solina ensemble effect, someone has details?

[brok landers]

hi all,

guys, i think this is the right forum to bring this question to ...
i have to recreate this famous stringensemble chorus (modulator) of the solina and the eminent 310u ...
i've gathered a lot of information on this, but i'm stuck on 2 important elements:

1. how are the phases set on the individual lfo's
2. what are the exact speeds

i have the diagram here, but there are no speeds and no phase offsets written down, but regarding the diagram there are some phase shifts made ...

basically the hard thing for me is not, to get the character, but the orginal has close to no movement, meaning you are not hearing the lfo's themself too much, and close to no phasing occours ...
i also can see, that there's some phase shifting of the dry osc going on, when mixing the modulator effect with the dry osc ...

can some experienced dev maybe kindly help me out on this?
maybe someone knows entirely how it's done?
that would be highly appreciated ...
thanks a lot in advance ...

[dharmawan]

I love the Solina ensemble - beautiful BBD chorus, the unit without the ensemble on sounds kinda dull but magical with it on.


Some interesting discussion on simulating one - has got the LFO speeds, phases and some real solina ensemble samples for comparison.


http://acapella.harmony-central.com/sho ... ?t=1571578

http://mail.electro-music.com/pipermail ... 03719.html


I've got interesting info on the Dimension D chorus as well if you're interested. Its also a great sounding chorus without a lot of audible wobbling or movement, would be great to have as (native) software

Peace
dharma one

[Pantsdown666]

http://www.native-instruments.com/index ... tchid=5840

[JCJR]

The solina chorus was very simple. Perhaps you could even call it crude. Probably you can find the schematics online if the diagram you saw was not the actual schematic.

Its been a long time since I looked at the schematics, but it is either two or three bucket-brigade chorus lines in parallel. Each chorus delay line is driven by its own free-running LFO, and IIRC there were trimmer resistors on the circuit board to adjust the rates.

The factory had its own spec for the LFO frequencies (which were probably notated on the schematic somewhere). But in such a circuit, the absolute speed of each LFO really doesn't make a lot of practical difference in the sound, as long as they are in an LFO freq range. Just play with setting some of them slow and others faster, until you like it.

Unless memory is failing, I spent time a long time ago toying with the Solina LFO trimmer resistors, and just about any setting still sounded like a Solina (GRIN). Its just a smooth wobbly wash.

The un-chorused straight signal was probably mixed-in with the delay lines.

The source waveform was basically sawtooth generated via digital organ 'frequency divider' technology. On most of the 'string unit' gadgets, the sawtooth was 'concave curved' rather than razor-sharp straight lines as in analog synth oscillators. Approx the shape of a capacitor discharge exponential curve.

The 'pointy-curved' sawtooths were made by passive filter circuits modifying square waves. One dedicated simple waveshaper for each note and octave on the keyboard.

I think the 'pointy-curved' sawtooths sounded more like strings, than mathematically proper straight-line sawtooth waves. I was never completely happy with the string patches on Prophet 5, Memory Moog, OberHeim OB, because without a high-pass filter, the sawtooth was too 'brassy' and narrow pulse-width square waves were too 'reedy'. You just couldn't quite get into that 'stringy' ballpark with the stock complement inside most of the early commercial analog or digital-analog hybrid performance synths.

The Yamaha CS line was one exception, mainly because it had a high-pass filter. Rhodes Chroma Polaris could do it pretty well. That was a very sweet mellow axe. Dunno why it was different, because the Chroma Polaris was mostly just Curtis chips like all the rest of that breed/era of USA performance synths.

[brok landers]

The solina chorus was very simple. Perhaps you could even call it crude. Probably you can find the schematics online if the diagram you saw was not the actual schematic.

i actually have a solina, and i have the schematics, like i said ... and yes, it's basically a very easy construction ...

Its been a long time since I looked at the schematics, but it is either two or three bucket-brigade chorus lines in parallel. Each chorus delay line is driven by its own free-running LFO, and IIRC there were trimmer resistors on the circuit board to adjust the rates.

yes, and lowpassfilters, to shape the rectangle into a kind of sine ...

