KVR Audio

mztk · Post by **mztk** » Fri Mar 18, 2011 8:50 pm

hi. i'm tinkering with a little juno(106) plugin in synthedit,
and could do with some infos to complete it. i don't have *any*
juno anymore to check against, so some details on waveform etc
and ranges of some parameters would be very helpful. even little
suggestions in the past couple of days have helped a lot..
infos, scope images, unusual/classic patches...

anyway, here's what was the first draft:
http://www.box.net/shared/ggyebvmznx

it's pretty much stock synthedit, which is sort-of the idea.

it's moved on a little, but this is the rough idea.
-need to know hpf slope and cutoff range(if possible)
-need to know vca level of saw/pulse, relative to sub osc
(here, these are half amplitude of sub, in volt)
-could do with better idea of chorus rate and delay/depth.
(this version allows mucking around with these, for comparison-
you'll find some hidden parameters, and everything's out of place

oh, and it appears an accurate RGB value for the panel background is
needed too

osiris · Post by **osiris** » Sat Mar 19, 2011 2:31 pm

http://www.hinzen.de/midi/juno-106/

Download the midi sysx editor. It will give you an idea of what the presets look like.
As far as sound, do a search on Youtube.

mztk · Post by **mztk** » Sun Mar 20, 2011 5:54 pm

ah, well i was more thinking of some ranges for parameters.
osiris, your luno sounds great. i'm sort of attacking it
from the interface point of view...really haven't even
considered sysex + i overwrote all the presets on mine as
quick as i could! really looking to define some things that
aren't specified in the service manual. i still have loads
of samples i did ages ago, but trying to set some ranges, etc.

nice colours on that page though! at least that's sorted then...
cheers!

aciddose · Post by **aciddose** » Sun Mar 20, 2011 6:14 pm

i haven't measured a 106 before in detail, but if they're anything like all the other roland synthesizers the levels for ramp/pulse/sub/noise should all be equal. the schematics show that resistors exist in the circuits that could be trimmed for equal levels, but i can't be sure of that because the values aren't shown.

http://www.hinzen.de/midi/juno-106/manual/juno-serv.pdf

since the main oscillator waveform (ramp, pulse) can't be adjusted in amplitude it would be useful if the sub could be set between -inf and +6db, maybe even +12db. most of the sounds i've made have no need for the sub to be more than 6db above - the famous "stairsteps" waveform made by -6db square and 0db -1oct sub square however needs that 6db range.

osiris · Post by **osiris** » Mon Mar 21, 2011 1:26 pm

Thanks. Luno is a good VST with a bad GUI, and a few flaws.
I will tell you some things I found out while researching Luno. The oscillators are fixed volume and can all be mixed together, but I could never get what their fixed level was. I do know the main VCA went from -5 to 5, I'm supposing because it got really loud (this was not a negative envelope). Also the HPF is NOT where you might think it is in the audio chain due to the synth layout. I can't remember where exactly, but it was sneaky. I got much better response on SE envelopes by using the milliseconds to volts converters attached to the ADSR, but used much more CPU. There's really not much info on the chorus, so I just winged that. Fixed rate with I being a 2 voice and II being a 4 voice - triangle mod on the first & sine on the second.
Hope that helps. Good luck.

mztk · Post by **mztk** » Tue Mar 22, 2011 1:16 pm

thanks, gonna study these in detail a little later.
well, it looks like the 106 has the HPF after the VCA/VCF,
and it shows HPF A+B, so i wonder if the mono signal splits
here into the streo chorus, or if it's a single HPF path, or
cascaded HPF(?for what slope? 6dB/oct or 12?)

in the alpha series, the block diagram indicates the HPF does
comes first. so you wonder how they initially conceived the
juno design..(was hpf an afterthought?)

as for the VCA levels, i originally had the pulse and saw
accidentally set to half the amplitude of the sub sqr, which
was pretty ok. atm, there's a hidden switch which i have set
to equal amp for all.

and the chorus is derived from what i've been reading lately
in the jx8p build, eg/ that one side receives inverted LFO.
it produces a slightly noisy chorus with no added noise. not
sure yet whether this is just some artifact eg phasing aliasing
clipp-age.. and not too bothered right now: it isn't a very
'delicate' or refined plugin just yet, quite 'square-edged' SE,
but i'm going to do it like this, bcs it has some interesting
aspects, and sort it out more later.

if anyone has -duh- scope images of waveforms, could be interesting.
i'll have something new in a few days. oops battery going...

osiris · Post by **osiris** » Tue Mar 22, 2011 1:38 pm

http://sequence15.blogspot.com/2008/10/ ... -from.html

I learned a lot frm this. It is a HPF, but actually a set of filters with each notch on the slider a routing select to the different filter.

