Studio Calibration

    • March 21, 2023 at 1:14 pm #5539
      Norman Varney
      Moderator

        Wondering if studio owners have calibrated their electro-acoustical system, and if so, how they went about it? Do you follow P&E Wing recommendations? What obstacles have you run into?

      • March 21, 2023 at 6:16 pm #5544
        Bob Katz
        Keymaster

          Hi, Norman. Where can we find any P&E Wing recommendations for monitoring? I know that there is an ITU-recommended listening room, but I am not aware that NARAS P&E wing recommendations anything to do with monitoring.

          In my case my room and monitors are extremely calibrated, down to setting and knowing the SPL at a particular monitor control gain. I’ve run into tons of obstacles, so nearly always end up with a combination of measurements and empirical listening judgments. To be honest, I’ve not met any acoustician worth their salt that doesn’t listen. The days have not arrived when anyone can predict the tonality of a system given variations in loudspeaker horizontal polar pattern for one, and a host of other variables that require making final adjustments by ear.

           

        • March 22, 2023 at 9:15 am #5548
          Norman Varney
          Moderator

            Yes, the ears have the final say. Measurements are needed for verification, sleuthing, to get a reference for comparisons, for QC, and most often to learn what needs to be done to meet the desired goals.

            I do believe that there are electrical and acoustical standards that should be met, that have little to do with personal opinions. For example in room acoustics; ambient noise floor, reverberations times, modes, first order reflection levels, dynamic range, mechanical isolation, etc.

            From an electrical POV; ground impedance, peak current capability, voltage distortion, common mode and normal mode distortion,  harmonic content, isolation, etc.

            In my opinion, these are fundamentals to be established in order to have a first class, neutral, repeatable, predictable environment conducive for critical listening. I wonder if studio owners know the associated numbers for their facilities? The next question would be if they know what the numbers should be, and finally, do they know how to improve them if needed?

          • March 22, 2023 at 9:30 am #5549
            Bob Katz
            Keymaster

              Hi, Norman! That’s an impressive and comprehensive list. Where we can help in this forum is especially for small studios with relatively few resources. Using freeware such as REW (REW is actually donationware and I urge people to contribute to its developer) — it’s possible to at least diagnose a number of acoustical problems that Norman has outlined. The correction of those problems may require acoustical experts such as Norman, but at least you will know where you stand.

              As far as electrical — if anyone has questions about the electrical design issues in a studio, we should either make a new forum or find a place in one of our existing forums to answer electrical design questions.

              • March 27, 2023 at 5:13 pm #5592
                Ted
                Participant

                  Bob,

                  I would be very much interested in a sub forum on electrical. I just put in the first order for lumber to start framing my new room, so electrical will be happening within a month. Any and all advice I could get on the topic would be greatly appreciated!

              • March 22, 2023 at 4:38 pm #5555
                Bob Olhsson
                Moderator

                  A major factor in measurements is diffraction of both the microphone diaphragm and the loudspeakers. Each will falsely increase the measured high frequencies.

                  • March 27, 2023 at 5:10 pm #5591
                    Ted
                    Participant

                      Disregard, replied to wrong comment, it’s a little confusing which reply button is linked to which comment, at least in mobile.

                      • March 28, 2023 at 10:52 am #5594
                        Bob Katz
                        Keymaster

                          Ted, the reply button is above each response. We don’t have the budget right now to improve that… maybe if we start taking ads or if you want to donate a bit 🙂

                    • March 22, 2023 at 6:24 pm #5557
                      Norman Varney
                      Moderator

                        I have downloaded REW to get familiar with it. The P&E Wing documents should be pretty easy to obtain. I was asked to contribute to it many years ago. I have not looked at it in several years. The last time I did, it was still very much in need of refining and defining.

                      • March 24, 2023 at 1:58 pm #5563
                        Phil Koenig
                        Participant

                          Studio Calibration is a pretty ambiguous term.  It could cover a lot of ground.  Room response, speaker response, monitor level cal, gain staging baseline levels for outboard gear, and much more for those still using tape.

                          I looked up P&E Wing, which appears to be an ad hoc commity of audio industry people.  Anyone have a link to their work on studio calibration?

                           

                          • March 24, 2023 at 4:37 pm #5568
                            Bob Katz
                            Keymaster

                              Long, long ago, a group of producers and engineers got together, somewhat Ad Hoc. But that grew into a formal organization under the auspices of NARAS, called the P&E WING, definitely not ad hoc. It’s a real known group within NARAS with officers and activities, one of which is to help define recommendations for formats of masters. But I haven’t seen any recommendations for listening rooms or monitors within the P&E, to the best of my knowledge.

