ACT6 Digitals Buzzing

[Ben Langfeld]

I've just had 3 Strand ACT6 Digitals installed in the studio, and two of the three produce a loud buzzing sound when dimming (silent at 0 or 100%), and due to the placement, this is unacceptable and must be silenced. I understand this is to be expected, but if one of the dimmers doesn't do it, then surely none of them should. Is there any reason why one of the dimmers is being nice to me, and the others aren't, and is there anything that can be done with the noisy dimmers to get them to shut up, or am I going to have to build some kind of box round them with some sound-proofing material?

 

Ta,

Ben

[mac.calder]

I've just had 3 Strand ACT6 Digitals installed in the studio, and two of the three produce a loud buzzing sound when dimming (silent at 0 or 100%), and due to the placement, this is unacceptable and must be silenced. I understand this is to be expected, but if one of the dimmers doesn't do it, then surely none of them should. Is there any reason why one of the dimmers is being nice to me, and the others aren't, and is there anything that can be done with the noisy dimmers to get them to shut up, or am I going to have to build some kind of box round them with some sound-proofing material?

 

Ta,

Ben

 

The buzzing is expected - the one that doesn't buzz is an oddity, rather than the norm in most cases. I would most definately NOT install a box arround them, as sound proofing will also insulate the box, turning it into a nice little sauna. Wasted energy escapes as heat... after a while of use... well it will get damn hot in there.

 

Is it possible to locate them outside of the space? If you have a foyer, can you install a large ventilated cabinet there for the dimmers and patch?

[J Pearce]

Depends on how loud the buzzing is as to whether it is normal or a malfunction.

Also I have found that different loads can make dimmers buzz more or less.

 

Act6s are at the budget end of the market, so I'd expect a bit of buzz, it might be perfectly normal and you've been lucky to find a quiet one. Having said that from modern dimmers I have never had anything that would be noticeable over conversation.

[axle]

trust me (I do some work with root in this studio) they are loud. You can hear them from across the room over conversation at certain levels if memory serves. My money is on the sparks, but I won't go into too much detail other than mentioning that instead of using appropriate cable glands they drilled through the body of the BRAND NEW dimmers to get the eletrics in, not even bodging it properly and drilling through the removeable plates of which there are 2 that were perfectly suited >.>

[djw1981]

I've just had 3 Strand ACT6 Digitals installed in the studio, and two of the three produce a loud buzzing sound when dimming (silent at 0 or 100%), and due to the placement, this is unacceptable and must be silenced. I understand this is to be expected, but if one of the dimmers doesn't do it, then surely none of them should.

 

instead of using appropriate cable glands they drilled through the body of the BRAND NEW dimmers to get the eletrics in, not even bodging it properly and drilling through the removeable plates of which there are 2 that were perfectly suited >.>

 

So the problem is probably only with the dimmers in the sense that the installation process was done incorrectly, possibly damaging the internal structure of the dimmer. Presumably this invalidates any manufacturers warranty etc with the product, and may even be dangerous. Maybe you should be thankful that audible buzzing is the only thing they are doing!

[axle]

Like I said, I could rant on for ages about how crap the sparks were. I didn't get enough privacy from prying eyes (both sparks and drama teachers) to check their work on the dimmers. I plan to do that when I can next get over there and meet up with root to go over everything.

[themadhippy]

very much doubt that the sparks bodged it in,ater all electrical work done in schools must be carried out by niceic company.

[axle]

iirc NICEIC relates to the company itself, not the sparks hired by it. I've seen the work, they drilled a hole into the body of the dimmers, actually OVERLAPPING one of the removable discs (the one for control cable entry incidentally, NOWHERE NEAR the designated electrical entry points). These are the same electricians that pointed out, as the first priority, that the rig needed earth bonding. Now, when they claimed they'd finished, I still saw no signs of bonding anywhere.

[Ben Langfeld]

Thing is, these are unusually loud. Buzzing, yeah, I'd accept that, but sounding like a cessna on the runway - kinda suspect. The electricians who installed the dimmers were also suspect - when quoting for the job, they claimed they couldn't install anything that used 15A plugs/sockets as these were now illegal :) . Unfortunately, we had no choice but to use them, and now I have to run everything at 0 or 100% when an audience is in, else they can't hear the performers on stage.

[Andrew C]

A possible cause, and not unlikely bearing mind the comments on the quality of the install, would be all the lives through one hole, and the neutrals through another. Not the first time I've heard of this problem.

[SEECOL]

Thing is, these are unusually loud. Buzzing, yeah, I'd accept that, but sounding like a cessna on the runway - kinda suspect. The electricians who installed the dimmers were also suspect - when quoting for the job, they claimed they couldn't install anything that used 15A plugs/sockets as these were now illegal :) . Unfortunately, we had no choice but to use them, and now I have to run everything at 0 or 100% when an audience is in, else they can't hear the performers on stage.

 

Andrew C with his comment on live through one hole neutral through another is spot on as to the most likely cause of the buzzing noise.

 

In addition to obtain the quietest installation line & neutral are best run in a cable rather then separate cores in trunking - too often the installation default in UK. Composite cable for supply mains is also important, SWA 4 core is far far better then separate cores in box trunk.

Even cheap dimmers can run almost silent if the electrical installation is done correctly. Done incorrectly & even expensive dimmers can wake the dead with the resultant racket.

 

People just forget the basics. 2PiF in this case. 50Hz of course the number is 312 and one can often forget about inductive effects in smallish installations.

Any dimmer has the effect of raising 2PiF to around 2 -3000, more for some very cheap dimmers. Obviously this grossly magnifies any inductive effect should the electrical installation be sub-standard.

[axle]

A possible cause, and not unlikely bearing mind the comments on the quality of the install, would be all the lives through one hole, and the neutrals through another. Not the first time I've heard of this problem.

 

Sorry if it's an obvious answer, but mind elaborating on what you mean by the lives going through one hole and the neutrals through another? (other than being seperated obviously)

 

Not sure if you meant on-route to the dimmers, entering them or something else. :)

 

SEECOL: IIRC from the brief glance I got of the wiring, they look to have used single core wire from the breaker panel through trunking and into the dimmers. And to elaborate a little more on the routing and the drilling, they re-used a piece of flexible plastic coated steel trunking(?) that went from the trunking to the old dimmers to go from the trunking to these new dimmers. Hence the drilling as the glands at the end were around 25mm I think.

[Andrew C]

Sorry if it's an obvious answer, but mind elaborating on what you mean by the lives going through one hole and the neutrals through another? (other than being seperated obviously)

Not sure if you meant on-route to the dimmers, entering them or something else. :)

If you take a pair of live/neutral cables carrying AC through one hole in a ferrous metal, any induced currents are cancelled. If you route the cables through separate holes, eddy currents are induced in the metal. It is basic transformer theory stuff.

 

This can be the cause of your mechanical noise. It doesn't matter whether this is supply or load side of the dimmers.

[axle]

Ah, ok, Thought that might have been what you meant but wasn't entirely sure, they definitely leavve the trunking and enter the dimmers through the same hole, haven't seen what they do on the other end.

[Ben Langfeld]

I'm going to phone Stage Electrics on monday and ask them to come down and have a look. The last thing I want is the electricians who did the install to get anywhere near them again. They should, however, expect to be asked to pick up the bill.