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Establishing Studio Reference Monitoring Levels ( 83 db SPL)

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Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Mon Jul 13, 2020 4:15 am
by csarami@ncsu.edu
Hi,

I skimmed through the article: Establishing Project Studio Reference Monitoring Levels by Hugh Robjohns and also the video by Bob Katz.

My DAW is Cubase and I can generate tones ( Sine, Pink, etc.) at different decibels.
My systems consists of:

1) iMac
2) Audio interface: MR816 Steinberg. I set the Master level to 26 out 128 so there is no Hiss sound coming off of my monitors!
3) a pair of M-AUDIO Studiophile BX5a Deluxe Studio Monitor ( 56 Hz - 20KHz) and Studiophile SBX subwoofer.
Initial speaker settings: I set the SBX subwoofer low pass filter to 56Hz. I had the monitors to position 6 out of 10 and subwoofer on 3 out of 10!
4) Listening position: Speakers are 4 feet apart, my head and the monitors form an equilateral triangle.
5) Radio Shake sound pressure level ( digital with A & C weightings and fast and slow response).
6) Connection: from analog XLR out MR interface to Subwoofer and two cables XLR cables from the subwoofer to studio monitors


Method: Here is what I did:

1) I turned off the right speaker and played a pink test tone with 0 dB ( of course full scale). I tweaked the knob to get it right at 83 on the meter. Then turned it off
2) Turned on the right speaker. I did the same thing as in Step 1. Then turned the speaker off.
3) Did the same thing as in 1 & 2 for the subwoofer.


Now to test, I just played back one of the tracks mastered by Bob Katz the maximum level, now it sounds much quieter.

Specifically, when I listen to Fusion --- McGill Manring Stevens - Umkhonto We Sizwe - "Hard Rock--Lizzard--Skyline--Mastered"

For the first 8 seconds is super quiet and again until time 30 sec is quiet and but then the level is pretty comfortable. I hear the details, etc.

I am thinking maybe I did something wrong.

What do you guys think?

Any help would be greatly appreciated.


PS. I just ordered the Sonarworks Reference 4 Studio Edition with Mic to further improve my listening experience. I will test it again after I set it up.

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Mon Jul 13, 2020 10:30 am
by ef37a
Hmm, must read Hugh's dissertation again, I might not have done it right?

Some years ago I simple played back pink noise at -18dB fs and set a cheapo 'C' weighted SPL meter on a mic stand where my head would be.
I initially set the Tannoy 5As to 12 o'clock and the same for the mixer I was using to control the output of the sound card, an M-A 2496. I then tweaked the Tannoy's pots to get 83dB on the meter and marked the setting.

However, 83dB SPL is too loud in a domestic setting (the average FSTV would struggle) and I backed off the monitors to about 75dB and also marked that.

All I really wanted to do was get repeatable levels day to day. My setup now is an NI KA6 (VC at max) feeding a Mackie BK passive and I have not calibrated that setup so far...So, all ears and eyes!

Dave.

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Mon Jul 13, 2020 10:53 am
by Hugh Robjohns
csarami@ncsu.edu wrote:Method: Here is what I did:

[i]1) I turned off the right speaker and played a pink test tone with 0 dB ( of course full scale). I tweaked the knob to get it right at 83 on the meter.

You really didn't read my Speaker Calibration article did you? A noise signal has a randomly varying amplitude which is averaged over time... so having a noise signal at 'full scale' is a nonsense.

Use the correctly generated reference noise signals available here:

The file descriptions and application are here: http://abluesky.com/support/blue-sky-calibration-test-files/

And if you read my article again you'll know that 83dB SPL is way too loud for most project studio control rooms which are typically much smaller than the movie dubbing theatres for which that spec was derived.

I am thinking maybe I did something wrong.
What do you guys think?

I think so too!

I really can't explain the process any better than I did in the article. Measure your room's dimensions and use the table in the article to guide you to a suitable target reference level. Bear in mind that the article assumes a standard reference level of -20dBFS -- ie, setting the system up with 20dB of headroom as per professional standards.

Calibrate your DAW and monitor replay path using the calibrated tone from the bluesky site (with the speakers off or muted!) and then use the two band-limited pink-noise files, one for the speakers and one for the subwoofer. You can then check the full aligned system with the full pink noise reference file.

