Magnavibe vibrato/tremolo blend mod for rotary speaker effect

[Ben Lyman]

Thanks Jon! Very good schoolin'! I've learned enough for today, anymore and my brain will melt.

Okay Rich, I have to try it now for sure. Hopefully later tonight

[Marcos - Munky]

Lots of learning too! I'm not a BB guy, so I can't try your ideas. But I'm keeping an eye - maybe both eyes - in this thread, I'm really interested in the results.

[duck_arse]

see? now Jon's told you, youse all got's to do it!

today we have the dual-rate version, using 1uF and 470nF caps. it comes in two versions, the faster and the slower, depends on how you wire which caps on the switch. you can use a 3pdt to select one range pot or the other, so you can use different tapers for each pot - something I'm NOT going to go into.

http://i.imgur.com/kK7fO2j.png
if you are no fun:
http://i.imgur.com/Gjo7Fuf.png

if yer toppest speeed still ain't top enough, I tested R4 down to 1k5 and it still didn't go cronk, but yr pot 'feel' will be screwy. a funny thing about the speed pot while testing - if that leg was left open, while fiddling with stop values, the oscillator went to a maximal slow freq, and just kept running. so, diminishing returns with increasing pot values.

and as for the tremolo/rotate pot. if you want the choppy trem, easiest is to just open the connection between the collector and phase-cap. the pot is now non-functional, the trem only runs at one depth. so, you could use a switch pot, when switched off you get the chopp-trem - but the pot will need to be wired backwards, otherwise you'll go from the chopptrem straight to no trem, then more trem w/ clockwise turn.

ah-hah I hear you exclaim! there is another way - you can take the pot apart and cut the conductive track close to the CW lug. then short the centre and CW lugs, and when you rotate the pot full CW, the wiper loses contact, the phase-cap goes out of circuit - full chop comedy trem! 24mm pot would be "best" to try, I'd suggest.

@ben - faster or slower?
@kipper - wombat sniffer?

[Ben Lyman]

I like it Duck. Top speed is great. Is there anyway to keep that top speed and make it go a little slower?
Sorry to be so demanding! It's actually a perfectly acceptable slow speed, I just thought it might be cool to go even slower if possible.

Kipper, I tried 1M5 too, but Duck's 2M2 helps it work better.

And Duck, I'm still trying to catch up so I'm a bit behind, still working on yesterday's, or was it two day's ago? anyway, if I use mono-ceramic caps in the POS, can I do it like this with the 47K to ground?
Also, how about adding a booster transistor w/volume pot instead of buffer? Pictured here is the LPB-1 like I did last time. Any suggestions to improve and/or simplify it? I'm all about simplify... less parts, etc.

[duck_arse]

the circuit in reply 102 is the one for if you have only 470nF and 1uF mono ceramics, want to pull them to ground, want a high and low range, with a pot each - and now you want to use 47k? I won't be responsible for the repercussions, let me tell you.

that top speed and slower - is this with the rev X.Z values, or the Y.Z values? (it might be possible to get a lowwerrr slow, but at the cost of a gap in the range betweeen the hi and low pots.)

the caps need to go to a low-impedance point, they don't care if it is V+ or GND or somewhere in between. electo's are meant to be more positive at one end, so it is easy enuff to pull them up to supply + end, and down to gnd the - end.

I think your Q3 might be making too much gain, I reset mine for fairly low gain. if you can find a spot on the volume pot that seems unity right across the trem/rotate pot range, replace it with 2 resistors, to simplify. does the trem pot affect the out volume?

and when you've got this all sorted, we can get onto the double phase version! you beaut!

[Ben Lyman]

Oh sorry, I should have specified just how far behind I am. I'm still on this one:
http://imgur.com/6tGyf1a 

I really like it too. I have all these values but I'm using 1uF monolithic ceramics and put that 47k to the ground.
Is there a reason to use electros with this? I have a few tantalum 1uF and some ancient radial electro 1uF also.

I will try to catch up to post 102 soon and see how it works for me.
btw, I think my 2n5088's run about 500 HFE so that could be an issue too.

