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Need Help/Advice about Sound System

J

JonM

Jan 1, 1970
0
Hi,

I have a question for anyone with experience with sound systems for
meeting halls, churches, PA systems, etc.

Recently I was asked to help with repairing a sound system in a meeting
hall. My job is to solder connections for cables etc.

Originally the system was set up as:

-About 80 speakers wired in parallel. Each one has a small
transformer mounted on it. I was told that this is set up as a 70 Volt
Speaker System.
-The speakers were powered by a TOA Amplifier that had a 70 Volt
speaker output.

Here is were my question comes in. The person responsible for
installing new equipment is using the original speaker system but
hooked it up to a ART SLA 2 Amplifier (see:
http://www.artroch.com/downloads/specsheet/ART_SpecSheet_SLA2.pdf). As
far as I can tell this amplifier does not output a 70 Volt signal to
the speakers. The sound does come through, however my question is: Is
it alright to use this amplifier with this speaker system? If not, how
can I present evidence to the person in charge in a convincing way?

Thank you all for your help.
 
L

Lord Garth

Jan 1, 1970
0
JonM said:
Hi,

I have a question for anyone with experience with sound systems for
meeting halls, churches, PA systems, etc.

Recently I was asked to help with repairing a sound system in a meeting
hall. My job is to solder connections for cables etc.

Originally the system was set up as:

-About 80 speakers wired in parallel. Each one has a small
transformer mounted on it. I was told that this is set up as a 70 Volt
Speaker System.
-The speakers were powered by a TOA Amplifier that had a 70 Volt
speaker output.

Here is were my question comes in. The person responsible for
installing new equipment is using the original speaker system but
hooked it up to a ART SLA 2 Amplifier (see:
http://www.artroch.com/downloads/specsheet/ART_SpecSheet_SLA2.pdf). As
far as I can tell this amplifier does not output a 70 Volt signal to
the speakers. The sound does come through, however my question is: Is
it alright to use this amplifier with this speaker system? If not, how
can I present evidence to the person in charge in a convincing way?

Thank you all for your help.

Check to see if he installed a step-up transformer at the power amp output.
I can't see it operating if not.
 
J

JonM

Jan 1, 1970
0
Check to see if he installed a step-up transformer at the power amp output.
I can't see it operating if not.

No, I can't see that he did.
 
M

Michael A. Terrell

Jan 1, 1970
0
JonM said:
Hi,

I have a question for anyone with experience with sound systems for
meeting halls, churches, PA systems, etc.

Recently I was asked to help with repairing a sound system in a meeting
hall. My job is to solder connections for cables etc.

Originally the system was set up as:

-About 80 speakers wired in parallel. Each one has a small
transformer mounted on it. I was told that this is set up as a 70 Volt
Speaker System.
-The speakers were powered by a TOA Amplifier that had a 70 Volt
speaker output.

Here is were my question comes in. The person responsible for
installing new equipment is using the original speaker system but
hooked it up to a ART SLA 2 Amplifier (see:
http://www.artroch.com/downloads/specsheet/ART_SpecSheet_SLA2.pdf). As
far as I can tell this amplifier does not output a 70 Volt signal to
the speakers. The sound does come through, however my question is: Is
it alright to use this amplifier with this speaker system? If not, how
can I present evidence to the person in charge in a convincing way?

Thank you all for your help.


How many watts is the new amplifier?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jan 1, 1970
0
JonM said:


At 5000 ohms per watt (70 volt constant voltage system) that would be
5000 ohms /200 watts for a 25 ohm load. It will work, but it would be
better if properly matched with a line transformer.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
C

Chris

Jan 1, 1970
0
JonM said:
Hi,

I have a question for anyone with experience with sound systems for
meeting halls, churches, PA systems, etc.

Recently I was asked to help with repairing a sound system in a meeting
hall. My job is to solder connections for cables etc.

Originally the system was set up as:

-About 80 speakers wired in parallel. Each one has a small
transformer mounted on it. I was told that this is set up as a 70 Volt
Speaker System.
-The speakers were powered by a TOA Amplifier that had a 70 Volt
speaker output.

Here is were my question comes in. The person responsible for
installing new equipment is using the original speaker system but
hooked it up to a ART SLA 2 Amplifier (see:
http://www.artroch.com/downloads/specsheet/ART_SpecSheet_SLA2.pdf). As
far as I can tell this amplifier does not output a 70 Volt signal to
the speakers. The sound does come through, however my question is: Is
it alright to use this amplifier with this speaker system? If not, how
can I present evidence to the person in charge in a convincing way?

Thank you all for your help.

Hi, Jon. The funny thing is, it works. Hmnnn.

I would guess the intrepid person who initially wired it up set the
outputs as bridged mono. Your tear-off sheet on your amp shows it can
pump up to 560 watts into 8 ohms in that configuration. That's pretty
close to 70 volts. And remember, the amp is primarily a voltage output
device, as long as there's not excessive current.

The thing is, if all 80 of your small PA 70.7 volt matching
transformers are set to a tap below 7 watts, there will be a total of
less than 560 total watts. Which means your amp is within safety
range.

Your setup is a little bizzare, but it might work well enough,
considering you've got PA speakers. If you don't trust your
installation person, you should call up the manufacturer in Rochester
to check for sure. Get specifics on the number of PA speakers, and
their tap settings (first guess, they're all the same, but you should
check).

Good luck
Chris
 
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