Behringer System 55

[mmckenzie]

Lol! That's a good one! I think I saw it done in the past too. I prefer a new tip at that point :-)

Well yes. You say that, but the floppy squidginess of the heatshrink made it work really well! Although the solder didn't always end up in the tube. I can now change out the T1 pot in no time!

It was the bottom pot on the 911a I had trouble with. It seemed to have a different layout to the 911. There was a tiny track on the top of the board next to the rhs of the pot. Still, I think my bodge has reconnected it back to the pot terminal. It works anyway.

[SkyWriter]

Lol! That's a good one! I think I saw it done in the past too. I prefer a new tip at that point :-)

Well yes. You say that, but the floppy squidginess of the heatshrink made it work really well! Although the solder didn't always end up in the tube. I can now change out the T1 pot in no time!

It was the bottom pot on the 911a I had trouble with. It seemed to have a different layout to the 911. There was a tiny track on the top of the board next to the rhs of the pot. Still, I think my bodge has reconnected it back to the pot terminal. It works anyway.

Whatever gets the job done! Try replacing the cap with a 1uf. You can get those very nice very low attack numbers in the 1-10 ms range to play Amp and Filter envelops against each other. I prefer this range the most. The pads can take several rework sessions once you get the feel. Just watch your soldering an de-soldering temps. It's the front panels that can't take the extra drilling :-) Gonna need another Timmy!

See what you think about the Esus pot now. If you have a scope check the old attack pot against the new attack pot. The OEM pots bounce around when settling. Looking for this same behavior in level setting like pitch modulation should be much easier to tune it in with an ALPHA pot vs OEM. Replacing the Decay and release pots are also a benefit, dialing in low values there is just as difficult.

[KSS]

[Muff McMuff]

Anyone not familiar with the Behringer System 55 modules might think they were a DIY project reading this thread

[KSS]

Well, they kinda are!

[mmckenzie]

Anyone not familiar with the Behringer System 55 modules might think they were a DIY project reading this thread

Ha ha. It's been great to assemble a little system that sort of looks and sounds like the original Moog which I have been dithering about building for the last 40 years. There were just a couple of disappointments which were addressed (1) by using the trimmer adjustments as supplied and (2) changing one pot for a better one for the part of the delay curve I was particularly wanting to use.

Thank you Mr Behringer for allowing my 40 year old dream to be fulfilled. Cheaper than a sports car.

[SkyWriter]

Thank you Mr Behringer for allowing my 40 year old dream to be fulfilled. Cheaper than a sports car.

Ain't it the truth? I'll end up replacing every pot, and still it's a fantastic bargain. And I didn't have to make it all from scratch!

[SkyWriter]

I looking for use cases involving the 911A and 961 On-time.

911A:
- 2-3 ms; attack ensembles for trumpet, steel drum, etc... complex small event timing
- 1/n BPM's; shuffle/swing offset for 960 sequencing
- I don't know where I would use a leading edge only delay for S-trig's in the 1-10sec range.
For the above, I have set my 911A delays to 1/10 standard range. When should I put a switch here for standard range, or even 10X delay for a three range?

961 On-time:
- 40ms-4sec; clearly gate length for the 960, or harpsicord-like, 0 hold-time, keyboard gate treatments.
- 1ms-100ms; these are the 960 gate lengths I would feed into a slew rate limiter for function generator like envelopes.
For these cases, I would provide a 1/40th range speed enhancement, maybe three-way but standard is the slowest. This may require some 960 changes.

[SkyWriter]

Today was a fun with 914 day - so far :0)

I only had ten B25K's with knobs, so I only swapped out ten today. More parts on the way!
I finally caught sight of the structure of the thermal via's surrounding a plated barrels. Important, as the larger card has larger copper ground plane. Haven't studied the stack up, but more copper needs more heat. So tweak your soldering irons up a little bit to tackle this baby. Didn't have an issue with the 961 though.

As always, all changes are Charlie The Ferret approved!

The larger knobs, and better pots let me control the per band feedback better in the quick test. A side by side sometime later will yield better data. I was playing note sequencer with the 960 last night (first time note sequencer - not my thing), did not appreciate tuning difficulties getting a solid value out of the value pots. I'll swap a row out and A/B two rows to decide.

I do like these larger knobs though. I even swapped my doepfer knobs for these. The extra radius helps angular definition - you really need that on these little buggers.

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I can't get the sideway picture to go away. Attachment act so weird here.
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And the verdict is FUN! Yeah, I spent a lot more time playing 914 feedback with the 960. After playing straight feedback, and noticing more stability; I'm using a 902 in the feedback path, and one in the feed forward path, to try to ping and modulate the resonance a bit. And i'm getting nice textures. As you can see from the center frequencies, this is not a precision RC job, it's a bit self-flat in places, but it sounds interesting. Just add it to the list. I wonder if I can drill out and wire up some inductors. It's a good platform for mods. It's not going to give you synchronized bell chimes, but it's got some cool tones going for it that replacing the pots lets you get to quickly now.

