Behringer System 55

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ishi
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Re: Behringer System 55

Post by ishi » Tue Jun 30, 2020 3:43 pm

I just received 8x 921b too.. on first listening they sound delicious. The system is almost ready now, apart from the 960 and possible unannounced future modules. The experimenting can really start of.

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Re: Behringer System 55

Post by SkyWriter » Tue Jun 30, 2020 4:31 pm

ishi wrote:
Tue Jun 30, 2020 3:43 pm
I just received 8x 921b too.. on first listening they sound delicious. The system is almost ready now, apart from the 960 and possible unannounced future modules. The experimenting can really start of.
Wow 8! :love: Looking forward to more news ishi!

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Re: Behringer System 55

Post by KSS » Tue Jun 30, 2020 10:43 pm

ishi wrote:
Tue Jun 30, 2020 3:43 pm
I just received 8x 921b too.. on first listening they sound delicious. The system is almost ready now, apart from the 960 and possible unannounced future modules. The experimenting can really start of.
Sounds wonderful!
I hope you will continue to add to your photos on your site. Saw the component side PCB of the 914 was added. Certainly understand it feels less important than using them, but it's a great and honest resource of what these modules actually are and the design choices Behringer has made.
Besides, your photos are crisp and clear! Without the artsy angles others seem to add.

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Re: Behringer System 55

Post by betovelandia » Wed Jul 01, 2020 8:23 am

KSS wrote:
Tue Jun 30, 2020 10:43 pm
Besides, your photos are crisp and clear! Without the artsy angles others seem to add.
You must be fun at parties

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Re: Behringer System 55

Post by betovelandia » Wed Jul 01, 2020 8:30 am

Boog 904A


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Re: Behringer System 55

Post by KSS » Wed Jul 01, 2020 8:35 am

At parties I don't care. But when I'm trying to figure something out from the photo, it matters.

But Your photos were great too. I didn't mean you, and apologize if it seemed that way. I was totally able to figure out what was needed from the B914 pics you posted for me!

You should see some of the photos I get from people wanting a remote assessment of their synth problem!

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Re: Behringer System 55

Post by KSS » Wed Jul 01, 2020 9:00 am

On the B914 mods, It seems it might be better to make two side sister modules. SFAM? One on the right for individual outputs, and one on the left for CV level inputs. These would take the 28HP B914 to about 36HP and add 28 patch points, and 16 VCAs. One could put the modules on the same side if that's preferred. Breaking them into two because adding outputs is less expensive to do than adding 16VCAs. Someone might find value in simply having all the outputs available at once, and not need CV control of levels. The Fumana is 42HP and Verbos Bark is 34HP, so the added width is not out of line for a controllable non-Fixed FB.

I first thought that putting jacks in the 'available' spaces would take care of at least one of these two add-ons. But the more I looked at it and thought about who could and couldn't make the mod, and all the possible problems going that route. Side-sister modules just makes more sense. Here's a modded faceplate showing where 13-14 jacks 'could' fit for someone who doesn't solder. The red circle is a jack that could be put there by removing and re-soldering one capacitor. And you'd still eitherneed to drill new holes, send a new plate with the mod kit, or ship modules back and forth.

At that point, it makes more sense to just buy them, mod them and then sell them direct already modded. Which comes with its own set of problems.

The yellow circle is a place one could put a feedback pot. Needs a bigger knob because the pot would have to mount to the panel and its panel nut will be visibly ugly with a smaller knob.

If someone can solder, then more capacitors could be moved to the PCB rear, but then the non-solder contact bolt-on PCB making the mod easy isn't easy any more.

It quickly gets to the point where someone who can already DIY doesn't need a mod kit, and someone who can't -or doesn't- DIY isn't getting an attractive and simple solution.

Side sister SFAM modules solve that, with the only downside being the added width. Compared to the price and size of other controllable FFB's that seems a small point.
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Re: Behringer System 55

Post by blaythe.steuer » Wed Jul 01, 2020 11:24 am

very interested in seeing where all this modding talk goes hmmmm

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Re: Behringer System 55

Post by SkyWriter » Wed Jul 01, 2020 11:28 am

Good analysis @KSS. In your SFAM design, how much rework of the B914 has to be done?

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Re: Behringer System 55

Post by Ebotronix » Wed Jul 01, 2020 4:51 pm

921b scaling
correction #2
after an hour of warm up the scaling was out .
I have 8 x 921 B and no one doesn't track 1v / Oct.
I made the scaling procedure from the model D, now they track over 3 octaves .