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Mon Jul 13, 2020 10:48 pm
by csarami@ncsu.edu
Thank you Hugh for the prompt response. Like I said I skimmed through it especially towards the end of the article.

Thanks for correcting me. About full-scale pink noise, I was wrong. The was for the sine wave. What I meant was at 0dB.

Also, thank you for the calibration test files.


Like I said, I bought my "Sonarworks Reference 4 Studio with the microphone" to tune my monitors ( I assume more or less for frequency response treatment and maybe also for loudness!) It arrives in a few days. Should I apply your approach first or then tune with Reference 4 or vice versa? Of doesn't matter.

One very important thing I forgot to mention is my room. My studio is in the Bonus room ( away from my kids!). It has skewed walls similar to this. I took the exact measurements.

The volume is 1461 cubic feet. It is basically a rectangular box with a Trapezoidal Prism on top of it. The volumes of Trapezoidal Prism, the rectangular base, and total Volumes are (678, 783, 1461) cubic feet, respectively. According to your table, I need to set the reference level to 74 dB SPL (C)! if I consider the full box containing the bonus room which has size 1461 cubic feet. Still, the table gives me 74 dB SPL for the reference table.

By next week, I will read your article and do exactly that.

Thank you very much, again,

CS

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Wed Jul 15, 2020 3:04 pm
by Martin Walker
csarami@ncsu.edu wrote:Like I said, I bought my "Sonarworks Reference 4 Studio with the microphone" to tune my monitors ( I assume more or less for frequency response treatment and maybe also for loudness!) It arrives in a few days. Should I apply your approach first or then tune with Reference 4 or vice versa? Of doesn't matter.

I doubt that it will make much difference unless your room has really bad acoustics, but since you're EQing your room with Sonarworks and their calibrated mic to sound flatter then you should ideally do the level calibration AFTER using Sonarworks.

By the way, I've got Sonarworks Reference 4 and one of their individually calibrated mics too, and was very impressed with the results.


Martin

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Wed Jul 15, 2020 3:27 pm
by Hugh Robjohns
Martin Walker wrote:
csarami@ncsu.edu wrote:Should I apply your approach first or then tune with Reference 4 or vice versa? Of doesn't matter.

...ideally do the level calibration AFTER using Sonarworks.

Sorry -- missed that question! Yes, Martin is quite right: the reference level alignment should be done after any room EQ simply because the latter may well change the overall level slightly.

H

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Fri Jul 17, 2020 3:57 pm
by csarami@ncsu.edu
Thank you Huge and Martin!

What if I do both over and over to see if I get to a stable state ( meaning, barely need to change the knobs on monitors and also reference 4 produces the least amount of change on the overall curve)!

Code: Select all
1. Start
2. Input:
   a. Initial guess values for studio monitors ( left and right positions, can be centered if desired)
   b. Tolerable Errors e1 (for room EQ), e2 (reference level alignment error)
   c. Maximum Iteration N
3. Initialize iteration counter step = 1
4. Do
        Apply room EQ
        Apply reference level alignment
   step = step + 1
   If step > N
      Print "Not Convergent"
      Stop
   End If
   While abs [ ∫(freq_response_new -  freq_response_old) dt  > e1] and
                   [(displacement_poisition_left_monitor_knob + displacement_poisition_right_monitor_knob ) /2] > e2

5. You are done ( reached the stable position/state)

6. Stop



If it reaches the stable state then I'd say it satisfy both perfect room EQ and loudness alightment! This way, it doesn't matter which one is first.

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Fri Jul 17, 2020 10:23 pm
by Hugh Robjohns
csarami@ncsu.edu wrote:What if I do both over and over to see if I get to a stable state...

That would be pointless and silly.... And demonstrates a lack of understanding of both processes.

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Sat Jul 18, 2020 2:29 am
by csarami@ncsu.edu
why you think it is silly, please?

Re: Establishing Studio Reference Monitoring Levels ( 83 db SPL)

PostPosted: Sat Jul 18, 2020 9:19 am
by Hugh Robjohns
The room correction EQ process and setting the reference listening level are independent processes.

However, setting the reference listening level will not affect the room EQ calibration.

In contrast, the very act of performing room correction will change the overall listening level, and may result in limits on the maximum listening level.

Therefore, the only logical procedure is to first perform room correction, and second to calibrate the desired reference listening level.

An understanding of the processes and procedures involved will confirm this.