Behringer System 55

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Re: Behringer System 55

Post by SkyWriter » Fri Oct 16, 2020 2:30 pm

To faithful readers everywhere:

- It's just as easy to choose doepfer for your envelope needs if just you're starting out. I don't recommend anyone to buy this gear to upgrade it yourself - unless that's something you like to do on a regular basis and can suffer the loss of warrantee. You break it you still own it, and it's easy to ruin these if you don't have experience.

- I only send back gear I have not modified or played with in any way. I specifically did not monkey around with the DOA 921 before returning it. I don't want folks to attempt any of this and end up sending it back when they break it. I spent many years as a tech, I don't want to add to anyone misery. Ok?
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Re: Behringer System 55

Post by galanter2 » Fri Oct 16, 2020 2:35 pm

OK, my apologies, but I’m going to have to try one more time. You’ve explained why I might want to change a pot on the 911. You’ve explained what is wrong with the stock pots in general.

What I’m asking is what I would notice as a user as an improvement if I changed pots on my 914.

(Sorry if I’m being thick. Having a forest for the trees problem here.)

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Re: Behringer System 55

Post by SkyWriter » Fri Oct 16, 2020 2:52 pm

galanter2 wrote:
Fri Oct 16, 2020 2:35 pm
OK, my apologies, but I’m going to have to try one more time. You’ve explained why I might want to change a pot on the 911. You’ve explained what is wrong with the stock pots in general.

What I’m asking is what I would notice as a user as an improvement if I changed pots on my 914.

(Sorry if I’m being thick. Having a forest for the trees problem here.)
Oh! I'm sorry. Sometime I get wrapped around the semantics of what's in front of me. :-) tunnel vision I guess.

You're a little ahead of me, I only started the 914 yesterday. No, I don't recommend* changing the 914.

It depends on what the use cases surrounding what the deficiency of each the control are. In the case of 911, the pot prevented an entire range of sounds that I like to play with; fast percussive tonalities in the 1ms to 13ms range. In the case of 914, it's merely operational efficiency. You can still use this 914 that way it is, you just might have to work at it more for certain adjustments. Same with the Frequency controls on the 921's; you can still tune them in stock condition. It's just a little bit better with a better pot.

Remember, "The enemy of good is better" - if you like what you have. You're all set!

I'm not trying to point out deficiencies as much as explain and address these that folks do find. To tell the truth, I don't hear anyone else talking about it. So it's either a fringe phenomenon or I've use up al the oxygen around it :-) lol.

*-but I will still do it. It costs me nothing to do this. And I'm super picky.
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Re: Behringer System 55

Post by SynthBaron » Fri Oct 16, 2020 2:56 pm

Has anyone figured out yet if it's a true 914 clone using the same sort of circuit topology just not using inductors (like JH did here http://jhaible.com/legacy/ffb/fixed_filter_bank.html), or is it just simple bandpass filters? The amount of circuitry on-board probably indicates the latter...

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Re: Behringer System 55

Post by galanter2 » Fri Oct 16, 2020 3:26 pm

SkyWriter...thanks!

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Re: Behringer System 55

Post by SkyWriter » Fri Oct 16, 2020 9:24 pm

SynthBaron wrote:
Fri Oct 16, 2020 2:56 pm
Has anyone figured out yet if it's a true 914 clone using the same sort of circuit topology just not using inductors (like JH did here http://jhaible.com/legacy/ffb/fixed_filter_bank.html), or is it just simple bandpass filters? The amount of circuitry on-board probably indicates the latter...
From what I've learned:

B914 appears it just 12db/octave passive RC bandpass filters.

The 823 uses a 6db/octave RC filter.

Jha uses gyrators instead of inductors.

Moog used inductors.

All 914's should be 12db/slope.

Maybe a Moog grey beard can authenticate?
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Re: Behringer System 55

Post by KSS » Fri Oct 16, 2020 9:28 pm

SkyWriter wrote:
Thu Oct 15, 2020 12:17 pm
============
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.
Don't neglect the effect of those long wires as they run in parallel to various switches and-or timing caps! You're introducing resistance, inductance, capacitance, and potentially cross-talk with this choice. Right at the very core of the circuit.