The factory had its own spec for the LFO frequencies (which were probably notated on the schematic somewhere). But in such a circuit, the absolute speed of each LFO really doesn't make a lot of practical difference in the sound, as long as they are in an LFO freq range. Just play with setting some of them slow and others faster, until you like it.

no, that's exactly the problem:
i can match the wobbling character, no problem with that ....
what i have a problem with is, that whatever phases i set on these 3 (sometimes i use more) lfo's, i cannot avoid an audible moving frequency that dominated, sounding like a vibrato ...
the solina modulator has exactly this behave minimized to it's very extend, while, and that is the important thing: still sounding rich and detuned and warm.
the original somehow sounds equally detuned, has this "sirring" character by some fast lfo (which i can emulate without any problems), but there's no real cyclic movement in the pitch, at least it's minimized by some phase cancellations and a tremolo and such ...
all stringmachines (at least the good ones, of the ones i call good) have this in common:
multiman, vp330, rs202, u310, even the crumar performer (though i never liked thatone) ...
i need to be very close, not just catching the character ... that's no problem, i did hundreds of patches for various synths with some solina-like patches ... thistime i have to nail it ...
the osc signal is nailled already, i got that ...
but the modulator ... hmmm ... it seems i didn't find the hidden switch yet ...
so i thought someone could tell me the rates and phases settings for each of the three modulated delay lines, and why there is 3 phase invetions going on ...

btw, not in the quote, but yes, the rhodes chroma polaris is on my wishlist since a long time already ...
such beatyful pads ...

[JCJR]

Well, here is one thing to possibly consider. I didn't go into it earlier, because without looking at the schematic or possibly even even probing with an oscilloscope, it would just be guessing--

The bucket-brigade pitch modulation (or generally, pitch modulation of any kind of delay line)-- The 'shape' of the pitch modulation is not NECESSARILY the same as the 'shape' of the LFO waveform.

You can probably web-search and get definitive explanation of the issue. I have a gut understanding of it, but can't give you exact math explanation.

Anyway, if you have a triangle-shaped LFO (very common in analog synths since it is so cheap/easy), and the triangle-shaped LFO LINEARLY controls the delay time, you don't get triangle-shaped vibrato. You get square-shaped vibrato (trill). The pitch is transposed a constant amount up on one direction of the triangle, and then the pitch is transposed an equal constant amount down on the other direction of the LFO triangle.

To get a triangle-shaped vibrato, one easy way to do it is to integrate the triangle LFO, and drive the delay line with the integrated signal. That makes the rate of delay change follow a triangular pattern, and generate triangle vibrato rather than square vibrato.

In short, the vibrato shape of the delay line depends on the RATE OF CHANGE of the delay.

Since in a bucket-brigade device, the LFO drives a voltage-controlled high-freq clock generator, you would have to do some investigation to find out if the clock generator is being controlled linearly, or non-linearly.

However, if the LFO is driving some simple 555 timer type of clock generator, in linear mode, then the Solina vibrato from each delay line COULD POSSIBLY be small subtle square-wave vibrato rather than the tri- or sine- vibrato you might expect.

Anyway, the differences you are hearing might be related to the shape of the vibrato coming out of the delay lines.

[JCJR]

Thread-drifting, the Chroma Polaris contained a quite-advanced-for-the-time 16 bit Z8000 processor.

My Chroma Polaris malfed after many years, some bootup problem with the Z8000, and I spent a lot of time poking around it with the oscilloscope without getting it fixed. I also have a donation Chroma Polaris for spare parts, which failed with the same symptom. They are lovingly stored away for some future time that will never come, when I have time to spend days debugging the issue.

So if that is as common a failure mode as I would think (having two different units with the same problem), then functional Chroma Polaris' might be very rare.

A shame.

[brok landers]

on the lfo shape:
i pretty much know it's a rectangle, beeing lowpassed, resulting in some "kind" of sine-thingie ... i am a ware about the triangle resulting in audible rectangle movements on the pitch ...
however, i doubt that this is the problem.
i think my problem lies mor fundamental.
i think it's the speeds and the phase-relations to each other ...
again, the problem is, that one can hear a periodically "vibrato" ...
what i meanis, that, whatever phases and speeds i set on the lfo's, there's always some "resulting" pitchmovement, a frequency that is the result of summing up the lfo frequencies and depths ...
it's a mathematical/physical tinking error i do ...
there has to be a mathematical relation of phases and frequencies of the 3 lfo's, in which one could get max diffusion _without_ noticable vibrato frequencies ...
meaning, the resulting frequency of the summing of the three lfo's is realized that way, that there's not much audible "vibrato", but still a maximum diffusion is reached ...
which makes me worry, as that would mean, that, if i i.e. would be able to generate that exact wave, and summ it up to the modulation, i'd cancle it out ...
but with that i am cancelling the modulation i initially intended to add, right??
f**king physics ...


i hope i'm not talking out of my are here ...

on the chroma polaris:
it's a long time ago that i had one under my fingers, but i never understood why everybody said "naahhh, chroma polaris? that's just a ceap box ..." i always love that sound, but as you say, i never found one for sale, as they seem to be rare ... a shame that there are stability issues, didn't know that ...


btw, to all:

thank you all for helping me out with links, etc ...
still heavy on it, accidentially forgot to thank you ...

