New Phaser Design - “Causality 4” – Built with you in mind!

[frequencycentral]

Fantastic--that's where I was thinking of looking first. You explain it in very practical terms. I'll fiddle around a bit when I get some time to dig into it again.

Thanks! If you've built a MkII those two resistors are 68k (r13-s13) and 47k (k19 - r19).

lol..yeah...I built the vero, and looking at the schematic, I can never tell which lug is which. Usually I orient myself to the layout by a volume control voltage divider pot at the output. Since there's not one here, I was counting on the 50/50 chance to fall in my favor  Not so much this time

That's a 'blind spot' I recently conquered myself. Looking at the back of the pot with the lugs pointing down, lug 1 is on the right. I'm just doing a build with a two knob Vox tonestack, I fully expect them to work backwards. 

[jacobyjd]

Yeah, the problem I run into there is that it's not always universal I'll know for your layouts in the future though

[sundgist]

 

I never remember which way pots are numbered. 2 is always the wiper. I tend to label 1 & 3 depending on which way round the symbol is on the schem. Then when wiring I go for 'pot' luck and if I have to reverse anything so be it. At that point I'll forget whether the labels on the layout were right or not.

[jacobyjd]

Ok--I put a 100k in parallel with the 68k resistor and it solved the volume issue (now it's too loud--i'll be adding a trimmer in its place)

I'll see how things sound when I rewire the pots--however, I'm getting a crazy thumping sound that occurs when the depth and speed are increased. I'm assuming it's mainly an issue of how wide the phasing sweep is, given how fast it has to make the sweep. It's pretty radical, but I think it'll settle down when i have all my tapers correct.

Other than that, it's pretty sweet--looks like i'm one decent evening away from getting it tweaked and boxed up Liking the design!

[stringsthings]

just finished putting the Mark I circuit together on veroboard .... and it sounds really interesting ...  ..... you guys did a really good job with this shifter ..... i plan to put a Mark II together in the future .... and i'll post some soundclips of the Mark I later this week ....

one question:  will the Mark I work on 12 volts?

[frequencycentral]

just finished putting the Mark I circuit together on veroboard .... and it sounds really interesting ...  ..... you guys did a really good job with this shifter ..... i plan to put a Mark II together in the future .... and i'll post some soundclips of the Mark I later this week ....

one question:  will the Mark I work on 12 volts?

Yeah I run mine on 12v.

[Spidermonkey]

Still trying to debug mine... Would a 1M speed pot cause the phasing to only happen at the extreme CCW end?

[stringsthings]

most excellent 

[frequencycentral]

Still trying to debug mine... Would a 1M speed pot cause the phasing to only happen at the extreme CCW end?

A 1M will work fine. To get the best out of it, it needs to be rev log though, no matter if you use 1M or 470k. A lin pot will cause bunching at the extreme CW. Not sure about log, maybe that's what you're using?

[Spidermonkey]

Ok cool. I'm using a rev log. The problem is that everywhere on the sweep of the pot, it sounds like the phaser is stuck, kinda like a stuck wah, and it only starts going up and down when I turn the speed all the way down.

[stringsthings]

soundclips of the Mark I

http://soundclick.com/share?songid=9192452/

recording details:   guitar with Seymour Duncan humbuckers --->  Mark I --->  line6 amp sim ( roland jc-120 with 4x10 bassman cab )

.... no other effects, hardware or software, were used in the recording .... [ as per instructions by my feline engineer, Lucky   ]

the Mark I build is pretty much verbatim from the 1.3 schematic ..... R12 changed to 47k as recommended .... regeneration pot = 47k ..... the build is not housed yet .... but it looks real purdy on the veroboard !   .....

... the phase shifting fun starts at 0:24 after the harmonics .....

[frequencycentral]

Nice clip. The very end reminds me of the effect on John Paul Jones's keyboards at the start of 'No Quarter', which was actually a Hohner Electra-Piano processed through a VCS3. Must try to get that sound with my Rhodes through the Causality.

[sundgist]

Nice clip. The very end reminds me of the effect on John Paul Jones's keyboards at the start of 'No Quarter', which was actually a Hohner Electra-Piano processed through a VCS3. Must try to get that sound with my Rhodes through the Causality.

