Stand-alone true pitch shifting vibrato for guitar

[tubeswell]

TFT Steve. I'll go back to the LFO /CF driving the SR (like in the earlier variants).

Re: the CF bypass, what are your thoughts on that? Waste of space?, or maybe instead have it driving the output of the whole effect?

Pete

[sluckey]

Re: the CF bypass, what are your thoughts on that? Waste of space?, or maybe instead have it driving the output of the whole effect?

I guess that's OK. I like (better) the idea of mixing the wet and dry at the grid of the CF then using the CF to drive the output jack. I don't have a clue what it may sound like, but if you plan for the extra circuit, you can try it either way.

[tubeswell]

I like (better) the idea of mixing the wet and dry at the grid of the CF then using the CF to drive the output jack.

Something like this?

[sluckey]

Yes, something like that. You may need another mix resistor in series with the input. Notice that you have a big feedback loop from output straight back to input? Dont know how that may affect the operation.

Why do you want a CF? Will you be using long patch cords and/or an A/B switch between the warbler and amp? The circuit is capable of driving a high z input such as a tube guitar amp input.

[tubeswell]

Re: the mix resistor, I was thinking that the 'recovery' stage's signal was sufficiently strong that just turning up the level pot with one mix resistor would be enough to overcome the guitar p'up level signal in going straight into the CF grid. Also I was thinking there would be no reduction of the dry guitar signal (whereas if I'd used a pair of (say) 270k mixing resistors, that forms a 50% voltage divider for the dry signal. The other way is a 250k pot for a mixer control, but the recovery stage's signal may be too strong for that to work well. (or would 1M be sufficient?) (The reason I was thinking a recovery stage may be good on this version with all the pots, is the otherwise-high AC load at the output).

Re; the CF stage, Sometimes I use a 3 metre cable going out to the amp, and there can be a lot of interference in some gig situations. My standalone reverb unit puts out a really nice dry signal in this regard.

[plexi50]

Im glad you all are still working the different ideas and changes. Long live this thread! Occupy Hoffman

[billcreller]

After reading this whole thread, I have to make an effort not to try building something like this !  The brain is getting too old.......

[tubeswell]

Got just about all teh parts I need and am making progress on layout design and chassis build. But yesterday whilst staring at the latest schematic, I spotted what I think will be a fatal flaw with the way the 'effected' signal is 'mixed' back with the dry signal, in that having the level pot wiper going more or less straight to the grid of the input stage creates a feedback loop. I might rethink the mixing of it a bit more - shouldn't be a biggie tho'. Either a straight mixing pot at the output, or a common anode mixer arrangement of some sort...

Looking forward to the sounds of getting it going

[tubeswell]

Okay, after staring at the previous schematics a bit longer I was wondering about a more direct copy of the 'Liquidator" but with a CF bypass - so that is variant #7 (which uses a dual ganged pot to blend the effected and dry signals without any other feedback going on. The effected signal is recovered by a gain stage because all the 'mixing' knobs would tend to be lossier than Steve's version, so I'm thinking that this would probably be necessary if I pursued this option). I had a spare triode, so it got a paralleled input stage, but you could have more fun with that too I guess.

 It could be simpler - but I'm quite keen to hear what the 'liquidator' sounds like.

[Jhtjon]

CLEAR!!!!!!!



I feel a pulse.

Sorry to revive an old thread but I am about to start building the stand alone vibrato and I have a few questions.

• I know that some have eliminated the fast slow switch from the amp, do must of you prefer it in the fast or the slow position.
• How much plate voltage and current do you really need I know that the original effect was built using a 500VCT transformer at 69mA, but could you use more or less voltage and what is the bare minimum current capacity. Using Ohm's law I calculated that the effect is drawing about 16.5mA of current assuming V4A is less than 1mA.
• Would it be possible to add a LED off terminal #7 on the SR to pulse with the beat of the LFO?
• The last thing I was thinking about changing was to eliminate the foot switch and add true bypass foot switching of the entire device. Do you think I will get residual pulsing in my circuit. I have seen a few pedals that even though they are bypassed they still have residual noise.

Thanks again.

[Jhtjon]

Finished the unit last night and I am really happy. I am going to add a two (2) button foot switch to switch between fast and slow and add true bypass. I did change the Slow By-pass cap to a .022 and I am happier with that value. I'll post pics shortly.

[Willabe]

I'll post pics shortly.

         


                    Brad     

[plexi50]

Looking forward to the pics. I have another tranny so i may build another unit using whatever upgrades you have come up with

[Jhtjon]

I've got two more. One is going into a rack mount.

