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Re: Distortion
Wid #289019 01/28/10 04:44 PM
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bdpf,

Welcome to the forum. Your M80s are capable of handling 1100-1200W continously as tested by Axiom, and I can tell you first hand that they can produce prodigious SPLs without distortion (I run them with the A1400-8). It sounds to me that your are getting clipping distortion when turning up your receiver too high. You can damage the tweeters in the M80s that way so I would not recommend doing this. Your receiver should be able to provide measured spl of 75-85dB in your room without distortion.Remember that each 3dB increase in volume will require twice more power from your receiver even though the difference you hear may be small. If you are getting distortion at 85dB as well, unloading some of the power requirement to sub(s) will help the internal amps of your receiver to better reproduce transient dynamic peaks. Wid, JohnK, and Murph have also made excellent points (some of which should be a sticky but there is no provison for this here, unfortunately).

Last edited by ihifi; 01/28/10 04:47 PM.

John
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Re: Distortion
bdpf #289028 01/28/10 05:06 PM
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Hi Bruno,

Much good advice already given, but I'll address a couple of your questions. Your Denon gets very hot when you are driving it to very loud levels because the output transistors are driving 4-ohm loads, the M80s, so more current flows through the output stage and it heats up (power is measured by both voltage and current).

The Denons do not seem to have thermal sensors on the output stage, which is why they will drive the M80s whereas some other brands historically will not. Older Onkyos used to shut down very quickly when driving M80s, either because of overly jittery protection circuitry that sensed too much current flow or because the output stage got hot. Newer Onkyos are better.

Consider "0 dB" on your volume readout as a rough guideline that you should not exceed, or if you do, you may risk "clipping" the output stage or incurring increasing distortion that may become audible.

Manufacturers still get away with a lot. In the old 2-channel days, most all receivers drove 4-ohm loads without difficulty.

In current av receivers, there are 7 internal amplifiers, not two, and dissipating heat is a big issue, so many manufacturers will recommend you do not connect 4-ohm speakers, or they set the protection circuitry to shut it down, on include an impedance switch that on the 4-ohm setting severely limits the power/current flow through the output stage (much reduced power output).

As to subjective volume sound levels measured at your seat, "85 dB" is interpreted by most listeners as "quite loud"; "95" dB as "very loud" or "twice as loud" as 85 dB; and over 100 dB, extremely loud. By the way, the levels I've measured of orchestra and chorus in New York at Carnegie Hall or various opera houses, never exceed peaks of 105 dB SPL (sound pressure level).

Rock concerts can be absurdly loud--dangerously so--and may approach 122 dB, not far from the threshold of pain.

Oh, ignore specs of "Dynamic Output"; this is totally bogus. It's quoted to get the numbers up. No regard to distortion, always a single frequency. Useless.

The correct spec is Dynamic Headroom and is quoted in dB, which most consumers do not understand, so it's never quoted.

Regards,
Alan


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Re: Distortion
alan #289060 01/28/10 08:53 PM
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I know you do not have an SPL meter (measures dB basically) but those speakers at + anything must be ridiculously loud. I have the same receiver (2310) and only little W22's and the loudest I have ever had it for about 30 seconds was +3. Normal loud listening is around -5 to 0, and even that is somewhat rare.

I do have to agree you are probably limited by the amp in the 890, as opposed to the speakers. Really though, listening that loud over time won't be good.

EDIT: I just saw Alan's point about rock concerts... I've been to more than a few, and they are freakishly loud, but I must admit they don't seem as loud as about ten years ago. One show, I was at a small venue and I was standing beside (two feet away or so) one of the floor speakers beside the stage for a good hour. Being so close and not wearing earplugs was stupid, my right ear was ringing for four days, no joke. Don't want to go through that again \:\(

Last edited by Potatohead; 01/28/10 08:56 PM.
Re: Distortion
Potatohead #289065 01/28/10 09:15 PM
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I tried cranking my 2809, well into "+" territory, but it became nearly unlistenable as it clearly became too much for the amp, too much for the room, and too much for my ears. With a separate it most surely would have sounded better, but it would still have been too much for my room and ears.


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Re: Distortion
Adrian #289083 01/28/10 11:06 PM
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I was just putzing around on Peavey's website and and came across this chart that I thought I'd pass along since many people have discussed or. in fact, warned others about high noise levels. It reads...

The US Gov't Occupational and Health Administration(OSHA) has specified the following noise level exposures:

Duration Per Day in Hrs....Sound Level dBA, Slow Response

8.....................................90
6.....................................92
4.....................................95
3.....................................97
2....................................100
1 1/2...............................102
1....................................105
1/2.................................110
1/4 or less.........................115


*** They also cautioned that everyone is a little different, and some may be more prone to higher noise levels, the chart is a guideline.


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Re: Distortion
Adrian #289088 01/29/10 12:48 AM
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Thank you all for the great input. As many of you said, I was probably experiencing clipping from the amp and as Alan said it's probably why the receiver got very hot.

 Originally Posted By: Murph
A xxx Watt amp will cause distortion in any speaker if it is driven to try and produce loudness levels that it wasn't designed to do. This is a limitation of the amp, not necessarily the speaker as the amp begins to clip when it's pushed too far and this clipping from the amp can actually damage your speakers.


Thanks, I didn't know that, I always thought it was the opposite, that you could damage the speaker if giving them more power than what they are rated for. Now let's say if a 100W amp is able to provide let's say 100dB without clipping, is it correct to say that a 400W amp would only be able to provide 106dB without clipping?

 Originally Posted By: alan

Consider "0 dB" on your volume readout as a rough guideline that you should not exceed, or if you do, you may risk "clipping" the output stage or incurring increasing distortion that may become audible.

It might have been a good idea for the Receiver manufacturer to limit it to 0dB if they cannot handle more to avoid ignorant people like me damaging their speakers.

 Originally Posted By: Potatohead
I know you do not have an SPL meter (measures dB basically) but those speakers at + anything must be ridiculously loud.


Indeed it was . It would have probably been bearable in a room 3x my size. Usually, the loudest that I will have it on will be -10dB and not for too long as it is already very loud.


Bruno
M80s/VP180/QS8s/EP600/AVR-890
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"The problem is choice..."
Re: Distortion
Adrian #289102 01/29/10 03:05 AM
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Adrian, those numbers should be ignored if the topic is listening to music in the home. As I commented in my earlier reply, those workplace numbers accept some level of long term hearing loss, while this should be totally unacceptable in the context of home listening. The EPA and World Health Organization numbers that I linked are substantially lower for "community" levels rather than the workplace. For example, at 115dB the limit is zero.


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Enjoy the music, not the equipment.


Re: Distortion
JohnK #289104 01/29/10 03:14 AM
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I missed your link the first time John, just saw it now. Regardless what statistics are used, 115 db is dangerous...I can't imagine what sound levels the concerts were that I used to go to in high school.


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Re: Distortion
Adrian #289124 01/29/10 04:41 AM
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Gotta agree on the insane concert levels. My problem with it is that I wear earplugs, which attenuate high frequencies more than lower ones, so the concert doesn't sound as good as it might.


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Re: Distortion
Ken.C #289126 01/29/10 04:45 AM
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Etymotic make linear ear plugs... they also make excellent headphones and headsets, like the HF2 set I have for my iPhone.

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