DSI / Prophet Forum

[twenex]

I wonder how difficult this would be. There is already a level mix for A and B oscillators .. and you would pro
bably have to clone the final VCA, it it seems that for the most part everything is there to basically do this.
---
I don't think panning all VCO As left and VCO Bs right would be that useful. Better to do like the OB-X/Xa/8 and
run the outputs of each full voice into pan pots... Should be pretty easy...
---
Well, so much for the drink .. re-reading my message it just seems like a silly idea. I think I was playing a w
arbly PW pad and thought how nice it would sound panned.
---
Heh, it's not that silly in concept though to have the outputs of each voice pannable..

[analogholic]

Now we´re talking...

I was just thinking about the same thing...

My Matrix-12 and OB-Xa sounds FANTASTIC when you pan the voices...

And then after the "stereomod" is done, we should add a voice detune function which is absolutely brutal when playing unison (with panned voices). The Matrix-12 and OB-8 has this (OB-X too ?) Unisono sounds SO much better when you eliminate the "phasing" which happens in mono. I mostly turn off one of the oscillators in unisono when I play my P5, again to avoid the "phasing"...

C´mon guys, how difficult could it be ?

[analogholic]

Hmm....Anyone?

I wrote DSI and asked how it could be done.
Their reply was that they concentrate on the P08. Understandable.
However, they said that the schematics are out on the net and that some clever tech should be able to pull it off.

I tried the P08 the other day. Was goofing around with the pan knob, and well....it makes a BIG difference if it´s panned or not. Sounds better, bigger and wider...not to mention how much better unison sounds...

This made the decision for me...I´ll HAVE TO do a stereomod on my P5.
Would be cool to do it the way it works on the P08, even if it wouldn´t be programmable...

Cheerio

[puppets]

Have you had any luck with stereo modify your prophet 5? would be interesting to hear the result

Best regards
Jonas

[sjones]

Being able to stereo pan (spread) osc 1 and 2 would work best in patches where osc 1 and 2 were doing basically the same thing. There are cases where you use osc 2 as a modulation source and you typically turn it down in the output mix. It could be easily done, its application is limited, but could be worth doing.

[analogholic]

I haven´t got any further on this as I didn´t get any info yet...

The way I want to have it done is like on the Oberheims, where the voices are panned rather than the oscillators.

I think I would prefer to have a fix position for the voices as opposed to like the OB-Xa, where they rotate in the stereofield.

I know that Lintronics have exactly this mod done to their LAMM Memorymoog:

"Stereo output circuitry is added. If the mono output jack is used simultaneously with the stereo output jack, then the Memorymoog's six voices are spread across the stereo field (the placement of the individual voices is fixed internally)."

Maybe I should try to contact them and see if they would share their "secrets"...

[rikusk]

As mentioned before stereo mod requires cloning of the final vca and output buffer circuitry. All models uses hard to get and expensive parts (ssm2020, ca3280) on their final stages, so I'd left the original output as is to be used as normal mono output or leave it unused and do the new panning and final vca / audio out pair on new pcb. By using new pair it's easier to make both channels sound and follow the volume cv in same way.

To do this the Oberheim way, good start for designing such circuitry is to copy the OB-Xa's final stages. This is simple mixer / panning circuit with vca and final stages. With the OB-Xa, there is another hard to get part, cem3360 involved so it might better to replace the cem3360 with any favourite vca circuit founded on various diy sites. The LM13700 dual ota might be one good candidate for this.

Easy way is to skip the vca part and just buffer the outputs with opamps and using mixer as final volume control. For studio work this might be just enough specially if the original adjustable mono output is still there. Super easy way is just tap these five outputs and let the mixer do the panning and level adjusting.

Installing this any kind these mods to p5 would be easy. On rev3 this circuit would be tapped on input of five 39k summer resistors (R4566-R4569). CV is found on U480. On rev2 the level adjustment is done bit different way. I'd install second set of trimmers on the stereo mod board and tap outputs from original trimmers. These trimmers might be good idea for rev3 too for further level adjustment.

To make this work as supposed it needs more designing as here. Mixing different parts from various synths and using component values as in original circuit without recalculating might not work here properly. Some buffering might be good idea too to keep the outputs of the ssm2020's or 3280's happy.

[analogholic]

Wow !!! Thanks Rikusk!

You´re da maan I needed...the next one is a tech that will do this...

Hmm...yes I will have to contemplate over this for a while, which way to go.

But I´m seeing the light, finally

Thanks again

[Acusonic24]

Analogholic. I agree with ya. I had the Lamm mod on my Memorymoog and I wish it can be done on the p-5. I have a rev3.3 and I can't see why it can't bee done. The memorymoog has a little more complicated circuits and the prophet 5 is a little simpler. It seems that it should be easy to get that mod done. I love that effect. I first notice that effect from Herbie Hancock and George Duke On the Oberheim SEM Polyphonic 8 voice on his late 70s to the early 80s album. One of the voice would have a different voicing and panning and gave it a bigger sound that spread the stereo image. Then I thought that the prophets and memorymoog will sound wonderfull in that stereo config. If You guys find out Let me know about that. That would be a wonderful mod. Too bad Lintronics can't do that to the prophets,,,maby if you give them the money for it and they'll do it. Might ask for too much money for it. I don't know but that will be a good idea. :idea:

[Acusonic24]

I saw this ebay auction on a p5 rev3 and had this strange mod on the back of it. Heres the liknk to it.

http://cgi.ebay.com/Sequential-Circuits-Prophet-5-analog-synthesizer_W0QQitemZ220378083096QQcmdZViewItemQQptZKeyboards_MIDI?hash=item220378083096&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A1%7C294%3A50

[heath]

I doubt that has anything to do with stereo. My bet would be something to do with CV/Gates...

[Acusonic24]

Yeah I just didn't know what that mod was and had no discription for it. I was realy curious. I thought the same,,, CV, or extra Pedals or External something.

[heath]

CV/Gates to me makes the most sense since it's a five voice synth. That would be one CV/gate per voice. (although you would already have that one that is stock)

[Acusonic24]

True True , Thats so right. I saw a Minimoog With a similar mod like this but other stuff with it on the back pannel CV/ Gate a few extra external in and some other odd ball even tho its on a mono synth, maby he routed another cv/gate to it but it said cv/g and couldn't tell what the others were. I hate when that happens, can't tell what out put s or connections its for.. This was in the early mid 80s. I think it was Billy Currie's minimoog from Ultravox. I saw that pic way back and he had 2 of them. Not to get out of the Prophet realm but thought that was interesting

[psyfi]

On rev2 Looking at the mono circuit the signal enters the TL082CP Op amp where the VOL CV is revived and then on the the 2020 but just wondering about the possibility of using these same ICs in place after what ever panning circuit you installed? would there be cross talk or other issues using inputs and outputs A and B or are these ICs just not set up this way? Its just looking at the schematic on different parts of the voice circuitry such as the TL082s on the filter feedback circuit the same IC is shared by two voices with no problem.

Also if I were to implement this mod I would want a rear jack set up where it was stereo until I removed one of the jacks and it would then default to mono on the remaining jack. I've seen this on other synths but can't track down a schematic on how its done. Any ideas?

In the mean time I've made a recording of what this mod might sound like both in unison and a held chord to see if it is something I would want to proceed with.
the audio has mono and then stereo examples of the same patch for the pseudo stereo versions each voice was recorded separately and then lined up and mixed in post.
http://www.sendspace.com/file/4m5gsf