we have been successfully using a non-subwoofer system for a couple of years, but the mains (2x qsc hpr122i) can't do it anymore. If the background level is more than 60dBSPL, you should increase the calibration level by 1dB for every dB above 60dBSPL, so if the background noise level is 63dBSPL, use a calibration level of 73dBSPL. Mark all the spots where the sound is strong by sticking some white tape to the carpet. That energy then continues its transit of the room's enclosed volume, eventually reaching your ears, delayed behind the first-arrival sound, and with amplitude altered. Room resonances truly are resonant systems: they have a specific Q ( the ratio of energy stored by the reactive components of the resonance - mass and compliance - to the energy dissipated (absorption, etc), bandwidth & characteristic natural frequency. There are some other test CDs available that have both a 100Hz low-frequency warble tone and a pink noise track, but Stereophiles Test CD2 has the triple virtues of being
21, at one end of your listening room, located on the center axis of the room and 1 meter out from the wall directly behind it, sits your subwoofer. published 24 July 15, Make sure you get all the performance you paid for. I like to avoid putting a single sub on one side or the other, not because if dispersion angles but because it makes the bass louder on one side of the room. Future US, Inc. Full 7th Floor, 130 West 42nd Street, ) We'll be using the 2 steradian system response as our reference measurement. At the opposite end of the room sits you, on the same central axis of the room and seated a meter away from the wall immediately behind you. As you crawl around, youll hear the bass alternately get stronger and weaker in fact at some points in the room the bass might be so weak that you will barely be able to hear it at all. Supporting Members list unlimited gear with no listing fees in the Classifieds, get instant Keyword Alerts, and get Free Shipping at the TalkBass Store. There may be exceptions but in my experience corner loading = mud. (The end result of Step 3 of the calibration process.) ), Dont be concerned that all the vertical bars are dancing up and down a little. (As in Photo 2 below.
Well, I got what Id paid for: BAM200 fail! What Hi-Fi? Yes, corner loading will increase output but in my experience it causes more problems than it cures since it introduces more reflected sound as opposed to accurate, time-aligned, direct sound from the speakers themselves. Imagine, as shown in Fig. For Android, the best RTA app available costs AU$7.49 and is part ofAudioTool (opens in new tab)available HERE (opens in new tab). The sound pressure level (SPL) you use during calibration will depend on the level of background noise in your room, because you do not want environmental noise contaminating the measurements you make during the calibration procedure. If it is less than 60dBSPL, use a calibration level of 70dBSPL. Wasn't going to say anything, but now that you mention it, it will reinforce a sub to stick it in a corner, but boundary reflections can cause cancellations in certain frequencies as well as these time-alignment issues, although I'd really like to see some data on how smeared the time alignment really becomes because it can't be by much. Some extra tweaking could have reduced the level here by a dB or so, but I preferred the sound of the slight forwardness in this region, and also wanted to show that you dont need to achieve absolute flatness. All the free apps I tried had intrusive advertising and some will run up big data charges (or worse!) If the bass is now weak at this point, remove the tape. Subwoofer Placement - The Place for Bass Part 1, Single Subwoofer Placement and Boundary Effect. Bite the bullet and pay the AU$10! Now play the 100Hz warble tone again, slowly increasing the level of the subwoofers volume control knob until the sound pressure level reading on your phone is the same as it was in Step 3. Copyright 19982022 Audioholics, LLC. Despite what their specifications might say, and their manufacturers might claim, very few hi-fi loudspeakers even the largest floor-standing models can reproduce the deepest musical frequencies at appropriate volume levels. The response is slightly high for the three third-octave bands above 63Hz (the actual centre-frequencies are 80Hz, 100Hz, and 125Hz). The "r" value is the distance from the system reference point (the center of the faceplate) to the boundary located immediately behind it. Please refresh the page and try again.
At the same time, sound is, of course, traveling in all directions, including those areas where the room modes are formed. The best RTA app for iOS devices (iPhone, iPad) comes fromStudio Six Digital (opens in new tab)and is available in Apples App store for $19.99. Get the Audioholics AV Gear Guide Ebook FREE! The resultant frequency response extends from 25Hz to 200Hz 3dB, which you can see because all the third-octave bars are between the 54dBSPL and 60dBSPL calibrations (scale is at left of screen). If the response is relatively flat, youre done: this setting of the crossover control is the best setting for your subwoofer to cross over to your main speakers. However, the frequency responses of the microphones on the smartphones I experimented with when preparing this article were flat enough to allow accurate calibration. Since you'll usually have a number of spots to choose from, choose the most convenient location, where the subwoofer will be the least conspicuous and the most out-of-the-way. If the bass is still strong at a point, leave the tape on the floor. For reference I'll start by modeling the system in both 4 steradian (full space) and 2 steradian (half-space) domains.