[omissis]

brok
have you got the Solina? Already tried to put a probe on the output of the LFOs and measure the speed through an oscilloscope?
Anyway, have you thought also about the ensemble effect into the RS-505/VP-330 ? It sounds even more complex because it uses 4+1BBDs to get that sound: moreover think that the signal coming out of each section is mixed into the BBDs with a phase inverted copy of it to get the stereo spread...it's a hell I think but have you ever thought about it?

[JCJR]

Hi Brok

Are you making the modulations on a single 'thin' oscillator, with a summed multi-delay line? Or 'faking it' with multi-oscillators modulated by multi-LFO's? You may have explained that already, but I was just wondering. If using multiple modulated oscillators, it might be difficult to make it sound identical.

Also, obviously it would sound different if each voice had its own multi-modulator. The solina mixed everything together before going into the chorus unit.

I'm guessing you are actually emulating the Solina signal flow, but wanted to make sure.

With a single mixed poly-signal going thru the delay lines (as in the solina)-- There would be the vibrato effect (of whatever shape), and also a flanging effect from interference of the different moving delays. Multiple modulated oscillators would have the vibrato-chorus effect, but not the additional flanging effect.

I can't recall the bucket brigade chip that solina used. Foggily recall maybe the early solina's used a part that was hard to find later on in the USA. Anyway, most of those gadgets used for musical chorus had 1024 delay stages. I saw some 512 stage units but they were rarer in music gadgets. Much larger 4096 stage and bigger chips could be found in some of the later-generation Analog delay stompboxes. SAD1024 and SAD512 were common parts in synths and stomp boxes.

If you are not already, then exactly emulating the delays used in the solina might be a good place to start. If the schematic doesn't specify clock rates, it would be easier to poke a scope in the circuit than mathematically try to calculate the frequency range of the clock generators.

Anyway, if you determine the min-max frequency of the clock generators (I'm guessing they will all be the same approx range except for component tolerances), you can divide the number of stages in the BBD chip by the clock frequency to calculate the maximum and minimum delay range of the circuits.

Maybe you already did that, but if not, then if you get the delays in the ballpark it might help.

====

Perhaps you like the solina sound better than me. When I would play it, would hear a pretty easily identifiable repetitive churning pattern that bugged me. That's why I played around with the LFO frequencies to see if it could be made more interesting and less mechanical. But there is a long-term pattern to any combination of LFO fixed frequencies.

I liked the Freeman, which had three banks of oscillators and multiple LFO's. Later I also built-in an analog delay chorus board in the Freeman, which was similar in intent to the solina chorus, except I used chaotic LFO's (cross-modulated LFO's), so that each LFO frequency would 'unpredictably' stagger. The 3 independently modulated oscillator banks feeding into a 3-parallel-delay random-modulated chorus, was an unlocked wobbly wash. You could hold a key for a long time and never find a pattern inside the agitation.

====

Chroma Polaris' biggest 'hifi' problem was a CA3080 on the master volume control of the output which was noisier than it had to be, and could mildly distort if driven too loud. But by then I had begun to avoid chopping on my equipment, so I never replaced the output circuit.

The Z8000 problem I saw on both the Polaris' I've tried to fix, IIRC, has something to do with the reset signal on startup. There is a little delay circuit that keeps the CPU off for a little bit on power-up, then toggles to set in motion the cold-boot process. Something seemed to be bad in the timing of that startup logic. Probably a single cheap part, if I could figure out which part to replace.

Chroma Polaris also tended to have power supply bugs. Not big huge bugs, just things that needed attention sometimes. Mine never had any power supply problems. Lots of those early synth designs had finicky power supplies.

[brok landers]

brok
have you got the Solina?

yes

Already tried to put a probe on the output of the LFOs and measure the speed through an oscilloscope?

no, i have't got a clue of electronic circuits, i always did my sounddesigning by ear (and reading facts of some special behaviour of the reproduced units) ...
sofar this has always lead me to success ...

Anyway, have you thought also about the ensemble effect into the RS-505/VP-330 ? It sounds even more complex because it uses 4+1BBDs to get that sound: moreover think that the signal coming out of each section is mixed into the BBDs with a phase inverted copy of it to get the stereo spread...
it's a hell I think but have you ever thought about it?

i'd rather love the rs202 than the rs505 ...
and yes,i know all that, and you're right, it's a hell ...

[jupiter8]

http://www.soundonsound.com/sos/jun04/a ... ecrets.htm

There's some stuff about old choruses here. Dunno if that's old news or if it is any help.....

[brok landers]

Hi Brok

Are you making the modulations on a single 'thin' oscillator, with a summed multi-delay line?

yes.
first i sampled the non-modulated, dry signal from my solina, every key, mapped it for my exs. after that, i placed a custom "mono chorus plugin", on which i have 4 independant delays with each have their own sine lfo, which are adjustable in rate, depth and phase (0-360°) and on/off, seperately.

