Buchla 218 Grounding vs. Balance Power - Resolved!

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Buchla 218 Grounding vs. Balance Power - Resolved!

Post by alt-mode » Thu Nov 20, 2014 12:17 pm

Edit: Go to the end to find out that the real culprit in this situation was EMI from other devices nearby....


[I didn't want to steal the other 218 thread since this set of issues is a bit different.]

I have both an original Easel and a new BEMI Easel. The BEMI Easel works fine when I plug it in anywhere in my house *except* my studio. I have the usual grounding problems when it is in the studio. If I use my body to ground between the keyboard, the lower left keyboard screw, any chassis, or the ground to my other banana jack gear, it works. Otherwise, I get noise in the keyboard signals when a key is pressed (lots of pulses and a short repeating sequence of notes).

What is different? My studio uses balanced power units from Equitech (http://www.equitech.com/FAQ/whatis.html). This means that the ground from the wall is between the positive and negative wave cycles, much like a balanced mic cable. It has really made my studio much quieter and I think made my gear last longer since there is less noise and junk hitting the power supplies. One catch, you really can't connect any devices between balanced and regular power since the grounds can be a different levels. So I can't connect the Easel to the wall outlet and then plug the audio into the rest of my studio.

I don't have any issues like this with my original Easel or any other touch plate devices (Serge TKB, Rene, etc.).

It seems like there is a poor ground connection between the keyboard and the rest of the system. I also tried wearing an anti-static wrist strap connected to the banana ground and with 1M of resistance, it was too much and didn't fix the problem.

Yes, I contacted Alex at Buchla and heard the "try different outlets" solution as well as the usual sensitivity adjustments and "don't touch it for 30 seconds after power up" solutions. Apparently, this is a frequent problem leading me to believe it is a design issue.

Any ideas? I'm happy to help try to debug and find a solution for this as the BEMI Easel is a bit difficult to use in my studio right now... :sadbanana:

Eric
Last edited by alt-mode on Fri Nov 21, 2014 10:54 pm, edited 1 time in total.

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Post by tobb » Thu Nov 20, 2014 1:38 pm

How is the bottom side of the 218e touchplate ,bottom and top you know that sits in contact with the boat?

If there is a ground plane you might solder a wire to it immediately to the gnd of the distro board inside the easel.

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Post by Guidotoons » Thu Nov 20, 2014 2:04 pm

I had a similar issue between the 208r and 218e when both mounted in a BEMI issue Easel rack. It was intermittent.

A ground lifter did the trick. I would GUESS, and it's JUST a guess, that the Easel power supply NEEDS full on current. MY electrical power in this place can be spotty, so my guess is that if the local power was not getting into the studio at 120 volts that it would make a difference in the BEMI supply power as well.

Again...just a GUESS.

I ground lift ALL my Buchla stuff to start with. I also ground each cabinet to the other.
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Post by alt-mode » Thu Nov 20, 2014 2:07 pm

Thanks for the ideas tobb. I'll take another look at what is contacting the boat. That might help.

I did try attaching a ground wire directly to the corner screw to see if that would help and it didn't. I also tried a 2-3 prong adapter to lift the ground to the power supply and also tried wiring that ground to the banana ground with no affect.

Eric

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Post by alt-mode » Thu Nov 20, 2014 2:10 pm

Yup, Guido. I tried the groundlift for the Easel. I have a common ground for all of my banana gear. I might try pulling that off some of the other gear to see if there is something with that ground that is causing a problem...

Eric

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Post by tobb » Thu Nov 20, 2014 2:33 pm

alt-mode wrote:Thanks for the ideas tobb. I'll take another look at what is contacting the boat. That might help.

I did try attaching a ground wire directly to the corner screw to see if that would help and it didn't. I also tried a 2-3 prong adapter to lift the ground to the power supply and also tried wiring that ground to the banana ground with no affect.

Eric
damn thats a hardcore problem :(

do you have a 200e or other cabinet with psu where you could hook that 218e plate to it to see how it reacts then?

edit: btw what kind of psu is used for the bemi easel?

an external adapter,but are there additional dc converters in the boats (like in the 200e boats)?

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Post by alt-mode » Thu Nov 20, 2014 3:38 pm

Just tried isolating to just the 218 and a 200e cabinet with the grounds connected and that didn't change things. The 218 alone has the problem and I can see by the output LEDs that unless I'm touching a ground with my other hand, any contact with the touchplates results in a noisy output (LEDs flickering). When I have contact with a ground through my body, the LEDs are solid when contacting the touchplates.

Again, this isn't a problem for me on non-balanced power.

