1. Home
  2. Hobby Electronics Basics
  3. Need Help/Advice about Sound System

Need Help/Advice about Sound System

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:

formatting link
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.

Reply to
JonM
Loading thread data ...

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

Reply to
Lord Garth

No, I can't see that he did.

Reply to
JonM

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
Reply to
Michael A. Terrell

200
Reply to
JonM

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
Reply to
Michael A. Terrell

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

Reply to
Chris

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.