kritikon · Post by **kritikon** » Wed Mar 23, 2011 2:35 pm

Maybe my HPF slider has always been poked, but gotta say that I almost never use it. It sounds to me that all it does is a simple hipass shelf - it's not resonant in the slightest and just cuts the lows in what seems like 4 notches. Useful for getting rid of bass in some mid patches, but not what I'd call a real HPF. You can't sweep with it or anything creative like that. Is it an afterthought? More like an afterbirth...the only genuine reason for it I ever found was to make weak sounds even weaker. I really dunno why Roland bothered putting it on the 106.

mztk · Post by **mztk** » Wed Mar 23, 2011 3:00 pm

eee-er...well, it's more of a low-cut, isn't it? seems to
remember it served on some sounds, especially to get ye olde
slow resonant sweeps, but also to get things to fit..
anyway my HPF defnitely needs a bit of help: i've limited it's
range and have a stepped fader, but it drops off in volume, which
i don't reckon it should. confirm?(i know it ain't such a big deal,
but might as well try to get it right, eh.)
that info looks interesting, osiris, gonna check it out. would
explain the schem annotation perhaps.

btw: put the 2nd draft back up. and done a bit more since, but sound is
still abt the same:

http://www.box.net/shared/iygcr63bid

aciddose · Post by **aciddose** » Wed Mar 23, 2011 6:27 pm

the highpass is definitely crap - it's put there to deal with the fact the synthesizer only has a lowpass mode for the filter. the complexity of the switches required to add bandpass and highpass to each voice was just too much to fit. with a "state-variable" 12db/o filter it would have been possible, but with the 24db/o filter it uses up too many components and too much space on the pcb.

it _is_ a stupid solution, but it nearly works. the thing that makes it stupid is anyone with parametric channel EQ in their console could apply the same effect at that point instead - in the analog world though that was rare. parametric low shelf eq on a channel strip just wasn't common at all.

the reason it works fine after the filter and even after the vca (which means you only need _one_, not _six_) is that it's a linear process and so the exact same result occurs whether you have six before the filter, or one after the vca.

osiris · Post by **osiris** » Wed Mar 23, 2011 8:32 pm

If I remember correctly , one notch is 6 db bass boost, one notch is bypass, The other two are different HPF frequencies. I'll try to find the things I read about it. I did put the last VCA after this filter tied to main volume. It can get pretty loud, and that's why I suppose, the volume level has negative decimals on it. It's not an inversion or anything like that.

mztk · Post by **mztk** » Wed Mar 23, 2011 10:02 pm

bass boost at 0, yeah i read that. so if it's a
switch for different circuits, maybe 'hpfA' +'hpfB',
as marked on the schem are preset/non variable routings,
as opposed to some cascaded thing.

regarding chorus settings, on the first version, there
is a parameter panel to vary settings. it'd be good to
get a comparison report for I and II (going to try to do
it with current config)if someone has a couple of minutes
with the real thing.

aciddose · Post by **aciddose** » Thu Mar 24, 2011 1:51 am

if you don't understand schematics don't bother reading them, you'd be better off learning first.

"hpf a" and "hpf b" are bits. they're digital lines leading to a multiplexor which select one of the four outputs. so it's a 1->4 selector switch.

y0 = 4.7n + 47k
y1 = 15n + 47k
y2 = bypass
y3 = this is slightly more complicated. it's a bandpass feeding into a lowpass. basically it's a low-shelf.

F = 1 / 2piRC
Hz
y0 = 720
y1 = 225
y2 = n/a
y3 = 65

the boost is actually about 10db, not 6db if you calculate it ideally. there is some resistance from the multiplexor though which is about 250ohms, which changes the filter and makes it 6db boosted (low) gain, with a constant gain of about 1db. so when you put the hpf mode to boost, the over-all level should increase by 1db.

the effect of the bandpass feeding it is to level off the top of the shelf, making it Q = 1/sqrt(2), or butterworth.

all the slopes are 6db.

mztk · Post by **mztk** » Thu Mar 24, 2011 7:56 pm

lol. i'm sort of building up to it

yeah i did some useful reading last night and it all became
clear(er). your info is very specific expansion on that, thanks.

as i drove back from work i concluded it had to be 6db. the
caps determine freq'. had remaining question how to implement
the 'boost', this should do it.

now hunting for a few waveform images. should be pretty 'perfect'
if generated by division of a square wave, so i think i have that.

still, i listened to some samples from the website above, and realised
it's still some way off.(worth checking out)

osiris · Post by **osiris** » Fri Mar 25, 2011 1:47 pm

Well, SE oscillators are just as good, but I think Roland used band-limited. Now you could do this with bp filter (I think), but you're creeping into high CPU territory.
for the bass boost I used DHFilter (can't remember the exact one) but he has a Peak filter that you can specify frequency and level. I thought 150Hz would be could for most basses. Like I said, there's quite a few filters in this thing.
One trick I did with the chorus was make 1 a triangle wave at a low mod freq and make II go through I with II a sine wave set a slightly higher freq. Roland had a similar design for a chorus using 4 LFO's and frequency dividers.

juno-(106)vst: owners please