What Does the Foxx Phase?

[nickbungus]

Thanks Jim, you are a legend.

The feedback pot is doing something... just very subtly.  On MKI I'd set the trimmer and pot to be just before the high squealing kicks in, which I haven't yet done on V2.  I'll put the 100n in and then have a play with the trim pot.

Video and/or sound files coming soon!  I've got a gig tonight \m/ but hopefully get something sorted soon! 

[nickbungus]

Mods work a treat.  Pop has gone!

I also put in the rotary switch.  Its a totally different beast.  The feedback Q control really makes a difference now and speed switch gives so much more control.

[armdnrdy]

Hey Nick,

Here is the correct rotary switch wiring that I verified on the bread board.

[nickbungus]

Actually Larry, I've wired it that way and I'm only getting phasing in  positions 1 and 4.

[armdnrdy]

Actually Larry, I've wired it that way and I'm only getting phasing in  positions 1 and 4.

Did you use the drawing that I just posted, (corrected) or the drawing that I posted a few pages back?

[nickbungus]

I'm comparing the 2 images from page 7 and 9 and I cant see a difference.  (Please remember I'm stupid!)

[armdnrdy]

I'm comparing the 2 images from page 7 and 9 and I cant see a difference.  (Please remember I'm stupid!)

When I replaced the drawing in dropbox...it replaced the drawing on page 7.

The new drawing (verified) is different than the one you followed.

The rotary switch lugs go to X, Y, and Z in a different order.

Wire the rotary as per the new drawing.

[nickbungus]

Wire the rotary as per the new drawing.

Ok Boss!!

Won't be tonight though, I've cracked open a cold one from the fridge!

[nickbungus]

Great stuff Larry.

I now have 4 speeds!!  Excellent detective work.

[nickbungus]

Here's a poor demo of the speed control.   Excuse the poor setup for recording, I need to mic up an amp really. 

[anotherjim]

Sounds about there now Nick. Congratulations. What's the plan for an enclosure?

[nickbungus]

Cheers Jim.  I still need to play with the trimmers a bit, I haven't really paid them too much attention while I was getting the rotary sorted.  Saying that, the wave seems a lot more even with the 6M8 resistor and the cap changes Larry discovered.

Enclosure wise, its such a beast.   The layout for MkII wont fit into a 1590BB but I've made a few changes in my design so that if I make another it will.  The circuit board is small enough, its more to do with height and getting the pots, switch and jack sockets it.

The Dearmond enclosures, as used in the original aren't easy to source.

I was also looking at this.   I'll probably make another one soon, this time without socketing (except for the ICs), this would give me less height restrictions.

I've got an enclosure that the top panel is the same size as a 1590BB but its much deeper.  This will give me loads of space, so I'm also going to fit in a treble booster.  I've also just acquired a Vox AC30cc2 so if I cant get that Brian May tone now, then I might as well give up.  So MkII is going to be expressionless.  The big enclosure would give me the option of adding an expression jack in the future but I'm not too worried about the expression feature.

[armdnrdy]

I've sourced two of the Dearmond volume pedals recently.
They come up at a reasonable price (under $40 US) from time to time.

As you know...I plan to build the Model 7 as true to the original as possible.
That's why I followed the board design and size as best I could from the images that were available.

One thing that I noticed about the Dearmond pedal....it has a much larger travel than a standard wah pedal enclosure.

This would be integral to exacting the sweep and the speed range as in the original.

Another thing that needs to be figured out is....where do you set the pedal potentiometer.
The pedal does not accommodate the full travel of the pot so...without having an original Foxx Phaser for reference, one would have to install the pedal pot to where it covers more useful frequencies and speeds.

If you do another sound sample...it would be nice to hear you go through the rotary switch speeds with the rate pot at minimum, and then the rate pot at maximum.

I bread boarded the LFO/rotary switch with an LED indicator so....I was only able to achieve a visual of the speeds.

[nickbungus]

Here you go Larry... as requested.

