What Does the Foxx Phase?

[anotherjim]

FET trimmer, I guess somewhere between 3 to 4 volts. Depends on Vgs of FET's. I think if you know Vgs then bias would be about half of that below the 6v supply. So, Vgs=-4v, then bias = +4v.
Diodes as 1N4148's should be fine.

[nickbungus]

Superstar Jim.  With the trimmer I meant in terms of resistance but that's also super helpful.  I bought some Bourns 10k, 100ks and some 1Ms.  Actually, I'll socket it and see which gives me the most control for achieving the 3-4 volts.

[anotherjim]

It's a potentiometer, so the value won't affect the range of voltage out, only the amount of current it's using from the 6volt supply. It's only supplying an amp pin which is almost negligible current, so 100k is probably a good choice. 1M might be noisy and 10k is just wasting a little current, but they're all workable choices.

[nickbungus]

Just a quick note to AnotherJim.  Thanks for all your help, its been really appreciated.  The reason for the lack of progress, if you see the image above is, some idiot broke my thumb, breaking off a bit of bone attached to the tendon (an unnecessary accident but another story).

This has hampered progress a little.  Not sure if its shit skills or a broken bone but I've etched the PCB 3 times but drilling is a bit of an obstacle.   

Anyway, the Foxx will Phase Again!!

[nickbungus]

Also I bought a 100 J112's for this build and matched them so if anyone wants to try a phaser build with some, then send me your details and I'll post 4, 6 or 8 matched ones to you.   

[1878]

I was just about to start a thread on this !!

I'm going through a 'conflict of phase' at the moment, I just can't seem to get my phase right. I've had a Nano Stone for a few years & I built a Phaseur Fleur a couple of years ago. I've recently borrowed a few different phasers but none of them cut it. My favourite phase sound is Brian May/Foxx Phaser, but I couldn't give all that space up on my board.

I will be watching this with great interest.

Best of luck !!

p.s. !! CHEEKY MONKEY ALERT !! I'd gladly purchase an undrilled PCB from you if you fancy knocking one up. P.M me if you're interested.

[nickbungus]

Hi 1878, I'd gladly sort out a PCB for you.  My PCB etching is probably my best skill as my soldering is woeful and I've also got a hell of a lot of matched transistors that I can send too.  I'd wait a bit though as I haven't verified this. 

I've drilled it now so I'll be getting on with it this week.

I also love the sound of the Foxx, I narrowly missed out on one in eBay at the weekend.  I've never played through one though but everyone says it has its own unique sound.  I hope I get it working.

[1878]

Cheers !!

I used to do a bit of session work & one of the blokes I regularly played for had a massive collection of vintage gear including an original foot phaser. It could get a bit noisy at times but it was worth it. Maybe it's just the fact that it's the phase sound from my youth spent listening to Queen & trying to figure out guitar parts, but they don't quite sound like anything else. I also seem to remember a volume drop though. I've tagged a LPB1 on to the back of effects before today as a recovery stage & it's worked out fine though.

Best of luck with the build !!

[nickbungus]

Nice.

If there's a volume drop then I could incorporate the lpb1 into the output. It's such a simple circuit.  Maybe the noise could be fixed with a little help too as long as it doesn't affect the overall tone.

[Tony Forestiere]

Is this the sound?

B side of Bohemian Rhapsody on $% Vinyl.  

*edit* ummm?

[nickbungus]

Yeah.  I think its most prominent on White Man (see my first post on this Subject), and White Queen (Live)

Its also used on the solos for Bohemain Rhapsody and We Will Rock You.  He normally uses it really subtly rather than an in your face phase sound

[nickbungus]

Hi All

I have phasing!!  Ok, I'm not sure if it all works as I had about 10 seconds of testing time.  I'll be back on it when I get in from work.

AnotherJim, just going back to biasing the Fets.  I chose 6 j201s with a Vgs of 3.03 to 3.05, so I'll be biasing to +4.5v  (6v - (3/2)).  I take it I measure at the drain of any of the 6 trannies?

Thanks

[anotherjim]

Good progress.
You know what? I think if you have phasing, you only need your ears for the setting. I'd want to hear it sweeping at maximum depth. The FET's have got to be operating somewhere between fully on and fully off. If the sweep sounds smooth and continuous, with no audible pausing at top or bottom - you've got it.
Then you need some extravagant white satin with feckin' great flares.

[nickbungus]

What do you think I'm wearing now?  That's my soldering outfit.

[nickbungus]

Can anyone help me with this?



Going off the schematic for the speed control, I originally had Y as the common either connected to X or Z.  After playing with it, I think I may have got it wrong and Y should be either connected to both or neither.

Can anyone please advise on the correct wiring?

Thanks

[bluebunny]

I would have interpreted that diagram as both or nothing, because of the dotted box around the switches - which are pointing in the same direction.

[nickbungus]

Thanks Marc (BlueBunny).  That certainly gives me the most noticeable effect of slow and fast.

So with my extremely limited knowledge I take it I could use a DPDT with Y going to both commons and X and Z going to the same throw on different poles?

Like this?

[bluebunny]

Yep.  It might look something like this with a real switch:

[anotherjim]

Exactly that, although you can use DPST too, since you don't need contacts for the "both off" position.

[nickbungus]

That's great guys!

It sounds just like the Foxx, the only thing not working is the depth control (Q on the schematic - top left).  It doesn't affect the overall sound.  I've played with the trimmer to no avail and I don't understand the schematic enough to begin to debug.  When I matched the 100 Fets, the Vgs seemed to range from -2.4 to -4.5.  I went for 6 around the -3 mark.  Would trying different fets in different ranges be a worth while experiment or does it not really matter as long as they are matched?

Here's the controls as stated at the Effects Database http://www.effectsdatabase.com/model/foxx/footphaser#:
•(treadle in mode 1)controls the depth/amplitude of the LFO that controls the phaser
•(treadle in mode 2)sweeps the phaser like a wah pedal
•Modeswitches between the 2 treadle modes
•Range (Slow-Fast)controls the speed of the LFO wave that controls the phaser in mode 1
•Depthcontrols the depth of the LFO wave that controls the phaser in mode 1