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Valcom Class Connect

all brand new -new building new wiring its a small building about 6 class rooms one speaker wire going to each room

hall ways -one wire going to 4 speakers
cafeteria-one wire going to 4 speakers

media room -one wire going to 4 speakers

These 3 locations have To go thru the AMP

all 25 volt speakers

there are also 2 other exiting building that are user the same system

this new building is the only one that is using a V6120 AMP

So where did the shielded cable come from? If you didn't wire the speakers and you don't know if they installed volume controls it seems like "they" (who is "they"?) messed around with what you installed. If your original cable was removed and replaced with shielded there is no telling what was done. If they knew anything they would know that shielded cable is not used for constant voltage speaker wiring. It can cause problems with the amp.

-Hal

Hal

There was no shielded cable used on the job .

when I went to the job on Monday I noticed that the pair of wires (using cross wire) coming from the 10 watt output on the V-6120 was on the Negative terminal & the ground terminal (where the shielded wire would normally go )

at this point the paging was working they were just complaining about the sound quality

there could be several reasons for this -not enough speakers ,tapped to low ,...ect

I looked at the wiring and thought that it should go on the positive & negative terminals


and during the process of moving the connections the amp stated smoking

anyways we went out there yesterday with a another AMP (Bogen) 100 watt and put these (3) individuals locations onto one zone it seems to be working fine

They only use the paging as all call at this point


I still don't understand what I did that would make this amp start smoking unless its a defective AMP


we installed this class connection in the other 2 buildings which has been working fine but this building is a little different because it has the Café ,Media room, and Hallways with 4 speakers were we need an Amp

Here is the installation manual. http://www.class-connection.com/vsp/v6120.pdf

I see what you mean about the speaker outputs with (+)(-) and ground. They do show shielded cable and the only reason I can think of is when retrofitting older systems there may be a crosstalk problem with old wiring bundled together and speakers tapped at low wattages, so the original installer used shielded cable. You will notice that the shield is only connected at the amp, the other end is not connected to anything. The speaker(s) themselves are connected between (+) and (-).

That said, undoubtedly the grounds on all the output terminals are connected internally to chassis ground. Why the speakers worked at all when connected between the (-) and ground only a schematic of the amp will tell. It's not the proper connection but it shouldn't have caused any damage. When you corrected the situation by connecting the speakers properly it certainly shouldn't have caused the results you saw.

So, now with another amp things are working fine. I usually believe Valcom makes good products but it looks like they dropped the ball on this one. Send it back.

-Hal

You still didn't answer my original question.

Why did you change the wiring at the amplifier when it was working? Just because the vendor said it should go to the negative terminal instead of the shield terminal is meaningless as they have to clue as to the actual on-site wiring.

Allow me.

Because customer was complaining about "poor sound quality" he called Valcom about it. When he told them that the speakers were connected to the (-) and ground terminals they said that was wrong, they should be connected to (+) and (-). When he did that the amp self destructed.

This is just two conductor speaker wire, black and white, no shield.

-Hal