The early ARP 2600s LFO caps had shielded wires and all three caps were next to switches on the same PCB. About 3-4 inches. In later versions one cap was moved 3 inches and the shielded cables were eliminated. And it does make a difference.<-- I do expect some will argue this.
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!
Buy a drill bushing. You only need one or two sizes. Then drill a hole -even a crappy one, with a crappy drill press or even a hand drill- in a piece of wood for the drill bushing outer diameter. A narrow long 'stick' shaped piece of wood is probably the best for this. It allows more variety in clamping positions.
Push the bushing into the hole and use whatever glue makes sense to keep it there. This will depend on how well you make the hole, type of wood, etc.

There's your jig. Easy-peasy. Doesn't have to be nice.

Clamp it to the panel with a couple small c-clamps. Now even a hand drill is -can be- as accurate as any milling machine. The bushing will guide the bit true and location is fully determined and assured ahead of time by how you position the wood and clamp it tothe panel. Just get the location where you want it before you drill the hole-s. To do that, take the drill bit by itself in hand and spin it a little against the panel when you think your jig is clamped close to where you want it. The small mark made will be removed by the actual drilling, and now lets you know how close or far you are from where you want to be. Adjust, retry until you've got it just where you want-need it.

Drill bushings may be had with or without a stepped outer diameter. Either will work, but the step type helps perpendicularity of the result if your tools or skills are poor. The stepped outer diameter also gives a place for epoxy or thick CA type gluing to resist rotation of the bushing which can happen as you use the jig over time. When you want to re-use the bushing, heat will help you release the glue. The bushing itself is hardened and as long as you don't go crazy with the heat, will not be adversely affected.

You don't need to be good with tools to do this! This trick is useful for even the most ham-handed non-mechanical person to effectively mod synth panels without errors or regret.

Even a lousy angled hole with a plain bushing will *still* end up in the right place using this method. The panels are thin enough, holes small enough, and our parts have coverage enough to absorb any angle through the panel thickness.

Mod on!

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Re: Behringer System 55

Post by KSS » Fri Oct 16, 2020 9:51 pm

@Skywriter
I think you're being -overly- generous in avoidance of saying that the stock pots -as used in some positions- simply aren't very good.

While it's easy to dismiss it as a function of price, let's not also dismiss its ill effect in actual use. You've explained all that. But with so many disclaimers and 'distancing' in an effort to be social, that the main points are diffused.

While I understand your tact and intelligence in not over-stating this, I -of less intelligence and social grace- *will* say it.

This level of poor pot should not have been used in these modules. Being able to directly dial in module parameters matters.

Uli Behringer, please use decent pots where it matters.
-------
^This is the thing that gets lost when people try to discount those who have concerns about what Behringer is doing. We're not haterz. We see things like these poor pots and the effect they'll have on people who don't even realize the shortcomings they're dealing with. More simply stated, an EG with three dead zones on its knobs is not -or should not be- acceptable. Especially if the low price makes them more likely to ve used by beginners.

Thankfully SkyWriter is showing simple ways to address these faults. Which really should have been corrected in the first place.

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Re: Behringer System 55

Post by galanter2 » Fri Oct 16, 2020 10:52 pm

Anyone have a napkin calculation as to the increase in list price to the 911 if it had acceptably improved pots in the first place?

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Re: Behringer System 55

Post by KSS » Fri Oct 16, 2020 10:58 pm

Maybe 25 cents more per pot, if that. At 5x that's a price increase of 1.25 at retail. Actual numbers both less and more.

Less because these prices are likely higher than what Behringer can procure. And the 5x factor is more than what Uli says he uses.

And more because parts cost and factor are not the only issues driving the decision. Extra SKUs, and all that go with that being the biggest. Everything from different assembly, additional containers, etc.

Edit: For a 911, maybe 3-5 dollars, and that's likely higher than it *can* be, based on what Uli has shared about his business and practices.
But the biggest driver in any increase will not be parts cost. It will be all the associated costs with using one or more new parts types.

