# Old Clear-Com Question



## Electric Carpenter (Sep 30, 2017)

Hey Everyone, 

This is my first post so bare with me... but!

The facilities I am working in right now just came across with a pretty big problem last night in tech with our clear-com system. We started to randomly getting a high pitched squeal through the entire system, almost like a "fire alarm or CO2 detector running out of battery" beep in our ears. It was the worst thing in the world. 

At first we started to take some packs out of the system, but nothing was working, it kept randomly happening, and getting worse. 

The one place we did not trouble shoot was back in the pit where the conductor also has a pelt back and headset. Come to find out his pack was running through the orchestra snack back to the sound board and into the clear-com system, is this why?! The person who set this up did this and I have never seen this before. Also, we added the full pit last night and it started last night, which was the only thing we changed from two nights ago and last night!

Any thoughts would be greatly appreciated!


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## MRW Lights (Sep 30, 2017)

sounds like a feedback loop has been added to the chain. The routing of that headset sounds like a convenience issue that may have been hooked up incorrectly or someone may have a misunderstanding of how program feeds work. Without more information these are my shots in the dark. 

If the last thing that changed was the orchestra I would check the conductor's pack and make sure they're not taking it off and leaving the talk button latched. The fastest solution may simply be helping someone be aware of an inadvertent error. Depending on the base station if you have a remote kill you can also be listening for this to occur and then close all mics when it happens which should get rid of it, but everyone who needs to talk will need to press their talk button again.


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## themuzicman (Sep 30, 2017)

Electric Carpenter said:


> The one place we did not trouble shoot was back in the pit where the conductor also has a pelt back and headset. Come to find out his pack was running through the orchestra snack back to the sound board and into the clear-com system, is this why?! The person who set this up did this and I have never seen this before. Also, we added the full pit last night and it started last night, which was the only thing we changed from two nights ago and last night!



This is very common, Keys 1/Conductor almost always gets a Clearcom belt pack at their location, via a turnaround in the Pit Snake.

I would re-null your system (typically I have a single person null out every location themselves) and then post someone at your Main Station and do a channel-by-channel, user-by-user check of the system to see where the fault lays with a second person visiting every belt pack or remote station in the system.


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## Electric Carpenter (Sep 30, 2017)

Thank you both so much! We did some investigating today and we think the conductor headset, which is one of the phone handheld ones, was being held on, causing feedback due to his volume. We have take some precautions for the next rehearsal and hope we can find a solution!


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## EdSavoie (Oct 1, 2017)

Just as a side note for anyone who may stumble on this thread, I've seen an older base station misbehave and have the microphone gain go off the charts, to the same feedback effect.

I've also heard the same thing happen moments before the Director's beltpack started burning.
(I do suppose that's what directors get for being on coms, but still.)


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## RonHebbard (Oct 1, 2017)

EdSavoie said:


> Just as a side note for anyone who may stumble on this thread, I've seen an older base station misbehave and have the microphone gain go off the charts, to the same feedback effect.
> 
> I've also heard the same thing happen moments before the Director's beltpack started burning.
> (I do suppose that's what directors get for being on coms, but still.)


If any channel loses its termination, its gain will rise radically to the point of feedback. 
A practical example of this occurs whenever you unplug a belt pack from a system with its mic live and its headset NOT on anybody's head. You get a momentary brief burst of feedback from the headset's earpiece from the time the termination is removed from the audio lasting only very briefly 'til the belt pack discharges and dies from lack of power.
I'm talking 'old school' party line Clear Com here, not new digital packs.
Toodleoo!
Ron Hebbard.


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## themuzicman (Oct 1, 2017)

Electric Carpenter said:


> the phone handheld ones, was being held on, causing feedback due to his volume. We have take some precautions for the next rehearsal and hope we can find a solution!



If you're coming out of a rental shop, ask the shop for an HS-6 hangar, and then take some tie-line and clove hitch it to a spare mic stand.


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## Aaron Becker (Oct 1, 2017)

RonHebbard said:


> If any channel loses its termination, its gain will rise radically to the point of feedback.
> A practical example of this occurs whenever you unplug a belt pack from a system with its mic live and its headset NOT on anybody's head. You get a momentary brief burst of feedback from the headset's earpiece from the time the termination is removed from the audio lasting only very briefly 'til the belt pack discharges and dies from lack of power.
> I'm talking 'old school' party line Clear Com here, not new digital packs.
> Toodleoo!
> Ron Hebbard.



Oh man. I still use party-line. That must make me old! ahh!


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## EdSavoie (Oct 1, 2017)

I'll second that one, haven't seen any newfangled digital packs in real life yet.


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## Aaron Becker (Oct 1, 2017)

EdSavoie said:


> I'll second that one, haven't seen any newfangled digital packs in real life yet.



