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[Evan Kirkendall]

So its all still just calculations based on what they say?

You've yet to measure anything?

So.. In that case you've really done nothing... Like Dave says, could be 50hz or 1.5k, you'll never know unless you measure it...


My .02
Evan

[Ivan Beaver]

Rory Buszka wrote on Fri, 14 April 2006 14:17

I happen to know that Community measures their sensitivity anechoically (by flying the speaker out some long distance from the third floor of their factory, pointed out across the Delaware River, as mentioned in a PSW article from some time ago).

That is untill the trucks get in the loading dock (directly below) and now the 3rd story is the 2nd story because of the reflections off of the top of the trucks.

I will add that Community is one of the companies that I have a lot of respect for.  Yes some of the their products are cheesy MI type crap gear-made to a price point, but even on that you get MEASURED DATA and not just a couple of numbers that the customer is supposed to guess as to what they actually mean.  In many cases Community give you TOO MUCH data-or at least too much for the average user, who want a single number to describe the total performance of the loudspeaker.

They use very little smoothing on the freq response, so it looks more "jagged" or not as smooth as other manufacturers-(if you can even get there response curve).  If you took other manufacturers data and used the same amount of smoothing, you would see the same type of thing.  With just a few exceptions the measured freq response agrees with the published numbers, or at least close enough so that is not a big deal.  They are not off 10-20 dB as are some other manufacturers.  How many other manufacturers give you MEASURED freq response/impedance/Q and beamwidth plots on the really cheap equipment? Or any of their products for that matter. Heck even Peavey gives more information than many of the PRO providers!

CHANT TIME--Everybody bow down and believe-------HUUUUUUMMMMMMM it is so and so-we are mesmerized-we believe and do not question. It is new product-we like it. Now drink the special kool aide so you do not forget, and see how good you think the magical sound is in your head.  But for Gods sake, don't let the real specs blur you vision of what you thnk is real. (stepping down now)

Most are to embarressed or realize that the published numbers will not reflect what the measured numbers state.

Hats off to Community for doing so.  I wish other manufacturers would do the same.

[Dave Rickard]

Rory Buszka wrote on Wed, 12 April 2006 21:20

One thing I can say for the MVP subwoofer is, it can peg 130dB for less than $400, whereas the Yorkville can give you 2 extra dB for $550 or thereabouts.

Not beating anyone up, just asking questions--

I fully understand what you calculated.

My original thought was:  

Does the MVP deliver 130 dB at 30 Hz, 40 Hz, 120Hz, or even 1kHz?  
Does the Yorkville give 2 extra dB at 30 Hz, 40 Hz, 120, or 1kHz?

Without knowing the actual frequencies, any calculated peak output is pretty meaningless.  It could be totally apples vs. oranges.  I guess I didn't state that as clearly as I could have.

I agree with Ivan, I wish more manufacturers would publish more real data.

Dave

[Ivan Beaver]

If you look at the Community website you will find the answers to the questions you are asking.  Just simply look at the freq response and see how loud it is at the particular freq you are interested in.  Then add the proper amount of dB increase that the particual power rating you are interesed in (that can be a 6dB difference as indicated earlier), and you will have your answer.  Of course this does not take into power compression, but that is a different thread.  But it gives you an idea.

You can do this on Community's website, but yorkville gives you NOTHING USEFUL to help answer that question.  That is the whole idea of my earlier post.  If given enough PROPER information, the customer can answer their own questions.  and DO NOT-UNDER ANY CIRCUMSTANCES take the -3db freq rating of the loudspeaker as it's actual -3 rating.  There is only 1 manufacturer that gives a TRUE -3dB rating-as referenced to the sensitivity rating.  All the others (that I am aware of) take the +-3dB as a "flat response.  This can result in an actual "flat response of 3-6dB lower than the stated sensitivity rating.  THEN they subtract -3db to get to the published -3db freq number.  This number is quite often 6-9dB down from what you can actually use.  Sometimes it is even lower than that.  They like to have 2 figures (sensitivity and freq response) not tied to each other, but they have to be in order to get an idea of what the particular loudspeaker is actually going to deliver/produce.

