Behringer System 55

Cwejman, Livewire, TipTop Audio, Doepfer etc... Get your euro on!

Moderators: Kent, Joe., luketeaford, lisa

Post Reply
User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Behringer 914

Post by SkyWriter » Mon Oct 26, 2020 7:30 pm

Ok!

Just want to remind folks that Rob (https://amsynths.co.uk/home/my-synths/s ... r-replica/) has done a wonderful job of framing up individual module circuits improvements. Definitely see caps in my future :0)
Prologue 16 - an adventure worth having!

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Tue Oct 27, 2020 8:11 am

Speaking of caps and the B914 I'm striping today; I read Rob's filter write-ups comparing Behringer's filter implementations to several OG versions. What I got out of it was it is important matching caps in a ladder filter, and there are several ranges of values might that work.

I haven't explored the filter design yet. Looking for some tips on what authoritative references are out there to research into improvements to Moog ladder filter.

Just to summarize we have:
- 7 TL074 packages. 2 opamps per filter banks and shelving filter.
- various sets of caps for ladder filter
- resistors for same
- 14 B25K pots.
TL074's are pretty good. There are pin for pin replacements worth exploring, but would like to characterize the application rather than shotgun subjective improvements.
Caps and resistors are a primary focus for this go-around.
Pots (and knobs) are covered already. :-)
=======
Hmm... anyone tried an IV curve tracer scope to compare these guys? Those things were great at comparing circuits. Also great for debug :-)

20 minutes later:
6B729BEB-DB6E-461F-9ABA-BAFD4671EA98.jpeg
Getting quicker! Pulling the polystyrene caps next. Don't like the bend angle on the leads though. 960 here I come!
======
Starting to get the picture :0) https://www.allaboutcircuits.com/search?q=Moog+filter math yay!
Prologue 16 - an adventure worth having!

User avatar
emuarc
Common Wiggler
Posts: 197
Joined: Sat Oct 02, 2010 4:23 pm
Location: Horsham, West Sussex
Contact:

Re: Behringer System 55

Post by emuarc » Wed Oct 28, 2020 4:29 pm

Hi,
The stock 914 does sound very good and the SMD caps in the upper frequencies are fine, not harsh. The next level up is matched polypro and polystyrene caps, maybe with OPA4134’s. To do polystyrene caps in the HF bands really means a new PCB and some careful meaurement of the SMD values, although there will be gains in swapping out polyester to polypro in the lower frequencies.

The 904A is easier to upscale and I am using a daughter board to hold 12 matched polypro caps, and to cable into my 904C.

905 Reverb and 984 Matrix Mixer (from the IIIP) are in design and the 993 is done and works very well, along with 911’s with LEDS. Dual Ring Mod is completed and the S&H is on the way.

A big thanks to the Behringer team in Manchester for creating fantastic modules.. :hail: :hail: :hail:
Rob Keeble
Owner & Designer
AMSynths

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Wed Oct 28, 2020 5:05 pm

emuarc wrote:
Wed Oct 28, 2020 4:29 pm
Hi,
The stock 914 does sound very good and the SMD caps in the upper frequencies are fine, not harsh. The next level up is matched polypro and polystyrene caps, maybe with OPA4134’s. To do polystyrene caps in the HF bands really means a new PCB and some careful meaurement of the SMD values, although there will be gains in swapping out polyester to polypro in the lower frequencies.

The 904A is easier to upscale and I am using a daughter board to hold 12 matched polypro caps, and to cable into my 904C.

905 Reverb and 984 Matrix Mixer (from the IIIP) are in design and the 993 is done and works very well, along with 911’s with LEDS. Dual Ring Mod is completed and the S&H is on the way.

A big thanks to the Behringer team in Manchester for creating fantastic modules.. :hail: :hail: :hail:
Smashing! I've cleared most of the field in a few spare moments. I'll order up the caps and OPA's tomorrow or so. I hear you about the upper registers, I have to end this someplace reasonable. The caps and pots were a snap. These SMT leadframes are still within my ancient skills :0)
D8320517-B0A2-4E6D-B85C-0E632B35E31F.jpeg
We'll see what we get. I do have to buzz this out for a schematic though... that'll take some time. I don't have the luxury of just glancing at it this time.

I'm saving the 904's for last. :0) appreciate all the review and upgrade tips you posted on your blog. Awesome stuff :0)

Indeed Manchester! Thank you! Super job! This is the most fun I've had in years :0)
======
Moved photos to next post.
Last edited by SkyWriter on Thu Oct 29, 2020 6:33 am, edited 1 time in total.
Prologue 16 - an adventure worth having!