Yes, trem pot affects volume but I might be able to find a compromise, I like that idea of eliminating the volume knob. The trade off would probably just be that when turned all the way towards "vibrato only" the volume would be a little above unity, which is probably okay.

umm... rev X.Z values? Y.Z values? sorry, I don't understand 

[Kipper4]

I'm using that PSO too Ben.
I really like it too. Using a 50k depth pot / 10k though.
And I'm using a super bright clear 5mm led for vactrol and to skew the sine wave a bit I have a red 3mm in series.
I also have a stash of 1uf taunts that have been begging for a use for ages thanks for the idea.
Not sure what my hfe is on the PSO tranny 2n5088......
A few changes to my concertina splitter though I'm still using a B10k trem pot. I found your 100k pot a bit hard to set, somehow it had a very narrow band for a pseudo rotary effect. Just my ears prolly.
If you find the trem side a bit choppy turn the depth pot down a bit.
You may find a little less discrepancy in the volume levels from with a 10k trem pot from trem to vibe.

[Ben Lyman]

Cool beans Rich. I gotta try some different color LEDs, that's a good idea now that I am running them series instead of parallel like before.
Ya, the 100k trem pot is hard to blend the two effects perfectly but I also like the choppy trem capability. Maybe I'll try a 50K pot and see if I can still achieve the same choppiness at the far end of the knob, and then a 20K pot, and then decide.
Right now, if carefully dialed in just right, I can get a lot of sounds from vibrato to feaux-rotary (Fotary?) and thick tremolo.

[Kipper4]

Let us know what you settle on mate.

[Ben Lyman]

It's great Duck, I think this is the best yet. I can't decide which one to go for, the previous version works great to and has less parts but maybe if I can fit this one into my existing double waggled box. I don't know yet

[duck_arse]

the last one posted, Y.Z, is specifically for your cap values/types, and your need for speed, both ends, and your liking for seperate rate pots. it has an alternate wiring for a faster top speed, too. it runs faster and slower than the one with electros, X.Z.

[Ben Lyman]

Ok, got it. I have tried both and I like both a lot. The last one, Y.Z is on the BB now and works great, two speeds and everything. I think I might have to go back and try X.Z again because it is simpler, easier for me to understand. I might make a single speed "normal" pedal or try to wire it up in my current double waggler box with two speed pots but both pots being equal just to keep it simple. I have to admit, I have a very hard time understanding how to wire the switches in this kind of situation and looking at switching symbols in the schematic isn't any easier for me. Also, I like the pot values better because I don't even have 250k pots, I'm testing with B500k w/510k resistor parallel and would rather not do that in the pedal

[Ben Lyman]

I'm back (after some very important fish-catching) and keeping it simple this time, no double speeds. Here is the current breadboard schematic. I want to build it with 4 knobs, well... I don't want to but I have to. The trem knob is working great for me but it means I need a booster and volume knob. Also, Duck's 4-stage POS is working so nicely that it really needs the depth control to appreciate how great it is.

I'm way behind the times and I want to get on to the double-phaser gadget but I need to build this one first, working on a layout that has 4 pots in a row mounted right on the board the same way I did Gus' "Silicon Supa Fuzz Like" with 2 pots. I hope it works out, I like the way the pots and LED bezel hold the board suspended in place.

Duck, you said you think my LPB-1 booster stage (Q3) might be too high-gain or something, and I agree it definitely doesn't need to be so loud. How would you go about adjusting it so it can have just a slight volume boost? Right now I just have that 100k in series (R19) to tame it some.

[Kipper4]

Try 330k R21 and 3k3 R23 ditch the 100k R19
And go from there.?

[duck_arse]

well, as kppr points out, your R19 100k will be voltage dividering with the Zin of the boost (about 100k), so half signal reaches the bboosstt. also AKPO, reduce that stages gain with the resistor ratio, and then see if it needs volume pot or just 2 resistors as fixed vol cont.

did you hear about the fisherman with one arm? he caught a fish this big (holds up one hand).

[Kipper4]

If you are a big big tree, we are a small fish.

You can't catch a Kipper. He has to be smoked, just not the magic blue smoke.

[Ben Lyman]

Thanks guys, that works. I'm working on some different cap values now, I went back to the original 220nF input and output caps last night. It's getting there slowly but surely.

Duck, I did hear about that fisherman... wasn't he the guy that invented cave drawings? 

One time in Alaska we brought a girl on board for a 10 day fishing trip... She came back with a red snapper   

[duck_arse]

REV24.21, corrected and updated to replace those in reply 81:
http://i.imgur.com/dPp4VDr.png
and B/W
http://i.imgur.com/JrXvw4v.png

still waiting for kipper's names (when he stops gibbering about the trees).

[duck_arse]

what's the easiest way to catch a kipper?

[Kipper4]

Get him out of the smoke house.
I'm in........