Some ideas for the P90

[Kipper4]

I like the mix pot mod too. All the way from vibe through phaser to very subtle phasing ,almost dry.
I reckon one could get a TL074 model in a 1590b with 4 knobs
Speed, Bias, Sweep, Mix.
I'd have to try my std perf (5cmx7cm) for a layout
I used a 10nf and 100nf caps btw Ben

[Kipper4]

They're 10x the price (uk) but 2SK30 fets work in this too.
Unless they're cheaper near you.
They make a viable alternative.

[Kipper4]

If you want to add a flashing indicator led.
from the U2a pin 1 put a 3mm red led anode and from the cathode put a 10k to ground.
It will wink in time with the lfo. Wire it to come on with the effect.
If you need help with this hit me up.

[Kipper4]

reread last Ben I edited a mistake. Op amp name and pin.

[Ben Lyman]

Very cool Rich, thanks!
So a couple things:
For me the mix pot made the volume change way too much... not so for you?
Even a switch to pull the dry path out and go straight vibrato created a big volume boost that I wasn't crazy about.

If you have a chance can you make a vid showing the deepest effect of using that 2M2 and how crazy you can make it sound at a fast speed? and slow speed? Please? How low can that resistor go Mark? Is there a limit?

The goal here is to make it cover ground from so slow that you get bored waiting for it... to so fast a wavy weavy warbly that it sounds like a million rubber balls fired from a cannon inside a metal trash can... over and over again. When we have achieved this range of operation, it will be complete.

[Kipper4]

Will do. Check back in a bit.

https://youtu.be/Fn8d1HuILDo

[Ben Lyman]

I love it Rich, great job! thanks
I'm thinking a simple switch to go from vibe to Phaser, volume jump be damned!
And a simple switch to go from 3M3 to 2M2 for shallow/deep... hmmm maybe less than 2M2?

[Kipper4]

If you wanted to combat the volume jump you could use a dpdt and change the value of R10 at the same time as you change the 3M3 to 2M2.
Kill 2 birds with 1 switch.

By the way I'd breadboard the 3M3 to 2M2 before you pcb it. I only say it because when the Hammer pot is all the way to the ends it went dead. It'll probably be alright with set resistors.
Double check the values Mark suggested before.

For the vibe to phaser mod just take out the dry signal path from input to output (R16). Boom Vibe.

[Mark Hammer]

Given that 3M3 still gives a reasonably wide sweep, I'd opt for 2M7 to set my maximum sweep width, and add resistance from there.  On the other hand, it may be wiser to start out with a 1M8 in series with a 1M trimmer, set to max, and see where the sweep limit is.

[Ben Lyman]

...combat the volume jump... ...as you change the 3M3 to 2M2...

This is not when I get the volume jump

...take out the dry signal path from input to output (R16). Boom Vibe.

This is the problem with volume jump for me. Also, big jump, dip and swing when using a mix pot.
My mix pot was 25K... can 3k off the proper value make a difference?

Here's the way I see it so far, no mix pot is needed, no vibe/phase switch is needed. My bias pot gets nice and strong in the center, turning to either side changes the flavor and mellows it out almost to the point of inaudible to the far left, far right.
I know it is doing something completely different than vibrato or a depth control but I think it provides enough sonic flavors.

I most definitely am going to experiment further with Mark's depth control ideas, but I almost feel that to have a depth pot will require the ability to have straight vibrato.
It should sound like two jack rabbits on a 1958 Flying V with a Bigsby or it's not worth building 

Also, perf is laid out, soldered and working. I ordered a 125B yesterday and the post predicts delivery tomorrow!
I love this particular parts supplier that I have no affiliation with! 

[Mark Hammer]

Being able to adjust sweep width is VERY useful for vibrato.  Sometimes you want it boing-ey (wide sweep) and sometimes you want it quivering (narrower sweep).

[Ben Lyman]

Rich- You were right, I got lucky on the fets. After swapping some around I realized not only did the two match but they were the only two I had that matched, and they biased dead center of the trim pot! What are the odds of that? So, the 5458's didn't work out for me because of my 50k bias pot plus 2x 100k on each side. I plan on starting another vibe P45 vibe asap because this thing sounds great! I am going to pay more attention to matching gets this time and adjust the bias accordingly.