[armdnrdy]

Perfect!

Thanks for that Nick!

It sounds like a pretty good, linear collection of speeds.

That's what I saw with the LED.

I would imaging that the pedal pot would be adjusted to "lose" that fastest speed.

Like I said, I'll have to play with it a bit to see what is "useable"

[nickbungus]

Something I've been thinking about regarding the expression pedal.

How about an external expression pedal that has a pot of a nominal (probably best higher) value.  Then have a microprocessor that can read the resistance from the pot.  The microprocessor can apply a multiplier to the value of resistance and then using a digital pot, 'output' a new resistance value.

I hope that made sense, but if it does then the treadle could be calibrated by reading the min and max possible values so that the full range of output values are possible.  Because the multiplying value is variable, then the output range of resistance could be changed.  Also, the microprocessor could actually be a bit more clever and apply log, linear and reverse log logic to the output.

[nickbungus]

I've just been messing on with all the bits I socketed, which is basically the differences Larry noted between the Studio Model 7 and the 1482.

For MKII I basically went with the Model 7 parts.  I cycle to and from work every day which is about an hour in total and whilst on this project I've been listening to Queen bootlegs from the 70s.  Brian May never had his fOXX switched off during that period.  Anyway, with the Model 7 components, I felt like the Phaser was doing too much phasing and not sounding like what I've been listening to. 

Also, I've felt that although I can hear lots of phasing of noise, the actual guitar signal wasn't that involved.  I take it that's what trimpot R2 and pot R7 are trying to manage?  I tried adjusting these but wasn't that happy.

Anyway, I just changed C16 and C21 back to 0.01uf from .1uf and then I changed the notorious R34.  On the 1482 schem its rated as 2M2 but Jim informed me this was causing an uneven sweep.  Larry using his skills, noted the Studio Model 7 used a 6M8.  Anyway, using Jims advice from a previous post, he said this should be 'Select On Test' and I think he is right.  I went with a 4M7 and although the sweep wasn't as smooth, it did sound a lot more authentic.

[armdnrdy]

Well Nick...

All I have to say is everything that is written about Brain May's equipment lists his phaser as a Foxx Studio model 7.

I spent quite some time with multiple board images verifying the components.

Lowering the value of the two capacitors that you mentioned (C16 & C21) will only cut back on the bass response a bit. (less apparent phasing) The .1µf value has been verified.

R34 is 6.8M on every Foxx Model 7 and Regal RE-35 phaser that I have images of.

If you are hearing strong phasing without the signal being affected, I would look elsewhere for an issue.

If you recall, we added C23 (.1µf) to the feedback path.
Try lifting one side of C23...see if it makes a difference.
I was planning to do just that when I get around to building this thing.

Did you use a 300K for R13 in the LFO?
The 330K could make a difference in the sweep.

[nickbungus]

Thanks Larry, you know I don't understand electronics!!  I'm just going off my ears!

There's a guy called Mike Ryde who's got a whole website dedicated to the Brian May tone who I've had a few correspondences with.  He told me that the earlier models are deemed the most authentic according to the Brian May forums he's on.  Even I'm not that much of a geek to be on them!!  Whether they mean the 1482 or the Studio Model 7 I don't know. 

Yes I went with the 330K I had rather than the 300K you noted.  I'll give that a go. I'll play with C23 too.

One thing I've discovered is how subjective your ears can be, this can also change from day to day without making any changes.

[armdnrdy]

I just had a look on this site:
http://www.brianmayworld.com/PeteCornish.htm

It looks like two knobs on the left of the pedal in two of the images.

The Sears 1482 has one knob and one toggle switch.

The original Foxx phaser was called Foxx Foot Phaser.



The first issue of the Model 7 was a completely different circuit board.
This model included two ring modulator settings on the rotary switch.

The Model 7 was changed to the original board and circuit of the Foxx Foot Phaser.
I guess the ring modulator settings didn't go over very well!