What Does the Foxx Phase?

[nickbungus]

Another possibility is that there is no clear divide between the 1482 and the Studio Model 7 and the thing just evolved. 

[armdnrdy]

As far as I can tell...the Sears 1482 is a castrated version of the Foxx Foot Phaser.

There are many examples where goods that are manufactured for a mass market chain are the cheaper, cut down versions of the original.

During WWII, the United States developed the "super charger" technology.
This was introduces on the P-38 Lightning.

The British witnessed test fights of the Lightning and placed orders for 667 of these fighters.

Three Lightnings were delivered sans superchargers.

The British promptly cancelled the remainder of the order.

These three aircraft were appropriately nicknamed....castrated Lightnings.

Sorry Nick!

[Luke51411]

I've browsed this thread a bit but haven't paid that close of attention. At any rate, I just came across a "broken" studio model 7 on ebay. Is this circuit sorted out or are there still some unknown values?

[Luke51411]

http://www.ebay.com/itm/311436905869?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Here it is, there are some gut shots in there too.

[armdnrdy]

http://www.ebay.com/itm/311436905869?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Here it is, there are some gut shots in there too.

Thanks Luke.

I collected these shots the other day.

This is an example of the original Model 7 with the ring mod settings.

[nickbungus]

Thanks Luke.  The eBay item does not ship to the UK, otherwise I'd be on it

I've modded my board to be able to satisfy both the 1482 and the Studio Model 7.  I've printed 2 out and I'll be etching soon.  Apart from the ICs, the only thing I plan to socket is R34.  I'll also use Larrys speed control on both, but I'll make each model.

I'll then be able to compare them side by side. 

I'm guessing the SM7 will be a better everyday phaser but for the authentic Brian May sound, it will be somewhere between the two.

[armdnrdy]

Hey Nick...

I just read something about Brain May's Foot Phaser that came as a bit of a surprise.
From your previous statements (reply #44), I was under the impression that Brian's phaser was rehoused in a different enclosure, and the speed pedal wasn't used.
If Brian didn't use the pedal speed control...then Pete Cornish went through a lot of hassle incorporating the cry baby pedal for the speed control....and the cry baby speed controller would have been a waste of space on Brian's pedal board. 
It would make sense that Brian adjusted the speed of the phaser for different songs/passages with the pedal.

"A modified Foxx phaser pedal was added with foot operated speed controller. The modifications were as follows:
The potentiometer was fitted into a CryBaby chassis, as the original speed control pedal was badly worn, along with a replacement heavy-duty bypass switch. The CryBaby chassis was fitted on top of the pedal board. The original Foxx circuit board was too large to fit in the CryBaby chassis so Pete incorporated it into the pedal board with a built in 9v DC power supply to power it. He did not do any audio modifications to it."

If you scroll down, you can see an image of the pedal board that Pete Cornish built for Brian.
It includes the Cry Baby shell that controls the speed of the Foxx circuit.
http://www.brianmayworld.com/PeteCornish.htm

[nickbungus]

Its a good point Larry.  It also asks the question as to why he didn't just buy a new one.  Even if they were no longer in production, someone like BM, with the resources available to him at the time could have sourced a new one.

[armdnrdy]

"why he didn't just buy a new one."

I think one of the key sentences is:

"As Queen moved on to bigger things, so did their stage show. Brian needed a more up to date system that would withstand the rigours of life on the road. In June 1982, Pete designed a pedal board and routing system that Brian could take anywhere in the world."

Pete Cornish built Brian a pedal board that  "consolidated" his effects into one user friendly module.

The pedal potentiometer in the Foxx phaser controls voltage for the sweep and resistance for the LFO speed control.

If the pot were worn...it would not have the same linear response of a new pot.....but it would still be usable.

This does not hold true with a worn wah pedal pot which "carries" the audio signal.

[nickbungus]

Well V2 is housed and sounds awesome.   I stuck it in with a Brian May Treble booster from Tonepad as the enclosure I had was so large. 

Like Jim reported, I also had a lot of interference and noise, so I made the cap mod suggested by Jim and when housed its as quiet as a mouse.

I wish I used a 1M log for the Feedback (I used a 1M Rev Log as that's all I had).  Its only effective from minimum (7 o'clock) to 8 o'clock.

I tried to do a video last night but couldn't get a descent tone going straight into a crappy sound card.  I'll sort something.

[armdnrdy]

Hey Nick,

I don't see a selector switch for the speeds. Which speed did you jumper?

