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| Re: Standard practice for installation speaker wiring? [message #319278 is a reply to message #319273 ] |
Sun, 04 May 2008 08:53   |
 Brad Weber
Messages: 1488
Registered: December 2005
Location: Marietta, GA |
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I've seen it done and such systems used to be fairly common practice, what was usually done was to home run all speakers to a terminal strip in the rack and create the series/parallel wiring there. However, in this application I think this approach is just asking for trouble for the reasons Jason noted and it is all to easy to envision someone else coming in that didn't understand what was done and messing up the wiring. It might also be difficult to get an 8 Ohm load with 8 speakers, a 4 Ohm load would be easier but we don't know if the amp could handle it. Probably best to get more amp channels or convert it to 70V.
Brad Weber
muse Audio Video
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| Re: Standard practice for installation speaker wiring? [message #319286 is a reply to message #319262 ] |
Sun, 04 May 2008 09:15 |
Charlie Zureki
Messages: 1365
Registered: April 2008
Location: Detroit Area |
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Loren,
Jason and Brad are giving you good advice.... exchange the speakers, the evid's with transformers are a bit more but it'll be well worth it. If they cannot be swapped out use transformers.
Hammer
Be prepared, you'll need it!
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| Re: Standard practice for installation speaker wiring? [message #319345 is a reply to message #319341 ] |
Sun, 04 May 2008 13:47 |
Brad Weber
Messages: 1488
Registered: December 2005
Location: Marietta, GA |
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| Loren Aguey wrote on Sun, 04 May 2008 14:35 |
I think I might have to trace the wiring on the other side and see how they did it. Because however they did it, it works fine.
So for most restaurants and such, and anywhere with lots of ceiling speakers is 70v the standard?
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70V is pretty much the standard for distributed systems. Along with reduced line losses, one of the benefits is that as long as the amp can provide the power required, you can add or remove speakers without worrying about the resulting load.
You might want to make sure it isn't a 70V system, do you know what the amp is, how it is wired for the speaker and how any related switches are set?
Brad Weber
muse Audio Video
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| Re: Standard practice for installation speaker wiring? [message #319434 is a reply to message #319262 ] |
Sun, 04 May 2008 18:38 |
Scott Hibbard
Messages: 319
Registered: April 2004
Location: New Jersey |
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Loren,
Yes 70v is very common for distributed systems with many speakers. Although not as common, low impedance speakers can be used but requires more amplification channels. There are some installation speakers that are 16 ohms which allows for more speakers per/channel.
Powering 8 - 8 ohm speakers from a single amp channel is asking for trouble, esp. is the levels ever get beyond low background levels - your amp will likely not appreciate the load and have trouble dealing with the resulting heat from a 1 ohm load.
As someone else mentioned, the most cost effective solution may be the addition of amplification channels. You might even find it beneficial to take some of the current speakers off the single channel they are currently on and move then to new, unused channels. Here's an example: One QSC 168 amp will provide 8 channels @ 130 watts each. Put two speakers on each channel (4 ohm load) and you can power (16) EVID's with one amp - giving each EVID ~ 65 watts (minus line loss). Or a QSC 254 (which supports 2 ohm loads) where you can put (4) speakers on a channel - powering all (16) with one amp safely. This would yield more power to each speaker. Worse case, get another (2) channel amp to power the 8 speakers you haven't yet installed. If the spare amp channel you speak of is on the same amp currently powering the already installed 8 EVID's, I would professionally advise you to avoid adding 8 more to the spare channel. Think longevity too - a 1 ohm load on any amp is like running your car's engine up against it's REV limiter all day.
P.S. What model amp are we talking about here?
ScottH
[Updated on: Sun, 04 May 2008 18:39]
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| Re: Standard practice for installation speaker wiring? [message #319471 is a reply to message #319434 ] |
Sun, 04 May 2008 20:17 |
Brad Weber
Messages: 1488
Registered: December 2005
Location: Marietta, GA |
Has No Life |
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| Scott Hibbard wrote on Sun, 04 May 2008 19:38 |
Powering 8 - 8 ohm speakers from a single amp channel is asking for trouble, esp. is the levels ever get beyond low background levels - your amp will likely not appreciate the load and have trouble dealing with the resulting heat from a 1 ohm load.
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You would only have a 1 Ohm load if you wired all 8 speakers in parallel. The concept suggested would be to use a combination of series and parallel wiring to get a reasonable load, an approach that was rather common not that long ago. It would be easy to get a 4 Ohm total load with 4 speakers in parallel wired in series to another 4 speakers in parallel or 16 Ohm total load with 4 speakers in series parallelled to another 4 speakers in series. You could also use approaches such as 2 sets of 3 speakers in parallel (2.67 Ohms for each set) and one set of 2 in parallel (4 Ohms) then wired in series for a total of 9.33 Ohms or 2 sets of 3 speakers in series (24 Ohms) and 1 set of 2 speakers in series (16 Ohms) with the sets wired in parallel for a total load of 6.9 Ohms. You can get a wide range of resulting loads with series/parallel wiring, but the wiring can easily become rather complex and it may later be difficult to figure out what was done.
Brad Weber
muse Audio Video
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| Re: Standard practice for installation speaker wiring? [message #319484 is a reply to message #319471 ] |
Sun, 04 May 2008 21:06 |
Hal Bissinger/COMSYSTEC
Messages: 297
Registered: April 2004 |
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I have been always been been told that wiring speaker systems with crossovers in series is not something you want to do. Seems to do unpredictable things to the frequency response.
-Hal
www.comsystecusa.com
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| Re: Standard practice for installation speaker wiring? [message #319510 is a reply to message #319484 ] |
Sun, 04 May 2008 22:14 |
Duane Massey
Messages: 1426
Registered: January 2006
Location: Houston, Tx |
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70v transformers can be found for as little as $5-7 each. If the amp has a 70v output, this would not be much $$$.
Duane Massey
Houston, Texas, USA
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| Re: Standard practice for installation speaker wiring? [message #319697 is a reply to message #319693 ] |
Mon, 05 May 2008 15:00 |
Charlie Zureki
Messages: 1365
Registered: April 2008
Location: Detroit Area |
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Loren,
there's more to this than you're telling us...
How did you measure the 30.2 ohms? Did you disconnect the speaker wires at the Amp? Because if they were wired in series I'd think it would be more than 30.2 ohms., with adding in speaker wire resistance.
What gauge is the wiring?
Hammer
Be prepared, you'll need it!
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