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Re: Behringer System 55

Post by Hyberus » Sat Oct 17, 2020 2:11 am

SynthBaron wrote:
Fri Oct 16, 2020 2:56 pm
Has anyone figured out yet if it's a true 914 clone using the same sort of circuit topology just not using inductors (like JH did here http://jhaible.com/legacy/ffb/fixed_filter_bank.html), or is it just simple bandpass filters? The amount of circuitry on-board probably indicates the latter...
There was a prototype built with inductors. The response curves were all over the place, it was noisy, and you couldn't rack it anywhere near the PSU.
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Re: Behringer System 55

Post by KSS » Sat Oct 17, 2020 4:05 am

@Hyberus
^ What is your source for this? Are you part of the design or test team?

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Re: Behringer System 55

Post by Hyberus » Sat Oct 17, 2020 4:28 am

KSS wrote:
Sat Oct 17, 2020 4:05 am
@Hyberus
^ What is your source for this? Are you part of the design or test team?
I was part of the test team, until November 2019
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Re: Behringer System 55

Post by mmckenzie » Sat Oct 17, 2020 7:27 am

SkyWriter wrote:
Fri Oct 16, 2020 2:01 pm
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.
Yes. On the 911, for me, the initial performance of the attack at the ms end was disappointing, again for what I wanted to do in boring old "real" instrument synthesis --- all those little things at the beginning of a harpsichord note etc etc. After changing the pot, I can now dial the attack from click to where it sounds good, instead of zipping right past the point it should sit at and never managing to find it in the 1mm of pot travel that should have contained the right value.

Now. Have I got enough 911s?

one for the main 2 x VCO voice,
one for the initial VCO transient,
one for adding a bit of noise,
one for a slight VCF change on the duration of the note as the higher harmonics die off,
one for a very slight pitch change as the string is plucked....

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Re: Behringer System 55

Post by SkyWriter » Sat Oct 17, 2020 7:28 am

KSS wrote:
Fri Oct 16, 2020 10:58 pm
But the biggest driver in any increase will not be parts cost. It will be all the associated costs with using one or more new parts types.
Indeed. And expect that behringer highly leverages common parts across all of their products. Eurorack is very cost sensitive.Hopefully the big boy's behringer develops has better pots.

Volume is king/queen when it comes to parts costs. None of their single products on their own has enough volume, but if they use all their eurorack targets and all those mono's and other eurorack modules that's big savings - for them.
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Re: Behringer System 55

Post by SkyWriter » Sat Oct 17, 2020 7:34 am

KSS wrote:
Fri Oct 16, 2020 9:51 pm
@Skywriter
I think you're being -overly- generous in avoidance of saying that the stock pots -as used in some positions- simply aren't very good.

While it's easy to dismiss it as a function of price, let's not also dismiss its ill effect in actual use. You've explained all that. But with so many disclaimers and 'distancing' in an effort to be social, that the main points are diffused.

While I understand your tact and intelligence in not over-stating this, I -of less intelligence and social grace- *will* say it.

This level of poor pot should not have been used in these modules. Being able to directly dial in module parameters matters.

Uli Behringer, please use decent pots where it matters.
-------
^This is the thing that gets lost when people try to discount those who have concerns about what Behringer is doing. We're not haterz. We see things like these poor pots and the effect they'll have on people who don't even realize the shortcomings they're dealing with. More simply stated, an EG with three dead zones on its knobs is not -or should not be- acceptable. Especially if the low price makes them more likely to ve used by beginners.

Thankfully SkyWriter is showing simple ways to address these faults. Which really should have been corrected in the first place.
Thank you KSS. I didn't want to be the only one who is saying this. It's a huge design miss in 911, bad in 923, the rest are somewhat arguable. It was a good cost effort*, but this digs too deep. I was design engineer my whole life, making design trade off's like this. I get it.

This choice for the T1 pot needs to be rethought if System 55 is a real product, rather than a good effort.

Btw: looks like I'm going to be putting switches on modules :-) thank you for your help there too KSS!
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Re: Behringer System 55

Post by SkyWriter » Sat Oct 17, 2020 3:18 pm

Hyberus wrote:
Sat Oct 17, 2020 2:11 am
There was a prototype built with inductors. The response curves were all over the place, it was noisy, and you couldn't rack it anywhere near the PSU.
Noisy like hiss, or noisy like EMI? Sounds like both.

