Lawrence wrote

BM Grabber wroteJust remember that the 83dB ... is VERY loud in a small room. Sadly this is NEVER mentioned in all the internet "advice" threads (where people only know the half truth).

I mentioned this in one of these minutia threads. Not as advice though, just mentioning that the "rule" someone was trying to force down my throat as an absolute has no practical relation to my smallish mix room... at all.

Like you said above (which is what I tried to convey in that other discussion) 83db is - way - too loud for my room. I was then given a subsequent unsolicited thesis on room treatment.

The table above is NOT something I have made up.
It is sourced from acousticans and science of the Dolby company. If you do NOT trust Dolby as one of the biggest assets in the audio industry, there are not many to trust out there.

You know Lawrence, it is the most knowledgeable ones who do ask the, not only the most, but the most important questions. And Always double check the info (especially internet provided), with official 3. parties and white papers.
I really hope PreSonus have thanked you, and acknowledged you as "One of the biggest resources on S1". I guess you are still learning (as I do, even if retired), because always looking for "why is that?"

Ask, learn, experience, then share, is my way to look at it

It's sad that someone take "help" from others/elder in their field as personal attacks. In the old days it was not only the only way, but the best way at learning were to listen to someone with the experience (and gaining experience as you go).

No matter what info you get on the internet forums, you CAN'T get 40 years of experience in a few days.
And I find it kinda funny (and frustrating) when someone have read 10000 pages in studying a field are told by someone who could be their grand child on "how things are", based on utter misinformaton and internet myths.

I know people today callig themself producers, who hadn't last a single day in a pro/commersial studio as an intern.
Try starting with doing the dishes, cleaning the garbage, making coffee (while always looking/learning over the engineer's and producers shoulder, while keeping shut).
Then after some time cleaning the patch bay (while being smart enough to learn all the routing/patching while at it, without the need of beeing told).
Maybe then, and only maybe then, you will be allowed to have your hands on the console (which you should have read its manual to way ahead of touching it).
Where there any tips in there?

Back on the topic: Yes, it's all recommendations all over the audio production field. But there are some "rules" based on many decades of.........experience. Things that work better than others. Why don't take advantage of that, as re-inventing the wheel is kinda...........stupid

Sorry for the "rant" (but it helps )

Have a nice weekend (music free on my part).

I don't know if anybody could please give me some guidance here.
I'm trying to calibrate my reference monitors to 72 dB for working at K14.

I bought myself a budget SPL meter from Amazon which has both 'A' and 'C' weighing options and loaded up the -20 dB pink noise files, downloaded from the Bob Katz website, into S1.
I increased the volume on both left and right wav files by + 6dB in the S1 track inspector.

The problem that I am having is that even at 1 metre away from my speakers the SPL meter readings are so volatile (up to +/- 10 dB on 'C' weighting) that it is difficult to know which reading to take.
It is not as bad using 'A' weighting: I think I have ended up with my speakers calibrated somewhere between 70 & 76 dBs, which doesn't seem very scientific to me

Am I using the meter incorrectly ? I don't think the meter is faulty. Does anyone have any tips to arrive at a more stable reading please ?

Thanks in advance.

Try room analyses software like Smaart. You may have some peaks and nodes in your room making it favour certain frequencies in the pink noise.

SwitchBack wroteTry room analyses software like Smaart. You may have some peaks and nodes in your room making it favour certain frequencies in the pink noise.

Thank you for the suggestion. I have download the Room EQ Wizard software and will do some measurements.
I'm not confident in being to interpret the results correctly, but will see how I go.
Thanks.

There are two types of pink noise on the Bob Katz site. One is full range pink noise and that sounds like the one you have downloaded. If you look around he also has a band limited pink noise file for download. This only has pink noise between 500Hz and 2 kHz. As a result the volume will drop by quite a lot but Bob has added gain to that band limited pink noise in order to bring it back to -20 dB rms.

Yes adding 6 db of gain to these files whould bring them up to the K-14 standard reference.

With the band limited pink noise A or C weighting has no effect because there is no low end to measure. It also avoids any low end problems you may have in your room as well. So A and C weightings are the same in this case.

C weighting though should be used for any music or pink noise that goes down to 40 Hz etc..The low end must be factored in.

Maybe your meter is not that great. I have a standard Radio Shack meter with a VU meter as well (much better as it can be set for slow) and I can get a perfect steady reading from either normal or band limited pink noise from both speakers. Both speakers are the same here too for level. Exactly.