                              • March 30, 2023 at 5:51 pm #5627
                                Norman Varney
                                Moderator

                                  Phil,

                                  I’m referring to the acoustic and electrical supply conditions of the room here. Yes, calibration of the electro/acoustical system is the next step, but first, know what your existing or ambient conditions are before you start making corrections in order to compensate for problems that should not exist in the first place.

                            • March 24, 2023 at 5:21 pm #5572
                              James Johnston
                              Participant

                                Capture of a room response at one point involves 4 variables. This might be the only use I would personally wish to put a basic ambisonic microphone to.   You have 4 variables, dx dy dz and pressure.

                                The ear detects pressure via the eardrum, but volume velocity interacts with the head at frequencies where the head is wider than maybe 1/8 wave or so, so it can create pressure in a spot where there would otherwise be no pressure component.

                                 

                                This is part of what Bob O has pointed out, but there’s more in the issue with high frequencies in rooms with microphones, speakers, etc. Typically speakers do not radiate the same pattern at all frequencies. This affects the timbre of the room reflections substantially. If you measure frequency response with a long window at high frequencies, the high frequencies are going to be “off” usually in the “too little” direction, even if the direct sound is flat.   So,  measurement must be made at a variety of frequencies.   This can lead to several mistakes, including turning up the treble until your earlobes start to bleed, but also causing ‘dark’ masters because the studio was too “hot”.  Even if your speakers are both direct flat and power-wise flat the room response can fool you here, and most speakers “aren’t even close” to being both power flat

                                There are a lot of interactions to cope with, and it’s easy to oversimplify.

                                • March 27, 2023 at 12:35 pm #5588
                                  Bob Katz
                                  Keymaster

                                    JJ’s post should be a sticky. Yes, it is easy to oversimplify. I think when it comes to defining the final target for studio calibration we have not reached the point where the same target frequency response, measured in exactly the same way, sounds the same in different rooms with different loudspeakers! JJ alluded to the issue with loudspeaker horizontal polar pattern and its interaction with wall reflections as one cause for the variation. Other variables are loudspeaker distance from the listener, room size. Room “reverberation” curve.

                                    With all these variables, it’s absolutely necessary to combine subjective judgment with the measurements. The measurements to help provide consistency and a baseline to compare. The subjective judgment to help deal with, largely, bass response below about 125 Hz and treble response above about 5 kHz. I find that the smaller the room and the nearer the loudspeakers, that I have to bias the bass response upward to get the same subjective perception as in a larger room. I have an empirical method to arrive at treble response and it works very well for me. I measure using the same measurement method as I always use, and then I know that some kind of HF rolloff will be required. But how much rolloff? It differs, and I have a method to help ensure consistency within that slippery subjective context. I don’t have the time to tell you about that today!

                                    • March 27, 2023 at 12:39 pm #5589
                                      Bob Katz
                                      Keymaster

                                        Oh yes, it’s not uncommon for mixing and mastering rooms to need different bass shelf targets. Here’s a thought experiment for you: Consider a mixing and a mastering room with everything identical, down to loudspeakers, distances, wall construction, etc. But still for reasons that you should be able to guess, the mastering room typically seems to need a slightly different bass frequency target level than the mixing room. Why do you suppose this is the case? Because it is!

                                      • March 30, 2023 at 7:56 pm #5631
                                        Norman Varney
                                        Moderator

                                          Of course we also have both interaurel cross-correlation or head related  (HRTF) time differences (ITD), not just intensity (IID).  The cross over happens around 750 Hz. and/or 0.66 milliseconds. With a standard stereophonic loudspeaker arrangement, the lateral localization of the auditory event at Just Noticeable Difference is between 630 microseconds and 1 ms.
                                          There are some good books on the subject, especially “Spatial Hearing” by Blauert.

                                    • March 29, 2023 at 5:00 am #5601
                                      Steve Hicks
                                      Participant

                                        Thanks for the invaluble input bob, makes alot of sense that a smaller room would require more bass in a flat room. also love the mention of subjective judgement, hence why mastering engineers seem to be visiting eachothers studios. i am a predominantly a producer who went from writing bad mix downs as a result of my perception of sound tied in with not being able to accurately judge the acoustics in my room. the quality of my mixdowns has drastically increased with the applied understanding of compression and sidechaining as well as low and high frequency shelving and cutting. I now find myself obsessed with everything mastering.. recently picked up the adam audio sp5’s and once again have made another jump at the possibilities of sound perception. so now im motivated more than ever to start installing plasterboard in this room as a solid framework for future acoustic treatment.

