ARP ‘Wow’ modulation effect

[Mididude]

I remember reading a while back (probably via Keyboard Magazine) that Billy Preston played an ARP synth on ‘Space Race’.  That got me thinking, there’s another song called ‘Struttin’ on ‘Billy Preston - The Best’ (CD that I think is out of print) that has him playing an ARP.  His lead synth has a cool tone that sounds to me like a large amount of lfo, assigned to filter with a pretty high rate, …and also either the same lfo simultaneously assigned to pitch or, (alternate theory) maybe another lfo assigned to pitch at a little lower rate.  Any ARP players out there who know if I’m correct in remembering there was a button called ‘Wow’ on some of the old ARP’s that did these kind of routings for you when engaged?  I think I played around on my Moog Little Phatty once before trying to do something similar, but didn’t nail the tone.  Maybe I’d need some additional c.v. (an extra lfo) brought into the instrument, since IIRC (the Little Phatty is in its soft case right now) the L.P. is designed stock, with simple mod. routing; I don’t remember the modulation section allowing routing of its one lfo to two destinations, namely filter & pitch in this case, at the same time.  I am not looking at the synth now though, so I apologize if I might have forgotten if it actually is simple to program the sound on the L.P.  Thanks.

[The Real MC]

Billy was known to have played the ARP ProSoloist which had a "WOW" option in the modulation section.

[Mididude]

Thanks, The Real MC!

[Tusker]

Is it this? 
 

 

 

i wonder if it’s an Odyssey.

[Baldwin Funster]

I think Billy Preston pushed alot of peoples WOW buttons.

[Tusker]

Struttin with a white Odyssey…

 

 

[Spider76]

2 hours ago, Tusker said:

Struttin with a white Odyssey…

 

That show is not live: the "wow" effect comes and goes but he only uses one hand, without touching the sliders. And the Odyssey doesn't have aftertouch so it's impossible he's modulating parameters with pressure. And then he changes to a different sound without changing any parameter. So it could be an Odyssey or any other synth in the recording, really.

That said, the Odyssey is definitely able to generate that effect: sounds like a simple high-speed LFO modulating the filter at medium-high resonance.

[AWkeys]

The video is mimed - the Odyssey isn't even plugged into anything!  He played a Pro-Soloist on the song - it's a typical Pro-Soloist "Wow" effect done with the aftertouch.

[JB Sherry]

I was just typing something similar!  Check out around 1:23 where Preston finishes a solo using that wow/growl sound, then comps 2-handed on the Clav, then starts playing a square-wave lead without touching any settings on the synth. You can also clearly hear acoustic piano in that rhythm break.

 

It definitely sounds pro-soloist to me. It is interesting that the filter warble sounds much faster than the vibrato (on Space-Race), but the instrument is supposed to have 1 LFO. I think it’s possible that the presets had some extra circuitry. For example, the fuzz guitar patch  is said by pro-soloist obsessives to use a 6 bandpass filter., which you dom’t find on any Arps. I lived with an Odyssey throughout high school, and its high-pass filter was limited by having no mod or controller routings. If an envelope could have been routed to it it would have been possible to create useful band-pass effects. Anyway, I’m thinking that maybe they used an octave divider  to get the filter modulation double the speed of the pitch vibrato using a single LFO.

 

i’m thinking this is also pro-soloist:

Deodato - Skyscrapers

 

This sounds like Deodato is working the filter cut-off (brilliance) after-touch and Transpose controls, and turning the growl on and off. The growl is used as an effect on low notes throughout. I really like how he milks the different qualities the patch has in different registers.

 

According to the pro-soloist service manual there are 14 fixed filters in addition to a VCF (reminds me of Polymoog). According to the same manual there is a separate circuit that generates a flip-flop signal at 32hz which is routed to the filter for the Growl. If you want to emulate the growl and a separate slower vibrato, you’ll need to LFOs.

 

[Tusker]

Thanks Spider, AW and JB for setting me straight on the pro soloist. This is an amazing community and I can always learn something. 👍

 

Here is a cool little video showing the wow, growl and other effects on the pro soloist. It looks to me like the "high rate lfo" the OP is referring to is called growl. (33 seconds in)...

 

 

 

 

 

 

 

[Mididude]

I had the Little Phatty fired up the other day, so I thought I'd have a go at that patch again.  Please excuse A. the poor (grainy etc.) image quality (made the video with wife's 2006 MacBook) so it looks like an ancient webcam, and B. the sloppy playing.  I wanted to just see if I could get good audio quality going into the computer from my old Tascam Firewire interface, and it worked.  I'll have to upload something more rehearsed next time.  Here's the link: 

. 

[Cynth6]

I know the point of Pro Solist was to have a very controlled circuit with presets to market to musicians (organ players at the time). I know technically this is a DCO, possibly the first, but I hear there is a 1 volt input to VCF as it was a 4034/35 in this model, is it possible or even recommended to add CV in on this one?

 

 

Cheers,

Justin

[The Real MC]

5 hours ago, Cynth6 said:

I know the point of Pro Solist was to have a very controlled circuit with presets to market to musicians (organ players at the time). I know technically this is a DCO, possibly the first

 

According to the US patent 3,930,429 it is actually a VCO.  The ProSoloist VCO incorporates the classic ARP charged cap core VCO with the ARP exponential converter feeding a unijunction based oscillator; it also has glide based on slewing the CV with the RC constant of a variable resistor and capacitor and aftertouch can modulate the pitch, thus the VCO pitch is continuously variable.

You're hardly the first to confuse it with a DCO, as many people see the DAC and automatically class it a DCO synth.  The DAC generates the analog key pitch CV, but the CV can be continuously varied using aftertouch and glide.

 

My webpage explains the VCO is layman's terms.

 

Quote

I hear there is a 1 volt input to VCF as it was a 4034/35 in this model

 

The stock ProSoloist never had any CV or trigger I/O.  There's a point in the circuit where a (-)1V/oct CV OUTPUT to the VCF can be tapped, but not an input.  See below.

 

Quote

is it possible or even recommended to add CV in on this one?

 

Not possible.  While it is a VCO synth, it is an unorthodox design.  The VCO core is placed in a control loop that includes octave selectors, frequency to voltage converter, and an opamp comparator providing error correction voltage in response to the DAC CV.  The DAC CV is a weird scale, it isn't close to 1V/oct.  And due to the novel design of the PS, the DAC CV only supplies pitch CV for one octave however with the octave selector in the control loop the VCO can provide a four octave range.  

 

The patent describes the control loop in detail, but there's no mention of it in the service manual.  Anyone armed with only the service manual would miss important details.  That's why attempts were made to use a MIDI to CV converter on the PS but it doesn't work with this circuit.  That's also why most techs won't service a ProSoloist, without the patent they can't make sense out of the oscillator.

 

It's a really oddball VCO circuit, but the tuning is rock solid even at cold start up.  That's another reason why it is confused as a DCO synth.  I've never seen this design in any other analog synth, probably because of its high component count.

There is a MIDI converter designed specifically for the ProSoloist here, I own one and it works.