"It's more deterministic"; that's a better way of describing most of the pot changes beyond the problems caused by gaps.

Center frequencies I measured - open air, iPhone, peak freq.

[grizzleb]

How doable would some of these mods be to someone who has no DIY experience? Been thinking about trying to put together a boog model 15 but would want to make these improvements!

[SkyWriter]

How doable would some of these mods be to someone who has no DIY experience? Been thinking about trying to put together a boog model 15 but would want to make these improvements!

I spent five years at a tech in my teens-early 20's. That's when I remember the heat-tube trick from. You pick it up very quickly - especially if your own gear you're working on - and most of it never changes. It's like riding a bike.

What you do need are good tools. The de-soldering/soldering iron setup is important to achieving a workable product. I did 10 pots in 40 minutes, and they were giving my trouble today with the ground plane. But once I tune up the temps, they'll fly off - they better fly off if I think I'm going to do three 960's!

Out of all the pots I replaced 40-50? I lost two pads, and that was in the first 3 modules.

If you're patient I wold wait until I'm at least at the end of what I would consider minimal changes to effects large gains. Today, it's the first three modules I attempted 911, 911A, 961. For my 'sound' only the 911 is absolutely essential to modify, and 80% of those purposes may be met by simply reducing the capacitance by 1/2 to 1/3, depending on tolerances, and number of 911's I had. At a minimum I would to do fast 911, and leave the rest stock. And that only required two easy electrolytic cap swaps.

The issue is two fold:
1) first and most important, the 'glue' that holds percussive sounds together is the first 20ms of the Amplitude envelope and a Filter envelope. This range is essentially missing from the stock module. You get a nice 800us attack, then a 11 ms gap of random values, then a 10ms range of hard to hit numbers, then it gets better. A cap change will shift that operable range above 20ms down to the 2ms range, and Bob's your uncle (to 800us goes down too, but I didn't do a cap change only to see what the stock pot presents for resistance).
2) conversely, changing the pot which improves many aspects of dialing in values, only marginally improves the end of track behavior and very low resistance values at the start of the element. There is still a smaller first gap of unattainable numbers after an initial 800us 'dead short', but it starts to behave around 11ms instead.

I think you can do either, or both and get a distinct improvement - for sounds I especially like.

N.B. Crisp snarky attacks have always been a synths achilles heel. And many products succeeded In the face of poor attack. So, YMMV, and you may not even care as long time performance is acceptable. It's all where your head is at. These are only improvements wrt to certain criteria, I am not saying "this stuff's junk without it", on the contrary "it's a kick-ass stating point!". And really is there anyone can truly ask more of from an instrument? Something to lead us on!

Personally, I'm cramming as much stuff as I can into these - just as I would do with the OG Moog modules if had them. The bonus with this kits is that it's so simple to use and modify, I can't NOT do it :-) and this is just a side project. Lol!

[grizzleb]

Thanks for your detailed reply, that all makes sense. I will definitely have a think about that then, maybe even would only need to really think about modding a limited number of modules if any depending on how I get on with the sound out of the box.

[SkyWriter]

Thanks for your detailed reply, that all makes sense. I will definitely have a think about that then, maybe even would only need to really think about modding a limited number of modules if any depending on how I get on with the sound out of the box.

Yeah, that's the idea I hope. @mmkenzie is the standard bearer for the 'one pot swap' pilot. I'm moving forward on many fronts, so I don't check each configuration or one change at a time, in different orders. Hoping folks can describe their experience with the changes to fill in the gaps.

Bring a joint and a good beer to a tech friend, and make quick work of it :-)

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WRT speed toggles, I think I'll do a system panel and aggregate all the timing logic on another module. Then the per 911 changes will be simply to add a two pin connector to the cap pads, then route that 'capacitor timing harness' to a 8/9 channel 4/8HP panel. I can route 8 truck lines from there too. After all, this is System 55 use a systems solution. It's too easy to muck up stock panels with the drills/drill press I have without a nice jig to control things. Too much fine detail - not my speciality!

Hmmm.... maybe good application for just a chopper... nah, caps are cheap. :0)

[SkyWriter]

Ok, here’s a link to soundcloud file. Inline recording of fast 911’s into feedback 914.

So it’s a fade into the source sound then I raise the feedback path To resonance. I had already preset the bank levels - which is the advantage in the 914 pot upgrade. The banks needs tuning - big time.


