Alternate transformer taps on PA speaker?

[tagger]

I've got a couple of JBL Control 29 speakers for outdoor use. They've got the standard 8 ohm taps, but they also have taps for 70V and 100V. Anyone know when you would want to use the alternate transformer taps?

[bodcaw boy]

the 70 v and 100v taps are meant to be used with 70v/100v amps. these amps take a standard 2.83 signal and boost the voltage to 70v or 100v while reducing the amperage. that way speakers can be located very far away from the amp and not require large gauge wire. the signal is then stepped down by the internal transformer in the speaker back to 2.83 v. this is very similar to power transmission by electric companies.

boy!!

[tagger]

Thanks for the info Roy, although now I have a couple more questions. How far away is "very far away?" And without a 70v/100v amp, what would be the minimum guage wire recommended? I ask because these speakers may end up 50' - 100' from the amp.

[bodcaw boy]

100 foot to 200 foot runs but also hooking up a large number of speakers (8 to 10) is another reason to use a 70v amp. 50 to 100 foot, i would probably use 14 gauge minimum. also because 70 v amps and the 70v speakers use transformers, you can have a low end rolloff.....

boy!!

[DrWho]

If you don't have a 70/100V amp, then you will never be running in the 70/100V settings.

100 feet isn't too long of a speaker run as long as you use the proper wire gauge(as Roy mentioned). JBL has a handy chart you can use:

http://www.jblpro.com/pages/general_faq.htm

Looks like Roy is right on the money with recommending 14 gauge too ("nerd") []

For what it's worth, I worked for a company that installed the JBL Control Series in all sorts of applications. We would have speakers runs on the order of 300 feet all the time using just 16 guage wire - not ideal, but in the non-critical listening environments you would never be able to tell the difference.

[tagger]

Who and Roy, thanks a million. That's exactly what I was looking for. []

[bodcaw boy]

If you don't have a 70/100V amp, then you will never be running in the 70/100V settings.

100 feet isn't too long of a speaker run as long as you use the proper wire gauge(as Roy mentioned). JBL has a handy chart you can use:

http://www.jblpro.com/pages/general_faq.htm

Looks like Roy is right on the money with recommending 14 gauge too ("nerd") []

For what it's worth, I worked for a company that installed the JBL Control Series in all sorts of applications. We would have speakers runs on the order of 300 feet all the time using just 16 guage wire - not ideal, but in the non-critical listening environments you would never be able to tell the difference.

for installing jbl speakers, we will need to cut off a pinky. and if you are installing jbl speakers go ahead and use any wire you want, since they all will be non-critical listening....[]

boy!!

[DrWho]

lol, we're not biased are we? Can it be a pinky toe? I need me fingers for mixing []

[colterphoto1]

Some of Klipsch's outdoor speakers have the transformers built in. Look for 'T' in the part number, like CA650T, it's ready to go out of the box. Has a knob where you can set the voltage on the transformer right on the outside of the case. Very handy!

[Guest " "]

"If you don't have a 70/100V amp, then you will never be running in the 70/100V settings."

If you needed to run wire across hundreds of feet, or wanted to manage power levels across multiple drivers on the same channel, a transformer can be put in to step up the voltage on the amp side, whereas the transformers on the speaker side would step it back down.

[colterphoto1]

I think that is what Doc meant, that you must have a transformer at BOTH the speaker side and the amp side. Your clarification that an external transformer can be used with a traditional amplifier is well taken.