Also, I'm sort of curious how you connected the "Depth" control.

I experimented adding a Depth control to the LFO on a breadboard....

There was only one configuration that truly worked. It's the "standard" pot to ground or reference voltage, attenuating the LFO signal.

I tried connecting lug 1 to ground, 1.8 volts, 6 volts, and a 1/2V divider. I didn't see much difference on the scope so....I ended up connecting it to ground.

Note: R21 (100K) is removed.

You might want to add a 4.7K resistor between lug 1 and ground....just to leave a touch of "wiggle" when the Depth control is fully CCW.

[pinkjimiphoton]

I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed!


sorry larry... just saw this... BWAHAHAHAHAHAHAHAHAHA.... when did i say that?
<j/k, all my fuzzes sound the same>

[armdnrdy]

I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed!

sorry larry... just saw this... BWAHAHAHAHAHAHAHAHAHA.... when did i say that?
<j/k, all my fuzzes sound the same>

No Jimi....I can't credit you for that one!

It's a little dig to all of the Fuzz connoisseurs out there.
as I work on yet another Flanger and Phaser!   

[nickbungus]

Sorry Larry.  A bit misleading.  I used lies for the depth control.  It's just the 100k 'speed' pot.  I used the same labelling used by Greg Covington on his version.  The one labelled speed is the rotary switch.

I didn't want to have a label for 'speed' and then 'more speed'.

[armdnrdy]

I see...
Why label things as what they actually are? Because....that's what they would be expecting! 

[nickbungus]

It's just for me and in really happy with it.

[nickbungus]

Actually Larry, that got me thinking and I had a look at the controls as stated on http://www.effectsdatabase.com/

For the 1482 Phaser:
•(treadle in mode 1)controls the depth/amplitude of the modulation (the size of the range in which the effect sweeps).
•(treadle in mode 2)sets the position of the effect when the LFO is in the center position or controls the effect when the LFO is switched off
•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

And for the Studio Model 7:
•(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

Clear as mud!

[armdnrdy]

Yes...I'm not sure who came up with that overview of the controls but...there are some discrepancies.

Even the name Foxx uses..."Phase Depth" isn't exactly correct.

Even though turning the control CW will "thicken" the sound...the control, as you are aware of is feedback.

This is probably a better description of the controls.



Question Nick:

When you tried the 6.8M for R38, did you leave in R25 and C12 as in the 1482 drawing?

[nickbungus]

Yeah I did.  I said I wouldn't and would socket them, but I was on a soldering roll!!

I looked down at my picked parts and went 'BOLL#*KS!!'.

Like I said in an earlier post, I'm making another 2, side by side - one for a friend and one for the hell of it.  I'm going to make one strictly 1482 (except R38) and one Studio Model 7 without R25 and C12.  I've got a Rat and a Boss CE-2 to finish first.

Regarding the word Depth, I was happy enough to use it on my decal even though I knew it wasn't right.  Any suggestions for the correct wording?

For the 'Phase Depth' as in the image, I liked Jims description, 'Swampy'.

[armdnrdy]

I would go with the label "Speed Select"
One turn of the knob and any questions one might have about the knob's function will disappear. 

This last weekend I was "playing" with the LFO on the breadboard while viewing the changes on my scope and taking voltage measurements with a DMM.

I tried including R25, C12 with R34 value 2.2M. (1482)

I then changed R34 to 6.8M.

Then removed R25 and C12...leaving R34 value 6.8M. (Model 7)

I found that the LFO in the 1482 configuration had a slightly higher amplitude at pin 7 of IC3.

Now let's get into some details.

With R25 and C12 in place, and R34 6.8M you will have less phasing because the LFO will have a lower amplitude....why??? because R21 (100K) and the R25, C12 combo make up a voltage divider.
With R34 at 2.2M...the gain is increased at IC3....so...it works.
When Foxx removed the R25, C 12 combo...they decreased the gain with the 6.8M

Now there has to be a reason why Foxx did this. Maybe the original component values were causing an issue with the upper end of the LFO slamming into the top rail of the IC, or causing distortion with a hotter signal. I'm not sure but...they were so adamant about changing the circuit that they sourced a not so common 6.8M as the only carbon comp resistor in the build.

If you remove the R25, C12 combo, and replace R34 with a 6.8M....you are probably going to have stronger phasing than you have now with the voltage divider and the 4.7M that you went with.