Question on an ADA Flanger Mod

[Paul Marossy]

I'm looking to give a vintage ADA flanger that Paul Gilbert "auto whammy" effect.  Gilbert told a friend of mine that his was done by ADA back  in the day and they basically made the enhance knob go to "11".  Does anyone know what you would have to mod to get this effect?

Any help appreciated!! 

[slacker]

Not sure if this is what you're after but there should be a trim or a resistor that sets the maximum amount of "enhancement". If you make this smaller then the pedal will self oscillate with the enhance control maxed out. I think the the Manual control or the Expression pedal will then control the pitch.

It's marked T2 on Moosapotamus's schematic http://moosapotamus.net/IDEAS/ADAflanger/ADAflangerSCH.gif

[Paul Marossy]

Cool, that might be worth a try. I don't actually have the flanger in hand yet... is the PCB marked, or I do I have to follow the schematic to find "T2"?

[Mark Hammer]

That would be the one.  It is a very common practice to fine tune the maximum amount of regen with a trimpot so that no panel-mount control setting will produce oscillation.  It is a simple matter to tune it to do what you want.  Just set the regen control to max, and either ease up or ease down the trimpot so that you juuuuuust break into oscillation at max regen.  Mudge it a wee bit more to get dependable oscillation, and there you are.  Happily, you can simply dial back the regen to avoid unpleasant or undesired oscillation.

Unfortunately, there are several 20k trimpots on the board, so simply looking for "the" 20k trimpot isn't going to work.  Fortunately, you need only follow the input lug of the regen pot back to the board.

[Paul Marossy]

Cool, thanks Mark! You guyz are the best. 

[StephenGiles]

But couldn't you do this with an envelope follower, then sample and hold the voltage when it reaches a level providing the frequency at which you want the whammy to stop. Then you might want to gate the delayed signal so that you don't hear it sweep up again. Do I hear "window detector"? See Aphex patent ??

Of course you might want to, but it would certainly be a useful building block. These sort of questions always take me back to the question I asked concerning my modified Microsynth envelope generator, which is somewhere on this site. But this promises to be an interesting discussion point.

[Paul Marossy]

One more question: Can you make any flanger behave like that, or is it the ADA flanger specifically that you can do this with?

[mdh]

If I understand what you mean, you can make John Hollis' Ultra Flanger do this as well.  You just mess around with the regen (IIRC there's a fixed resistor in series with the regen pot... reducing it increases the maximum regen).  I seem to recall that the "manual" control on the Ultra Flanger is also pretty interactive with regen when it comes to producing oscillation and pitch bending.

[Paul Marossy]

So, you could do the same thing on say a DOD flanger? I'm looking to get that sound towards the end of the tune called "King Of The Monsters" by Racer X, at around 4:25 into it. You can hear it here: http://improvisingguitarists.ning.com (#19 on the playlist)

[mdh]

I don't know for sure, but what I would do is look at the schematic, and see if there's a fixed resistor in series with the regen pot.  If so, try making it smaller.  This still assumes that I know what you mean by "auto-whammy" effect... sort of a whooping oscillation at the extreme end of the sweep?

[Paul Marossy]

I don't know for sure, but what I would do is look at the schematic, and see if there's a fixed resistor in series with the regen pot.  If so, try making it smaller.

I was just looking at the schematic for the DOD flanger, and there is a resistor in series with the regen pot. I was also thinking that changing the size of that resistor would be the place to start.

This still assumes that I know what you mean by "auto-whammy" effect... sort of a whooping oscillation at the extreme end of the sweep

You need to listen to the tune I linked above, I have no idea how to describe it. It almost sounds like a spaceship...

[mdh]

You need to listen to the tune I linked above, I have no idea how to describe it. It almost sounds like a spaceship...

Hmm... if you're talking about the descending, screaming sound that happens at 4:25, I'm not sure how you'd get that with a modded flanger.  Maybe with an expression pedal controlling the delay, as Ian suggested way up near the top of the thread.  If you're talking about the little "whoop whoop whoop" thing closer to the end (say, from 4:37 on) that's more in the ballpark of what I think you'd get by upping the regen.  To my (admittedly very uneducated) ears, the descending sound at 4:25 almost sounds like pick slide, which can sound kind of like the descending sweep of a nice slow flanger.

[Mark Hammer]

You will note that the A/DA Flanger, along with the Boss CE-1 and other BBD-based pedals of that era, incorporates a FET-based gate for noise-reduction purposes that is controlled by an envelope follower.  In the Moosapotamus schematic, this is IC3.  In traditional analog synths, that type of circuit is perfect for generating a trigger pulse (well, actually, perfect for feeding to a comparator which THEN ionitiates a trigger/gate pulse), that can then be used to initiate "events". 