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55 914

Post by SkyWriter » Thu Oct 29, 2020 6:32 am

Edit and move to new post. I have real problems trying to read the traces with these colors.

Top and bottom ground plane removed* for less visual noise.
870C2DFB-796A-4C96-B107-792620F47F04.jpeg
719AE58B-14BC-4468-B66B-60266E2D2A6F.jpeg
*-YaY! Procreate on iPad does wonders. I flipped the backside horizontally so you don't have to flip it in your head to follow traces from front to back.
Prologue 16 - an adventure worth having!

User avatar
olix
Common Wiggler
Posts: 60
Joined: Sat Apr 01, 2017 10:42 am
Location: Paris

Re: Behringer System 55

Post by olix » Fri Oct 30, 2020 12:22 pm

KSS wrote:
Sun Oct 25, 2020 12:49 pm
Did I not give enough 4MS Pod details?
It's a much shallower option than the Doepfer. If that matters.
Yes, the 4ms Pod is only 34 mm depth, not enough for the 914 (42 mm).

User avatar
KSS
Super Deluxe Wiggler
Posts: 4069
Joined: Mon Jan 25, 2016 7:28 am

Re: Behringer System 55

Post by KSS » Fri Oct 30, 2020 12:50 pm

Thank you for that feedback, olix!

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Fri Oct 30, 2020 1:53 pm

Just finished the pot+knob swap on a 960. Lost one pad - had to top solder the pot lead. I've started to switch up my desoldering tips with this job. An 0.8mm tip works well with the pot leads - it just slips over so there's nice lead contact and good hole coverage. It will clear the grounded leads with thermal reliefs first time - just use the same temp and dwell time. For error free work like this, always write your dwell and temps. It's worth not losing some work. The solder tails on the pot strain relief require a leader tip to accommodate the larger tail - here I use 1.6mm. It's a bit oversize, but I like to 'wring' the lead while I clear it. Keeps the solder from recontact with a weak joint so it'll pull easier. Use a very fine needle nose pliers to 'shake' each lead, breaking any recontact. They fall out like rotten teeth. This took 20 minute sessions to clear all the pots - had an interruption. Total time was about 1:30 hours for the whole thing including knobs and screws. Putting a pot in is about as long as taking it out once you factor in the rework.

Anyway! Pots constant tension helps final positioning. Larger knob increases angular resolution. First pass test found the 960 easier to setup the channels, and only one pot is off from the others - I'll check it out later. Time to rest my aching back :-)
85422847-8FC4-46BD-A214-75C3B9AF4B9D.jpeg
B3A9E174-F0BB-4608-8DD5-3CBC6E172400.jpeg
49ED7013-B3F9-4EA2-9816-859902B72201.jpeg
Note the finer pitch etch. Much denser routing. Didn't look closely yet, anything could be there!
Did not check the stack-up either, but doubt they added a layer from the cost alone.
=======
Well! I DO like the change. I can just dial in the note - guitar tuner and keyboard to fetch the reference note, and pretty much dial, overshoot, undershoot, done. No more, nudging and brushing the knob into place. I know it's modern to use a quantizer - I just enjoy the ride as much as the destination :-)

So sooth, there are still aberrations to address, although I do need to go through calibration before looking for another problem to have to fix. Lol.
Prologue 16 - an adventure worth having!

kwaidan
Super Deluxe Wiggler
Posts: 1822
Joined: Sat May 12, 2012 3:14 pm

Re: Behringer System 55

Post by kwaidan » Fri Oct 30, 2020 9:00 pm

olix wrote:
Fri Oct 30, 2020 12:22 pm
KSS wrote:
Sun Oct 25, 2020 12:49 pm
Did I not give enough 4MS Pod details?
It's a much shallower option than the Doepfer. If that matters.
Yes, the 4ms Pod is only 34 mm depth, not enough for the 914 (42 mm).
I mounted a 914 in a 32hp Pod with no problems. It’s one of the original, shallower models.

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Sat Oct 31, 2020 11:01 am

FWIW, I forgot to mention on the where used sheet for pots that the 1B103 is a DUAL GANG pot. We covered this earlier, but I didn't mention it on the sheet, and consequently forgot to order the parts. There goes another week! :-)
1F45129E-ABE3-499F-98EF-07473AAF4414.jpeg
Worked on mixer, 902's, and another 921B frewq knob. CP3A-M works much better for CV purposes now. Even better with the Master control has the right part. Lol. Freq control much better. Reviewing the 902.

