ceiling speakers and correct amp

[llewop]

My church has six previously installed 70v ceiling speakers wired for 5 watts.
I have a crownXLS402 amp available but i doubt that it will work with the speakers. Am I right? I think I understand that for reasonably good fidelity a 35 or 40 watt 70v paging amp is what I need. Do I just add the watts for each speaker to come up with the wattage required to power the set?

 

[DuckJordan]

there is a specific system for 70v systems as it requires the outline voltage to be sent at 70v and at the speaker dropped to the speaker requirements. I am pretty sure in this situation you need to find ohms and other than that i am pretty sure you don't need any more than 10 watts because of the way a 70v system works. What speakers are installed at the location and whats the original amp if available.

Correction: You would need a 70v amplifier that puts out at least 30 watts, if you account for 20% loss for things such as transformer leak and line degradation that would put you at 36 my suggestion would get an amplifier that puts out 40 watts and is a 70v system. ohms really shouldn't matter in this situation... my mistake.

 

[derekleffew]

This document might help: Crown Audio - Guide to Constant-Voltage Systems.pdf.

 

[Chris15]

reasonably good fidelity...70v

This causes me to chuckle somewhat. Constant Voltage Systems are not renowned for their high fidelity. With voice paging their main application, the transformers on the speakers are generally less than stellar and hence getting good fidelity is an uphill battle.

That's not to say you can't. There are some ceiling speakers that do sound adequate or even good, but the vast majority leave something to be desired (at least in my experience...)

You can use the spare XLS IF you install a suitable transformer to the output.

 

[museav]

Let me start by saying that I am not recommending this approach, however with the proper amplifier you can direct drive a 70V system without a transformer.

Using P=V**2/R, if V is 70.7V and R is 8 Ohms then P is 625W. So an amp rated 625W into 8 Ohms is capable of direct driving such a system. And an amp rated 1,250W into 8 Ohms is capable of direct driving a 100V system. So the XLS402 in bridge mono mode could direct drive a 70V system but is extreme overkill for this application and not a recommended approach.

 

[llewop]

Thanks for that. That is exactly what I thought. Some one before me had installed this system. We do have an excellent FOH system complete with subs and four 12" floor monitors (JBL112), sounds great. The ceiling speakers are for an assembly hall and only for presentatons and background music. The previous installation had to be changed. The installer used one side of a QSC1450 to power the ceiling speakers and the other to power the FOH in mono. Poor amplifier. I have re wired the system and now the QSC1450 is n stereo and happy.. Sound is now great.
Thank you for your response.