                                        • April 1, 2023 at 12:40 pm #5661
                                          Bob Katz
                                          Keymaster

                                            No one yet has answered my thought question of how two rooms, each with IDENTICAL louspeakers, placement, wall construction and acoustics, could still require a slightly different bass response. So I’ll answer:

                                            A mastering room typically may listen at a slightly higher listening level than a mix room. And often may listen to more compressed material. As such, the bass response curve may not have to be turned up as high as in a mixing room.

                                            This has proved true in my mixing and mastering rooms. They are far from identical rooms and speakers. The mix room is much smaller. Anyway, the bass response in the mix room is turned up +0.9 dB above flat measurement, below 125 Hz, and it sounds “just right”. The bass response in the mastering room is turned up only about 0.2-0.3 dB. Again, I think part of the reason is that in the mastering room we listen at a slightly higher level than in the mix room. ——-> Equal loudness curves, folks. That’s a reason.

                                        • March 29, 2023 at 9:43 am #5604
                                          Bob Olhsson
                                          Moderator

                                            I don’t understand why mixing and monitoring can’t be done on an identical system although preferably not by the same person.

                                            Here are some of my experiences:

                                            Isolation creates more low frequency issues. Unless you have performers (or neighbors) in the next room, I’d avoid it!

                                            Diffused, flat frequency response reflections off the walls makes a big improvement. We learned this at Motown from RCA in the mid 1960s. I currently have a 4 inch thick foam absorber living behind my head because I need to be close to the wall. My only other room treatment is my collection of about 2000 LPs.

                                            Felt diffraction treatment around drivers can make speakers both measure and sound flat without needing magic high frequency correction  curves. I also avoid ported speakers like the plague. They interact with a room at low frequencies far more than speakers in sealed cabinets do. My first experience of this was a pair of BBC LS3/5as in 1976 and my current Duntech Sovereigns work exactly the same way only with LF response down to 27 Hz..

                                            This was also something we learned about at Motown in the mid ’60s. We called B&K to ask why eqing our control room speakers didn’t sound right. We found out that nobody they knew of had ever tried this before. The microphone designer didn’t think it would work outside an anechoic chamber because of diffraction in both the microphone and the speaker drivers. I moved to San Francisco in 1972 and watched “name experts” screw up room eq. to the point that people were getting better mixes monitoring with KLH 6s, JBL L-100s and Yamaha NS-10s than their ten thousand dollar mains! That eq insanity ended with Dick Heyser’s Time Delay Spectrometry that solved a lot of the measurement issues but it has reared its head again in recent years.

                                            • March 30, 2023 at 8:03 pm #5632
                                              Norman Varney
                                              Moderator

                                                I too would think and hope that mixing, monitoring and mastering can all be done with the same monitors.

                                                How can “mechanical” isolation create more low frequency issues? Am I misunderstanding?

                                                • April 1, 2023 at 12:57 am #5648
                                                  JasonHiller
                                                  Participant

                                                    For what it’s worth, I use and love KLH5s for mixing and mastering. I have 3 pairs. And have NS10’s to make the studio look professional. (But I do love them too) To be honest much of my initial mixing is done on Radio Shack Minimus 7s but don’t tell anyone. 🙂

                                                    Bob O I’d like to hear any story you may have about the KLHs. 🙂

                                                • April 1, 2023 at 4:16 pm #5663
                                                  Bob Katz
                                                  Keymaster

                                                    Isolation can create a low frequency issue only if the acoustic treatment is done improperly. Norman Varney could enter in here with more detail, but what I know is that if you have a wall which is leaky, that can reduce some low frequency buildup. But a leaky wall invites leakage (poor isolation). You’re not damned if you do, damned if you don’t, once you create a totally sealed (non-leaky) wall you have to do even more significant trapping to deal with the bass nodes which did not escape out the leaky wall! That’s what Bob Olhsson was referring to.

                                                    I see that just below, Bob Olhsson amplified on his post and referred much to the same thing regarding acoustical isolation.

                                                    • April 3, 2023 at 6:20 pm #5693
                                                      Norman Varney
                                                      Moderator

                                                        Just ordered the book, thanks Bob! This is why this forum is great.

                                                        As far as sound energy isolation, we really need to break it up into two areas; airborne, and structureborne. There are a couple of things to remember- everything resonates (materials are excited into vibration that then becomes airborne), and vibration is a two-way street. If sound can get in , it can get out. It can do so through air leaks and flanking, and/or through mechanical excitation. Note also that structureborne vibrations reflect back too. This might mean the shell back into the room, the floor back to the loudspeaker cabinet, etc.

