speaker calibration

[paleface]

ive been reading ian sheperds and bob katz stuff on the
k metering sytem
and today ive been out 2 buy a sound level meter from maplins
ive used the -20 pink noise tone from bobs site
to find 0 (83 db) on my amp
and it says to mark down to -12 from there
and use a fixed level
the 83 db thing is far to loud for me
am i doing this right ?
am i even using the right pink noise ?
one of his article states 2 use - 18 n not -20
mr sheperds article also mentions -18

which should i use n where can i get the -18 pink noise from

can anyone enlighten me here?

and whats a more realistic yet usable level eq wise
to listen at?

[Aliweasel]

Bear in mind that different styles of music will have a lower RMS than -18 so when you start to use the system for monitoring you'll be able to use your calibrated system to judge how loud it'll be on other systems.

Bob's book states how he has to turn down to -12 for some styles of music as it's so compressed.

Have you tried listening with music to see if it's more palatable than solid pink noise?

[paleface]

hello ali

its far to loud played at the level on the amp (83db)

im just sat listening at i level i find ok

n its hitting 66 on the c weighted sound meter

which is more than loud enough for me

could u write down in idiot proof steps
the proper way to set up for the k system ?

and if i use the minus 20 pink noise thing
and turn it down 2db on my trak level is that the same as
a -18 pink noise tone?

[Aliweasel]

-20 is quieter than -18. If you attenuate (turn down) -20 by 2dB you get -22, not -18.

I've not set a K system up before so don't take my word as gospel (pun intended). Is the sound measurement device you're using set to A weighted? This is the setting that best matches the human ear's response to sound. I have a feeling (I'll check at home when I can refer to Bob's book) that this is the setting you need to use.

To anyone else who knows better, feel free to step in...

[Hugh Robjohns]

I suggest you get Katz's Mastering Audio book and read Chapter 15 very carefully a few times. It is complicated, but he explains it all very clearly.

The first point to say is that the reference 83dB SPL (SMPTE RP200 recommendation) is only relevant or practical in a very large room (at least 30 square metres). Smaller rooms can't cope with that kind of level at all and you'll need to find an aceptable lower level. 79dB SPL is commonly used, but if your room is very small it might need to be lower still.

The best way to set the level is with a 1/3 octave real time analyser, working on the level of a single mid band. If the overall level is supposed to be 83dB SPL, then a single 1/3 octave band should be 68.2dB SPL. Working with a single mid band avoids the inherent anomalies caused by reflections and bass modes when analysing a broadband signal... but if you only have a broadband SPL meter you'll still get reasonable results... they are just likely to be slightly less accurate.

Whatever level you end up choosing as comfortable, the system should have 20dB of headroom above that -- ie, able to reproduce peak levels of 103dB SPL at the listening position if you go for the 83dB SPL calibration.

The K-System then goes on to define the working headroom above the reference level. So K20 employs 20dB Headroom and is appropriate for audiophile-type recordings with natural wide-ranging dynamics (and feature film soundtracks).

K14 has only 14db of headroom and is intended for more heavily compressed material. You would set the monitoring gain control to -6dB from it's calibrated position to work with this meter range. K12 is for even more compressed formats (like radio broadcasting) and you would set the monitoring to -8dB to work with a meter calibrated to K14.

Hugh

[paleface]

hugh
could you explain step by step in simple terms
cos im lost by this

eg
step 1 play the pink noise n measure ect

step 2 mark the amp at whatever db
ive not got and cant afford bobs book
pleeeeeeease help

[Hugh Robjohns]

I'm dashing out right now, but I'll try to come back to this tomorrow if I have time.

I'm sure your local library could get the book for you to borrow if you really can't afford £24 for probably one of the best and most wide ranging and useful audio books on the planet.

hugh

[ef37a]

I'll not stop long but you can generate noises of various hues and specific levels in Adobe Audition 3. Don't have it? Well, download the demo and record some!

As to setting loudness don't forget you can always make a live recording of speech say at a known distance and then "calibrate" from that to get a rough idea. It has ever been the case that people listen to reproduced music at too high a level, adrenalin junkies, all of us!

Dave.