Crazy Trem becomes Leslie ?

[phatt]

Ok Crazy stuff happening,, so I'm looking for clues?

I found an Old tremolo circuit,, revived it into a working pedal type unit.

Inserted into my Parallel efx loop and yay it worked/ sounded as expected.
i.e. Volume goes up and down at a rate set by the frequency knob. second knob is just a depth control.

Now I'm not big on pedals but I do have a couple, one being a very cheap Behringer Delay, (DD400).

So I decided to insert the DD400 *After* the Tremolo, thinking it may add something more to the straight tremolo effect.

To my amazement I got Rotary speaker sound.

The tremolo effect had all but disappeared the pulsing up/down throb was gone and the sound was now rotating.

For those that have experienced a REAL Leslie or at least a rotating speaker you can't miss the sound as it is distinct from other effects. (digital or analog)

YES I DO Have a Rotating Speaker,, so I DO know the sonic effect when compared to Phasing, Chorusing, Tremolo, and basic Vibrato efx.

My Problem is thus;
I remain close to clueless as to what I've done. Yet it works ?

Some observations;

If I connect these two units into a *series loop* (the more common approach) the effect is no longer present.
It reverts back to what I expected to happen which is Tremolo throb with Delay.

A friend has a lot of pedals and after hearing this quite stunning Effect He offered to pop over with his gear and do some more testing.

In His collection He has a Marshall Tremolo stomp and a Boss DD3 but as much as we tried we could Not recreate the same sound, even using my Amp which has the *parallel loop*.

My Tremolo into Boss DD3 = No go.
Marshall Tremolo into my DD400 = No go.

In the end we had the 2 delays both tremolo's engaged an old phaser and a Boss CS3 chorus.
Again = No go.
So if anyone can shed any light as to why this is happening I'd be very grateful.

I have a hunch that many things are happening all at once?

Sadly I can't find any Behringer Schematics for the DD400 but at least I do have the circuit for the tremolo.
One clue might be that the *Dry signal is flipped* at input and flipped again at output which means the *Dry Signal is in phase BUT I have no real idea if the XR2206 signal out is also inverting something which may alter the final outcome.

I'm going to try in the next few weeks to get some recordings up here but meantime here is the Schematic of the tremolo I refer too.

This was originally a kit to make your voice sound like Darth Vader or Darlek (sum and difference stuff if I remember correctly)
But by tweaking the values around the XR2066 chip you can create a decent Tremolo sound.

The *Soundbender* kit I refer to is ETI-492 (February 1982) DS kit K3509. The main IC, XR2206
sold in Australia way back.
I simply added a buffer in front for guitar use.

Cheers, Phil.

[Nocentelli]

Can't shed any light on your particular awesome discovery, but parallel connections can do weird things: My very ordinary DOD 280 optical compressor turns into a Boss Slow Gear if you put it in parallel with the straight guitar signal (I used the Boss LS-2 for the parallel loops). No idea why this would happen, either....

[pz]

So if anyone can shed any light as to why this is happening I'd be very grateful.

I have a hunch that many things are happening all at once?

Yep, a few things at the same time:
1. The tremolo circuit is more like ring modulator, or wave multiplier. At lower modulation speed it produces tremolo sound, but other things are happening:
lets assume that we have bipolar supply and the DC level is at 0V. What happens when you multiply the incoming signal by the first half if the sinusoid? The amplitude will follow the sin curve. What happens when we pass the 0 and the 2nd half if the sinusoid starts? The same, but with the phase flipped.
The result is a hypertriangular waveform tremolo sound with constantly flipping phase.
2. Add to that probably poor latency on the Behringer delay pedal.

So what you have here is amplitude and phase modulation blended with slightly delayed signal (latency).
I think this is the mechanism of your rotary speaker sound.

[phibes]

Can you make clips at all?

[phatt]

Hi PZ,

I think your observation would be very close to what is happening.
I've also realized that the Parallel loop in the Amp is actually flipping phase also and that maybe effecting the end result.

I had some time today and I've recorded a very poor quality clip so you chaps can hear what I mean.
Disregard distortion and popping,,, but good enough to give the idea of the effect. The loop in the old Laney KB30 Amp was originally a *Series Loop* but I've tweaked it to do Parallel loop but failed to note the phase issue.