Mark- You are absolutely right, I need a sweep depth control and then I can probably throw on the vibrato toggle to make it boingy. I'm still not sure if I want the mix control, I want to keep it down to two knobs so the bias will go back to the trimmer as well... "Less knobs equals more music" 

So up next is a P45 vibe mod with sweep and rate knobs, possibly a vibe/vibrato switch.
In the meantime, I will try to post a vid of this one but I don't really see the point as Rich has already covered it plus so much more with that breadboard vid of his.

Ponder this for me if you will:
How can we make this... um... "V45" if you will, into a stereo contraption? What is stereo anyway? 

[Kipper4]

I just added a further 2 phase stages to mine. V90 and its much less musical.
maybe all the fets where not close enough matched.

Stereo to my way of thinking is the two output signal out of phase with each other.
So spilt the input signal after the input buffer to go to the two x2 V45s but invert the output signal of one of the outputs, Jfet or bjt buffer will do.
That's where i'd start anyway.
You may find it more intresting to invert the lfo signal to one of the V45s instead of inverting the output signal.
Duck showed us how to do this with vactrols in the Dub1 magna recently. Although the final project name might have changed.
I hope this makes sense, It made sense in my head when i was writing it.

Why do you want a stereo phaser?



Going back to the V45, I could make all the non matched fets work. 57's, 58's, 2sk30 work.
Didnt try the j201 or mpf103 or 2N3819's.

"So up next is a P45 vibe mod with sweep and rate knobs, possibly a vibe/vibrato switch. "

Do you mean a vibe/Phaser switch?

Go ahead mate put a video up. Show us with your great chops and the super fast rate too please.

[Ben Lyman]

Ok Rich, here ya go. I tried to show the speeds and all  the "voices" from the bias knob.
Yes, i meant vibrato/phaser but in the end it still has the JCM 10:1 phase caps, 10nF and 100nF instead of 2x 47nF, I don't know what that means but it sounds great 

I like your idea of stereo, it should create a very strong vibe. I think maybe the original Uni-Vibe had a dry signal output on the mix knob for a different kind of stereo effect but i'm not sure. It might be easier to do that but maybe not as lush sounding.

Why? I dunno, just something to do i guess... plus i have two amps 

[Kipper4]

I tried 7 different fets, a mix of 57's and 58's.
Combinations of the 57 and 58 together. 2x 57's together, 2x 58's together and all worked fine.
Definitly different sounds depending on the assortments. especially with moving the bias pot.
my fake j201s would hardly work. You could just hear something but not good.

I took voltages too.
input buffer and both phase stages all 5v1 (reflecting the zener I used)
lfo output 2v7-7v
the other two lfo pins wiggling around 4v5

fet volts
D 5v1
S 5v1
G 2v4-3v1 depending on bias pot setting.

[Kipper4]

I'd made a mistake with the biasing on the input buffer initially which is why the V90 version was so funked up.
Now I have it breaded right the V90 works good too. However its much better if i use all the same fets (my case 57's for this experiment).
It does however make less of the bias pot usable. Much less of the rotation works.
So less range of sounds there. but at least we know it will work.
And if one was to make it with a bias trimmer it wouldn't matter.

Edit.
Thanks for the demo Ben. Another good job done.
That enclosure is crying out for a swirly paint job.......

[Ben Lyman]

Ha! I can't do swirly paint jobs, I've seen the youtube tutorials... argh, forget that!
Most of my own pedals are boring, black, white, or no paint... I only paint them for my friends

[Kipper4]

Another idea, cause if your gonna drill a hole for a vibrato/phaser switch you might as well do a pot.
First change R9 to 10k or 12k. (upping the gain of U1b)
instead of putting a switch between phase and vibe
wire the U1b output to one side (lug 1) of a 20 or 25k mix pot.
Wire the phasers stages output to the opposite lug 3 mix pot.
Med sized cap from lug 2 to output (470nf maybe)

rotate completely one way; Dry signal.
rotate tother;                   Vibrato only
to 12oclock                       Phaser
Anywhere between those setting you get to mix in what you want, more dry, more vibrato.

When you breadboard it again. give it whirl mate I think you'll like it.

[Ben Lyman]

Thanks, I like that idea! I will try it and see if the volume stays constant for me

[duck_arse]

Most of my own pedals are boring, black, white, or no paint...

no, no, no, Ben, please don't say boring black and white .....

and on this stereo business, why don't you do that thing kipper did? no, not miscount the holes. and no, not that gnat mis-connection, the other thing, when he did the phase inverting mixer on his fibe-er thing. maybe if you jamb in a pair of opamp mixers, and have one normal and one kipper inverted, send nomal to out one, and inverted to out two.

and then we'll be calling you "five vibes Lyman".