Behringer Roland System 100M clone

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KSS
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Re: Behringer Roland System 100M clone

Post by KSS » Sat Jun 06, 2020 4:15 pm

Synthbuilder wrote:
Sat Jun 06, 2020 2:33 pm
One thing that bugs me about the module is that the CV inputs are only 1V/octave at their maximum settings. It would be nice to have at least one of the CV inputs to be more sensitive so you can get really big sweeps from envelopes that have a 0V to 5V output.
It's one of the great coulda-beens in synth history that the 1/10 -1x switches on the Roland 700 VCOs modulation inputs were not appreciated more and didn't become common on all module types. For filters too the switches woulda-been great. Some were modded for this.

I remember reading -or a video?- of STG talking about making sure at least one his filter mod inputs had a larger range. I think he said 2x. He gets it.

The ability to quickly switch the range of sliders or knobs is a huge benefit to effective patching. Like so many other great ideas from early modulars it's fallen away under economic and 'societal' pressures. Can't really blame the ones creating the IMO misplaced pressure. They don't know what they don't know.

People don't even know what they're mssing. Fiction evolves around vintage mojo with magic parts, when often times it's just a simple topology choice. Single control inputs replacing triples is another lost opportunity. Stack cables don't give the same result.

Fortunately 1/10 attenuating patch cables are easily made, and the wrong use of shield in most systems means it doesn't hurt the way it would if shield was really shield, instead of the much more common 0v. But amplifying patchcords are noticeably more rare! ;) At least now that there's only one control jack. We used to just double patch a control input for a x2 amplification.

The sad after-effect of these kinds of choices=losses is a certain belief -and unfortunate end-result reality- about which modules do best, and it misses what simpler modules could do if-when the restraints on their architecture is removed. The needed conversation never happens, because too many don't realize there's even a conversation to be had.

Ema41
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Re: Behringer Roland System 100M clone

Post by Ema41 » Sat Jun 06, 2020 5:35 pm

OK, thanks Synthbuilder!
I opened up the 121, there are 4 tiny trimmers inside.
For each 2 filters, one is called "freq", and the other "with".
What is "with"? Is it "width", so scaling, and the freq is the offset? Or something else?

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Re: Behringer Roland System 100M clone

Post by KSS » Sat Jun 06, 2020 6:32 pm

Yes, On the original 121 schematic, trims VR10 and VR20 are marked "width"

The service notes use a scope in XY lissajous mode to adjust width first, then frequency.

(1) WIDTH
Make sure that VCF oscillates when RES knob is set oround 7-8th line.
While quickly playing 2v and 3v keys alternately, Adjust width trim for 1:2 in frequency.
Notes show lissajous waveform.

(2) Frequency
Notes show panel diagram with left lower slider full down and both Freq and RES slider full up.
Adjust Freq trim for 20kHz (50us).

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Re: Behringer Roland System 100M clone

Post by pmarchitect » Sat Jun 06, 2020 7:45 pm

One or two of these modules are looking a bit sexy to me 😍

Ema41
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Re: Behringer Roland System 100M clone

Post by Ema41 » Sun Jun 07, 2020 2:55 am

Thanks KSS.
I found the service manual here:
http://www.midimanuals.com/manuals/rola ... manual.pdf
It's page 23 (down).

So, for the wi(d)th, I can do it with a tuner/ by ear (no oscilloscope here...).
For the Freq and the 20 kHz, I could ask my neighbor's dog, but maybe it's better to have the filter fully open when up (by ear) and then adjust a note on the grid for the 2 filters.

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Re: Behringer Roland System 100M clone

Post by KSS » Sun Jun 07, 2020 3:29 am

You could also run the filter out into a divider and /4 turns 20kHz into 5kHz that you can hear. Or beat against another reference you may have?

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Synthbuilder
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Re: Behringer Roland System 100M clone

Post by Synthbuilder » Sun Jun 07, 2020 3:33 am

KSS wrote:
Sat Jun 06, 2020 4:15 pm
It's one of the great coulda-beens in synth history that the 1/10 -1x switches on the Roland 700 VCOs modulation inputs were not appreciated more and didn't become common on all module types.
Agreed. The System 700 is a beautifully designed ergonomic system. An excellent mix of sliders, rotaries, and switches.
I remember reading -or a video?- of STG talking about making sure at least one his filter mod inputs had a larger range. I think he said 2x. He gets it.
Absolutely. I try to use 0.5V/octave inputs on at least one of my CV inputs. See CV2 on the COTA module below. I'd use higher sensitivities if I could but without switches like the 700 it gets a little unwieldy at lower modulation depths. I think I'll modify this Behringer 121 VCF at some point for a more sensitive CV input but I need to purchase some of those weeny SMD resistors first.

Image

The older 5U system I did had a couple of 1:10 attenuators on the multiple module. Very useful for having more control over more subtle modulations.

