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Any experience with the Electrovoice tour-x speakers?

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Banibal Yonadam:
HI

Would like to hear from someone about the Ev tx1152. Has anyone used them or had experience with them?
The specs for the speakers say that you can use one amplifier (2x550w in 8 ohm and 2x900w in 4 ohm) to run  a pair of Ev tx1152 tops and a pair of Ev tx1181 subs. The weird thing about that is that the specs also say that these speakers have a minimum impedance of 5,4 ohms. But won't connecting the speakers in parallell to one amplifier make them go down to 4 ohms or am I missing something?

H/

Banibal

Tom Young:
The short answer is that almost all professional power amplifiers can handle the load presented by (2) of the these drivers wired in parallel.

Longer answer:
When we speak of 4, 8 and 16 ohm speakers and drivers these are "nominal" values. I have never (until now, see below) seen a clear definition of what "nominal impedance" means. In practice we basically assume that this means an average impedance or the impedance at 1kHz.

But the impedance of a speaker driver varies with frequency and in this case EV has provided a minimum impedance of 5.4 ohms for the driver. This is perhaps worth noting but there is not enough information provided with this to "raise a red flag". Two of these drivers in parallel will yield a combined 'minimum' impedance of 2.7 ohms. Chances are quite good that this will not be a problem (again) with a modern day professional amplifier.

Note: I just discoverd that wikipedia has a detailed explanation of speaker impedance and includes a defintion of (and mathematical formula for determining) "nominal" impedance. Because wikipedia is not peer-reviewed and there are no cited references, I am holding off from endorsing this until I research it more.

Ivan Beaver:
Nominal impedance is one of those things that different people have all different kinds of descriptions for.

Anything that is not 4-8-16 ohms confuses many users.

We have a loudspeaker that we origionally rated as 6 ohm nominal.  I got all kinds of phone calls asking what size amp to use becuase they could not find a 6 ohm output spec.  

Even though we gave a minumum and a showed an impedance graph, it remained a "mystery".

When we changed the rating to 4 ohms, those phone calls stopped.  It was easier for people to understand. even though nothing changed with teh actual loudspeaker.

The average impedance was closer to 8 ohms.  So where do you rate it?  We went for the next lowest number, just to be on the safe side.

And if you try to rate the sensitivity on power-what impedance would you use? the rating?  Which one.  Hence the reason for sensitivity based on voltage-let the user figure out what impedance they feel should be used.

Impedance is just another one of those things that "seems" simple, but really has a lot of different ways in which it could be read.  A simple number with a complicated meaning.

Banibal Yonadam:
OK thanks. Things are starting to get a little clearer now on how the minimum impedance of these speakers matters.

Tom wrote that a modern day professional amplifier will probably not have any problems with a minimum load of 2,7 ohms (when parallell). I think I already know the answer to this, but just to be sure, is the QSC plx1804 considered one of those amplifiers that should be able to handle the parallel wiring i was talking about? The specs of the amp say that it can go down to 4 ohms but they add that it is stable in low impedance situations.

Another question I have is if the EV tx-1152 speakers are any good?? I know that this is a very general question but I want to know what kind of thoughts you have, the
guys that have tried the speakers out.

H/

Banibal Yonadam:
OK thanks. Things are starting to get a little clearer now on how the minimum impedance of these speakers matters.

Tom wrote that a modern day professional amplifier will probably not have any problems with a minimum load of 2,7 ohms (when parallell). I think I already know the answer to this, but just to be sure, is the QSC plx1804 considered one of those amplifiers that should be able to handle the parallel wiring i was talking about? The specs of the amp say that it can go down to 4 ohms but they add that it is stable in low impedance situations.

Another question I have is if the EV tx-1152 speakers are any good?? I know that this is a very general question but I want to know what kind of thoughts you have, the
guys that have tried the speakers out.

H/

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