Mutron Biphase.

[JakeFuzz]

I have been getting a lot of interest in some of the old Mutron stuff. Specifically the filter (available from GGG) and the Biphase.

Schematics for the biphase are available and it looks like two mutron phase II's in one box with a slightly different oscillator section. It would definitely be a beast of a project. There are 4 custom LED/LDR's (1 LED to 3 LDR's each). The power section can be made easily without a transformer and the vactrol switching can be replaced with hard switches. Footswitch and expression pedal circuitry can be removed. Overall it might be do-able and from reading around there would be quite a high demand for a project like this.

[maysink]

+1 (or as many as needed).

BTW, the 'Neutron' (MuTron III clone) over at GGG is fantastic and wasn't nearly as complicated as first appeared.

[JakeFuzz]

+1 (or as many as needed).

BTW, the 'Neutron' (MuTron III clone) over at GGG is fantastic and wasn't nearly as complicated as first appeared.

Good to know. I am in the process of building one for a guy right now. I am still trying to decide whether to use two Vactrols or the LED/Photo-FET packages.

[maysink]

I went with 2 vactrols. I made the hard-to-find 150K 'PEAK' pot out of a 250K pot w/ 375K worth of resistors strung between lugs 1 & 3. That gave me a pot just under 150K.

[JakeFuzz]

I will probably go with two vactrols and I will use your pot idea! Thanks.

As for the biphase I think I am making this my next major project. I just cant figure out phaser A's oscillator section. It has a bridge rectifier and a bunch of extra gain stages  . I may just go with a more versatile LFO (different waveforms...) and preserve the optical phasing and the input/output stages. 

[madbean]

Can you guys school me a little on the different Mutrons? So, the Bi-Phase has not been seen as a DIY project, correct? Just the Mutron III and the Filter one at GGG? I've actually never built any of them.

[pandadandan]

http://m.bareille.free.fr/biphase/biphase.htm

Here's a biphase project.  PCBs are available for 45 euros for the pair.

A LOT of stuff in a biphase.

[JakeFuzz]

I am thinking the Biphase might be possible. I have definitely seen that French guys site and I think that 45 euros is a little pricey. It is for 3 boards though so maybe not.

The Biphase is essentially two 6 stage phasers; the phasing sections are optically modulated and are of the opamp/resistor-capacitor type (MXR). There are some clever order switching options to stack the final two signals and also options to sync the LFO's. You need an output buffer after the phasing section to avoid loading. The original had AC power and a selectable foot switch to control the sweep as well as inputs and outputs for each phasing channel.

The most difficult part would be making the LED/LDR's that control the phasing sections. The original used three LDR's to one diffused LED inside a black canister. You could make one inside a copper water-pipe end cap hot glued to a small perfboard with the components soldered in the correct places.   

[hoyager]

I think the Phasor II is half a Bi-Phase, so would an idea be to make a Phasor II which is modular or connectable in a way where you can build 2 and have yourself a Bi-Phase?


Andy

[JakeFuzz]

I think the Phasor II is half a Bi-Phase, so would an idea be to make a Phasor II which is modular or connectable in a way where you can build 2 and have yourself a Bi-Phase?


Andy

Yes that is the idea. A well done schematic for the Phase II is over at FSB and someone has confirmed it (with his own layout). There is one discrepancy between the two designs I cannot seem to figure out. There are an additional two gain stages in phaser A's oscillator section and a bridge rectifier diode setup, could be for the expression pedal? Not really sure if I can just take them out. All the switching and syncing can be done via hardware so two separate boards would be possible but probably more tedious and messy than just having the whole thing on one pcb.

I know I would want to go straight to a Biphase but others might want just a phase II.

[bigmufffuzzwizz]

This would be a great project but i imagine quite complex! I have always wanted to try one of these but have never gotten close to one