Tony

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Re: Behringer Roland System 100M clone

Post by Flexyflier » Sun Jun 07, 2020 4:50 am

Had a 100M back in the early nineties,but sold it along with my PPG 2.3.......what an idiot.....Anyway just ordered two that were available and Will give them a try.
I will spend out for the current price of the original 100M.
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Ema41
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Re: Behringer Roland System 100M clone

Post by Ema41 » Sun Jun 07, 2020 5:34 am

OK, wi(d)th tuned with tuner/ ear/ analyser. It took me 5 seconds for the right filter, 10 minutes for the left... As each micro turn on width trimmer put the reference note out of tune, you have to tune it at each step. So now I understand why the trimmer are not on the back of the module, but on the side of the tuning slider. ;)
I didn't have to touch the freq trimmer, as the width was only slightly out of tune.
I did see auto-oscillation can go to 20 kHz (max) on the analyser, and goes low (20 Hz?), but of course can't be used as a slow LFO without mod.

Anyway, I can experiment with kind of tuned bongos, now...

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Re: Behringer Roland System 100M clone

Post by Ema41 » Thu Jun 11, 2020 2:53 pm

I experimented with duplicating the same signal to the same type of intput (for exemple, 3 times on first filter input), in order to increase the drive input as stated upper.
The question is: do you think it's possible to make a simple wiring mod with actual jack sockets to have the 3 inputs normaled to each other? It could operate the overdrive/ override without having to multiple patch, and operate normaly if input unused pots are down.

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Re: Behringer Roland System 100M clone

Post by Synthbuilder » Fri Jun 12, 2020 3:33 am

Ema41 wrote:
Thu Jun 11, 2020 2:53 pm
do you think it's possible to make a simple wiring mod with actual jack sockets to have the 3 inputs normaled to each other?
I don't think can be done easily, if at all. Ordinarily, to do what you're saying would need the normally closed (NC) lug of each input socket disconnected if it is connected to anywhere, and then joined to the adjacent socket's signal lug.

But I'm not entirely convinced that these sockets have a NC lug. Generally most sockets have three lugs, the signal lug (connects to the tip of the inserted plug), the ground lug (connected to module 0V or chassis ground) and the NC lug (that connects to the signal lug when no jack is inserted). These sockets have four lugs, and there appears to be two ground lugs and two signal lugs. Maybe they do have a signal lug and an NC lug, but if so all the sockets, including the outputs, have the signal lug and NC lug connected together on the board underneath the socket so I can't see what's going on.

I could take a socket off to find out just how these sockets are made but I'm not sure how easily I can desolder them.

Tony

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Re: Behringer Roland System 100M clone

Post by Synthbuilder » Fri Jun 12, 2020 3:47 am

OK, I have had another look and I think there is a NC lug and it is connected to the signal lug on the top side of the circuit board. This means to free the NC lug you'd have to remove the socket, cut the trace and solder the socket back. Not easily done as the socket's ground lugs are soldered to pads connected to the module's 0V planes which will make desoldering tricky unless you've got a fancy desoldering tool.

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Re: Behringer Roland System 100M clone

Post by Ema41 » Fri Jun 12, 2020 6:37 am

Ok, thanks synthbuilder. It looks much more difficult than pluging 2 more wires, so I give up.

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Re: Behringer Roland System 100M clone

Post by RichyHo » Fri Jun 12, 2020 8:54 am

Quick question - are the panels metal or plastic? It's hard to tell from the photos.

:cat2: Thanks

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Re: Behringer Roland System 100M clone

Post by KSS » Fri Jun 12, 2020 3:29 pm

Metal

Ema41
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Re: Behringer Roland System 100M clone

Post by Ema41 » Sat Jun 13, 2020 7:08 am

Yes, good quality, well adjusted metal panel. Standard Doepfer thickness (much thicker than Model D, Neutron, Pro-1...).
Grey paint and lettering seem sturdy too.

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Re: Behringer Roland System 100M clone

Post by RichyHo » Sun Jun 14, 2020 1:55 pm

KSS wrote:
Fri Jun 12, 2020 3:29 pm
Metal
Ema41 wrote:
Sat Jun 13, 2020 7:08 am
Yes, good quality, well adjusted metal panel. Standard Doepfer thickness (much thicker than Model D, Neutron, Pro-1...).
Grey paint and lettering seem sturdy too.
Thanks for clearing that up for me :)

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Re: Behringer Roland System 100M clone

Post by Sushi2k » Tue Jun 30, 2020 4:48 am

hi, just got my Behringer 121 filter this morning, the resonance behavior is somewhat strange, around 8.5 it starts to get extremely loud.
there isn't a smooth rise in resonance peak volume, you have to be careful not damaging your ears. :foul:
can anybody confirm this is normal behavior?

besides that it sounds good, maybe not quite as "squelchy" as the system 500 512 though.

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Re: Behringer Roland System 100M clone

Post by Sushi2k » Wed Jul 01, 2020 2:53 pm

Sushi2k wrote:
Tue Jun 30, 2020 4:48 am
... you have to be careful not damaging your ears.
ok, my fault :doh: I used the System 55 921 oscillators for the first tests, which are quite low in level compared to standard eurorack levels and in relation to the resonance level of the filter itself.
Had much better results with a Rubicon :-)

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