Could it cause damage - Underpowered Speaker

Joey.lyons01

Member
Messages
18
My old PA was setup majorly incorrectly like this: Yamaha EMX2000 Powered Mixer into one PV215 (700watts RMS). I was powering the PV215 incorrectly by going directly out of the left stereo channel of the EMX2000 (200watts). I know this is not an appropriate setup, and that's why it's my old PA. But I was obviously severely under powering my speaker. As far as my ears can tell though the speaker isn't damaged.

The rule I've read is roughly/ideally to: "Buy a power amp that has 1.5ish-2 times the wattage of the speakers your powering."

So that's what I've done. I now have a new Crown xTi4002 (1200watts per channel @ 4ohms) into two PV215s (4 ohms/ 700watts RMS/ 1400watts peak). And a little yamaha unpowered mixer with some cheesy effects that I plug my mics into.

I haven's set any of it up yet, because I'm concerned that the old PV215 that I was using may cause some sort of damage to my new setup. (Even though, like I said, it doesn't sound like it's blown). I feel like maybe I'm worrying for no reason, but I would always rather be safe than sorry, and I always value the knowledge of people more experienced and knowledgable than myself. Even if the old PV215 is busted (which I don't believe it is), would it cause damage to anything else? Is it the amp that I more like ruined by trying to force it to power such a large load with one left channel? (I wasn't even informed enough to try bridged mono).

My humble thanks, Joey
 

GCDEF

Silver Supporting Member
Messages
28,245
The whole underpowering thing is nonsense propagated by people who have no idea what they're talking about. Your speaker is fine.
 

335guy

Member
Messages
5,228
Your speaker is probably fine. Under powering it won't damage it. Speakers are damaged by overheating due exceeding their wattage limits and/or exceeding their excursion limits. Your amp is probably fine as well.
 

J M Fahey

Member
Messages
2,940
True.
NOW your system is mis matched and you can definitely blow your speakers, unless you use a very well set up limiter . Maybe your amp includes a built-in one, check the manual.

You should feed some signal into it (such as a 1kHz tone http://www.mediacollege.com/audio/tone/download/ played by a smartphone or Mp3 player through the mixer) , no need to connect the speaker, SS amps work well without them for adjustment, rise volume until you have 60 or 70VAC output and ajust the limiter so that output voltage (at the speaker terminals) goes down to some 50VAC (which is over 600W RMS) and can never go beyond that.

Then your system will not distort (the limiter keeps it below clipping) and won't burn your speakers ... if their rating is realistic, that is.

That said, high frequency feedback/squealing can still blow your horn drivers, so be careful about that.
 

335guy

Member
Messages
5,228
I now have a new Crown xTi4002 (1200watts per channel @ 4ohms) into two PV215s (4 ohms/ 700watts RMS/ 1400watts peak).
FYI. Your PV215 speaker cabs are rated at 700 watts PROGRAM, not continuous/rms.

" The PV® 215 is a two-way double 15" speaker in a trapezoidal enclosure capable of handling 700 watts program and 1400 watts peak power "

Program watts are roughly 2 x's the rating of rms/continuous.

So the true rms/continuous power handling capacity of your PV215's are closer to 350 watts. By using a power amp rated at 1200 watts per channel into a 4 ohm load ( your speakers are 4 ohms ), you could be seriously over powering your speakers. Fortunately, that Crown amp does have built in limiting, so if I were you, I would thoroughly understand how to set up the power amp's limiter/s and use them.
 

walterw

Platinum Supporting Member
Messages
38,960
my speakers are sitting in my storage space getting underpowered right now! i hope they're OK ;)

(and +1 to the above, you now have a monster power amp pushing barely better than hobbyist speaker cabs; keep the volume down and you should be OK.)
 

Joey.lyons01

Member
Messages
18
"Generally you should pick an amplifier that can deliver power equal to twice the speaker’s program/continuous power rating." I got this quote from Sweetwater's power amp buying guide. They lumped program and continuous together which obviously screwed my perception of what I was getting. So is that just not a particularly accurate rule? Also, I understand that my amp is apparently capable of delivering close to 3.5 times my speakers RMS...So that means I just have to heavily limit the amps output in order to keep from burning my speakers??? I do plan on obviously reading the manual before I plug in any cables, but I just wanted to understand my equipment better before I opened any boxes? I was misinformed about the PV215 and haven't opened it yet, so theres a good chance I may return it. Is there a better, more powerful pair of speakers that would be more appropriate for my amp, that won't completely drain my bank account that you guys could recommend?
 

GCDEF

Silver Supporting Member
Messages
28,245
Several things.