The RF environment is magnitudes more noisy than it was in the 70's. I did EMI work back then :-)
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Re: Behringer System 55

Post by SkyWriter » Sat Oct 17, 2020 6:37 pm

KSS wrote:
Fri Oct 16, 2020 9:28 pm
Don't neglect the effect of those long wires as they run in parallel to various switches and-or timing caps! You're introducing resistance, inductance, capacitance, and potentially cross-talk with this choice. Right at the very core of the circuit.

The early ARP 2600s LFO caps had shielded wires and all three caps were next to switches on the same PCB. About 3-4 inches. In later versions one cap was moved 3 inches and the shielded cables were eliminated. And it does make a difference.<-- I do expect some will argue this.
Man, it takes me all day to unpack one of your posts :-)

My first engineering job was in an EMI facility with an anechoic chamber. We did everything; emissions and susceptibility testing for both radiated and conducted. We had shielded, anechoic and free-field sites. We did ESD testing, man we did the whole crazy gamete.

And you're right! It might be terrible susceptible to noise inside the case too. But, those fat transistors and my own fat fingers thought it was worth a try without doing the math. And it was devilishly attractive way to hide my poor work :-)
Buy a drill bushing. You only need one or two sizes. Then drill a hole -even a crappy one, with a crappy drill press or even a hand drill- in a piece of wood for the drill bushing outer diameter. A narrow long 'stick' shaped piece of wood is probably the best for this. It allows more variety in clamping positions.
Push the bushing into the hole and use whatever glue makes sense to keep it there. This will depend on how well you make the hole, type of wood, etc.

There's your jig. Easy-peasy. Doesn't have to be nice.

Clamp it to the panel with a couple small c-clamps. Now even a hand drill is -can be- as accurate as any milling machine. The bushing will guide the bit true and location is fully determined and assured ahead of time by how you position the wood and clamp it tothe panel. Just get the location where you want it before you drill the hole-s. To do that, take the drill bit by itself in hand and spin it a little against the panel when you think your jig is clamped close to where you want it. The small mark made will be removed by the actual drilling, and now lets you know how close or far you are from where you want to be. Adjust, retry until you've got it just where you want-need it.

Drill bushings may be had with or without a stepped outer diameter. Either will work, but the step type helps perpendicularity of the result if your tools or skills are poor. The stepped outer diameter also gives a place for epoxy or thick CA type gluing to resist rotation of the bushing which can happen as you use the jig over time. When you want to re-use the bushing, heat will help you release the glue. The bushing itself is hardened and as long as you don't go crazy with the heat, will not be adversely affected.

You don't need to be good with tools to do this! This trick is useful for even the most ham-handed non-mechanical person to effectively mod synth panels without errors or regret.

Even a lousy angled hole with a plain bushing will *still* end up in the right place using this method. The panels are thin enough, holes small enough, and our parts have coverage enough to absorb any angle through the panel thickness.

Mod on!
Wow! I am feeling much more confident pulling off five copies of this that will sit close enough to see the differences - I'm one of those guy you see staring at floors looking for where the repeats are. I hate trips to the flooring store.
===============
Getting back to the 914 pots. The trouble I initially had in dialing in the feedback was exacerbated by the OEM pots. The issue with the 914 design is that the filter banks aren't buffered with respect to the input driver stage. When a bandpass Q goes higher the impedance* changes - quote dramatically. Once you start dialing in a few, you have to keep tweaking the previous ones. The more you have In feedback, the harder it is to keep them balanced in feedback. The 'loose-linkage' feel of the pot makes dialing much harder. With the ALHPA pots the dialing is much more direct. So there's less monkeying per knob required. You still have top monkey the knobs - that's an other feature. :-) The Resonant Noise clip sounds pretty good to me. That was right out of the FFB through a CP35. Very airy.

*-that's what I suspect, but It could easily be ground plane and power distribution impedances causing the cross talk as well. Could add some more bulk cap in places to have more reservoir to draw on?
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Re: Behringer System 55

Post by Hyberus » Sun Oct 18, 2020 2:25 am

SkyWriter wrote:
Sat Oct 17, 2020 3:18 pm
Hyberus wrote:
Sat Oct 17, 2020 2:11 am
There was a prototype built with inductors. The response curves were all over the place, it was noisy, and you couldn't rack it anywhere near the PSU.
Noisy like hiss, or noisy like EMI? Sounds like both.

