Mixing brands - Mains and Subs - good idea?

There's no reason why that would not work. Many systems I've seen and run over the years, from pro touring systems all the way down to garage band systems, have some mixture of speakers from different makers. I don't have experience with the particular JBL sub you're talking about, but in general there's no reason why speakers from different makers won't play nicely together.

 

there's no good reason that this can't be done.
i'd listen to the jbl's vs. the ev subs that match your tops, and don't pay much attention to the spec sheets.

 

I'd audition first... I had the elx112Ps with a single elx118P and it did nicely... The EV sub delivers well. I would not expect the PRX sub to out perform it. The EVs mate very nice.

 

can you post the specs of the two speakers? the specs generally don't hold much merit. readings are taken at different distances, etc... trust your ears, not the spec sheet....but if you can't find the speaker to listen to, it makes this a bit more difficult.

 

on paper, they are pretty close. don't worry about the 33Hz vs. 32Hz (both measured at -10db). the crossover point of the jbl's is 120Hz, vs. 100Hz for the ev's. 120Hz, to me, is a more reasonable point. again, i'd suggest listening and not looking at these numbers. i can't seem to find the prx series current pricing (discontinued, perhaps?), but i can tell you that the ev's map price is $799, and dealer cost is more like $530 (apx.), and the cost of the jbl's in '09 was map $1299, and dealer $940 (apx.). big difference in pricing for two speakers that spec vs. spec match up fairly closely.

 

What about the diference in SPL? The JBL supposedly is 133 max compared to the 125 for the EV. If this is true the JBL would be almost twice as loud. If I was only using one sub this could be a deciding factor.

 

well, since JBL doesn't list where they are taking the measurement to get their reading of 133db, and EV listed theirs as 1m, it's impossible to do a true comparison on paper. that's exactly what i mean by use your ears, not the specs.

 

I'd give the edge to the JBL over the EV in terms of overall volume. It maybe that because of the DSP used in the JBL, they are able to get more sound and speaker extension from their 18". But neither will give you gobs of chest thumping lows at high volume levels. You would need more speaker and more power for that. But IMHO, either would work nicely in a small to moderate venue where a band wanted to re-enforce the kick drum and bass guitar a bit. Plus take some of the low duty off the upper cabs.

 

i have a set of older powered JBL 18" bottoms (MPro's, I think) that we rent out to DJ's and for small PA systems, and clients love them. they get the job done, but i'm spoiled when it comes to speakers, and can't say that i love them. but, again, they get the job done, and they weren't a fortune.

 

I wonder where the OP got his specs from. This is what is listed at musicians friend.http://www.musiciansfriend.com/pro-...-x-series-active-18-subwoofer/h70838000000000

 

I went to the ev website and it showed the specs you listed.

 

Well they probably had to make up a higher number since the competion all have subs in the 130 db range. Rokpunk is right, let your ears be the judge. I suspect that the JBL is a better sub though.

 

you top is probably wired backwards.