originally Posted by Clark Dark

Is this varitone example close to the BC Rich Mockingbird design?

The Megatone's "boost" section should be close to what's behind the BC Rich 6-way switch (and Aria Pro II SB series by the way), but capacitor values are probably different. Actually I don't know what their values are, and they probably wouldn't like us to reverse-engineer their gear...

[T-34]

As requested, I've made some modifications (correcting the typo spotted by Angel LaHash and modifying the schematics to match the very last prototype). I've created an assembly diagram too.

From now on, the "thing" has its proper name: Megatone Duo!


Schematics:


Assembly Diagram:
The numbers from 1 to 12 and letters A and C are as marked on the Lorlin switch body.



Some assembly steps illustrated:




Resistors of the "classic" section:


The grape of resistors and caps for the "boost" section - this part is tricky, the assembly and soldering requires some patience for sure...


Done!


Now go and heat your soldering irons

[NorCal Dog]

Originally Posted by T-34

As requested, I've made some modifications (correcting the typo spotted by Angel LaHash and modifying the schematics to match the very last prototype). I've created an assembly diagram too.

From now on, the "thing" has its proper name: Megatone Duo!


Schematics:


Assembly Diagram:
The numbers from 1 to 12 and letters A and C are as marked on the Lorlin switch body.



Some assembly steps illustrated:




Resistors of the "classic" section:


The grape of resistors and caps for the "boost" section - this part is tricky, the assembly and soldering requires some patience for sure...


Done!


Now go and heat your soldering irons

that looks simple enough

thanks for sharing this info & posting the photos

i plan on dropping one of these into my Epi Allen Woody, should sound quite interesting

may i ask, do you know of any clips available to hear one of these Megatones in action ?