I have seen them, as a digital party-line.  haha


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## EdSavoie (Oct 2, 2017)

The newest I've seen are the RS 700 series of beltpacks we rented to supplement our aging RS 500 system.


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## Aaron Becker (Oct 2, 2017)

EdSavoie said:


> The newest I've seen are the RS 700 series of beltpacks we rented to supplement our aging RS 500 system.


I still use RS 500s on a regular basis. Those things are workhorses!


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## RonHebbard (Oct 2, 2017)

Aaron Becker said:


> I still use RS 500s on a regular basis. Those things are workhorses!


 @Aaron Becker We've got at least three amateur groups in our area still regularly running the original, stainless steel [with gooey black potted PCB's] RS100A belt packs, although I will admit to having changed call light lamps at least once per pack.
(Talk about your "workhorses"!)
Toodleoo!
Ron Hebbard.


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## EdSavoie (Oct 2, 2017)

Well they charge so much for them it's easy to understand why we don't let go!

Also, I previously mentioned that our RS 500s were "aging" as we've lost two packs to self combustion, and two to a peaceful failure.

That and our base station desperately needs to have it's little potentiometers recalibrated.


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## RonHebbard (Oct 2, 2017)

EdSavoie said:


> Well they charge so much for them it's easy to understand why we don't let go!
> 
> Also, I previously mentioned that our RS 500s were "aging" as we've lost two packs to self combustion, and two to a peaceful failure.
> 
> That and our base station desperately needs to have it's little potentiometers recalibrated.


 @EdSavoie What's failing / burning in your 500 series packs and I'm not understanding what needs "recalibrating" regarding your base station's packs. Please 'splain. [And exactly which pots?]
Toodleoo!
Ron Hebbard.


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## EdSavoie (Oct 2, 2017)

Well, the two packs that died violently were a touch too chared to tell what was at fault in the first place. My guess based on the char-iest components is that either a transistor or adjacent resistor released the smoke first, encouraging others to do the same.

One of the ones that died silently was repaired by a local shop, the other one "wasn't repairable". Unfortunately I wasn't able to learn what it was that had failed.

The base station has potentiometers inside to calibrate various things, which I'm not entirely familiar with. One of the pots is for calibrating the base station's microphone gain, which is currently far too sensitive and needs to be adjusted. This is primarily what I'm referring to.

My original theory was that the base station was responsible. While the repair shop ruled that out, they replaced most of the capacitors as a preventative measure, (which seems to have knocked the aforementioned mic gain out of whack...) and I've heard no reports of subsequent failures since.

Nor have I heard of any directors getting on headset since...


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## RonHebbard (Oct 2, 2017)

EdSavoie said:


> Well, the two packs that died violently were a touch too chared to tell what was at fault in the first place. My guess based on the char-iest components is that either a transistor or adjacent resistor released the smoke first, encouraging others to do the same.
> 
> One of the ones that died silently was repaired by a local shop, the other one "wasn't repairable". Unfortunately I wasn't able to learn what it was that had failed.
> 
> ...


 @EdSavoie Isn't that why ClearCom invented their HS6? [Due to director's heads being too swollen to be encompassed by headsets sized for mere mortal minions?(And in white so blind directors could find them in the dark?)]
Toodleoo!
Ron Hebbard.


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## gafftaper (Oct 2, 2017)

By the way, if you get around to needing any replacement gear, I'm a big fan of Production Intercom... now renamed Pro Intercom. http://prointercomllc.com/ I've used their beltpacks and Headsets and love them especially the tiny BP.15 beltpack and the SMH 710 headset (light weight, comfortable, $80, and fairly durable considering how little is there). I haven't used the base stations but if I remember right @Van has and was very impressed with the quality at a lower price. Check them out.


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## RonHebbard (Oct 2, 2017)

gafftaper said:


> By the way, if you get around to needing any replacement gear, I'm a big fan of Production Intercom... now renamed Pro Intercom. http://prointercomllc.com/ I've used their beltpacks and Headsets and love them especially the tiny BP.15 beltpack and the SMH 710 headset (light weight, comfortable, $80, and fairly durable considering how little is there). I haven't used the base stations but if I remember right @Van has and was very impressed with the quality at a lower price. Check them out.


@gafftaper I've installed three of their 2RU 'bare bones' power supplies, a redundant pair in a PAC and a single in a local amateur group's venue and can attest to them being solid, durable and reliable. I will note I diode coupled the outputs on the redundant pair so the DC indicator would extinguish if one of the units failed or was inadvertently switched off. Without external summing diodes, both supplies' DC output indicators remain lit so long as either is producing output. 
Toodleoo!
Ron Hebbard.


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## Van (Oct 3, 2017)

I LOVE PI! < Which is funny 'cause my Grandfather went by the name P.I....>
I didn't know they had changed names. Good to know.


