Do I need to change my set-up? Are my LSIs drawing too much power?

[cheddar]

jdhdiggs,

I hope you don't mind if I start this in a new thread so I didn't end up taking dizzy's thread off topic. So you suggested that there might be something wrong with my system? I'm sure that my system is nowhere near a flat response. All I did was enter my distance from the speakers to my listening position and adjust the test tones on my denon receiver so that all the speakers were at 80db at the listening position. That was the extent of my calibration. But like I said, I haven't done anything to compensate for room effects.

The volley I'm talking about is the opening one out of the fog that comes in and smashes the ship's bell. Also, those are peak watt levels that probably show up for less than a second on my meters, but they have a short peak hold function. And I'm at -16db on my 3803s volume control.

My subwoofer is a PSW450 that obviously cannot keep up with my amp and LSIs. It does add some low end, but I wouldn't think it would show a fair comparison to a real capable subwoofer.

It's just my observation that the kind of bass being reproduced heavily effects both the draw on my amp and the resulting perceived volume with the classical disk sounding softer and my pop and jazz disks sounding louder at a given power draw. But I thought that just had to do with the frequencies they were trying to reproduce at any given time, not something wrong with my set-up.


Any help would be greatly apprecieated. I copied the last exchange from dizzy's thread below, thanks:


jdhdiggs
Polkologist


Join Date: Jul 2003
Location: York, PA
Posts: 2,095

--------------------------------------------------------------------------------

Quote:
Originally Posted by cheddar
Just checked the numbers and what you listen to really has an affect on SPL and watts delivered.

Master and Commander Cannon volley:

Peak Watts on LSI15: 53W
Peak SPL: 101db

Cossack Dance on 1812 DVD-A

Peak Watts on LSI15: 79W
Peak SPL: 94db

So I wasn't just hearing the difference in classical music dynamics. Those bass hits are power hungry, even if they don't necessarily sound real loud relatively speaking.



I wonder how you keep your LSIs so reigned in?

jdhdiggs-

Your power to volume is really out of whack. Somethings seems to be going wrong in your setup. By simple calculations you should be hitting ~107 dB @ 79W each speaker and if you have them setup correctly, that would be 113 with just the fronts, 116 all speakers. That is earbleeding above 50 Hz (Ok, ear ringing). It looks like you have something out of phase causing you to use a whole lot more power than you should.

With my setup I'm getting over 120 dB on the MC track you listed, over 104 with the sub off and only ~10W/channel peaks on the front channels. That is with an "at reference" level on a calibrated system.

[McLoki]

We need the distance you are from your speakers as well. (DB's drop by 6 db every time the distance doubles.

1 meter (what most speakers are rated at)
2 meters (6.5 feet) = -6 db
4 meters (13 feet) = -12db

If the LSi's are 88db efficent
88 db for 1 watt at one meter. If you are 13 feet away from the speakers (about my listening distance) that would be about 76db efficent.
1 watt = 76 db
2 watts = 79 db
4 watts = 82 db
8 watts = 85 db
16 watts = 88 db
32 watts = 91 db
64 watts = 94 db
128 watts = 97 db
256 watts = 100 db
512 watts = 103 db
1024 watts = 106 db

It is not quite that bad really because you have 2 speakers coupling together to make the sound so that adds volume, plus mine are corner loaded and that helps as well - but in my situation - no way in hell I am going to be able to hit 104 db with only 10 watts per channel. (thankfully, I have a little more than that... :D )

The thing that throws many people off is they look at the efficency ratings at 1 meter, and then calibrate their systems to reference level from their seating positions.

Good Luck,

Michael

[cheddar]

Thanks Michael,

This is helping me to think about the problem much more systematically. The thing that brought this up was that jdhdiggs said that he had never driven his LSIs over 10 watts. And so I started playing around with some tracks to just see what my speakers would draw at various levels and then posted two of them because they were definitely way more than 10 watts.

But of course I wasn't systematic at all and measured the total SPL at listening position eventhough I only posted the peak of one of my mains, duh.

So of course the total SPLs are going to vary all over the place because I've got 4-6 extra speakers plus LFE via a subwoofer.

So to get closer to a true measurement, I need to only drive 1 speaker and set up the SPL meter 1 meter in front of the midranges? It already sounds like the distance to the listening position can explain a lot of the variance. I'm still curious to how jdhdiggs could keep within 10 watts, but I'm learning a lot about what those efficiency numbers really mean. Thanks again.