The overall indicated SPL level will not be the same as the one you noted in Step 3, but this is normal and does not matter. You will find you can alter the displayed frequency range on the screen by pinching and 'unpinching' your fingers horizontally across the screen. Very few people even experts are capable of doing this by ear and, until recently, the measuring equipment required to correctly tune a subwoofer was prohibitively expensive. Further imagine, for the sake of discussion, your subwoofer has an on-axis amplitude response that measure perfectly flat, anechoically. is part of Future US Inc, an international media group and leading digital publisher. Once you have these, and you have loaded the app onto your phone, youre ready to go. Of the three types of modes (axial, tangential & oblique) that can set up within a listening space, it's the axial modes (e.g. The only problem with using these apps is that because they use your phones inbuilt microphone there is no guarantee that the microphones frequency response will be flat, so the measurements you make could be incorrect.
Once you have covered the entire floor area, your carpet should be littered with bits of white tape. we need a sub. HDMI ARC and HDMI eARC: everything you need to know, Best stereo amplifiers 2022: the best integrated amps you can buy, PS5 restock news: where to buy a PlayStation 5 console on Prime Day 2022, The best home entertainment buying advice, Issues delivered straight to your door or device. Once, a Real Time Analyser would have set you back thousands of dollars, making its purchase completely impractical for the purpose of a single home subwoofer calibration. On the other hand, if the acoustic energy applied to the listening room's space is at a frequency where no mode exists, no resonance sets up, thus no effect on the perceived response at the listening position; there's no frequency-specific modal energy build up in the space. If the response is not within 3dB, go to Step 8. As expected, it behaves like an omnidirectional radiator bolted in to a wall of infinite linear dimensions. You should always position your subwoofer in the spot in your room in which it works best acoustically but, if you have already decided for other reasons to place your subwoofer elsewhere (such as where it looks the best), the following calibration procedure will still ensure its output integrates correctly with that of your main speakers. For Sale: Bass Guitar Strings and Accessories, The TB Bazaar: Gear For Sale from our Sponsors, For Sale: Double Bass Amps, Strings & Accessories, Wanted: Bass Guitars, Amps, and Accessories, Wanted: Double Basses, Amps & Accessories, (You must log in or sign up to reply here.). [Disregard the level of the left-most (25Hz) vertical bar, because this cant be adjusted.]. When youve finished this second 'crawl around' process, this time around you will find that you can put the subwoofer anywhere theres tape and be assured of getting good bass at the listening position. In theory, you could continue this process for each person who could potentially be listening, but the availability of 'good' places will narrow once you're past three people. Now let's fire up the subwoofer. Visit our corporate site (opens in new tab). While playing the warble tone, gradually increase the volume level on your amplifier/receiver until the SPL meter shows a figure of somewhere between 70dBSPL and 80dBSPL, depending on the level of the background noise in your room. You will only end up wrecking all the work youve done. Getting all the third-octave bars within 3dB in a normal acoustically untreated room is a good outcome. I appreciate this may mean some creative use of stacked milk crates and/or furniture items, and the temporary moving-aside of the seat or couch you would normally be sitting on, but its worth it. Heres why you can trust us. DO NOT attempt to adjust the level of the subwoofer to increase the level of deep bass. But before you start your calibration, let's look at how to position the subwoofer correctly in your room. Turn up the volume of the subwoofer a little higher than normal, so youll be ready for the next step. Reaching those areas, it then excites the mode or modes, which store the energy, then release it, after a delay. You must ONLY adjust the crossover and phase controls on the subwoofer. The photo above shows the frequency response of the subwoofer/satellite speaker combination after calibration using the method described. Now, thanks to the processing power found inside any smartphone, it is possible to accurately calibrate a subwoofer with a smartphone running an AU$10 app and a low-cost CD with appropriate test tones. However, if you regularly listen with another person, there is yet more to be done. Stereophiles Test CD2 is available for US$12.99 (plus postage) fromMusic Direct (opens in new tab). Although the meter will be doing some averaging, you will also have to use your eyes to average the vertical movements. Step 1: Position your phone at the listening position, at the point where your head would be. If you are particularly fussy, and want to use a calibrated microphone, both these apps allow you to use an external microphone. Alternatively, you can buy Test CD2 direct from Stereophile itself for US$9.99 (plus postage) or you can buy a set of all three Stereophile test discs (Test CD1, Test CD2 and Test CD3) as a bundle for US$24. Gold Supporters see zero ads! .683m is also the depth of the system's cabinet, therefore when r = .683m, the back of the cabinet is situated flush against the boundary immediately behind it. The net effect is that you now perceive the subwoofer's response through the "lens", as it were, of the room's acoustic signature and the perceived frequency response now features all the evidence of the room's resonances: peaks & dips that in some circumstances can reach 10s of dBs in magnitude. If youre still unhappy, adjust the subwoofers crossover control to the position that gave the third-flattest response, and do Step 9 all over again. we're close to buying the qsc ksub, but we only want one. What Hi-Fi? You will receive a verification email shortly. The location of the microphone isnt really important so long as its not blocked so you should position the phone where you can easily see the screen and make adjustments to the measurement parameters (using the on-screen soft keys). Step 7: Now, look at the third octave analyser spectrum on your phone to see whether all the vertical bars are relatively flat and smooth across the screen. In Figure 23 we see the cabinet positioned such that its back panel is flush against a wall. No other boundary effects are presented in the simulation. P-J pickups: Genius? Discussion in 'Live Sound [BG]' started by hgregs, Mar 4, 2013. This is normal, and you should ignore it. After youve tried ALL settings of the phase control, move it back to the position that gave you the flattest response and leave it there: youre done. Thank you for signing up to What Hi-Fi?.