Now that I'm down to the plumbing, nothing flashy to show left. But here's some more rework hints.
- use a 1.6mm desoldernig tip for package solder tails, and a 0.8mm for potentiometer leads. These will suck them out first time everytime with a 3 second dwell time for leads and 4 sec with tails.
- some pots are very close to the power connector. You can slip these connector header off the pins. There's insufficent clearance for some types of tooling. Better to do it right than scrape plastic off your irons.
- some panels you can flip over and use as a little work table for your PCB :-)
6994C569-D37C-4E66-8D10-F24863895111.jpeg
Couple of people have asked for some sort of demo of the pot difference. I'll put something unimpressive together soon. Lol.
Prologue 16 - an adventure worth having!

lorez22
Learning to Wiggle
Posts: 18
Joined: Thu Jun 09, 2016 1:10 pm
Location: Scotland

Re: Behringer System 55

Post by lorez22 » Sat Oct 31, 2020 3:32 pm

Interesting work your doing skywriter , I'm not sure that my soldering skills are good enough to do this, I'm still putting together my 'Big BOOG' still need a few modules to finish it off, and hoping that Uli will make the Bode frequency Shifter , Reverb and filter coupler.
123399755_3649971701721283_960036549277247153_n.jpg

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Sat Oct 31, 2020 4:09 pm

lorez22 wrote:
Sat Oct 31, 2020 3:32 pm
Interesting work your doing skywriter , I'm not sure that my soldering skills are good enough to do this, I'm still putting together my 'Big BOOG' still need a few modules to finish it off, and hoping that Uli will make the Bode frequency Shifter , Reverb and filter coupler.

123399755_3649971701721283_960036549277247153_n.jpg
That's really coming together! I see you got a couple of 960's going up there :-) nice! Once they get in stock state-side, I'll grab a couple more - they work great - cross-coupling them should be fun!

I doubt a useful filter coupler can be made doing it their way - exposing the back-side connections on the front panel*. It's mostly a big switch and a couple of dials and some voltage dividers and buffers, but so is the 921A, and the CP35, and well 1/2 the other modules I guess :0)

*-with 2500 apparently "they way they're going to do keep doing it"; all stand alone modules with front-side connections. Sort of a de-systemized version.
Prologue 16 - an adventure worth having!

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Mon Nov 02, 2020 5:51 pm

I love Monday's, always so productive. Did a little work after my afternoon nap :-)
B80B81AD-338E-479D-84A4-6F6B6B9B106A.jpeg
@KSS, plenty of room for switches and junk behind a CP35 :-)

Mostly done with pot swaps. When the dual gang come in I'll finish off the mixers and VCO's.

Dead soldier pile so far:
27A31FDF-5C6D-492E-B5B7-C9671B6288A7.jpeg
Friday a Behringer Poly D comes in! Pot swap's in store there as well - for some other message board of course... - since those friggerty "Foot Pedal" pots seem to be in everything. I was going to wait for MonoPoly to check it out. So this is a dry run... anyone want to buy a pot swapped Poly D when I'm done with it? :-) I've had lots of practice! I was even a factory tech in the 70's at DEC. So it's a professional job. lol!
Prologue 16 - an adventure worth having!

User avatar
emuarc
Common Wiggler
Posts: 197
Joined: Sat Oct 02, 2010 4:23 pm
Location: Horsham, West Sussex
Contact:

Re: Behringer System 55

Post by emuarc » Tue Nov 03, 2020 4:19 pm

The AMSynths 993 module is up and running, with LEDs in the 911’s, no patch cables here...904C and 984 next

Image
Rob Keeble
Owner & Designer
AMSynths

lorez22
Learning to Wiggle
Posts: 18
Joined: Thu Jun 09, 2016 1:10 pm
Location: Scotland

Re: Behringer System 55

Post by lorez22 » Tue Nov 03, 2020 4:38 pm

emuarc wrote:
Tue Nov 03, 2020 4:19 pm
The AMSynths 993 module is up and running, with LEDs in the 911’s, no patch cables here...904C and 984 next

Image
how can I get one Rob?

User avatar
KSS
Super Deluxe Wiggler
Posts: 4069
Joined: Mon Jan 25, 2016 7:28 am

Re: Behringer System 55

Post by KSS » Tue Nov 03, 2020 6:57 pm

Looks Great, Rob! :tu:

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Tue Nov 03, 2020 8:28 pm

Wow! That is some slick work :-) if/when you productize it, count me in for first batch!
Prologue 16 - an adventure worth having!