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Re: Behringer System 55

Post by ishi » Wed Jul 01, 2020 6:31 pm

KSS wrote:
Tue Jun 30, 2020 10:43 pm
I hope you will continue to add to your photos on your site.
I just added photos for the 921B:

http://sonectron.nl/?page_id=23
Certainly understand it feels less important than using them,
Haha.. it's been a very busy time. I haven't been in the studio that much this last month. But I'll try to add more modules on a regular basis. And of course I'm also planning to do comparisons with the MosLab.

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Re: Behringer System 55

Post by KSS » Wed Jul 01, 2020 8:02 pm

SkyWriter wrote:
Wed Jul 01, 2020 11:28 am
Good analysis @KSS. In your SFAM design, how much rework of the B914 has to be done?
None.

Still have to see how the theory -educated guesses, really- matches up with reality, but everything points to this answer. And is part of the choice to pursue SFAM's instead of other means to the end.

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Re: Behringer System 55

Post by KSS » Wed Jul 01, 2020 8:04 pm

Ebotronix wrote:
Wed Jul 01, 2020 4:51 pm
921b scaling
correction #2
after an hour of warm up the scaling was out .
I have 8 x 921 B and no one doesn't track 1v / Oct.
I made the scaling procedure from the model D, now they track over 3 octaves .
That's abysmal. Thank ypu for sharing your results.

Uli Behringer, Can you hear this ^?? Or is the Behringer ear and "We hear you" slogan an empty promise?
Last edited by KSS on Wed Jul 01, 2020 8:18 pm, edited 2 times in total.

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Re: Behringer System 55

Post by KSS » Wed Jul 01, 2020 8:15 pm

ishi wrote:
Wed Jul 01, 2020 6:31 pm

I just added photos for the 921B:
Love, love, love the full photo sets. Ya got me with the RH side pic! I mislabeled LHS before noticing the panel controls.:doh:

You know, it's hard to fault these modules on a design basis. They're *really* decent, solid designs Obviously the elcaps aren't first class, and the TH soldering sucks -but will be good enough- and allows the copper under the jacks to be exposed to 'weather'. And the quality of the switches, jacks and especially -given ebotronix reports- the trimmers still needs time to fully assess. But the overall picture of these modules is quite a bit better than I expected given the pricing. Once the issues -like ebotronix's- get sorted, it will be *really* hard not to embrace these fully.
But I'll try to add more modules on a regular basis. And of course I'm also planning to do comparisons with the MosLab.
Looking forward to that. Thank you again for taking time to show and help others. It's appreciated.

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Re: Behringer System 55

Post by galanter2 » Thu Jul 02, 2020 2:52 am

KSS wrote:
Wed Jul 01, 2020 8:02 pm
SkyWriter wrote:
Wed Jul 01, 2020 11:28 am
Good analysis @KSS. In your SFAM design, how much rework of the B914 has to be done?
None.

Still have to see how the theory -educated guesses, really- matches up with reality, but everything points to this answer. And is part of the choice to pursue SFAM's instead of other means to the end.
Please forgive my spotty understanding of electronics…

Looking at the original Moog 914 schematic I don't see how those bandpass filters could be individually tapped without inserting opamp buffers for each before they go to the output "mixer."

But the B914 uses an simulated inductor (gyrator?) I think. Would that, in fact, also act as a buffer to allow each band to be individually tapped and unmixed with the others?

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Re: Behringer System 55

Post by galanter2 » Thu Jul 02, 2020 2:57 am

(FWIW…my taste would be to just get the 14 filters to 14 output jacks, and that's it. I might then add some quad VCAs. I'm not so worried about rack space.)

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Re: Behringer System 55

Post by lorez22 » Thu Jul 02, 2020 2:48 pm

Can someone tell me what the Behringer CP3A-O OSC Controller is used for, to me it looks like a buffered multiple & attenuator with an external in, how would you use it with 4 x 921vc ?

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Re: Behringer System 55

Post by KSS » Thu Jul 02, 2020 6:08 pm

lorez22 wrote:
Thu Jul 02, 2020 2:48 pm
Can someone tell me what the Behringer CP3A-O OSC Controller is used for, to me it looks like a buffered multiple & attenuator with an external in, how would you use it with 4 x 921vc ?
If you look on pg 51 of the moog modular technical service manual, you'll see it's even less than that. one pot, four switches and four resistors.

It exists to provide performability of a system 35 or 55 'modular'. What is sometimes missed about these old moogs is that although they're modular in appearance, they're quite heavily normalled in fact. The two lighted quad switch modules of the originals are ther to replace patchcords.

It's funny -and sad- that behringer have not used any behind the panel connectionm so this module -and its cohort for the filter- uses patchcords to replicate modules that removed patchcords in the original.