[terminalgs]

Finished the unit last night and I am really happy. I am going to add a two (2) button foot switch to switch between fast and slow and add true bypass.

I've found that true by-pass switches don't work well  with tube pedals (too hard to eliminate popping when switching).   The easiest thing to do is to let the input always go to the 1st tube (this won't  weigh down the signal) and switch output between the effect and the source.  When you have the switch bypassing the effect, use another switch  section of the DPDT (or 3PDT) to send the effect signal to ground  through a resistor,  so no DC builds up between your CF coupling cap and the switch.   

[Jhtjon]

Crappy Cell Phone Pics





I seem to get significant signal loss with the mix control in the middle position. Is this normal?

[alerich]

Oops - I was replying to a months old post. Doh!

[plexi50]

That looks very well done! How did you make your faceplate and what did you use?

[Jhtjon]

I drew the design in Corel Draw and sent the file to BNP lasers. The material is 1/16 reverse engraved black plastic with white fill. it costs about $18-20 per panel.

[tubeswell]

I've got another SR unit that Brad sent my way. I'm going to put that one in an amp with vibrato

[plexi50]

I drew the design in Corel Draw and sent the file to BNP lasers. The material is 1/16 reverse engraved black plastic with white fill. it costs about $18-20 per panel.

Thanks Jhtjon.

[Willabe]

I seem to get significant signal loss with the mix control in the middle position. Is this normal?

I think the guys might have missed this question? 



                           Brad     

[Willabe]

I drew the design in Corel Draw and sent the file to BNP lasers. The material is 1/16 reverse engraved black plastic with white fill. it costs about $18-20 per panel.

Very nice looking, inside and out!     

I'm going to put that one in an amp with vibrato.

Interesting.     


                           Brad     

[tubeswell]

I seem to get significant signal loss with the mix control in the middle position. Is this normal?

I think the guys might have missed this question? 



                           Brad     

Which schematic?

[sluckey]

I seem to get significant signal loss with the mix control in the middle position. Is this normal?

I lose volume too. Almost sounds like some phase cancellation going on when mixing wet and dry. Does it even with the depth control on zero. But it does give some different sounds when the vibrato is on. I still prefer the mix to be all wet though.

Very nice work BTW. Wish I could make my stuff look that good.

Tubeswell, it looks like revision 1 since there is a mix control, only one filter cap on the board, and only half of V3 is being used.

[Willabe]

Which schematic?

There you go Thtjon, show us please so they can work it out with you.


         Brad      

[tubeswell]

I seem to get significant signal loss with the mix control in the middle position. Is this normal?

I lose volume too. Almost sounds like some phase cancellation going on when mixing wet and dry. Does it even with the depth control on zero. But it does give some different sounds when the vibrato is on. I still prefer the mix to be all wet though.

Very nice work BTW. Wish I could make my stuff look that good.

Tubeswell, it looks like revision 1 since there is a mix control, only one filter cap on the board, and only half of V3 is being used.

Isn't the vol drop just because there is only 1 gain stage on the 'dry' side of the mix control? (Or are you talking about the vol dropping on the 'wet' side?)

[sluckey]

There is plenty of volume at each extreme of the pot and the full wet volume is pretty well matched to the full dry volume. But when the mix pot is somewhere in the middle the combined signal volume is somewhat lower than either extreme. The lower volume is not useless. There are still some good sounds, although I prefer the full wet sound. I may put a scope on it today to see better what's happening.
 

[tubeswell]

Then it probably is NFB as you say.

[plexi50]

I have the same problem with the mix pot some where in the middle. It looses the mix and seems to be cancelling out the signal

[bobmegantz]

I've been using a Warbler for some time, and, in addition to the favorable comments made about the effect, I'd like to add:

1. It sounds great with the LFO off - really fattens up the sound, so I leave it hooked up even when the chorus is off.
2. The LFO's slowest speed is a little too fast for my taste, so I upped the cap values to slow it down a little.

Bob

[tubeswell]

My warbler (I posted this on another thread some time ago but can't remember what its called)

[plexi50]

tubeswell your pics look so good i just want to touch and pull that warbler right out of my computer screen. Great workmanship/

[HotBluePlates]

My warbler ...

I recognize Hoffman's old chassis in that pic! The one with the solid aluminum endblocks...

[tubeswell]

The end-blocks on my warbler aren't solid aluminium, they're steel sheetmetal (and everything is welded on - even the flanges). I wire-brushed the outside and then clear-coated it with plastic urethane straight away.

[DummyLoad]

nice work TW. bravo! how does it sound?