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## josh88 (Oct 3, 2017)

Van said:


> I LOVE PI! < Which is funny 'cause my Grandfather went by the name P.I....>
> I didn't know they had changed names. Good to know.


Name changed when they sort of went under and if I recall, his daughter took over most of the stuff and renamed it slightly so people would still recognize them.


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## Van (Oct 3, 2017)

josh88 said:


> Name changed when they sort of went under and if I recall, his daughter took over most of the stuff and renamed it slightly so people would still recognize them.


You know what? Now that you mention that I seem to remember something about his Daughter, and talking to her on the phone about this... I'm really glad they are still around. They were always a great company to work with.


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## derekleffew (Oct 3, 2017)

Van said:


> You know what? Now that you mention that I seem to remember something about his Daughter, and talking to her on the phone about this...


https://www.controlbooth.com/threads/production-intercom-shipping-delays.28741/#post-264297 and subsequent, including a post from @Van https://www.controlbooth.com/threads/production-intercom-shipping-delays.28741/page-2#post-279075 who seemingly has less than five-year total recall.


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## Van (Oct 3, 2017)

derekleffew said:


> https://www.controlbooth.com/threads/production-intercom-shipping-delays.28741/#post-264297 and subsequent, including a post from @Van https://www.controlbooth.com/threads/production-intercom-shipping-delays.28741/page-2#post-279075 who seemingly has less than five-year total recall.


I'm managing 45 jobs right now I can't remember if I put on socks this morning.

I HAVE, however, switched to Chrome and now have integral speelchaeck.


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## themuzicman (Oct 3, 2017)

RonHebbard said:


> We've got at least three amateur groups in our area still regularly running the original, stainless steel [with gooey black potted PCB's] RS100A belt packs, although I will admit to having changed call light lamps at least once per pack.
> (Talk about your "workhorses"!)



You can't knock RS100A's, I run shows that routinely have all 700 series Clearcom, Helixnet, or Riedel, but I will ALWAYS give the MD an RS100A. The hard On/Off switch means that they never have to remember to latch their belt pack when they get in for the day. It saves me a week of reminding them to latch the belt pack before using the handset. It's old, but it is the BEST tool for that job.


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## Electric Carpenter (Oct 4, 2017)

WOW, thank you everyone for commenting and sharing their experiences! When I first looked up clear-com on this site, I didn't find anything so hopefully this can answer future questions also! 

In terms of the specific original post, it seems to have been the conductor or main rag operator were leaving their packs "talked-on". Why the feedback was so random, who knows, but we removed the main rag operators pack and told the conductor to not leave his pack on, and all is well, knock on wood! 

Thank you all so much!


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## RonHebbard (Oct 4, 2017)

Electric Carpenter said:


> WOW, *thank you everyone for commenting and sharing their experiences!* When I first looked up clear-com on this site, I didn't find anything so hopefully this can answer future questions also!
> 
> In terms of the specific original post, it seems to have been the conductor or main rag operator were leaving their packs "talked-on". *Why the feedback was so random, who knows*, but we removed the main rag operator's pack and told the conductor to not leave his pack on, and all is well, knock on wood!
> 
> *Thank you all so much!*


TLDR warning *boldly* in place: @Electric Carpenter When you wrote: "Why the feedback was so random, who knows"; Here are a couple of plausible explanations: With ClearCom and similar "party line" systems, there is what is termed "Side tone" along with an adjustment for it. "Side tone" does not have anything to do with an actual "tone" like you'd expect from an audio oscillator / tone generator / call signal or feedback. The term dates from the early days of telephone systems and relates to how much of your own voice you hear in your own headset while you're speaking. * 
[Forum members, please don't stone me for my oversimplification]*
If your belt-pack / station's "side tone" is set too low, you'll be speaking louder and louder as you're not getting much sense of your headset working. You'll be thinking "Well I can hear them so my earphone's working but maybe my mic is NFG?" 
If your "side tone" is set too high, your headset will appear too sensitive; If your beard / moustache brushes against your mic while speaking, you'll find the bristling noise in your ear very distracting. 
When your headset is on your head, too much side tone won't feedback as your skull is preventing your mic from hearing your earphone. If you take your headset off your head and hang it on an unused rail pin with its mic still switched on, there will be nothing but the short physical distance of open air between between its mic and its earphone and this may create a clearly audible feedback howl which of course will be heard by all users on your channel.
*For explanation's sake*, let's say you whip your headset off your head [With its mic still switched on] and don't hang it on a pin but lay it on a nearby flat surface, a chair, stool, table or even on the floor. First of all, the loud unexpected mechanical noise will annoy other users [likely leading to rude comments on your parentage] but secondly there will no longer be only the direct, through air, path from your earphone to your mic but also the reflected path(s) caused by bounce between the earphone and the mic effectively making the mic more efficient / sensitive at which point the headset that was close to feedback is now definitely contributing feedback. 
Let's not belabor this too much more as I'm sure you can see where I'm going. 
Hang it on an unused pin in the middle of the rail, it's back in free air. Hang it on a pin near the DS end close to the rear side of the prosc' and it MAY have slightly more gain again. Rotate it a little differently next time you hang it on that DS end pin and possibly, by virtue of how gravity happens to position it; maybe more sensitive and maybe not. Of course the same physics apply when you casually abandon it on the handiest flat surface.
If the mic is switched off, no problem.
If the side tone is low and the mic is left on, no problem for YOU but the mechanical noise will still annoy your fellow users and they'll be back to discussing your parentage.
Same comments apply to your conductors as they often hang their headsets on the lower lips of their music stands or drape them over a nearby mic boom. This tags us back to @themuzicman 's comments regarding giving orchestra conductors HS6 [ClearCom Hand Set Six] handsets with PTT [ Push To Talk / Squeeze when you grip ] handsets to use rather than headsets with several of the following advantages: The instant they let go of the handset, its mic is switched off long before they've dropped it down on the handiest surface plus the handset's mic is automatically switched off while the orchestra's playing and other users aren't competing with the brass section to be heard.
With apologies for droning boringly on, I hope some of the foregoing is of some use to you.
All the best @Electric Carpenter 
Toodleoo!
Ron Hebbard.