What kind of events?  Well, howzabout an envelope generator that feeds a control voltage into the "manual" input jack of the A/DA?  So, the instant you play (well, several milliseconds after the instant you play, but roughly instantly), an enevelope generator forces the clock of the flanger to swing wildly in a specific and predictable pattern, resulting in a specific detune or pitch sweep.  Stick some serious regen in that mixture and you should have a specific kind of oscillation every time you pick.

Since the relationship between rectifiers and trigger/gate generators usually involves a comparator of some sort that initiates a trigger/gate only if the rectified signal exceeds some threshold value, you can essentially turn the instant detune off by simply adjusting the threshold control.  The way thatthe gate works in the A/DA is that the dry signal always reaches the mixer stage, but the wet signal is shunted to ground unless the input amplitude is greater than some predetermined range.  In this manner, any clock bleedthrough or BBD-related hiss/noise only reaches the mixer stage when there is enough signal to mask it.  Note that since the gating FET works in a largely graded fashion for noise-reduction purposes, while the pulse generator add-on section works in an all-or-none manner, you will be able to (in theory, anyways) continue playing with a flanging tone, even if you don't get the instant detune.  Then, when you want it, smack the strings hard enough to generate a trigger/gate and whatever the CV input sees will do what it does..

Make sense?

That's one more reason why I love voltage-controlled devices.

[Paul Marossy]

Hmm... if you're talking about the descending, screaming sound that happens at 4:25, I'm not sure how you'd get that with a modded flanger.

Well, all I know is that Paul Gilbert told a MySpace friend of mine that his ADA flanger was modded by the people at ADA to do that. This guy is a guitarist for a hot pop singer, and he wants to get this same sound. He has asked me to do this for him. Maybe I need to ask him a few more questions about this.

If you're talking about the little "whoop whoop whoop" thing closer to the end (say, from 4:37 on) that's more in the ballpark of what I think you'd get by upping the regen.  To my (admittedly very uneducated) ears, the descending sound at 4:25 almost sounds like pick slide, which can sound kind of like the descending sweep of a nice slow flanger.

Maybe that sound is a pick slide and an upped regen? It's not just a pick slide on its own, though.

Well, howzabout an envelope generator that feeds a control voltage into the "manual" input jack of the A/DA?  So, the instant you play (well, several milliseconds after the instant you play, but roughly instantly), an enevelope generator forces the clock of the flanger to swing wildly in a specific and predictable pattern, resulting in a specific detune or pitch sweep.  Stick some serious regen in that mixture and you should have a specific kind of oscillation every time you pick.

I wonder if that is what ADA did to Paul Gilbert's flanger? That's what it sounds like it is doing to my ears - like a specific detune type of sound...

[Rodgre]

That sounds like Flanger oscillation before a distorted amp to me. It specifically sounds like the range of the delay time is getting really long, which the A/DA can do. The end of the song has a similar sound, but not in oscillation, and a faster sweep. I've gotten a similar sound to the ending sound years ago with an A/DA flanger through a dirty amp, with a bass feeding back.

Roger

[Paul Marossy]

I got the pedal just now, so I will begin working on it the first chance I get. This one appears to be one of the originals.

While I have it apart, I'm going to take pics of the circuitboard and all that. Maybe I'll make my own sometime with the PCB I can make from this example. Hopefully I can make good on my promise to make it do that Paul Gilbert thing. This could be good publicity for me if this goes well since this guitar player is probably well known by the young whipper snappers... I know most everyone would probably know who the singer he works with is, and she happens in the top 12 money making female acts at the moment...

Anyhow, I'll keep y'all posted on my progress. 

[Paul Marossy]

Just a follow up to confirm what some members have said earlier in this post: messing with T2 does get you that strange detuned spaceship sound. Thanks for the help on this! 

[rowla]

One more question: Can you make any flanger behave like that, or is it the ADA flanger specifically that you can do this with?

Sorry to dig up an old post but I'm about to finish my Moosapotamus flanger and was really pleased to see the confirmation about T2. 

In answer to the above quote I did get halfway towards the PG effect by tweaking the regen trimmer in an old Ibanez (Maxon mfd) FL9. I reckon it's going to be amazing in the 18V ADA circuit

[slacker]

I reckon it's going to be amazing in the 18V ADA circuit

It is 

On mine you can get a really cool effect by setting enhance and threshold pots so it only oscillates if you play hard otherwise you just get normal flanging.

[jstone]

I met Paul last November and he said that the mod he had done to his ADA just allowed the full sweep cycle of the flange to be heard when the enhance knob is maxed.  He said that without the mod, you would hear half the cycle and then it would start again from the beginning.  The mod allows the cycle to complete all the way around. 

BTW, his new Ibanez signature flanger is supposed to do this right out of the box.