                                                        When talking about the shell of the room, too much mass will help noise from transferring to other spaces, and sound infiltration from other spaces, but will also mean the sound energy will be more contained, be allowed to build up, and be allowed to linger more than we would like from a sound quality POV.

                                                        Shell construction is a delicate balance between noise control and sound quality. Both existing (or estimated) conditions must understood, as well as the goals for noise control and sound quality. Then with information of the sound energy paths, and any physical, budgetary, decor, etc. constraints understood, solutions can be considered.

                                                        Ideally, the shell is allowed to flex mechanically, yet is sealed resiliently air-tight. As always, acoustics is never a one-size-fits-all. Construction materials and methods and interior treatments will be needed- the right type, at the right location, at the right quantity.

                                                  • March 30, 2023 at 8:11 pm #5633
                                                    Bob Olhsson
                                                    Moderator

                                                      I was referring to acoustical isolation. An advantage mastering rooms often have is minimal isolation building up low frequency reflections. The bass just sails out of the room.

                                                      • April 1, 2023 at 1:24 am #5649
                                                        JasonHiller
                                                        Participant

                                                          And this thread has been so informative.  My room treatment was done all by ear by an acoustician I trust. And when I listen to great mixes (not mine) they just sound wonderful. So if multiple decades of beautiful mixes sound great in my room it stands to reason that I should be able to make a great mix in that room too.  Thank you all so much for sharing your knowledge!

                                                      • April 1, 2023 at 6:27 am #5651
                                                        JasonHiller
                                                        Participant

                                                          When I tried Sonarworks it made everything so bright. So even older mixes I liked became unlistenable.  Is thia possibly due to the Speaker/Microphone issue Bob O referred to? I k ow Sonarworks is immensely popular but I just can’t use it.

                                                          • April 1, 2023 at 4:41 pm #5666
                                                            Bob Katz
                                                            Keymaster

                                                              Hi, Jason. Every correction system requires setting a “Target”. Obviously Sonarworks’ default target must be set too bright. Using Acourate I adjust the high frequency slope of my target using my collection of 50 reference recordings. I don’t rest until the center of the reference recordings sounds absolutely right, and the brightest and dullest of them are neither too bright nor too dull. That takes skill, knowledge and experience. Personally I’m not a Sonarworks fan, but I can tell you that if you want to do it yourself, if your room is properly treated, you can accomplish the final EQ with REW and a superb, high resolution equalizer, and lots of experience and training. Or, you can do it yourself with Acourate and Acourate Convolver. If you’re curious about that, I recommend to anyone considering what I think is the most transparent-sounding (no sound of its own!) correction system, then look into Mitch Barnett’s excellent how-to book:

                                                          • April 1, 2023 at 9:26 am #5653
                                                            Bob Olhsson
                                                            Moderator

                                                              I still have my Minimus 7s although I haven’t used them in a decade. They were popular in UK studios and I thought they worked better than my Auratones or NS-10s.

                                                              The KLH-6s were popular in New York but I never used them in Detroit or the west coast. Old control rooms from the ’50s didn’t have enough room to spread the big monitors out so bookshelf speakers on the  console became the norm to monitor stereo. KLH-6s were the biggest selling bookshelf speakers until the JBL L-100s replaced them in sales figures and on consoles.

                                                              I’ve only used Sonarworks on headphones. It was better than nothing on my Sennheisers but disappointing with my Audeze.

                                                              • April 2, 2023 at 11:07 am #5671
                                                                JasonHiller
                                                                Participant

                                                                  Ok I will check out Acourate! By any chance would you want to post your list of 50 reference mixes?  I only have 3:

                                                                  Buddy Holly – Everyday

                                                                  Stan Getz – Girl From Ipanema

                                                                  Taj Mahal – Leaving Trunk

                                                                  What else could there possibly be? 🙂

                                                                   

                                                                  • April 2, 2023 at 2:11 pm #5673
                                                                  • April 3, 2023 at 12:01 pm #5684
                                                                    Bob Katz
                                                                    Keymaster

                                                                      My Qobuz “best sound” playlist includes about 10 of the references I use.

                                                                      Here it is: Well, I had to put quotation marks around it or somehow the forum changes the link name

                                                                      https://open.qobuz.com/playlist/6920944”

                                                                      Even though only about 10 of my references are include din this Qobuz playlist, I think every one of the recordings in the Qobuz playlist is reference quality. Pity that Qobuz does not have the “Anniversary Edition” of Ray Charles “Genius Loves Company” or I would have included that in the playlist. You can purchase the anniversary edition I believe at 96k or above from HD tracks. The first cut “Here I Go Again” is a masterpiece of recording by Al Schmidt. I don’t know who mastered it, but it is impeccably mastered.

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