Eric

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Post by 3001 » Thu Nov 20, 2014 4:04 pm

I had horrible grounding issues too, when the easel was hooked up I'd get a horrible noise out of my TC electronics Flashback(I thought I fried the damn thing at first). opened it up, reseated some connectors and it seemed to do better. but some random ghosts kept popping up when it was on in other gear, so it went...

Maybe MA electricity is no good ? It wants to be back on the west coast?
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Post by tobb » Thu Nov 20, 2014 4:28 pm

alt-mode wrote:Just tried isolating to just the 218 and a 200e cabinet with the grounds connected and that didn't change things. The 218 alone has the problem and I can see by the output LEDs that unless I'm touching a ground with my other hand, any contact with the touchplates results in a noisy output (LEDs flickering). When I have contact with a ground through my body, the LEDs are solid when contacting the touchplates.

Again, this isn't a problem for me on non-balanced power.

Eric
Did you try in another room,standup,i had once very weird issue with a jomox neuronium,when i sat down on a chear almost impossible to change the function via the touch sensitive knobs.

Do you have carped on the floor?

It could be you are too much static electricity loaded due to carped on floor or laminate,a chear.. or simply the air

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Post by alt-mode » Thu Nov 20, 2014 5:20 pm

Works fine in other rooms and without the balanced power. I'm very very careful to discharge any static (blew my old Easel keyboard once with static). The floor is carpeted but why would this not affect other gear?

Eric

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Post by Zeitdehner » Thu Nov 20, 2014 5:51 pm

I experience that exact same phenomenon with my Bemi Easel, but it is intermittent.
Actually I have found that this behavior is depending on what type of shoes I'm wearing (don't laugh...), or to be more precise what material the soles of the shoes are made of, maybe also depending on the material that is covering the floor.
This of course is not really acceptable as is and tends to make me think there might be some kind of a design fault, even more so if the original Easel does not present this kind of problem in the same conditions of use...
If so, I really hope there is a simple fix that would make the Bemi Easel's touch controller act normally in every situation, in my studio or somewhere else, me having rubber or leather or whatever soles, even barefoot should be no problem imho :despair:
I've noticed there are some small metal washers in between the 218 panel and the boat it's mounted on but did not test if they are conductive or not. Maybe they are just there to adjust the mounting height of the panel, maybe not... Maybe I'll try to remove those washers and see if that changes anything :hmm:
It's a strange thing that the Bemi Easel is so sensitive to the quality of its power feed , grounding and radiation fields in its immediate environment (cfr. the sometimes really loud background noise on all of its audio outputs, even with all level controls at zero, this can sometimes be solved by plugging the Easel into a different outlet). This makes the usability in some settings rather uncertain, when taking it to a gig or to another studio you never know how it's going to behave... I know it's considered being an electro organism, but still...

Oh, could someone please describe the correct procedure to adjust sensitivity of the touch controller ? I've read it here somewhere a while back but can't find it anymore. Can I adjust the "range" of the pressure output ? I mean right now it's like all or nothing and I would like it to put out minimum voltage with just the tip of a finger and reach maximum voltage only when the whole finger is applied to the touch surface, not jumping to full output with just a square millimeter of surface covered by skin... to get more progressive control with more nuance in between nothing and all ( I know I can attenuate this voltage with the slider of the targeted CV input but that's not really the point...)

Thanks

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Post by Cobramatic » Thu Nov 20, 2014 6:50 pm

Zeitdehner wrote:
Oh, could someone please describe the correct procedure to adjust sensitivity of the touch controller ? I've read it here somewhere a while back but can't find it anymore. Can I adjust the "range" of the pressure output ? I mean right now it's like all or nothing and I would like it to put out minimum voltage with just the tip of a finger and reach maximum voltage only when the whole finger is applied to the touch surface, not jumping to full output with just a square millimeter of surface covered by skin... to get more progressive control with more nuance in between nothing and all ( I know I can attenuate this voltage with the slider of the targeted CV input but that's not really the point...)

Thanks
I had that problem too. I got this instruction from Alex:
"To program sensitivity on keyboard first turn all knobs to 10 and switches to none. Now press on a key and you can adjust how sensitive you want it by turn the 4th Octave knob. "
It does work but sometimes it 'forgets' the setting and you need to do it again.

As for grounding issues - My Easel is fine but I sure do notice the problem on other 'vintage' equipment. As an example - I have a Roland CR68 that I like to hook up to the Buchla, but at my place the ground hum on it is awful. At other locations it sounds crystal clear.
I also use a TR77 at my place which is even older, but quieter than a mouse - maybe there is a frequency spike in some locations that interferes with particular components??