Like manufacturers that rate a particular processed speaker without processing to get the sensitivity rating and then add the processor to get the freq response.  The problem is that now you are not delivering 1W to the loudspeaker in the lowest freq, often up to a 10dB increase to get the published freq response.  Of course they do not take off 10dB off the max output spec because it has been added to the bottom.  That would be like tellking the truth and they might not look as good if they did that-now would they?

Let the buyer beware.

[Antone Atmarama Bajor]

I like this one too the inverse of Rorys.

    This would be power required for desired dB increase.

10^(.dB)

note:
3dB= 10^(.3)  
10dB= 10^(1.0)


By the way its easy enough to say every 10dB reqires 10X the power.

10 Watts +10dB
100 Watts +20dB
1000 Watts +30dB
10000 Watts +40 dB Etc.

Antone-

[Erik Osland]

I just need something that can perform like a dth-218.  The specs for the ls808 and the peavey are almost identical except the peaveys are bigger, heavier, require more wattage and go up to (I believe) 1.1k.  I can't seem to get a demo no matter how hard I try, so what do you think?  Has anyone worked with both?

E  

[Douglas R. Allen]

Erik Osland wrote on Tue, 25 April 2006 02:13

I just need something that can perform like a dth-218.  The specs for the ls808 and the peavey are almost identical except the peaveys are bigger, heavier, require more wattage and go up to (I believe) 1.1k.  I can't seem to get a demo no matter how hard I try, so what do you think?  Has anyone worked with both? E

Compared my DTH218b to the Ls800p

The Ls800p is the powered model of the 808.

I use a yamaha 01v96 board with a Cex5 dsp.
The Dth was feed with a QSC plx 3002.The Cex was set for 3.5dbv for full rated power as the Plx requires 3.5 dbv at 4 ohms for rated power. 900 watts 20-20k 1050 watts at 1k. I called it 1000 watts. Some may diss the Plx but I always liked it on the subs. I always used a 45hz low cut on my sub out with a 110hz high cut. 24 db l/r so I stayed with that. All eqing was shut off as to not favor any box. The ls800p's crossover was set at 150hz to not interfear with the crossover from the cex. Shape was set straight up at first.

The dth sub. Contains 2 500 watt 18 inch drivers.
128 db's with 1000 watts rms
131 with 2000 watts program
134 with 4000 watts peak
I figured I could get 128 with the amp I had with the ls800p at least keeping up. Dth was laid on its side for best coupling in the ground plain.

Ls800p 134 peak
One would think that 134 peak would be
131 program - 128 rms.....Read on.

I set the Cex at 4dbv for rated power for the ls800p as in the manual but I found this is to high. I think it is closer to 4 Db"U" Than Db"V"
What I did was run the QSC up to clip under load then run the Ls800p the same signal and turned up the input knob so that the limit light hit at the same time as the qsc's clip-limit light. This was at APROX 9 oclock on the dial. This was the same 3.5 dbv signal that was feeding the qsc.

With both boxes reaching full power at the same time I took a look at the boxes with smaart software. Both boxes now at -6 db input. Mic on the floor at 3 feet. Boxes were checked one at a time in the same location. The box not being tested was removed so not to effect the box under test by acting as a passive radiator.

Smaarted the dth first and got 18.19ms impulse time. Entered it in the delay time and stored the transfer function trace. The phase trace was a smile in the bandpass and looked good.

Got a 24.34ms delay time on the ls800p. I would guess partly from the longer port-horn length. Entered the delay time and looked at the transfer function trace and phase trace. With the longer port length the "Smile" was just slightly bigger than the dth's so not bad. The trace was the same as the dth as far as freq response with just a slight dip of about 1.5 db's at 50 hz. When I turned up the shape 1.5 dbs the freq response between the two boxes was the same. You could overlay the two.When I unhid the dth trace I noticed the Ls800p was 4db's louder than the dth sub. I did several traces at different levels and every time the ls800p out run the dth by 4 db's with it being fed 1000 watts.
I even tried a full power trace. ( As fast as possible ) and it remained the same.
With a bass drum track I could get 3 db's more out of the ls800p for short term.