The above illustration shows the Android version of the Audio Tool RTA app (opens in new tab) [http://tinyurl.com/audiotool-app] running in its SPL mode on a Samsung GT-S7562 Smartphone, measuring a 100Hz warble tone (from Stereophile Test CD2, Track 16, Index 4) at 70dBSPL. on your account even when theyre not being used. (a) the most comprehensive (b) the easiest to obtain and (c) slightly cheaper! The degree to which any of these discrete, LF modes, affect the perceived response depends largely upon the location of the listening position and the location of the subs within the listening space. ), Step 3: Disconnect the subwoofer from your amplifier or receiver and play the test CD through the main speakers using the 100Hz warble tone on Stereophile Test CD2 (Track 16, Index 4). TalkBass utilizes technology from Skimlinks that may give us a small affiliate commission on purchases made via links on our site. Now play Track 15 (Pink Noise at 20dBFS) on Stereophile Test CD2 and, while its playing, adjust the vertical resolution of the screen (by pinching or spreading your fingers) until each horizontal calibration is 6dB and all the vertical bars are on-screen. NY 10036. The actual level you end up using is not important, but you do need to make a note of it. For this measurement, either button can be in either mode, as they dont affect the measurement. Step 11: Now that youve finished, play a track with deep bass (Track 1 of Pink Floyds Dark Side of the Moon should do) to hear the balance of the subwoofer with your speakers. Please note that in these simulations, as the cabinet's position is changed, the listening position of the microphone changes accordingly, thus maintaining the 1m, on axis orientation of the mic. With the front panel of the subwoofer modeled flush with the radiation boundary (which illustrates the half-space model) and the source of acoustic energy being small compared with the wavelengths being radiated (not forgetting the low pass -3dB point is set at 80 Hz), the effects of diffraction & increasing directivity will not be seen in the response. However, before you start the calibration process, you will first need to acquire a suitable test CD, such as Stereophile Test CD2 (more details below), an iOS or Android smartphone and a suitable Real Time Analyser app (details below). If the resonance decays at a rate such that the primary sound event ends before the resonance decays to a sub-audible level, than the LF portion of the audible spectrum begins to sound, subjectively speaking, "loose" or "poorly defined".
Join our Exclusive Audioholics E-Book Membership Program! Greg Borrowman The two small tabs visible between the tabs that show SPL and Medium are for Peak Hold (On/Off) and Valley (On/Off). Most music contains deep bass only at very low levels, so it should be reproduced at those same very low levels. Proximity to a power point would be another consideration. is supported by its audience. Sign up below to get the latest from What Hi-Fi?, plus exclusive special offers, direct to your inbox! It is the same principle as a bass amp. Using the SPL meter function, measure the background level of noise in your room. These room modes don't require a special type of signal set up: sine wave, pink noise, music or a hand clap: so long as energy is applied at the correct, required frequencies the mode will be excited. To establish the correct dBSPL level you should use, shut all windows and doors to the room in which you will be making the measurements, and turn off any air-conditioning. The simulation is then re-run, this time with the cabinet moved 1m away from the wall. All Rights Reserved.
