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Series parallel
Christopher Young:
I've got something open for debate here. I'm doing a side job (normally I do the all the installed AV for a Univiversity) for a friend of my who owns a bike shop. It's a brand new big store, (the old one burned down) and we're putting in a BGM/paging system. The problem is, that as usual, no one thought about AV until the drywall was going up. They brought in a guy to run the wires that were needed but to my taste no where near enough. So I'm stuck with two pair running to the main floor and 2 pair running to the second floor. I'd like to put 8 to 12 small good fidelity speakers (probably PSB) on the 2nd floor and another 6 to eight on the Main floor (smaller floor space). Normally with so little wire I'd just do it all 70V, but normally I'm more concerned about voice intelligibility than music fidelity. So I'm wondering if anyone can see a reason not to simply combine the speakers in a series/parallel configuration to make up a reasonable impedance. I've never done it before, but I can't for the life of me come up with a reason not to.
Cheers
Jonathan Kok:
--- Quote from: Christopher Young on May 02, 2011, 02:32:53 PM ---I've got something open for debate here. I'm doing a side job (normally I do the all the installed AV for a Univiversity) for a friend of my who owns a bike shop. It's a brand new big store, (the old one burned down) and we're putting in a BGM/paging system. The problem is, that as usual, no one thought about AV until the drywall was going up. They brought in a guy to run the wires that were needed but to my taste no where near enough. So I'm stuck with two pair running to the main floor and 2 pair running to the second floor. I'd like to put 8 to 12 small good fidelity speakers (probably PSB) on the 2nd floor and another 6 to eight on the Main floor (smaller floor space). Normally with so little wire I'd just do it all 70V, but normally I'm more concerned about voice intelligibility than music fidelity. So I'm wondering if anyone can see a reason not to simply combine the speakers in a series/parallel configuration to make up a reasonable impedance. I've never done it before, but I can't for the life of me come up with a reason not to.
Cheers
--- End quote ---
The biggest downfall to series/parallel is the fact that if one speaker in the string goes down, you lose them all. But if you can find 16ohm speakers, it'll reduce the amount of series wiring required. Fulcrum Acoustics and Martin come to mind, I'm sure there are others.
Though frankly, there are a number of good quality 70v speakers out there, available from a number of manufacturers. EAW, Tannoy, JBL, Turbosound, Martin, etc.
Hal Bissinger/COMSYSTEC:
I can't see any reason not to use a 70 volt system. You will only use 1 pair to each floor. Forget stereo and the hairbrained idea of series/parallel. That's amateur hour stuff that just isn't done. A 70 volt system will sound just fine if you use quality speakers.
-Hal
Brad Weber:
--- Quote from: Christopher Young on May 02, 2011, 02:32:53 PM ---It's a brand new big store, (the old one burned down) and we're putting in a BGM/paging system.
--- End quote ---
--- Quote from: Christopher Young on May 02, 2011, 02:32:53 PM ---Normally with so little wire I'd just do it all 70V, but normally I'm more concerned about voice intelligibility than music fidelity.
--- End quote ---
Especially for a background music and paging application it's hard to believe that there are no 70V speakers that would provide sufficient fidelity. And while I am not familiar with PSB speakers, they seem to be a residential product which means that you may want to verify if their warranty covers commercial/professional use.
--- Quote from: Christopher Young on May 02, 2011, 02:32:53 PM ---So I'm wondering if anyone can see a reason not to simply combine the speakers in a series/parallel configuration to make up a reasonable impedance. I've never done it before, but I can't for the life of me come up with a reason not to.
--- End quote ---
One potential problem challenge with series/parallel wiring is accommodating changes or the possibility of others trying to service/modify the system. Add or disconnect a speaker and it could have a significant effect. Another potential drawback in some applications is that unlike a transformer with taps, you have no easy to adjust the level of individual speakers.
Christopher Young:
Thanks for the input as usual guys.
I hadn't thought of someone else having to service it, that is a real concern. I did consider "one goes they all do" but I'm still running several channels so it's not a huge concern.
PSB is the default choice for 2 reasons;
The GM, Owner and I, are all long time friends with someone at PSB
I've never heard a pair of PSBs that didn't sound great, and even better, still sound great at their price point.
With all due respect Hal, I don't dismiss a design based on whether "it just isn't done" or not. I never said anything about stereo. I'm not interested in a system that sounds 'just fine'. I've got over 100 systems on campus that sound 'just fine' that is not the goal this time around. I've installed countless 70V systems from JBL, TOA EAW and have heard several other brands in other locations. When I walk into a retail store or restaurant and am surprised by how good it sounds, it's never a distributed system.
I'm not saying 70V can't sound good, I've just never heard it. Really if I was going to go that route, I'd probably buy the PSB's and stick transformers on them, (I'm likely using the Crown 108MAx and a 660) but I'm worried that that would degrade the signal enough to make it a pointless endeavor. We all know good audio transformers are expensive for a reason.
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