I don’t have much referents than my previous unmoderated 914 (an improvement) and a Sweetwater Model 10/15 demo. It performs fairly well for an RC.

Same exciter, now I bring up each bank to near resonance one by one.





Wow, that last one sounds really good. Trying to gain stage it out so the feedback mixer doesn’t clip. Sooo cool! Hella improvement for me.

[galanter2]

I suspect others may feel like I do...appreciative, but buried in details.

Regarding the 914, could you summarize why one would want to change the pots?

[SkyWriter]

I suspect others may feel like I do...appreciative, but buried in details.

Regarding the 914, could you summarize why one would want to change the pots?

This is my engineering logbook. :0) I’m messy that way - better to put too much than not enough.

Simply put, the stock potentiometers lack the ability to accurately translate your motion turning the knob into a proportional tracking change in a corresponding resistance. Have you ever drove one of those fair ground kiddy 2-stoke lawn mower engine car rides where the car is on a captive track and the steering wheel linkage and front wheels have literally no connection?

Trying to turn a circuit with multiple resonances, where each bank influences the other banks resonant point with a potentiometer that you fine control is entirely unpredictable. You want to be able to dial it right in, no overshoot, no under-compensate.

Does that make some sense?

The potentiometer construction of all behringer pilots seem to have fine control selectively and non-monotonicity problems. Granted, you may never notice why it’s hard to get the sound you want every time. Or notice that it is hard.

This is important to say: This is eurorack, I have a 5U mentality. I am a retired engineer. I have test equipment - a scope, and I use it, I turn everything into an engineering project. Nobody has to do any of this to enjoy Behringers stock product. It's crazy good fun as it is. After all I bought it first! It's so good, I want to make it better. I feel all of these are improvements; except the resonance, I can't find a problem with it the way it is now but maybe a later development will reveal something.

I'm just having fun, and sharing my results that would benefit those that like what I do.

There’s going to be stretches here and there. But I’ve had this issue even with the 960 pots trying to tune a note sequencer on 2X. If I can bolt-on a better part, I’ll do it. It’s nothing for me to do it. So even small issues get their triggers pulled.

[KSS]

I looking for use cases involving the 911A and 961 On-time.
- I don't know where I would use a leading edge only delay for S-trig's in the 1-10sec range.
For the above, I have set my 911A delays to 1/10 standard range. When should I put a switch here for standard range, or even 10X delay for a three range?

Generative. Ambient. Environmental. 'Noise'. Cross modulation. All these benefit from having longer delays available. In general I think you'll see the answer by thinking in terms of "song" or "performance" timing rather than "voice" timings.

[galanter2]

I suspect others may feel like I do...appreciative, but buried in details.

Regarding the 914, could you summarize why one would want to change the pots?

This is my engineering logbook. :0) I’m messy that way - better to put too much than not enough.

Simply put, the stock potentiometers lack the ability to accurately translate your motion turning the knob into a proportional tracking change in a corresponding resistance. Have you ever drove one of those fair ground kiddy 2-stoke lawn mower engine car rides where the car is on a captive track and the steering wheel linkage and front wheels have literally no connection?

Trying to turn a circuit with multiple resonances, where each bank influences the other banks resonant point with a potentiometer that you fine control is entirely unpredictable. You want to be able to dial it right in, no overshoot, no under-compensate.

Does that make some sense?

So you’re saying as you turn the knob sometimes you get a lot of change, and in some other positions not as much? And you are trying to even that out?

[SkyWriter]

So you’re saying as you turn the knob sometimes you get a lot of change, and in some other positions not as much? And you are trying to even that out?

Sorry, I always need to put it in context.

Hmm, I thought I posted this image. This is what the OEM pot looks like to me.

There are three 'dead' zones that cause problems:

- lower, counter clock wise, dead zone: causes a gap in attainable 911 timing in the 800us to 11-20ms timing range. You can't reliably set timing in this range.

- middle dead zone: causes a gap in the attainable timing in the 400ms to 1sec timing range. You can't reliably set timing in this range.

- upper, clock wise, dead zone: causes a gap in the 923 attainable cutoff frequency at the top of the dial. Sounds like a jump in CF.

This is a normal plot of the resistance over the rotation of the dial. It's called a taper plot. Only the 15A plot is of interest here.

That's the initial finding that led to a series of findings. IMHO, only the 911 attack timing hobbles the System 55 product for me. the rest of the changes are for completeness - my completeness. :-) I want to use System 55 as a reference, so I need my rig to be as accurate as it can be, and I can do that - with help :-) - writing it down helps folks that would like to improve the performance of their rig too.

Does that help?
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The bottom like is cost reductions always show up somewhere, this is where it shows up in this one. Nobody has to modify it to enjoy the product. Many, many other products have issues like this from other manufacturers too.

