Badstone voltage and Headroom

[idy]

There was a thread that mentioned this, characterizinging cmos phasers as "nice sweep but poor headroom," and the logic chips taking maximum 15v (7.5+ and 7.5-).

I have noticed that when used after a fuzz (or booster) it adds its own less-than-elegant distortion. Would like it to play nice with a hotter signal. Would raising the voltage help?
If caps are rated.....

Any suggestions for 6 stage phaser that would have better headroom and a manual sweep knob?

Afterthought: I think my version has a little booster inside to counter volume drop... maybe just pad the level going in and boost out....Yes?

[idy]

Scruffies' reply dissapeared, but he said that the Badstone is already cutting signal before the CMOS part and that I should look for a 6 stage optical, mentioning his "countdown" phaser project.

Are FET controlled bad? what about OTA's?

I think I could add a "manual" sweep knob to any phaser I build.

I found these possibilities:
Countdown
Ross phaser with extra stage board
masestro phase (mad bean's stage fright)
phaseur fleur
foxx phaser

Any other suggestions?

[idy]

mxr phase 100 is six stage optical too.

[Rob Strand]

Would raising the voltage help?

No.  The MOSFETs aren't limit by the supply.

The circuit can clip because the MOSFETs effectively have clipping diodes across them.
Also the Badstone doesn't linearize the MOSFETs.  I'm not sure if the tonal changes you
are hearing is from the diodes or the linearization.  More likely the diodes.

Using this schematic as a reference.
http://www.muzique.com/schem/badstone.gif
http://generalguitargadgets.com/wp-content/uploads/badstone_2.jpg

Scruffies' reply dissapeared, but he said that the Badstone is already cutting signal before the CMOS part

Yes is it.   It also uses pre-emphasis and de-emphasis to improve the signal to noise.    Getting the optimum pre-emphasis/de-emphasis and the amount of attenuation before (and matching boost after) the CMOS stage is a bit of a juggle.

On the second schematic you can see a 100nF cap near B1 and a 47nF (C1) cap near B2 connecting to R6.   You might be able change these to 68nF and 33nF to reduce the signal level in the mid-range region a tad (which could be higher when using distortion.)

One thing that bothers me about the second schematic is the 10nF cap (C13 or C15) and 470 *ohm* resistor.   470k looks more sensible to me.  The first schematic has a larger cap, which makes more sense, but is missing the resistor.   The reason I mention this issue is the 470 ohm will affect the behaviour of the de-emphasis network.

The circuit is a little messy and it's some time since I've gone through all the details.

[idy]

More general: Are optical phasers "better" re distortion (nasty clippy stuff) than FET based? I like the idea of making a "poor mans Instant Phaser" with a Ross and an extension board and an option or three for feedback and number of stages...?

[Rob Strand]

More general: Are optical phasers "better" re distortion (nasty clippy stuff) than FET based?

From the point of view of distortion and freedom from maximum signal level issues optical methods are hard to beat.

The down side is lack of predictability and unit-to-unit variations between the control input and the resistance but this can be trimmed using trimpots.

[idy]

trimmer on input, turning up the "anti-volume-drop" boost, works. Pedal is much more useful with a hotter signal. But I still have to look at a multi-stage optical phaser....