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Post by alt-mode » Thu Nov 20, 2014 10:06 pm

Wow, while I'm pleased to hear that I'm not alone with my challenges here, I'm disappointed that this sort of problem is happening to others. :sadbanana:

I can't believe that different shoes affects performance for you Zeitdehner. For me the fix is to be connected to ground by touching something or holding onto a wire.

I'll continue to experiment. I would really like to talk with the designer/developer who brought the 218 out to see if some better grounding techniques can be found. Capacitive plates are a bit tricky to get right, witness the attempts Doepfer made and, as far as I know, has never delivered. And grounding issues can be very mysterious because of all of the possible ways electricity can travel!

Eric

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Post by tobb » Fri Nov 21, 2014 12:48 am

alt-mode wrote:Works fine in other rooms and without the balanced power. I'm very very careful to discharge any static (blew my old Easel keyboard once with static). The floor is carpeted but why would this not affect other gear?

Eric
its not because you touch with your hand a ground you are unloaded ,as soon you release it you might get charged immediately if you just a conducter between the loaded source and ground,that explain when you touch gnd with your hand why plaining the kb it works and as soon you release it the 218e acts weird again.

you can try too put an isolator on the floor like wood just to try to issolate the source,if it still happens iit could be the air that its charged by the floor covering,this happens when the air is very dry inside your room.

do you house have an earth pen somewhere in the Basement our outside (a metal rod into the ground)?

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Post by MGA » Fri Nov 21, 2014 12:55 am

Just a bit more info from my own Easel:

It uses a standard switch mode PS 12v DC @5.5 amps. The sleeve is -ve and the centre +ve. It looks like there is direct continuity from the earth AC pin to the -ve sleeve and to the 208 and 218 panels.

Check for earth continuity from the PS earth pin to the 208 (the Tinijax nut is a good place) and also the 218 (a bit more tricky but the 2 stainless philips head screws near the portamento and r/h preset knobs are earths on mine).

As you say, capacitive kbs are tricky beasts and I'm wondering if you are acting as an antenna and picking up stray RF which is then passed on to the kb unless you earth yourself.

Just a thought...
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steel foundries and tapes played back at a wrong speed..." (Gradenwitz, 1953)

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Post by tobb » Fri Nov 21, 2014 4:52 am

MGA wrote: As you say, capacitive kbs are tricky beasts and I'm wondering if you are acting as an antenna and picking up stray RF which is then passed on to the kb unless you earth yourself.

Just a thought...
is a possibility,but when he test it in another room problem is gone,RF goes through walls,so...

He should test it near the doorway of the room if problem disapears or not.

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Post by MGA » Fri Nov 21, 2014 5:17 am

That's certainly an easy test. Maybe even take an extension cord with the balanced power into another room.
I'd still look carefully at the 218 ground - it seems a bit sus when you can correct the problem by touching a ground with your hand :hmm:

Or maybe the Easels just don't like balanced power :despair:
"One can sympathize with listeners who make comparisons with railway terminals,
steel foundries and tapes played back at a wrong speed..." (Gradenwitz, 1953)

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Post by alt-mode » Fri Nov 21, 2014 10:26 am

All good ideas and I have heard from Buchla with a few other things I can check. I need to go find some information on the theory of operation for capacitive touchplates too.

To answer a few comments: I did try removing my shoes with no affect and the floor of my studio is a thin carpet over a raised wood floor so there is lots of isolation. The other room where the Easel works has the same flooring.

I'll try some experiments and get back to the thread.

Thanks,
Eric

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Post by gddfp » Fri Nov 21, 2014 9:42 pm

I've had miserable experiences with my 218 as well; intermittent & stuttering triggers, some keys not working, random activation of the Voltage Presets, unusable Pressure out, etc...
BEMI people suggested several different "solutions" (as mentioned in this thread), and I went a long (and rather expensive) way to come up with a solution myself. All to no avail.

Until... I found the culprit.

I always had thought my [home] studio had a clean power line (sound quality is good, no hum nor noise, all equipment works flawlessly, using galvanically-separated power distribution, etc), but it turned out there was a light dimmer somewhere before power enters my studio. A fluorescent-tube dimmer, no less, which - apparently - makes your power line look like something coming out of a Source of Uncertainty...

Removing that dimmer from the power line chain solved all my 218 problems.

The reason why that dimmer didn't cause any problems for my other equipment (or at least I'd like to think so), is because the 218 is indeed a fragile & finicky beast. It really needs a very clean, properly earthed power inlet.

Todd Barton had a vaguely similar problem. He had an non-earthed desktop lamp (a fluorescent one, if I recall well) in his power supply chain (a distribution block) to his Easel. Removing that lamp solved most of his 218 problems.