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## themuzicman (Oct 4, 2017)

It also ties back into nulling out your system as the sidetone adjust on most Clearcom is a part of the nulling circuit -- if your system is nulled properly everyone has a nice and even Clearcom experience.

Start at your main station and then move on to your rack mount remote stations. Pop open the panel underneath the Channel buttons, on your belt packs there is often a little inset knob. A single person should hit up every station, set the Master Volume to half-way up and with a tiny screwdriver, and channel by channel turn the Sidetone knob right until it is at its maximum volume. Then turn it left until there is no, or next to no side-tone. Then crack it open a little bit more by turning that knob to the right a hair. Do this on every single channel at every single com location, and you'll have a nice even system where the user is experiencing the same sound at every position.

Typically I do a full system null on load-in after all com and tech com is in, and then I re-null after tech com has been struck, because pulling a few hundred feet of cable out of the system will change some things. Afterwards, I'll hit up the system maybe once every two or three months on a long running show just to make sure no one is messing with any knobs.

Also make sure your system is terminated at a single location, typically at your master station there are switches on the back by the A, B, C, and D XLR and you engage them. On more complex systems you can accidentally end up terminating your system in multiple locations, but for smaller systems it's generally not a problem.


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## RonHebbard (Nov 12, 2017)

Van said:


> I LOVE PI! < Which is funny 'cause my Grandfather went by the name P.I....>
> I didn't know they had changed names. Good to know.


 @Van @EdSavoie @gafftaper @Aaron Becker ; Expounding further about ClearCom channel terminations, where one termination per channel is mandatory and two is verbotten. 
On a number of installs, I've found consultants spec'ing two ClearCom power supplies for redundancy and using one to terminate one channel and the second to terminate the other channel. Similarly, I've installed four channel systems where the consultant uses two dual channel supplies for redundant power yet uses the four terminations to provide four channels. 
So far, so good. The oversight shows up when one of the two supplies fails, is removed and sent to ClearCom for service. At that point, the failed supply's termination, or terminationS, leave the building with it reducing the system to half its original number of channels. What we chose to do was fabricate our own outboard termination PC board, for up to 12 channels on one install, and use the supplies ONLY for power and redundant power without using any of the termination networks included in the power supplies. Doing so allowed any power supply to fail and be removed for service with all terminations remaining in place and all channels continuing to function normally. 
One more point. When installing in this manner, we only connected the common and power leads to the power supplies. Intentionally NOT connecting the audio lead to the power supplies meant people could play games with the supply's termination switches to their heart's content WITHOUT having any effect on the terminations of the various channels NO MATTER HOW HARD, or well intentioned, they tried. 
Sometimes it was interesting to listen to folks discussing how they could hear the effect of the various termination switches on the supplies. Kind of like listening to folks telling you how much better their EQ settings were without realizing the EQ was bypassed. It takes all kinds. 
@TimMc You've NEVER met anyone like that have you?
*EDIT:* In earlier days, ClearCom's termination network was comprised of three parts per channel; a resistor, a capacitor to prevent shorting DC to ground when flashing the call light and a potentiometer to finesse the termination with all three connected in series between the audio line and the common ground. At some point, they removed the potentiometer reducing the termination to a simple resistor and capacitor in series. This is all I've ever used per channel when adding independent outboard terminations per channel. I've done this successfully on one, two, four and twelve channel installations.
Toodleoo!
Ron Hebbard.


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