Even if the dth was only getting 900 watts and was only putting out 127 at most the Ls was hitting 131-132 with 134-135 db peaks. Sounds right on Yorkville......

So in my humble testing One Ls800p was aprox 4db's louder that my 2-18 dth 218b sub being fed by a 1000 watt amp.



I would have to dump another 1000 watts into the dth to keep up. In the of course subjective listen test both subs passed and sounded great. Both myself and a friend thought the ls sounded slightly tighter.

Kindest regards
Douglas R. Allen

[Lee Jacobson]

I agree with the above. Very short version, reader's digest if you will. I used to have four MT2L copies, loaded with RCF L18P300s. I ran these on AP6040s when I needed brute force, and PL236s when I just needed a sub. Got some EF500P powered tops, figured I'd try the LS800P. The 800P compared VERY favorably to the MT2L on the 6040, and outperformed the MT2L on the 236. Interestingly, even though there is a difference of less than 3dB in the power rating of the two, 1100/1300WPC@4 vs 2000WPC@4, the 6040 walks all over the 236 as a sub amp. Anywho, the 800Ps did so well that they caused me to look into the 1208s. The 1208 is as loud as the 808, while going lower. I sold my four MT2Ls and bought eight 1208s, run them on two AP6040s and I am happy. The 800P makes a killer sub with the 500P top. I can run two tops to one sub and have more than enough low end. The 500/800 combo makes a great drumfill. To review: the 800P rox, period.


Lee

[Mike McNany]

Scott Hibbard wrote on Wed, 29 March 2006 20:42

Erik, It's accurate - the 18" driver is mounted on the face of the front baffle, so it will be time aligned already with any other "conventional" (front baffle loaded) top cabinet. There is the rear horn, but the first wave of energy out of the sub will be that off the front of the cabinet. This is what you hear first, the lower frequencies produced by the rear horn are close enough together with that of the front face that the human ear can't perceive any delay difference between them, merely that it sounds "fuller" than if the rear horn weren't there.

Oddly enough the U15 processor manual recommends using the 5msec delay on the tops with the LS808    

Scott Hibbard wrote on Wed, 29 March 2006 20:42

BTW: it's a GREAT peice of equipment for the money.  I've got some and love them!!! I power them with bridged RMX1850's. ScottH

Scott,
That's a single bridged RMX1850 per sub? What's that, 1400 watts to each sub? Just curious. I'm running a single PLX2402 bridged to two LS808 for 1200 watts each and am considering bumping up to/adding a bridged PLX3002 or 3402 for the subs while rearranging my amps to allow more power to my new monitors and bi-amping our U15s.

It does seem that Yorkville is very conservative in their program ratings for the Elite series. Every post I read uses more than listed program power for those subs.

Mike McNany
edit: checked QSC myself. RMX1850 is 1100 or 1200 watts depending on the test at 8 ohms bridged.

[Evan Kirkendall]

Mike McNany wrote on Wed, 26 April 2006 20:01

I'm running a single PLX2402 bridged to two LS808 for 1200 watts each and am considering bumping up to/adding a bridged PLX3002 or 3402 for the subs while rearranging my amps to allow more power to my new monitors and bi-amping our U15s. It does seem that Yorkville is very conservative in their program ratings for the Elite series. Every post I read uses more than listed program power for those subs.

I wouldnt want to put more then 1200w into them... Everyone does go over the program ratings, but they stay within the 70% of the max power of the speaker. The LS608/808's use the same woofers and are 400/800/1600. 70% of 1600 is 1200, so thats right on the money. I'd be worried about putting anymore power into them...


Evan