In Room SPL Measurements/Power requirements

[Robh3606]

Any of you guys ever measure what levels you listen at?? I always have been a little paranoid about my hearing. My trusty Radio Shack SPL meter died about 4 months ago. I bit the bullit and got an auto ranging digital one. Holly Cow what a difference. For the first time I got to really see what kind of dynamic swings I was getting. The older meter was analog and way to slow. I set this one up fast with C weighed and wow. I was averaging in the mid 80's but the peaks were up around 110Db!!!! Highest one was 108 and change. Was not even loud!!! I was listenning to Steely Dan, Every Thing Must Go, the drum snaps are as dynamic as they sound. What really surprised me was even with drivers sensitivities from 96 to 101 db and 100 watts on each driver I am coming close to eating all my available headroom with an average level in the mid 80's. If I was running drivers/speakers with 90Db sensitivity I would be clipping on every one of those peaks. I would need a Kilo Watt to be clean on them. Amazing how much power you actually need to get the short duration peaks.

Rob :)

[Ian Mackenzie]

Rob,

Very interesting, ergo.

IMHO transients are where the peak voltage of your amps goes certainly.

But what distance were your measurements taken?

SPL drops 6 db for every doubling of distance.
A 10 db increase is only doubling the real loudness.

Are you going deaf ? (joke)

Assuming your 2122s are 98 db 1 metre @ 2.8 volts (1 watt), 10 watts is 108 and 100 watts is 118 db @1 metre.

Add to this two channels ,so plus 3 db for 2nd speaker channel and amps for the other channel plus 3 db again.

So you have effective transient headroom of say 124 db @ 1 metre and at 4 metres 112 db for 100+100 watts.

Now if you are bi or tri amping, you will need to calculate the total applicable crest voltage drive of the amps in use.

For bi amping at 300 hertz, the split os 50/50% voltage, so you get 4 x (6 db more) the power of the single amp of the same power rating, ie 400 watts total headroom for a pair of 100 watters. Ths improves your available headroom siginificantly as I am sure you are aware.

Also a clean dynamic system may not sound loud, but you may still risk hearing damage for 15 minutes or more exposure.


Enjoy
Ian

:cool:

[Robh3606]

Hello Ian umm Ian what did you say??

But what distance were your measurements taken?

About 7 1/2 feet away so close between 2 and 3 meters at my listening position.

Using one of the online calculators it came out I could hit 115db peaks cleanly using 100 watts not acounting for headroom or biamping.

"For bi amping at 300 hertz, the split os 50/50% voltage, so you get 4 x (6 db more) the power of the single amp of the same power rating, ie 400 watts total headroom for a pair of 100 watters. Ths improves your available headroom siginificantly as I am sure you are aware."

Didn't realize it was 6db. Thanks for that. I figured I still had about 6Db left didn't realize there was another 6 db in there.

"Also a clean dynamic system may not sound loud, but you may still risk hearing damage for 15 minutes or more exposure."

Those peaks were short duration drum snaps average was much less. I hear you though that's why I got the sound meter. One of my fears going to high efficiency was just that hearing damage. I was surprised they were that loud. The peaks didn't sound loud, they were too short, just quick and clean, good snap/impact, natural sounding. The recording is very good just didn't expect to see almost 20Db peaks like that.

Rob :)

[Ian Mackenzie]

Kind of reminds me of the fine print on the JBL monitor brochures about hearing damager.

Ian:eek:

[locanti]

Hi Rob

Funny how the things goes on.This week I choose to listen Steely Dan 's records.So I do the measure this evening,using an old TANDY/REALISTIC SPL meter while I was listening Steely Dan "Daddy don't live in that New York city no more".A new battery in the SPL meter, weighting on C and respons on fast,the measure never exceed 106db at my listening place(4m from each enclosure) .I'm 43,listening music since I was 13(First HIFI system,but got a little tape deck when I was 9),playing Bass in R&R bands between 18 to 43 but not too loud and never in big place where highs levels are required.I live in a quiet house,work in a quiet office(With computers and electronics machines)drive big quiet cars(Volvo's are big cars for Europeans).I never use a walkman or listen too loud in my cars or had head traumatism.

Last year when I pass the audio test at my medical center,My left ear was 10% deficient and the right one 20%.I know why.

I think we are going to be quiet STONEDEAF oldmen. :no: :no: :no:

[AudioGeek]

Rob, et al -

I've been measuring dB levels lately with my old RS analog SPL meter, "A" weighted, slow response, which is I think the way it's "supposed" to be measured. For serious listening, I'm usually between about 90dB and 98dB, in the nearfield (6'-7' or less) - the way 4412's are MEANT to be heard!!! ;)

The peaks must definitely (or should I say 'DEAFinitely'!?) be much higher, assuming the amp can do it properly.

According to the manual:

"This chart, gathered from Federal, State, and Local agencies, shows standards for just how much noise is acceptable."

90dB - 8 hrs.
92 - 6
95 - 4
97 - 3
100 - 2
102 - 1.5
105 - 1
110 - .5
115 - .5 or less

So if I don't want to get further hearing damage, I guess I'm good for about what, 3-5 hours of fun with my audio system - depending on levels.

Yeah it's scary, but we all get old and break down in some way or another. If it isn't loss of hearing, maybe it'll be the need for a Viagra 'script soon?

ie: take your pick of poisons, and die later. Meanwhile, I'm going to listen to Dire Straits and enjoy it!!

:eek:

[locanti]

Hi AUDIOGEEK

I do the measure with A weighting and slow response.The level didn't exceed 100DB which is nearby your 98BDB.I listen to one or 2 records each day.Never more.:cool: Maybe I won't be deaf in my last years.

[AudioGeek]

Hi locanti,

With playing just 1 or 2 albums at a sitting, I don't think you'll have a problem with hearing damage at those levels.