# Amps

#### kovacika

##### Active Member
I know this could turn into a massive turf war between crown and behirnger but, here is my delima.

I have 2 1000rms watt subs, 2 250rms mains. I currently have 2 Crown XLS 402 amps. I can use one for each sub, works awesome. But a i also need to power the mains.

#### SHARYNF

##### Well-Known Member
Usually I go by the spec sheet, and the spec sheet does not show any 2 ohm usage or bridged in under 8 ohms, plus some personal experience has shown me that there are only a few amps that can reliably run 4 ohms bridged for an extended length of time on subs.

When you said 1000 watts on the subs I assumed dual 18s in parallel. You are correct it is very rare to have 4 ohm individual 18's speakers. Most of the designs for cabs for high power large venue are dual 18's at 4 ohms, 4 ohms in standard dual channel mode is typically the sweet spot for amp power.

W Boxes were the rage years ago, they are very efficient, don't have a great very low end but put out a lot of bass and project it pretty far. Don't know if the ones used were dual 15 or dual 18's but you are talking about a performance that is way beyond what you have in your cabinets. Your design probably will go lower but will be no where near at loud. Remember that a lot depends on the horn design and the driver in it and that every 3db increase is doubling the apparent sound level

Your eaw imitations again it is hard to tell how efficient they are typically the imitations look like the real thing but don't match up to the full performance, the rating for the real ones is 100 db at 1 watt probably rated in the high end since it does not say, the eaw at the concert you were at are rated at 107 in the high end so you again are looking at way way more output, and there were two of then per side.

Your cabinets have a 1 inch driver on the horns, the other eaws have a 3 inch driver.

at the end of the day it is a combination of how much air you can move, and how efficient your design is to turn that air movement into useful sound.

Outside in a decent location you can get away with a different speaker set up you don't have side and ceiling reflections, so the sound can sound cleaner and project further since you have eliminated a lot of the interfering reflections and canceling and "sound alley's"

In a pro setup you also tend to spec a system so you are not attempting to run flat out since you run the risk of failures, so could you get away with less gear, possibly but the old expression you can either bring it to use or bring it to replace can apply

It also depends on the type of music you are playing, and is it live or recorded/

A system for dj will tend to get more out of the install but will need a lot more bass, since the dj;s like that pounding heart rate controlling base

A live band for jazz can get away with a very different system than a rock band

In addition once you get to larger groups over 500 you typically want to put more and more of the backline sound thru the pa so you are not just looking at vocals, and you want to keep the spl level down on stage but up out in the audience, so you need quite a bit of power

anyway good questions,

Sharyn

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