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using the Radio shack SPL meter

I got a digital Rad Shak SPL meter the other day. I'm trying to figure out just how to use it. At this point all I want to do is find out how loud is loud, for me.

I got it set to the C weighted setting. Set the Range to 80db, and then on to 90db.

Pointed it straight ahead fixing it at the listening position where my head would be and turned up the music. Slowly..Stopping now and then.

At a level surely loud enough for me, and off 85-86db speakers, the highest number shown on the meter was 91-92db.

Given the +/- 10% variation the gizmo is professed to have, does this mean I was listening to 91-92db, or 100-101db? Or 82-83db?

While on the 100 range the numbers remained the same with 91-92db still the highest numbers reflected on the screen at the loudest level I could stand, without worry of gear issues or for just brief periods like a single song or at best two. They’d need be short ones as well.

I've done nothing else. In fact whatever those numbers actually represent, it was certainly too loud for extended listening. IMO. I didn’t turn it up past that level either... though it may have produced greater numbers. From repairs or on the meter.

Checking the vol knob later I had some more room to go but not safely as I was about the 1-2 o’clock position on the preamp.

I heard no audible clipping or distortion at any time.

How loud was I listening?
blindjim

Showing 6 responses by shadorne

shadorne's avatar
shadorne
7,477 posts
 
Makes me really wonder about speakers PROFESSING OR providing 100+db SPLs.

Who can handle that? Unless only a watt or two is used.

Jim,

My speakers "profess" to handle up to around 115 db SPL average continuous level with head room of around 10 db at 1 meter. This is with distortion levels extremely low (around 1% or so) and only modest compression.

Of course I never listen this loud.

At 2.5 meters back I sometimes listen up to about 105 - 108 db SPL (AVERAGE level - confirmed with Radioshack Meter) which is equivalent to attending a rock concert. This is loud.

However, to put things in perspective, at the hockey game last night the SPL meter in the crowd showed 115 db SPL - yet nobody was covering their ears and complaining that this was piercingly loud.

What actually sounds piercing and awful to the ears is DISTORTION - even at modest SPL levels!

Modest amounts of distortion will sound terribly loud at 90 db SPL (distortion levels are inherently linked to perceived "piercing" loudness)

What you might have experienced was increasing distortion at high SPL's (for your system) making it sound extremely loud when you only had a maximum of 91 db SPL at the listening position.
shadorne's avatar
shadorne
7,477 posts
 
Jim,

That sound is not one I have today, nor do I want any part of it again.

Glad to hear it. Unlike yourself, there are many who still suffer and remain unaware of how systems degrade rapidly when pushed to more challenging volume levels.

A touch more jump perhaps, but that's about it.

Sorry I can't help you with a dollop or two of more jump (unless you can be a bit more specific).
shadorne's avatar
shadorne
7,477 posts
 
91-92db SPL is the peak level you listened to unless you had the meter set to "average" in which case this was the average peak level (and actual peaks may have been higher).

Rock concert levels typically run up to 105 db SPL average (although this will be average for some songs and not others...a good rock concert will always have a variety of dynamic range in the music, as consistantly high SPL's eventually lose their excitement and become tiring...music is all about contrast or dynamic range...many artists will do a little "unplugged" stuff in the middle of the show for example).

An unamplified piano can go to 110 db SPL. Enjoy!
shadorne's avatar
shadorne
7,477 posts
 
The digital radio shack meter is not a precision instrument. I don't think you can trust the absolute "accuracy" of readings to more than +/- 3 db SPL between roughly 50 HZ and 5 Khz. I read somewhere that the 10 db errors you talk about are at extremes of 20 Khz or at 20 Hz.
shadorne's avatar
shadorne
7,477 posts
 
10% of a 90db reading is 9db. that is pretty big if you ask me.

No.

If the accuracy is +/-10% then this is equivalent to +/- 1 db SPL at 90 db SPL.

Decibels are a logarithmic representation of a signal.
SPL = 20 Log (Actual Signal Reading/Reference Signal Reading)

Reference signal level was set by Bell Labs as the quietest sound the average person can detect at 1 Khz (defines 0 db SPL)
shadorne's avatar
shadorne
7,477 posts
 
Jim,

Here is an example.

Take a classic famous well respected "hall of fame" type speaker like the Wilson Watt Puppy 7.

Look at the two distortion plots at 90 db SPL and at 95 db SPL (top curve is output SPL and bottom curve is THD+N SPL)

Notice that as the sound level is raised by 5 db SPL the distortion components increase by much more (8 or 9 db SPL)....this is always the case, even on great speakers such as this. The higher the output levels (towards realistic live sound) the relatively greater distortion ...until eventually the distortion becomes audible (and perceptively very loud). This point will vary for each system of amplifier and speaker but generally even small systems can be made to be perceived as sounding very loud (but in a small system it is mostly the harshness of distortion and not ACTUAL SPL level that gives the impression of loudness)
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