Jemusic wroteThere are two types of pink noise on the Bob Katz site. One is full range pink noise and that sounds like the one you have downloaded. If you look around he also has a band limited pink noise file for download. This only has pink noise between 500Hz and 2 kHz. As a result the volume will drop by quite a lot but Bob has added gain to that band limited pink noise in order to bring it back to -20 dB rms.

Yes adding 6 db of gain to these files whould bring them up to the K-14 standard reference.

With the band limited pink noise A or C weighting has no effect because there is no low end to measure. It also avoids any low end problems you may have in your room as well. So A and C weightings are the same in this case.

C weighting though should be used for any music or pink noise that goes down to 40 Hz etc. The low end must be factored in.

Maybe your meter is not that great. I have a standard Radio Shack meter with a VU meter as well (much better as it can be set for slow) and I can get a perfect steady reading from either normal or band limited pink noise from both speakers. Both speakers are the same here too for level. Exactly.

Thanks for your response.

I am definitely using the 500Hz - 2 kHz wav files from the Bob Katz site.
They are set up in S1 as you describe earlier in this thread; one track for the left side and one track for the right.

I am using this digital SPL meter -

http://www.amazon.co.uk/DIGITAL-SOUND-LEVEL-METER-MEASURING/dp/B004WWTNX2/ref=pd_rhf_gw_p_img_1?ie=UTF8&refRID=1X43YTBTQMJ5NV3K0PX2

I got this one because it offered A & C weighting, fast / slow / hold / functions and it had some good reviews.
However I'm inclined to think, as you say, it's not very good at all.
Even in an ordinary quiet room in the house, with no movement, appliances on or outside street noise; the readings fluctuate up to +/- 7dB using A weighing (between 38 and 45 dB).
So I am going to return it. I did look for a Radio Shack SPL meter, but I don't think one can get them here in the UK.

I have used the Room EQ Wizard software along with an AKG D5 dynamic mic to take some room frequency response readings. I did 4 sweeps.
The room had has not had any acoustic treatment yet. I wanted to do some baseline measurement first before just doing 'random room treatment stuff'.
To my inexperienced eye, I didn't think the readings looked too bad ?
I think I definitely need some bass traps and and some acoustic tiles on at least some of the area of each of the four walls.

I have attached the REW graphs if anyone can be kind enough to give me some guidance on interpreting them properly.

I think I need to get another SPL meter (that is more stable) and start again with calibrating my monitors (M-Audio BX5a) basically.

Looks like you have got some wild varying frequency response dips. More than 10 db which is concerning. Are you pointing the microphone directly at each speaker and set its distance from the speaker to equal the distance the speakers are apart.

But judging from that graph it looks like you have got much bigger issues than getting an even level from both speakers.

Jemusic wroteLooks like you have got some wild varying frequency response dips. More than 10 db which is concerning. Are you pointing the microphone directly at each speaker and set its distance from the speaker to equal the distance the speakers are apart.

But judging from that graph it looks like you have got much bigger issues than getting an even level from both speakers.

Thanks again for your help with this.
No, I positioned the mic midway between the speakers, pointing at them and at a distance of 1 metre.

I will do some fresh measurements for each speaker with the mic pointing at the speaker and the same distance as the speakers are apart. This is the same distance that I used to attempt to calibrate the speakers with my SPL.

As a rough rule of thumb, what is an acceptable dB margin for frequency response dips ?

Bear with me as this is new territory for me

Are you really soloing the one speaker that you measure, or are you actually measuring with both speakers blasting pinknoise?

roblof wroteAre you really soloing the one speaker that you measure, or are you actually measuring with both speakers blasting pinknoise?

Do you mean for the speaker calibration or for the Room EQ Wizard measurements ?

When I tried to calibrate my speakers, I did them separately as in the procedure that Jemusic outlined earlier in the thread. That is, I measured each speaker separately using the left side .wav file un-muted and the right side .wav muted for the left hand speaker and then measured again but vice versa for the right hand speaker.

When I did the Room EQ Wizard measurements, I did them both together with my mic between the two speakers at 1 metre away. The REW software doesn't use pink noise for its room frequency response measurements.

I am going to try re-doing the REW measurements tomorrow with separate measurements for each speaker as Jemusic suggested.

To give you some context, I have a 'spare bedroom' type home studio as opposed to a proper pro studio set-up. I am primarily a musician / songwriter rather than a recording engineer.

