Kef ls50 output

[Jeff R.]

I am very intrigued by the kef ls50. I am concerned they wont have the output capability I am looking for. They would be replacing my mb quart towers.....they would paired with my dual 15' subs to assist on low end. My emotive xpa3 would power them....
Thoughts...

 

[shadyJ]

The higher you raise the crossover, the more dynamic range that system will have. I don't think the LS50s will be that badly outpaced by two Umax 15s. If they were Umax 18s with a kilowatt each, maybe.

 

[Jeff R.]

Thx shady

How do I know how loud they can play?? Yes a very basic question. I just don't want be constantly pushing them to the max....



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[TLS Guy]

Thx shady

How do I know how loud they can play?? Yes a very basic question. I just don't want be constantly pushing them to the max....



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You will not know how loud they will play until you fry a voice coil!

Again we have this myth perpetuated that a sub reduces power demands on the front three speakers. It barely does at all. What it does do is reduce cone excursion of the other speakers. Now you don't hear the effects of over excursion like bottoming. So you feed a small speaker more power and the cone excursion is less, and the VC heats up faster and hotter and burns out.

The real power range is above sub range. The big power hog range is 80 Hz to 2.5 KHz and especially from 80 Hz to the BSC point of 400 to 600 Hz. Remember the smaller and narrower the speaker the higher the BSC point.

There is little acoustic power required below 80 Hz and very little indeed below 34 Hz. It is just that most subs are terminally inefficient and so you think there is..

So if you you think these

will be as dynamic and handle the power these will.

Then I have the proverbial bridge to sell you in Brooklyn!

Unless you use highly efficient horns, I can tell you it takes at least two voice coils to handle the midrange, and well engineered ones at that. Otherwise you have thermal compression and burn out.

If you play at low volumes you will be OK, but if it concert hall levels you want, then you will soon miss the Quarts.

We have been over this ground that a couple of puny speakers and mega sub will equal a larger more capable speakers. They won't and not by a long shot.

 

[Steve81]

You will not know how loud they will play until you fry a voice coil!....What it does do is reduce cone excursion of the other speakers. Now you don't hear the effects of over excursion like bottoming.

I agree, but there are a couple of caveats to keep in mind in this case.

A. Keeping the excursion down on the LS50's woofer is desirable, as this allows it to act as a stable waveguide for the tweeter. Of course it's not exactly a high excursion driver in any case.

B. The LS50's mid/woof has a relatively large VC (~55mm diameter), given that the tweeter assembly takes up a fair amount of space in the middle of the driver.

In short, the LS50's can take a fair amount of power (something Dennis affirmed with the lesser Q100 driver), but they can't back it up with the displacement needed to deliver gobs of low bass. In that case, a subwoofer with a relatively high XO frequency makes a lot of sense. Will it compete with a big horn loaded speaker like the JBL M2's? Of course not. But you'll net quite a bit more clean output than you would running the LS50's full range. Obviously it's possible to burn up a VC if one isn't careful, but the same could be said of any speaker.

As to the question of "how much output", if you're asking the question, it's probably not enough

 

[PENG]

Again we have this myth perpetuated that a sub reduces power demands on the front three speakers. It barely does at all. What it does do is reduce cone excursion of the other speakers.

Once again you are generalizing. Depending on the speakers, subs and crossovers, subs could in fact reduce power demands from the front 3 speakers. I took enough measurements on my front speakers with at different crossover points to know that for a fact. It's not like a 30-50% reduction but there can be reduction of as much as 20%. True, I wouldn't consider that significant at all, but in some cases it can help a little.

 

[Jeff R.]

Maybe I should seek out smaller towers in the reference line? I do like some volume.....


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[Steve81]

Define "some volume" A pair of R500s can deliver a decent amount of output backed by a sub or two. If you're looking for +10dB over reference level, that calls for a different solution.

 

[Jeff R.]

I run in 90 db range for sustained periods....I do sometimes get close to 100 db for short windows of time....I can not get my 15" to distort, but I can push my towers fairly hard if I have a lot of mid bass...

 

[Steve81]

If you're talking 90-100dB average levels with something left in the tank for short term peaks, you'll probably want to look at something like this as opposed to a mini-monitor.

 

[Jeff R.]

kind of my thoughts...I have been eyeing the R line....I need to find a place to audition....I was hoping maybe the LS's could fill the need...I just really like the style and color options...and I all I read is rave reviews...

 

[KenM10759]

The LS50 will put out 90dB all day if you want it to, as it peaks at about 106dB.

I wouldn't hesitate to try them in your application, they do "punch well above their weight" as is often said.

 

[Steve81]

kind of my thoughts...I have been eyeing the R line....I need to find a place to audition....I was hoping maybe the LS's could fill the need...I just really like the style and color options...and I all I read is rave reviews...

Something like the R700 might do the trick, but honestly if you find you're hitting the limits of your current towers even with the aid of your subs, the JTRs I linked or something similar are what you need to get the clean output levels you seek.

The LS50 will put out 90dB all day if you want it to, as it peaks at about 106dB.

Keep in mind, that 106dB rating is at 1m, not the listening position. That's also with feeding the LS50's ~150W, which is more than you'd want to give them on anything approaching a continuous basis. If the OP is trying to get 90dB-100dB continuous levels at the listening position with some headroom left over for peaks, a mini-monitor isn't going to cut it. The LS50's may "punch above their weight", but physics always limits how much output a small speaker can deliver.

 

[charmerci]

If it's volume you want, I've read nothing but good things about PSA speakers also.

http://www.powersoundaudio.com/collections/speakers

 

[KenM10759]

I'm glad I've spent very little time listening at levels above 90dB. I can still hear whispers in the room, otherwise I might not. Hearing damage is cumulative, and permanent.

 

[Jeff R.]

I am generally not in the room at that sustained level....usually some where else in the house.

 

[KenM10759]

Wouldn't you just be better-off getting a Zone 2 going with your receiver and put a pair of speakers where you actually are? When you're that far away the high frequencies fade dramatically.

 

[Jeff R.]

This us a reasonable suggestion...I have never utilized multi zone functions....maybe I should think about this.

 

[KenM10759]

I don't know what you have for head end equipment but many of today's AV receivers have Zone 2 (and some Zone 3) outputs for stereo pairs. Combined with remote control from a smartphone, it's so nice to be able to shut off the mains and pipe everything to another area of the home right from your pocket.

You don't even need to run wires if you use the right kind of active speakers, just a power cord to (at least) one of them.

 

[Jeff R.]

I just stumbled across a new in box pair in craigslist for $1100.... Never used not refurbished....now my curiosity is getting to me...I go on vacation Friday if I come back and they are still available I think I will buy.


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