70V Audio System: Junction Boxes Needed?
#1
70V Audio System: Junction Boxes Needed?
I'm going to be changing some 70V outdoor speakers tomorrow. Currently, the speaker wire runs to connections right on the back of the speaker, which have since corroded away. On the new speakers, there is a length of SJO-like cord that runs out of the speaker housing. I will be running that into the building, where I will be making my splices inside. Will these splices need to be in a box, or is this still considered class 2?
#6
Drip loop between the speakers and wall?
Just an FYI -- The new amp should be at least 20% overpowered after you add up all of the speaker wattages you've tapped. IOW if you have 100 watts on the speaker lines the amp should be at least 120 watts.
Just an FYI -- The new amp should be at least 20% overpowered after you add up all of the speaker wattages you've tapped. IOW if you have 100 watts on the speaker lines the amp should be at least 120 watts.
#7
Drip loop between the speakers and wall?


#10
The amp should be at least 20% overpowered ...
While a lower powered amplifier will usually provide adequate sound volume, it is important not to turn it up so high that distortion is noticeable. In a multi-speaker unit, the tweeter(s) will burn out before the power rating is reached if the audio is unusually rich in higher frequencies. Such speaker burnout is likely if an amplifier is overloaded or can occur if the content is not representing sounds heard in nature or from performances using non-electronic instruments.
A system reproducing music with a lot of bass requires more power than a system used for background music or voice announcements.
Last edited by AllanJ; 10-05-14 at 07:48 AM.
#11
While a lower powered amplifier will usually provide adequate sound volume, it is important not to turn it up so high that distortion is noticeable. In a multi-speaker unit, the tweeter(s) will burn out before the power rating is reached if the audio is unusually rich in higher frequencies. Such speaker burnout is likely if an amplifier is overloaded or can occur if the content is not representing sounds heard in nature or from performances using non-electronic instruments.
A system reproducing music with a lot of bass requires more power than a system used for background music or voice announcements.
Beautiful! Too many people forget or ignore the details!
#12
You should set the amp level so that when the remote volume controls are at maximum the level is where you want it. Running an amp at 100% volume and then setting each volume control to low will cause the amp to overheat.
#13
Don't confuse constant voltage speaker systems with low-impedance speaker systems.
Each CV speaker will draw wattage according to its transformer tap settings. The standalone volume controls in these systems are actually autoformers. They take no portion of the signal to ground. As you turn down the volume the impedance increases (into the thousands), so the load presented to the amp gets lighter as they are turned down. Turning them all the way down opens the circuit. The only limitation on the volume control is, again, the wattage tap of the speaker. The VC must be rated for equal or higher wattage than the speaker tap.
Potentiometers that are incorporated into a CV speaker (for example, in the center of a ceiling mounted speaker baffle) are inserted on the low-impedance side between the transformer and the voice coil. In this case, they take a portion of the signal to ground when turned down. The effect on the primary side of the transformer -- and therefore the amp -- is minimal.
Justin, are those Community R series speakers?
Each CV speaker will draw wattage according to its transformer tap settings. The standalone volume controls in these systems are actually autoformers. They take no portion of the signal to ground. As you turn down the volume the impedance increases (into the thousands), so the load presented to the amp gets lighter as they are turned down. Turning them all the way down opens the circuit. The only limitation on the volume control is, again, the wattage tap of the speaker. The VC must be rated for equal or higher wattage than the speaker tap.
Potentiometers that are incorporated into a CV speaker (for example, in the center of a ceiling mounted speaker baffle) are inserted on the low-impedance side between the transformer and the voice coil. In this case, they take a portion of the signal to ground when turned down. The effect on the primary side of the transformer -- and therefore the amp -- is minimal.
Justin, are those Community R series speakers?
Last edited by Rick Johnston; 10-08-14 at 05:41 AM. Reason: "effect", not "affect"
#14
Justin, are those Community R series speakers?
#15
Probably the R25's. An 8" coaxial speaker in a gray cabinet. Those bad boys are like $400 a pop.
But they do sound good.
But they do sound good.
#18
Those are cranking speakers...... I can imagine how good that must have sounded.