Uncertain if this can be conclusive, but just make sure there are no dimmers nor fluorescent lights near your Easel.

And also: I replaced the Easel's standard Cincon brick with a similar SL Power medical-grade brick, which uses ferrite beads around the cables. It's a somewhat better & more stable power supply, though I doubt it can/will solve any 218 problems all by itself.

_g

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Post by alt-mode » Fri Nov 21, 2014 10:53 pm

gddfp - THANK YOU!!! My problem is solved! I do have dimmers in my studio but they are very different circuits and the balanced power is supposed to clean them up.

I was ready to shut off the lights and test out the Easel without anything else on in the studio when I wondered if there were other sources of electromagnetic 'noise' near the Easel. I had forgotten about an "Ionic Breeze" air cleaner that was sitting under the table *right below the Easel*!!!!! Shutting this off made the problem go away!

So, the issue isn't grounding, it is shielding from EM interference! All of those keys act just like a big antenna... I also have one of those sort of "jacob's ladder in a tube" lights that I rarely turn on and switching that on causes all sorts of noise problems with the Easel.

Hmmm, it makes me wonder if the metal suitcase of my original Easel does a lot to help shield it from EMI....

Anyway, I'm :bacon: :bananaguitar: :banana: :nana: now!

Thanks for all the suggestions and it looks like we need to start fashioning tin foil hats for our Easels going forward. :hihi:

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Post by gddfp » Fri Nov 21, 2014 11:18 pm

alt-mode wrote:gddfp - THANK YOU!!! My problem is solved! I do have dimmers in my studio but they are very different circuits and the balanced power is supposed to clean them up.

You're welcome.
After six months of trouble[shooting], and then finding this not-so-obvious solution, I suggested to BEMI to include a warning note about dimmers & fluorescent lights with each Easel delivery. A simple thing to do, which -- I'm sure -- could spare them from quite a few angry mails, but apparently they didn't take my advice.

I've done some more research on light dimmers. Those nasty buggers really shouldn't have been invented. There are good dimmers though, which have complete galvanic separation from mains and do not interfere with it, but alas, those aren't the ones regularly found in homes and cheap Ikea shades.
alt-mode wrote:I was ready to shut off the lights and test out the Easel without anything else on in the studio when I wondered if there were other sources of electromagnetic 'noise' near the Easel. I had forgotten about an "Ionic Breeze" air cleaner that was sitting under the table *right below the Easel*!!!!! Shutting this off made the problem go away!
I guess you'll just have to open the studio windows now and then. :razz:
alt-mode wrote:So, the issue isn't grounding, it is shielding from EM interference! All of those keys act just like a big antenna... I also have one of those sort of "jacob's ladder in a tube" lights that I rarely turn on and switching that on causes all sorts of noise problems with the Easel.
I think it's both grounding and dimmer/fluorescent lights issues. The former really needs to be in place, whilst the latter shouldn't be found in the vicinity of any Easel.
Capacitive touch keyboards are tricky bastards; as I've found out earlier when trying to get a DIY Serge Touch Keyboard to work...
alt-mode wrote:Hmmm, it makes me wonder if the metal suitcase of my original Easel does a lot to help shield it from EMI....
Perhaps. Though I doubt it. A modern 218 also sits in a metal housing.
alt-mode wrote:Anyway, I'm :bacon: :bananaguitar: :banana: :nana: now!

Thanks for all the suggestions and it looks like we need to start fashioning tin foil hats for our Easels going forward. :hihi:
Have fun weaseling now ! :-)

_g

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Post by MGA » Fri Nov 21, 2014 11:38 pm

Excellent! :yay:

Some cheap and nasty mains voltage gadgets are a total PITA for sensitive equipment :mad:

So do you think that is was an RFI issue or noise through the PS?
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steel foundries and tapes played back at a wrong speed..." (Gradenwitz, 1953)

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Post by Zeitdehner » Sat Nov 22, 2014 3:33 am

Another great post Guy, thank you !

Though, I have no fluorescent lamps, nor dimmers, nor air conditioners , BUT, there must obviously be some sources of electromagnetic radiations... we are literally bathing in them, constantly... just ask Christina Kubisch about it :hihi:

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Post by alt-mode » Sat Nov 22, 2014 1:05 pm

I'm quite certain that my issues with the air cleaner and light are RFI/EMI and not through the power. The balanced power system really cleans that up and I have very separate circuits for studio power vs. lights.

Interestingly, the Easel works fine on my repair bench under two fluorescent lights so it can tolerate some amount of EMI but these particular devices are very 'noisy'.

Eric

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Post by tobb » Sat Nov 22, 2014 2:13 pm

Glad to read you found the problem!

:tu:

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