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Wed Nov 04, 2020 10:35 am

Welp, I'm 96.2%* done with pot/knob swaps. Just waiting on the four dual-gang CP3A-M Master controls.
A9137E81-9A53-4163-A875-60BECC469C4E.jpeg
Couple observations:
- Of the three types of knobs; set screw, d-shaft, T18, the set screw are the best. The d-shaft knobs on the OEM pots don't have enough grab at the proper knob depth. And the T18's are hard to align. The screw set screws go on easy, and continuously adjustable rotation and depth. I use two strips of cut up credit card taped together as a depth gauge. Although the D-shaft on ALPHA knobs do fit snuggly, at identical cost, I would go set screw.
- Tuning is a breeze. The fluid bearing tensioners have non-uniform tension - the worst of which is at low velocity where viscosity is minimal there is no tension. As a result, when my fingers leave the knob, unless I'm very careful I'll impart a slight off-axis deflection, and out of tune it goes. Then I have to nudge and brush it back into place. Annoying.
- The ALPHA mechanical bearing exhibits moderate uniform tension at all speeds. As a result, the controls stays put as soon as I reduce angular force. This aids in all pitch related controls either through direct manipulation of CV modulation, or any other use cases involving fine pitch accuracy.
- The 16mm set screw knob aids in increased angular resolution, providing finer control positioning, while not imparting destructive torque to a high wear electro-mechanical component; common points of reliability failures. With proper depth control, much of the original panel vernier is still visible.

- I can see the pointer now. :0)

- There's still plenty of grab space left for getting to the knob, although it is less than before. But this is eurorack. :miley:
- Use the right tools, correctly, and it's a very easy upgrade. I spent about 1-2 hours four times a week or so.
F3C19E79-02EC-4AE0-A7A3-22EFE30FC4FA.jpeg
So, now that the majority of the mechanicals are done; time to do a set of 911's, and start tackling the caps and IC issues.

*-103 out of 107 dials.
Last edited by SkyWriter on Mon Nov 09, 2020 7:39 am, edited 2 times in total.
Prologue 16 - an adventure worth having!

User avatar
KSS
Super Deluxe Wiggler
Posts: 4069
Joined: Mon Jan 25, 2016 7:28 am

Re: Behringer System 55

Post by KSS » Wed Nov 04, 2020 11:06 am

SkyWriter wrote:
Wed Nov 04, 2020 10:35 am
The screw screws go on easy, and continuously adjustable rotation and depth. I use two strips of cut up credit card taped together as a depth gauge.
While you've got the credit cards out -or a Thin PE cutting 'board', grab a leather punch and make some plastic pellets to go between the s/s and pot shaft. That way you dn't have to woek against the raised portion the setscrew creates when-if you want to remove a knob. And it's not like these are getting the kind of use that reequires that sort of securing anyways. Of course that raised portion is *supposed* to be handled by an appropriately located flat on each knob. But i'm betting you're not going to do that? ;)
------------------

Janes Husted -ersatzplanet- and I have often brought up the issue with T18's AKA "knurled" pot shafts. The mfr has to put ALL the pots in a 0,180 OR 90,270 orientation. Else you end up with knobs a half 'click' off. T36 in the knob fixes the problems but *may* not stay on as well. <-- when made well, there's no effective difference for pots, but for Rotary switches there can be, due to the greater expected and actual torque. And T36 are usually an MOQ thing.

Nice to see it all coming together and that it seems to have been well worth the effort! Thanks again for sharing your processes, conclusions and results!

:tu:

User avatar
KSS
Super Deluxe Wiggler
Posts: 4069
Joined: Mon Jan 25, 2016 7:28 am

Re: Behringer System 55

Post by KSS » Wed Nov 04, 2020 11:23 am

The fluid bearing tensioners have non-uniform tension - the worst of which is at low velocity where viscosity is minimal there is no tension. As a result, when my fingers leave the knob, unless I'm very careful I'll impart a slight off-axis deflection, and out of tune it goes.
So good to see someone explaining this clearly. It's not well understood based on posts wondering and disliking pots that rotate when they shouldn't.*

The other place this comes into play is when a patch cord brushes across a knob of the fluid damped type. But we need to be careful not to mistake *poor* fluid damping with the results that *can* be had -and *are* had dailiy by military areound the world!
As always, details matter.

MW member paults -with extensive mfg experience in the audio realm- has said that the actual 'liquid' being used for damping in cheap pots is plain old petroleum jelly. Which jibes with your actual case notes.