LOL,, This mistake might turn out to be the best mistake I ever made.

Re the clip;
First is DRY>> Then Tremolo circuit engaged >>> Then adding DD400. Wow! (last Chord is back to all dry) No other efx used.

Give me time and I'll breadboard the whole FX loop circuit so that I can develop some understanding of what the hell is happening.
I have a hunch it might be smarter to implement the FX in the Amp into a dedicated unit along with the trem and DD400.

Side note;
I play keyboard as well as guitar so this is a BIG asset because REAL rotary speakers are not exactly a light weight addition.
Saves me carting more gear to gigs.

Damn shame I can't find a schematic for the DD400

**Forgot to mention that the Delay only has to be engaged for this to work.
Feedback, Time and Depth can all be at zero but still the rotary effect is still working.**
Phil.

[ik6gpy]

That's impressive

[phatt]

That's impressive

Yeah mate in 30 odd years of playing around with circuits I've only made about 3 or 4 worth mentioning,, LOL
This I believe is one such circuit.

Wish me luck ,,, let's hope that one day soon I can Ezplan,,Explain it
Phil.

[phatt]

Can't shed any light on your particular awesome discovery, but parallel connections can do weird things: My very ordinary DOD 280 optical compressor turns into a Boss Slow Gear if you put it in parallel with the straight guitar signal (I used the Boss LS-2 for the parallel loops). No idea why this would happen, either....

Agree,, There maybe many wacky efx Yet to be discovered by the home hobby tinkera who has no idea what He has made???

Problem for me is how do I explain how it works to the patient officer?
I could try to baffle them by saying it's made with *Reverse wound Unobtainium*

Oh and here is the Laney FX loop Modification I installed on the Laney Amp.
In Series it would not matter but when used as parallel setup the *WET signal* is inverted.
But then so is the DRY signal path???
Which suggests the Quirk is still likely to be found in the DD400 or the Tremolo or both.

Arrh,,,, Floppin Hang it all,,,, maybe I should just forget trying to Dunderstand some things and just enjoy it.

Hope it gives folks some ideas to work on.
Phil.

[mictester]

Can't shed any light on your particular awesome discovery, but parallel connections can do weird things: My very ordinary DOD 280 optical compressor turns into a Boss Slow Gear if you put it in parallel with the straight guitar signal (I used the Boss LS-2 for the parallel loops). No idea why this would happen, either....

There's probably a phase inversion of the guitar signal in one of the effects, so as the compressor gain decreases during each note, the cancellation probably increases, giving an expansion rather than a compression effect - this is going to be close to a "Slow Gear"!

[phatt]

Hi Chaps,
I know ,, old post but as it's related to the ongoing search for how this works I'm happy to say I found a neat circuit.
After some help from some clever chaps here and a bit more testing I've found a way to make the circuit work without the complexity of 2 pedals.

For those wanting all possible parameter control I've also implemented the phase section of the *PHozer* into the proto circuit and it works with a little more depth. (just swap the green box for the top half of the Phozer surrounding u2,, oh and hang 10k R's from points A /B to ground)

http://www.runoffgroove.com/phozer.html

More parts off course but does add a liitle more control. Might have to toss a coin?
As to actually building this ,,,well that will be a while yet as other more pressing things taking up my limited space.
Oh be warned running this from 9 VDC it will likely distort. 18VDC will get you there.

Sonic impression,,, sounds nothing like analog or digi chorus pedals.
Some old phaser circuits might come closer but not having a warehouse full of pedals I can't make a judgement on that.
A fellow guitar player has an ME 50 Boss pedal and it's rotary speaker emulation is a toy by comparison to My *PhAbb LessLee*

And having Now heard the LessLee working ,, He wants one built like yesterday.
Made a rod for my own back I thinkz.

I have no doubt that similar circuits where done long before I stumbled upon it but it is definitely cheaper to
build than some exotic Valve rigs from years past.

Hope it gives better minds something to tinker with.

Cheers,, Phil.

[BMS1971]

interesting