Also, obviously it would sound different if each voice had its own multi-modulator. The solina mixed everything together before going into the chorus unit.

i know that.

I'm guessing you are actually emulating the Solina signal flow, but wanted to make sure.

yes, the osc is no problem, as it is availlable isolated, fft > ifft ...

With a single mixed poly-signal going thru the delay lines (as in the solina)-- There would be the vibrato effect (of whatever shape), and also a flanging effect from interference of the different moving delays. Multiple modulated oscillators would have the vibrato-chorus effect, but not the additional flanging effect.

yes, forget the multiple osc's, it's not done like that, and ayou'd hear flanging of the phase differences of the detuning ... you could not detune the osc's, but still, if they're freerunning there still would be a static phase cancellation on each keystroke, and, why using 2 osc's, if you wouldn't detune them?
but you described exactly what i don't understand:
in the solina there is infact just a very little vibrato (a bit of tremolo, yes), and close to non flanging effect whatsoever, even when one grabs octaves, they're not flanging.
lik i said, i managed to get the character of the solina, but again, there'always some audible, disturbing vibrato, and, when grabing octaves (or partials like 7nth or 5th), there's this weired flanging going on, which doesn't happen with the solina ... but i think, that is overcome in the solina by the fact that it has individual osc's for each key ...

I can't recall the bucket brigade chip that solina used. Foggily recall maybe the early solina's used a part that was hard to find later on in the USA. Anyway, most of those gadgets used for musical chorus had 1024 delay stages. I saw some 512 stage units but they were rarer in music gadgets. Much larger 4096 stage and bigger chips could be found in some of the later-generation Analog delay stompboxes. SAD1024 and SAD512 were common parts in synths and stomp boxes.

iirc, it's the 512 ... but again, i don't think that is the problem:
the problem is imo, to know at which speeds the 3 lfo's modulate each delay, and which phase-offsets are used, also if the dry osc is mixed phased inversed with the modulator fx ...

If you are not already, then exactly emulating the delays used in the solina might be a good place to start. If the schematic doesn't specify clock rates, it would be easier to poke a scope in the circuit than mathematically try to calculate the frequency range of the clock generators.

i don't have a hardware-scope ... is there maybe a free plug that you are aware of that can do this? and, how would i do this? i can't isolate the seperate delays, to then be fed into the scope for examination, can i ...?

Anyway, if you determine the min-max frequency of the clock generators (I'm guessing they will all be the same approx range except for component tolerances), you can divide the number of stages in the BBD chip by the clock frequency to calculate the maximum and minimum delay range of the circuits.

well, how would i do that?

Maybe you already did that, but if not, then if you get the delays in the ballpark it might help.

no, i didn't, i wouldn't know how ...
but yes, that might help ...

Perhaps you like the solina sound better than me. When I would play it, would hear a pretty easily identifiable repetitive churning pattern that bugged me. That's why I played around with the LFO frequencies to see if it could be made more interesting and less mechanical. But there is a long-term pattern to any combination of LFO fixed frequencies.

well, first off, my favourites in stringmachines are the vp330, rs202 and the eminent u310 ... there might be others, but those were the ones i owned, exept the u310, but i've heard it, as a friend of mine had it, and i was playing on it for hours when i was young ... today i only have the solina left, also, i have to do the solina, it's on demand ...

I liked the Freeman, >snip<
The 3 independently modulated oscillator banks feeding into a 3-parallel-delay random-modulated chorus, was an unlocked wobbly wash. You could hold a key for a long time and never find a pattern inside the agitation.

hmm, i only heard the freeman once, but i didn't like what i've heard back then ...
but afaik, it was highly configurable, so i maybe just heard an unpleasant setting, who knows ...
on the chaos lfo:
that's exactly what i don't want.
you'd hear a change all the time ...
on those great stringmachines there of course are some repetitive cycles one can hear, but the signal nevertheless was wide, rich and lush, and you wouldn't notice these repetive "vibrato's" as unpleasant or disturbing, also, again, they're really minimal, compared to what you can reach with conventional chorusses, whatever you tweak them ...
like i said, i have my independant lfo sections with independant phase settings, rates and depths .. but still ...
slowly but surely i'm going nuts on this ...

oh, and btw:
thanks for your detailled info's and will to help!

[brok landers]

http://www.soundonsound.com/sos/jun04/a ... ecrets.htm

There's some stuff about old choruses here. Dunno if that's old news or if it is any help.....

thanks jupiter, will examinate ...

[duncanparsons]

If you've ever heard Jeff Waynes War of the Worlds, Freeman himself is playing a Freeman, I think it was the 3rd version which was in a constant state of flux with him changing things depending on what sounded better in a given environment..

DSP