I *do* wonder if using a better grade of *real* damping grease would help? You've certainly got a few fallen soldiers with which to give it a shot.
------------------
I know that Song Huei does not use Petroleum jelly. They use Fumio 350, which is an actual lubricating damping gel-grease.

*Need to add that there's another typs and reson for such unwanted rotation, and that's the incredibly slick surface of conductive plastic pots of decent quality. A different reason and by now kind of accepted -and even preferred- for that style pot by many who use them. Funny how a problem becomes an asset when it appears there's no other solution! We hate CP pots low rotation but we love their life and precision. Hint. They too can benefit from proper damping grease

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Thu Nov 05, 2020 1:44 pm

KSS wrote:
Wed Nov 04, 2020 11:06 am
Nice to see it all coming together and that it seems to have been well worth the effort! Thanks again for sharing your processes, conclusions and results!

:tu:
No, no, Thank you! And everyone else, for sharing their insights and plans as well :-) I'm really happy with a fully re-potted System 55. Much easier to balance CV's on a CP3 mixer, and tuning! My gosh! The 960 is actually fun to use - even without a quantizer. And finally, I can see what I'm doing too. Lol!

Still have a long punch list left. Plus, found exactly the same issues on the Poly D - so that's a another project too.

I get what you mean about the fluid bearing. It feels nice, and you'd think it would be good for handling. Definitely a high frequency damping oooze is helpful, but it doesn't go anything for low frequency response. Where have I heard something like that so many times before??? :0) Yet, on the scope, you see it that doesn't do what you think; it drifts at the end.

This picture sums up the mismatch between outward appearances, and unseen limitations.
CC34199F-B26F-46F0-8987-DE30A87E8084.jpeg
Lift those restrictions, and now we can get some work done.
Prologue 16 - an adventure worth having!

User avatar
emuarc
Common Wiggler
Posts: 197
Joined: Sat Oct 02, 2010 4:23 pm
Location: Horsham, West Sussex
Contact:

Re: Behringer System 55

Post by emuarc » Sun Nov 08, 2020 4:25 pm

The AMSynths AM904A Daughter board replaces the Behringer filter caps with larger value polypropylene,matched caps, to recreate the Moog IIIP 1967 low pass filter. The filter resonance has improved, with resonance down to 40Hz and a 3rd harmonic in self oscillation, low end response has also improved, plus the PCB enables the 904C Filter Coupler to be patched in. A very enjoyable upgrade!

Image

I will post an audio demo next week..
Rob Keeble
Owner & Designer
AMSynths

lorez22
Learning to Wiggle
Posts: 18
Joined: Thu Jun 09, 2016 1:10 pm
Location: Scotland

Re: Behringer System 55

Post by lorez22 » Sun Nov 08, 2020 5:21 pm

emuarc wrote:
Sun Nov 08, 2020 4:25 pm
The AMSynths AM904A Daughter board replaces the Behringer filter caps with larger value polypropylene,matched caps, to recreate the Moog IIIP 1967 low pass filter. The filter resonance has improved, with resonance down to 40Hz and a 3rd harmonic in self oscillation, low end response has also improved, plus the PCB enables the 904C Filter Coupler to be patched in. A very enjoyable upgrade!

Image

I will post an audio demo next week..
Fantastic work Rob, will these be available to buy?

User avatar
Tboy
Learning to Wiggle
Posts: 41
Joined: Wed Apr 18, 2018 2:54 am
Location: Earth

Re: Behringer System 55

Post by Tboy » Sun Nov 08, 2020 5:55 pm

Bob Borries wrote:
Thu Sep 17, 2020 6:08 pm
The Boog 55 modules won’t fit in the non-powered Behringer 104 Hp case (1.5” depth) I have to buy the Moog 104 case (1.9” depth) instead! The CP1A PSU module and 921B modules are 1.9” deep, get out the lube, it’s going to be a tight fit.
That’s weird, in Europe the Behringer 104Hp case is also sold as a set with the CP1A module, and actually shown in images, so that should fit in that case?

User avatar
SkyWriter
Wiggling with Experience
Posts: 342
Joined: Fri May 16, 2014 6:18 pm
Location: Absolute Elsewhere

Re: Behringer System 55

Post by SkyWriter » Sun Nov 08, 2020 6:00 pm

Nice work Rob! I have two orders for you. I have my filters in the deeper cab area already and waiting. :-)
Prologue 16 - an adventure worth having!

Post Reply

Return to “Eurorack Modules”