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Re: Behringer System 55

Post by KSS » Thu Jul 02, 2020 6:28 pm

clicked quote instead of edit.
Last edited by KSS on Thu Jul 02, 2020 6:44 pm, edited 1 time in total.

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Re: Behringer System 55

Post by KSS » Thu Jul 02, 2020 6:30 pm

galanter2 wrote:
Thu Jul 02, 2020 2:52 am
Looking at the original Moog 914 schematic I don't see how those bandpass filters could be individually tapped without inserting opamp buffers for each before they go to the output "mixer."
It's important to note that Behringer only claim to have replicated the input and output structures. Looking at the right central portion of the PCB's component side, one can see the three output transistors -and one more- along with the elcaps seen in the moog schematic. It's not exactly the same, but looks close enough for them to make the claim. On the left we again see the single transistor and elcaps of the moog input schematic. And again see more than what's shown on that schematic. We know this FFB is not really very close in its topology compared to the original. This brief look only confirms that is true.
But the B914 uses an simulated inductor (gyrator?) I think. Would that, in fact, also act as a buffer to allow each band to be individually tapped and unmixed with the others?
At the risk of shooting myself in the foot, here's the educated guesses. I've not gotten one of these yet, and have worked from the photos shared. The first thing to note is that there are exactly 28 box film capacitors arranged in quad pairs -in two vertical columns- around quad OPAs. There is a pcb trace connection between pairs, and this shows the refdes used by Behringer does not match that used by moog. So we can forget trying to match up the original schematic to this PCB, and have to look at structures only. Now what's just been described outlines 14 filters. Exactly what we need! Turning the PCB over we see that there are test points located -mostly- where you would expect to find individual filter outputs.

Assuming behringer has set up a bed-of-nails test rig, or uses flying-probe ATE to read these test points, it's not a bad guess to expect these to be the individual filter outputs. A sensible mod would use buffers from these points to individual jacks.

Again, they've only claimed to have the discrete input and output structures, which it appears they have done.
Last edited by KSS on Thu Jul 02, 2020 6:43 pm, edited 1 time in total.

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Re: Behringer System 55

Post by KSS » Thu Jul 02, 2020 6:40 pm

galanter2 wrote:
Thu Jul 02, 2020 2:57 am
(FWIW…my taste would be to just get the 14 filters to 14 output jacks, and that's it. I might then add some quad VCAs. I'm not so worried about rack space.)
Sure. Existing quad VCAs could be used. But that changes the use perspective quite a bit along with significantly increasing space required. You've said space issues don't apply, but removing the bulk of the patchcord jungle so the workflow is better may not be something to ignore.

I think anyone with a way to punch the panel holes and good soldering skill could move one or more capacitors, drill some holes and run wires to a buffer PCB, then to the jacks. There's adequate space to do so below the knobs, as shown in my earlier post.

Who wants to send their FFB for this mod?

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Re: Behringer System 55

Post by SkyWriter » Thu Jul 02, 2020 7:16 pm

I'll spring for a B914 for the mods project. But it may take a while by my SE @ sweetwater - fall.

Hopefully the test points are useable. Probably flying probe; too many clamshells, too low volume. Not sure of the costs these days - I'm 5 years out of date, but this close to scrap vs repair, they may be placed more for cost containment than strict circuit functionally. Hopefully the cheap chinese scope I bought that arrives tomorrow, matches the probes to the last cheap chinese scope I bought that's too incomprehensible to use, and I can slowly start to check some stuff out.

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Re: Behringer System 55

Post by galanter2 » Thu Jul 02, 2020 10:18 pm

ishi wrote:
Wed Jul 01, 2020 6:31 pm
KSS wrote:
Tue Jun 30, 2020 10:43 pm
I hope you will continue to add to your photos on your site.
I just added photos for the 921B:

http://sonectron.nl/?page_id=23
Certainly understand it feels less important than using them,
Haha.. it's been a very busy time. I haven't been in the studio that much this last month. But I'll try to add more modules on a regular basis. And of course I'm also planning to do comparisons with the MosLab.
Hi, the first pair of 914 fixed filter bank images are fine, but the second pair of image links seem to be broken.

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Re: Behringer System 55

Post by Ebotronix » Sat Jul 04, 2020 2:36 pm

I don't get warm with the 921 b, it's always out of tune....the 921 VC is much better

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Re: Behringer System 55

Post by ishi » Sat Jul 04, 2020 3:19 pm

galanter2 wrote:
Thu Jul 02, 2020 10:18 pm
Hi, the first pair of 914 fixed filter bank images are fine, but the second pair of image links seem to be broken.
At the moment there is only one pair of 914 FB images.. will post some more.

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