--DL

[tubeswell]

http://www.nzguitars.com/forum/download/file.php?id=9003

http://www.nzguitars.com/forum/download/file.php?id=9002

Or, for a more subtle vibe:

http://music-electronics-forum.com/attachments/17060d1327830636-fbi-jm-viberater-.mp3

http://music-electronics-forum.com/attachments/17061d1327830879-flingle-bunt-2-jm-viberater-.mp3

http://music-electronics-forum.com/attachments/17062d1327830918-man-mystery-jm-viberater-.mp3

[HotBluePlates]

The end-blocks on my warbler aren't solid aluminium, they're steel sheetmetal (and everything is welded on - even the flanges).

I see. Doug used to have a few chassis that looked exactly the same, but were aluminum with aluminum endblocks thick enough to tap for screws.

[moondog2u]

nice

[Jhtjon]

I seem to get significant signal loss with the mix control in the middle position. Is this normal?

I lose volume too. Almost sounds like some phase cancellation going on when mixing wet and dry. Does it even with the depth control on zero. But it does give some different sounds when the vibrato is on. I still prefer the mix to be all wet though.

Very nice work BTW. Wish I could make my stuff look that good.

Tubeswell, it looks like revision 1 since there is a mix control, only one filter cap on the board, and only half of V3 is being used.

Sorry I've been away. Yes it is rev.1

I was wondering if there is also a way to make the depth control a little more responsive. mine doesn't do much below 1/3 on the dial

[moonbird]

Tubeswell -

Really like the tone you are getting in the last 3 MP3s (fully mixed ones). What are you using for the reverb and amplification? thx.

[tubeswell]

A PR clone (with a Weber 12A125A) IIRC

[moonbird]

Tubeswell - You should send one of these MP3s to Weber to post on their 12A125A page! Great tone, playing, and recording IMHO. Thanks kindly for the info!

[Willabe]

Hey Pete, I really like those songs!

I can't get the 1'st 2 open but the last 3 were great!

Your playing through that rig is top shelf, IMO.


                  Brad       

[Willabe]

Tubeswell I was thinking about the sounds you are getting from the Warbler on those clips.

Are you using all 3 phase shift sections? You have pots on each section to dial in/dial out the stages output, IIRC.

It sounds more like the pitch shift vibrato Fender used in the brown face amps. I didn't realize the Warbler could do that sound. Sluckeys sound clip does a real nice Leslie type sound.

I guess I'm asking how did you have all the controlls set?


                          Brad     

[tubeswell]

I haven't started taking notes of where the controls are set yet ;-)

I'm still just fiddling with the knobs until I hear something different to what it was before. There's quite a range of sounds.

[shoggoth]

I just bought 2 AO-41's and 2 AO-47's ($75 + $20 shipping on ebay, w/o tubes), so I should have more than enough saturable reactors now.  I might try six stages to see how that impacts things.  The project will have to wait until spring though.

In the meantime, I was wondering if these might be work as off-the-shelf replacements for the reactors:

http://www.mouser.com/ProductDetail/Xicon/42TL013-RC/?qs=sGAEpiMZZMv0IfuNuy2LUU84BnGSKFUnNRUMZXD4nDg%3d

That's a 11:1 winding ratio, and center-tapped so you can feed the oscillator signal into both ends of the winding and ground the center tap. They won't saturate as easily being audio transformers, but maybe increasing the oscillator signal voltage would help?

Something for me to try next spring...

[Willabe]

Very nice, glad you got a hold of them. Nice price too by saving on the shipping, 4 at < $25 each.    

Be carefull with them as the wire fly leads from the coils are pretty small and can break fairly easely.

As far as the transformer you mention, I don't think that will work. IIRC, an SR is a different animal. It's core material is different and is used/picked by choice and meant to saturate. I don't think that by just overloading 1 side of an OT that it will act/function the same as an SR.


                    Brad      

[HotBluePlates]

In a nutshell, the way the whole circuit works (and any vibrato working with a similar principle, like the Magnatone circuit) is to have a variable impedance cause a varying phase-shift, which is controlled by the circuit's oscillator.

In the Magnatone, varistors are paired with capacitors, with the varistor being a voltage-controlled variable impedance. In the Hammond circuit, the saturable reactors are a current-controlled variable impedance, and work against other cirucit impedances to create a varying phase-shift.

So you can't sub normal transformers or chokes for the saturable reactors, because they really are designed and built differently, to accomplish a different task than typical transformers. If you want to side-step using them, you really ought to look at some other control element for your variable impedance (the old varistors are expensive, new varistors may not work the same way, but vactrol optoisolators are used successfully in tremolo and Univibe-like products).

[Jhtjon]

Is there a modification to drastically slow the oscillator down. I find I can never quite get it slow enough.