[SkyWriter]

I looking for use cases involving the 911A and 961 On-time.
- I don't know where I would use a leading edge only delay for S-trig's in the 1-10sec range.
For the above, I have set my 911A delays to 1/10 standard range. When should I put a switch here for standard range, or even 10X delay for a three range?

Generative. Ambient. Environmental. 'Noise'. Cross modulation. All these benefit from having longer delays available. In general I think you'll see the answer by thinking in terms of "song" or "performance" timing rather than "voice" timings.

Ok, got it. The fact that it only delays the leading edge of S-trigs, and not the trailing edge seemed to limit it. A real 'pended' event-neutral delay would have more utility.

[KSS]

In delays of that length gate time would typically be set 'locally' with something like the Roland 717 SEQs Pulse Shaper. Which is a very simple circuit well-suited for a DIY dual unit in a moog-Boog-5U setup. Alternatively use an EG -w/or w/o comparator and-or slope detector, flipflop, latch, sequential switch, ASR, etc.

There's enough time between the first event and the second that -at least in old analog days- you'd not expect to require the original gate time be preserved. If you did, tape could be used creatively. Or more complex patches can be employed.

If you need to preserve a gate length over a relatively long time for re-use, you can utilize an EG with suitable -slow- attack time in conjunction with a S/H sampling the EG out at gate end to store the gate on time as a voltage level. Then when you need the time again the S/H out is fed to a Lag-comparator combo -by the delay pulse. The comparator re-creates the gate as the lag decays back to low level. The S/H used can be an ASR.

Of course doing this digitally is a doddle.

[SkyWriter]

Excellent @KSS! Thank you!

I see, I was expecting something a bit more visible like the delayed-vibrato use case. So, basically an operator for 'pulse' stretching, etc... nice. A three position speed switch makes sense here as well. Probably the 961 too - someones going to use a 100sec on-time :-)

Legato should be an interesting solution too!

Yes, digital and modern do-everything-modules obfuscate the low level mechanics born of the System 55.

Today, I'm looking at how a pot change improves the Frequency tuning control response on the 921, A and B.

Perhaps a video of the old pot vs new pot on the 911 would help?

[SkyWriter]

Today, I'm looking at how a pot change improves the Frequency tuning control response on the 921, A and B.

So, well. Guesses anyone?

Tuning with the OEM pot is like, get close, nudge it a bit one way.. too much!.. nudge the other way.. little more.... ugh, little over now...touch.. touch.. touch.. there got it. The knob is loose to the touch, easy to turn, indefinite in value once you stop. The knob has hysteresis, the linkage is loose. It's a control where the final position is less important than the fiddling you do to get it there.

The ALPHA pot, is firm accurate. I dial the tune in, a little high, back it off a little. There, perfect. Every time.

I changed the 921 and the 921B Frequency control in one unit each to compare with an unmodified unit. Like all these knobs, the difference is night and day. But, I want to emphasis this is an improvement only, it's certainly possible to use these in stock condition. It's just more work. This is pretty much the experience for any of the linear pots that are level controls; after the change you get superior selectivity and predictability. A larger knob will improve performance here too, where it doesn't help with the OEM pot.

Definite improvement!
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RE: toggle timing panel, can also incorporate 993 trigger/envelope switch functions in toggle mode too.

[galanter2]

So you’re saying as you turn the knob sometimes you get a lot of change, and in some other positions not as much? And you are trying to even that out?

Sorry, I always need to put it in context.

Hmm, I thought I posted this image. This is what the OEM pot looks like to me.

There are three 'dead' zones that cause problems:

- lower, counter clock wise, dead zone: causes a gap in attainable 911 timing in the 800us to 11-20ms timing range. You can't reliably set timing in this range.

...
Does that help?
-------------------
The bottom like is cost reductions always show up somewhere, this is where it shows up in this one. Nobody has to modify it to enjoy the product. Many, many other products have issues like this from other manufacturers too.

So you aren’t talking about changing the pots on the 914 filter bank, you are talking about changing the pots on the 911 envelope generator, and the advantages that yields when used with a stock 914 filter bank?

[SkyWriter]

So you aren’t talking about changing the pots on the 914 filter bank, you are talking about changing the pots on the 911 envelope generator, and the advantages that yields when used with a stock 914 filter bank?

I have talked about changing at least one pot on each of; 911, 911A, 961, 960, 914, 921, 921B, 921A, 923, 902, etc...

I have changed many pots with a demonstrable improvement in performance, including 911 and 914 specifically.

Some pots really don't make measurable difference.

Nobody has to change any pots. The kit is fine the way it is.

However, if one wanted change a pot. The T1 pot on the 911 would be the best opportunity to gain some respectable performance for your trouble.