Thank you.

I listened to the clips last night and the fact I couldn't recall what it reminded me of was bugging me.

[stringsthings]

Nice clip. The very end reminds me of the effect on John Paul Jones's keyboards at the start of 'No Quarter', which was actually a Hohner Electra-Piano processed through a VCS3. Must try to get that sound with my Rhodes through the Causality.

thanks for the comments.  being anywhere near the sounds of Led Zeppelin is a great compliment.  i'm planning on building the Mark II this summer and i'll be sure to post a clip ..... i think it's great how the DIY community has grown .... this phaser project is a wonderful example of the positive power of the internet .... [ back in college, i didn't know anyone else that was really into DIY .... no one to share my dream of owning an obscenely large number of fuzz boxes    ]

[Spidermonkey]

Hey rick, would you mind putting up your voltages for the NE5532?
Thanks

[frequencycentral]

Hey rick, would you mind putting up your voltages for the NE5532?
Thanks

Sure, I'll post a full set of voltages for all the IC's tomorrow.

[Spidermonkey]

Thanks a lot man. It's bothering me how i just can't get this working right.

[frequencycentral]

These are voltages from my MkII, using the PCB layout (although I used perf). Of course they are all jumping around like crazy as the LFO cycles, so I've recorded the minimum and maximum voltages for each pin.

Speed at minimum. Shape midway. The rest at maximum.

Supply voltage: 9.10v


NE5532

1.    1.32v  to  8.44v
2.    3.56v  to  5.81v
3.    3.45v  to  5.77v
4.    0v
5.    3.56v  to  5.84v
6.    3.55v  to  5.85v
7.    2.89v  to  7.02v
8.    9.10v


TL084

1.     3.89v  to  5.34v
2.     3.87v  to  5.37v
3.     3.85v  to  5.30v
4.     9.10v
5.     3.63v  to  5.02v
6.     3.87v  to  5.33v
7.     3.87v  to  5.33v
8.     3.87v  to  5.33v
9.     3.87v  to  5.35v
10.   3.85v  to  5.31v
11.   0v
12.   3.87v  to  5.33v
13.   3.88v  to  5.33v
14.   3.87v  to  5.33v


LM13700

1.     1.304v  to  1.373v
2.     0v
3.     3.87v  to  5.33v
4.     3.87v  to  5.33v
5.     5.05v  to  6.51v
6.     0v
7.     5.03v  to  6.53v
8.     3.87v  to  5.33v
9.     3.87v  to  5.33v
10.   5.03v  to  6.53v
11.   9.10v
12.   5.05v  to  6.51v
13.   3.87v  to  5.33v
14.   3.87v  to  5.33v
15.   0v
16.   1.304v  to  1.373v



EDIT @ 8.25pm: I've been pondering these voltages since I took them a couple of hours ago. I was somewhat surprised that pins that I had assumed would be static are in fact moving. The vref is moving. I've come to the conclusion that it might be that R33 referencing the vref is causing the vref to wobble. Forunately my R33 is socketed, so tomorrow I'm going to pull it and give it it's own vref and see what happens. I think the effect sounds great, but a vref is a vref and should be static, so I wanna find out what's happening.

[keto]

I look at pots the same way you do....back of pot, legs down, left to right is 3-2-1.  OK where do I hook up WIDTH 3?

**edit** looking at the schematic, I'm going to guess that width 2 is really width 3, and width 1 is also width 2...yes? /edit**

Thank you.

[keto]

OK I wired it up.  Don't have time to go get pin voltages at the moment, but I want to see if this specific set of symptoms point to anything in particular...

• bypass works 100%
• all knobs work, that is, do what I expect them to
• guitar signal passes thru when turned on, but does not seem to be particularly effected - this, to me, is the wierdest of the symptoms
• when the RANGE is turned up, I get a very loud thumpy signal, that can be directly effected for shape and depth and speed by the other knobs

No parts substitutions other than a 100k trimpot, which is obviously working, at R12.

It could be as simple as a pot wired wrong (see post above), for another example leg 1 of speed is not connected - wasn't sure if to run it to ground, or ground it to itself, or not.