The RF environment is magnitudes more noisy than it was in the 70's. I did EMI work back then :-)
More like static, with added mains hum, particularly if it was near a transformer.
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Re: Behringer System 55

Post by SkyWriter » Sun Oct 18, 2020 6:39 am

Hyberus wrote:
Sun Oct 18, 2020 2:25 am
More like static, with added mains hum, particularly if it was near a transformer.
Yup, yup. Basically same issue we discussed with extending cap lines. Needs a bit of care. Modern PCB construction with ground planes are probably helping us more than we're aware of. Ferrite cores normally shouldn't be acting as a vector for susceptibility, so it probably needs a shielded cable in places. The static, though would need a closer listen. Doesn't sound like normal analog noise source, more like digital board-band noise - remember any chugging? Like cell phone data transfer?

Did you try to box the whole thing in a faraday cage?
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Re: Behringer System 55

Post by Hyberus » Sun Oct 18, 2020 6:50 am

SkyWriter wrote:
Sun Oct 18, 2020 6:39 am
Hyberus wrote:
Sun Oct 18, 2020 2:25 am
More like static, with added mains hum, particularly if it was near a transformer.
Yup, yup. Basically same issue we discussed with extending cap lines. Needs a bit of care. Modern PCB construction with ground planes are probably helping us more than we're aware of. Ferrite cores normally shouldn't be acting as a vector for susceptibility, so it probably needs a shielded cable in places. The static, though would need a closer listen. Doesn't sound like normal analog noise source, more like digital board-band noise - remember any chugging? Like cell phone data transfer?

Did you try to box the whole thing in a faraday cage?
It's a while ago now, but no. The engineer gave it to me for an opinion, I ran some tests and basically told him it was a non-starter as it was; which he had already decided, but wanted a second opinion on.
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Re: Behringer System 55

Post by SkyWriter » Sun Oct 18, 2020 6:53 am

Hyberus wrote:
Sun Oct 18, 2020 6:50 am
It's a while ago now, but no. The engineer gave it to me for an opinion, I ran some tests and basically told him it was a non-starter as it was; which he had already decided, but wanted a second opinion on.
That's a shame for all the work put into it. Oh well.
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Re: Behringer System 55

Post by Hyberus » Sun Oct 18, 2020 6:55 am

SkyWriter wrote:
Sun Oct 18, 2020 6:53 am
Hyberus wrote:
Sun Oct 18, 2020 6:50 am
It's a while ago now, but no. The engineer gave it to me for an opinion, I ran some tests and basically told him it was a non-starter as it was; which he had already decided, but wanted a second opinion on.
That's a shame for all the work put into it. Oh well.
Agreed. I would have loved for it to have worked properly. Although the final iteration does the job pretty nicely, and is the only module from this series that I own an example of.

I think that the thing that needs to be remembered is that Bob Moog had more space to work in, and was making what was, in effect, a luxury product that would sell in small numbers for a high price; so could spend the time (and money) getting coils handwound.
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Re: Behringer System 55

Post by SynthBaron » Sun Oct 18, 2020 2:41 pm

Hyberus wrote:
Sat Oct 17, 2020 2:11 am
SynthBaron wrote:
Fri Oct 16, 2020 2:56 pm
Has anyone figured out yet if it's a true 914 clone using the same sort of circuit topology just not using inductors (like JH did here http://jhaible.com/legacy/ffb/fixed_filter_bank.html), or is it just simple bandpass filters? The amount of circuitry on-board probably indicates the latter...
There was a prototype built with inductors. The response curves were all over the place, it was noisy, and you couldn't rack it anywhere near the PSU.
IIRC, the capacitors and resistors had to be hand-matched to the inductors at the Moog factory to get them into spec. Not gonna happen on a Behringer assembly line, lol.

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Re: Behringer System 55

Post by Hyberus » Mon Oct 19, 2020 1:23 am

As I said previously: Bob Moog was hand building a luxury, high priced item.
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