New York, If you cant achieve a relatively flat response, go to Step 9. Step 4: Now turn the main speakers off using the Speakers On/Off or Speakers A/B button or, if this is not possible, disconnect the speaker wires, and then reconnect the subwoofer, with the subwoofers volume knob set to zero, its phase control set to 0 degrees, and the subwoofers crossover control set at its highest possible frequency. Once the subwoofer's energized, the first sound that reaches your ears is the direct sound, with the systems dead-flat frequency response intact and unaltered by the room's acoustic signature. To purchase direct from Stereophile, details areHERE (opens in new tab): WARNING:If you are going to buy only one CD, youMUSTbuy Stereophile Test CD2, because the Stereophiles most recent test CD (Stereophile Test CD3)DOES NOThave the pink noise test track you will need to complete the calibration successfully. You have correctly set your subwoofers volume and phase controls to positions that allow your subwoofers output to best-integrate with the output of your front left and right loudspeakers. If you only ever listen to your system yourself, you can now move the subwoofer anywhere theres a bit of tape, and this will be the ideal position for the room and your listening position. Thank you for your support! Once positioned, leave the phone in this same position for the duration of the calibration process. There was a problem. (If the RTA app youre using offers neither of these options, instead select C-weighting. Step 8: While watching the RTA spectrum display, slowly move the subwoofers crossover control counter-clockwise from its maximum position until you get the flattest response possible. The next step is to start crawling around the floor (and no, I am not joking) with some white electrical tape in your hand. As you adjust the phase control you should see the levels of the various vertical bars change. However, whatever you do, DO NOT alter the position of either your subwoofers volume control or the volume of your amplifier/receiver to try to fix the response. Step 6: Reconnect the main speakers! To do this requires a properly-tuned subwoofer: one whose volume, crossover frequency and phase controls have been set in such a way that the subwoofers output integrates perfectly with that of the main stereo or front/main loudspeakerswherein lies the problem. For this portion of the analysis I ran a series of simulations using a vented subwoofer, sporting a single 12" driver, with an amplitude response characterized by -3dB points at ~14Hz and ~80 Hz. Leave the subwoofers volume control knob in this position. Step 9: Adjust the subwoofers crossover control to where the response was the most flat, and then slowly adjust the phase control while looking at the RTA spectrum. Or the mullet of pup configs. Once the subwoofer is in place in this exact position, connect it to your system (you will need a long RCARCA lead, which you can either buy, or borrow from your friendly local audio store), after which you should start playing a music track with plenty of low bass. Along with room resonances, the effects of the room's boundaries play a key role in determining the subwoofer system's response as perceived at the listening position. ggunn and Jimmy M, If you are only using one sub you will get more output by getting it closer to walls or better yet a corner. 22) we can now exam the effect of boundaries on system response. (See following paragraphs.). You can see from the blue soft keys that the averaging is set to Off, the mode is SPL, Meter Response is set to Medium and that weighting is set to Flat. Whatever you do, DO NOT purchase one of the many free SPL meter apps that are available, or one of the (less readily available) free Real Time Analyser apps. However, to be successful youd need to use a good, calibrated, external microphone, for which purpose Id recommend theDayton imm-6, from Dayton Audio. Anyone who is regularly installing and calibrating subwoofers should use a professional-standard portable RTA, such as NTIs XL2 fitted with the M4260 microphone, information about which can be foundHERE (opens in new tab). There is much nonsense published about positioning a subwoofer, the most egregious of which is the advice that you should not place one in a corner. Step 5: Now change the function of your smartphone app from SPL to RTA, and apply the following settings. If someone usually listens to music with you or watches movies with you you will now have to physically move the subwoofer to where their head would usually be, and repeat the entire crawling around the floor process, but this time it will go much faster, because you will only have to listen at the spots you have already taped. Step 10: If you are unhappy with the flatness of the response after you have completed Step 9, return the phase control to its 0 position, then adjust the subwoofers crossover control to the position that gave the second-flattest response, and do Step 9 all over again.
These days, thanks to the computing power inside a smartphone, you can buy an app that will turn your phone (or tablet) into a Real Time Analyser. Movie sound effects contain more deep bass than most music tracks, but you should still resist the temptation to increase the level of bass issuing from your subwoofer: The rule-of-thumb is that if the deep bass sounds obvious, the subwoofers volume level has been set too high. Having established a 2 steradian (half-space) response of the system as a reference point (as seen in Fig. Step 2: Set the RTA app on your phone to its SPL mode, then set the Meter Response to Medium; and the Weighting to either Flat or No Weighting. However, you most definitely should not place full-range loudspeakers in corners (either the left or right channel speakers in a hi-fi system, or the front-left and front-right speakers if it's a multi-channel home theatre speaker system) unless that speaker has been specifically designed for corner-mounting (some full-range loudspeakers made by Klipsch and Allison were specifically designed for corner-mounting). DO NOT try to 'compromise' by putting the subwoofer anywhere there is not a piece of white tape!