The guys that write the marketing crap aren't immune to the internet nonsense.

They make more money selling you bigger amps than you really need.

There is a teeny inkling of truth to the story in that if you really, really, really want to squeeze every last micro-decibel out of your speakers, you'll need clean power to do it, so having an amp that exceeds your speakers ratings will get you there. Somehow that's morphed into underpowering is dangerous. If that was really the case, you'd be risking your speakers every time you turned the volume down. However, running any piece of equipment at its limits is begging for trouble.
 

335guy

Member
Messages
5,228
"Generally you should pick an amplifier that can deliver power equal to twice the speaker’s program/continuous power rating." I got this quote from Sweetwater's power amp buying guide. They lumped program and continuous together which obviously screwed my perception of what I was getting.
This is what Sweetwater's power amp buying guide said:

" When you’re matching a power amp to a PA speaker setup, a good rule of thumb is to pick an amplifier that can deliver power equal to twice the speaker’s program rating. "

It doesn't mentioned continuous/rms. Be that as it may, the concept is to provide adequate power for transient peaks without sending the amp into clipping. So, according to Sweetwater, the Crown amp that you got does just that, ei:, is double the program rating of your speakers. But that is their somewhat simplistic opinion. According to Crown, more is involved with choosing the correct power amp for a speaker, and it has much to do with the kind of music/program material the speaker will be reproducing.

Crown's rule of thumb is to choose an amp that can deliver 2 to 4 times the speakers continuous power rating per channel, to allow for 3 to 6 db of headroom for peaks in the audio signal.

" If you can prevent the power amp from clipping (by using a limiter), use a power amp that supplies 2 to 4 times the speakers continuous power rating per channel."

Your PV215's are basically 350 watts continuous, or half the program rating. They go on to say this:

"If you are mainly doing light dance music or voice, we recommend that the amplifier power be 1.6 times the Continuous Power rating per channel. If you are doing heavy metal/grunge, try 2.5 times the Continuous Power rating per channel."

So, it appears that Crown's opinions on the amount of power a speaker should be given are based on the intended use/type of music, and if limiting will be used. That is important. The use of a limiter prevents the amp from delivering too much power to the speaker/s. Since your amp does have limiting, in theory, you can use that amp safely with those PV215 speakers, assuming the power handling rating of those speakers is close to being accurate, AND, the limiter is set to limit the amp from over powering the speaker/s.

But a word of caution from Crown.

" If you use much more power, you are likely to damage the speaker by forcing the speaker cone to its limits. If you use much less power, you'll probably turn up the amp until it clips, trying to make the speaker loud enough. Clipping can damage speakers due to overheating. So stay with 1.6 to 2.5 times the speaker's continuous power rating."

http://www.crownaudio.com/how-much-amplifier-power

If you use Crown's max power recommendation of 2.5 x's the speakers continuous rating, then the max wattage rating for your speakers would be 875 watts continuous @ 4 ohms. The amp you were sold is putting out 1400 watts per channel continuous into a 4 ohm load, 525 watts more than Crown recommends.

And try to figure this out. If those passive speakers were capable of handling 1400 watts, then WHY did Peavey install a 400 watt amp in the powered version of this same speaker with the same drivers? Is it because Peavey knows that a more powerful amp could damage the drivers? Quite possibly.

So, although I like Sweetwater for the most part, I respectfully disagree with their opinion of using this amp with this set of speakers. And their recommendation does smack of GCDEF's assertion that " They make more money selling you bigger amps than you really need."

As to alternative speakers that can be powered by that amp, IMO, you're getting into pro territory. And in general, I'm not a big fan of dual 15 speaker cabs, as I think there are better ways to go in speaker configurations. That said, if you're sold on dual 15" speaker, consider the JBL PRX425, the Peavey QW 4F, the JBL STX835 and the EV TX2152.
None of these are as cheap/low cost as the PV215's, and there's a reason for that. They are better made speakers approaching pro quality.

But if you can't go the route of getting better speakers, then perhaps consider getting a less powerful amp that is also less expensive and more suitable for your speakers, such as the Crown XLS 2500, which is half the cost of the Crown amp you have now AND it also has peak limiters.
 

walterw

Platinum Supporting Member
Messages
38,960
...in general, I'm not a big fan of dual 15 speaker cabs, as I think there are better ways to go in speaker configurations.
a yep!

dual 15 tops are too short to get the horns high enough, too heavy to go up on stands, don't really handle sub frequencies, and if you get real subs to set them on, then the second 15 becomes pointless.

you'd be better off with single 15 or even single 12 tops on stands and one actual sub.
 






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