"Sonic Death Ray" Phaser - a phase insurrection!

[Strategy]

this looks great, will definitely make this my next phase shifter!
- strategyh

[frequencycentral]

this looks great, will definitely make this my next phase shifter!
- strategyh

Thanks! A few caveats:

• Wait until it's verified
• The FETs are everything
• I've built this around a specific set of FETs
• The FETs are everything
• It may well not work without a specific set of FETs
• The FETs are everything
• As the 14 stage calls for 14 matched FETs of a specfic range you may need to buy 100's
• The FETs are everything
• A classic case of 'the unrepeatable circuit' ?

[Strategy]

I will add this to the "challenge" pile! 

[doc_drop]

O.K. well as long as it is

Swwwwwwwwwoooooooooooooooooooosssssssssssssssssshhhhhhhhhhhhhhh!

and not just Swwwooooshh.

I guess the FETs don't make a difference either!

I do wonder if there aren't "magic" combos of unmatched FETs and just dumb luck in getting a nice/unique sounding phaser. Hmmm, socket them all?.... Maybe get a SSSSHHHHHHwoooooooooshhhieSHHHWooooooooooooosh going...

[tuckster]

OH NOOOO now I have to build another phaser

[stringsthings]

..... interesting, Mr. Spock .... 

[frequencycentral]

Here's the prototype on the breadboard. 4 x TL084 and 14 x 2N5485 with a Vgs of 2.3 to 2.5. The toggle switch bottom left is the parity switch, and feeds the regen path back into either the first or the second phase stage, for odd or even numbered stages in the regen path. On the breadboard I'm just using jumpers to select which stage I'm feeding back from, but on the finished unit it will be a 6 way rotary. The even regen stages all have a very different sound to the odd stages. Using the 10, 11 and 12 stage regen paths are almost verging on flanging.

[daverdave]

Bloody hell Rick! That looks like an absolute monster, I'd be very very very interested to hear it.

[Puguglybonehead]

Wow! This looks very radical! When can we hear a soundclip?

[frequencycentral]

By request, here's the layout for the 6 stage version. By using the Mode and Parity switches in combination, any of 3, 4, 5 or 6 stages or regen can be selected. I decided on two toggle instead of a rotary as they'll take up less room, but if you do want to use a rotary there is provision for that too by using the additional (unused) grey pads. I can't be bothered to explain how right now, but a full explanation will be forthcoming if anyone actually builds this and decides to use a rotary.

Just a couple of things missing from this layout:

- no polarity protection diode (no room!)
- a (1K) resistor is needed to limit the maximum speed of the LFO (no room!), hook it up between the LFO either of the LFO pads and the LFO pot

Please bear in mind that this is a phaser designed to work with a particular measured set of FETs as opposed to a phaser designed to be biased to suit whatever FETs you use.

[frequencycentral]

Hey! Wow! Just found something really cool - toggling the Parity switch really fast while playing sounds awesome. I think I'm going to have to add this as an automated feature, controlled by a second LFO. Hmmm just need to work out how to implement it........

[igerup]

Oooo, that's a lot of nice coloured wires there. Reminds me of a tube amp, for some reason. 

[frequencycentral]

Ok, this is how I've implemented parity modulation:



I've made a second LFO, driving two home-made vactrols. The LEDs are so configured so that they flash alternately as the LFO goes through it's cycle. So at the top of the LFO sweep the regen path is returning through an odd number of stages, and at the bottom of the sweep regen is returning through an even number of stages. I cannot begin to describe the sound this is making. I guess it's hard to imagine what a 14 stage phaser sounds like, let alone the difference between odd and even regen paths, let alone what modulating between odd and even regen paths sounds like. It kind of imprints another modulation over what's already there. Used clean, with slow phase and fast parity modulation it's like a vibe on top of the phase. Used distorted it's a talking-robot-synth-guitar-armageddeon-machine. You'll just have to wait for the soundclips. Does anyone have any idea what I'm talking about?

[soggybag]

This is a very intriguing thread, great work. I like the look of that 6 stage version. Although the idea of matching FETs sounds like a problem, not to mention the FETs you are using are not the standard stuff floating around my parts box.

[igerup]

I think I speak for everyone when I say "soundclips and Youtube vids are a must for this circuit". No pressure, though. 

Here's an idea for a future modification: expression pedal jacks so it's possible to change the sound while playing.

[~arph]

Yeah man take it easy, we're not eager to see "HD videos with separately recorded audio mic'ed from the amp" at all.. ... I mean you've just had two tiring days of recording videos behind you now, right?  we understand.

[frequencycentral]

Yeah man take it easy, we're not eager to see "HD videos with separately recorded audio mic'ed from the amp" at all.. ... I mean you've just had two tiring days of recording videos behind you now, right?  we understand.

  I have no mic at the moment, but I'll record some clips DI'ed tomorrow. You won't be dissappointed........

[frequencycentral]

Here's some clips, recorded direct to soundcard, so a little sterile. Tele Custom > BMP > Phaser > Soundcard

Stepping through the stages

Parity modulation

I'll do some clean clips a little later.........

[~arph]

Cool!

Good deep phasing, the parity modulation sounds interesting, you do seem to loose a lot of depth in the phasing.

Thanks for posting!

[frequencycentral]

Yeah the parity modulation is interesting, though a little too 'square' at the moment. I've got to play with the LFO to get the LEDs to fade on and off instead of switching on and off. I may try some different LFOs, maybe a PSO. I think you lose some depth with the parity modulation as the two regen paths are out of phase and cancel to some degree.