The problem with sine wave testing for frequency response is that if the room is not well treated as yours is right now you only have to move the measurment microphone say 6 inches forward or back and you will get a very different frequency response. Try this as well as see what happens.

The band limited pink noise test is good for calibrating your speakers so they both produce accurate levels at the same time (by doing one then the other etc)

But this is different situation to uneven frequency response caused by nulls and peaks in your room etc..I would be looking into ways on how to make your room more even frequency response wise first. eg bass traps. Diffusion at the back of the room. Absorbtion panels in key spots on walls, above your mix position etc..Floor coverings etc..

Jemusic wroteThe problem with sine wave testing for frequency response is that if the room is not well treated as yours is right now you only have to move the measurment microphone say 6 inches forward or back and you will get a very different frequency response. Try this as well as see what happens.

The band limited pink noise test is good for calibrating your speakers so they both produce accurate levels at the same time (by doing one then the other etc)

But this is different situation to uneven frequency response caused by nulls and peaks in your room etc..I would be looking into ways on how to make your room more even frequency response wise first. eg bass traps. Diffusion at the back of the room. Absorbtion panels in key spots on walls, above your mix position etc..Floor coverings etc..

Just a follow up:

1. I returned the digital SPL meter and got an analogue one (which I think is similar in design to the Radio Shack one) and have now calibrated my reference monitors to 72 dB within +/- 0.5 dB. So yes, the first meter I was using was indeed useless.

2. I have re-done the Room EQ Wizard measurements for each speaker separately, with the mic positioned at half the distance between the speakers away from the speaker I am measuring. The variance is now around 5 dB at the same frequencies as the previous measurements showed.

Thanks for all the help and guidance.
After Christmas / New Year, I will be getting a basic room treatment kit (bass traps and panels) to make a start on improving the room acoustically.

Since the subject is here, I have a question that has been puzzleing me for some time about Monitor Calibration. I calibrated my speakers to close to the 80 db that most instructions tell you to. My question is why? I get the Left/Right think, but I'm sure we're not all listening at a constant 80 db when we mix. Is that irrelevant and just a number used to calibrate the speakers? There are other variables after the calibration is completed that will effect the volume such as interface main output, fader volume, etc.

Any clarification here?

Thanks!

Make it louder and you hear more detail. Make it too loud and your ears get tired or worse before you get some work done. 80dB SPL is the middle ground.

Presonus has a YouTube tutorial for calibrating speakers but my understanding is that the sine wave setting for calibrating a subwoofer is different. Can anyone clear this up for me?

My understanding is that the sine wave calibration is purely a level & balance tuning method. It should be performed after getting your system and room tuning right.

Ideally you would take your whole system outside, no reflections, and use your output/driverack EQ to tune things flat and get phasing right at studio listening distance. Have your speakers positioned as you would have them indoors.

Then you take everything back inside and use room treatment to tune things flat. Resist fiddling with EQ until you've got it pretty much right for you listening position with some room to move. If you find you have to move your speakers around then you may have to repeat the outdoors tuning.

And then you use the sine wave method to get levels and balance right.

Doing it this way you may find you need huge bass traps to curb the low end, especially if the room is small and can't 'breathe'. When EQing the low end instead then know that your room favors certain low end frequencies and that you fiddled with EQing so phase in that range to iron things out.

I use the ARC II too. What I found is that the LM2n (Loudness Radar Meter) from TC Electronic has also helped me to get the loudness where I like it at around 14 and some times I also have to adjust the Master Out fader too to get it just right in the mix. It's not a crime.
If it sounds right it usually is right.

Interesting thing is that when you move your speakers outside and do a frequency calibration and I have done this actually the speakers end up being almost flat without any EQ involved and the amount of correction EQ required can be very little. So in some ways it may not be that helpful.

It does work though if the speakers have a slightly skewed response then the correcting EQ can work very well to return them to a much flatter response. But the better the speaker the less and less corrective EQ is actually needed. Studio monitors would be closer to being accurate.

I have several pairs of PA speakers and one set had a slightly weird sound and the outside freq curve made them sound amazing. But then later I picked up a set of Turbosound live speakers and the correction curve is almost flat! Meaning the speakers are almost flat.

The Presonus video is also mainly about getting both speakers to produce the same level as well, not so much to make them sound flat. Which is also important. The band limited pink noise is good for this too.