mijostyn, thank you. I know there is something wrong with my room response, but I will fix it later. At least I have tool. My room is too reflective. I don't hear any particular resonances but listening louder makes sound less clean. It is most likely multiple echo, that it is reduced at low volume levels (further echoes fall below hearing threshold).
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You are absolutely correct. But, if you don't know what the problems are especially peaks and holes in your system/room response, you are stabbing in the dark. but, you are right. fixing it is serious business. Room correction has got to be the most difficult mind numbing expensive experience. not for the faint of heart. The good thing is if you know the problems, it is no longer trial and error. enjoy |
Minorl, It is easy to see the problems but much harder to fix them. Kijanki, don't feel bad. It always looks awful. When I show people what their system is actually doing they usually puke. Remember a lot of the variation below 150 Hz is room effect. If you move the microphone three feet in any direction it will look totally different. |
The easiest I've used is a free download app called audiotools. It provides a sound level meter and also real time analyzer adn fast fourier transform tools. You can see gaps in your system and room. I use the stereophile test cds and play pink noise or other signals to see where the system and room is lacking. not complicated at all and quite easy and simple to use. Not professional quality because you are using your Ipad or Iphone's microphone, but it works pretty well non-the-less. enjoy |
@oldears I did few frequency sweeps only, so far (results look pretty bad), but program has a lot of tools: It includes tools for generating audio test signals; measuring SPL and impedance; measuring frequency and impulse responses; measuring distortion; generating phase, group delay and spectral decay plots, waterfalls, spectrograms and energy-time curves; generating real time analyser (RTA) plots; calculating reverberation times; calculating Thiele-Small parameters; determining the frequencies and decay times of modal resonances; displaying equaliser responses and automatically adjusting the settings of parametric equalisers to counter the effects of room modes and adjust responses to match a target curve. |
Thanks for the great responses. I have already done the simple setup a couple of years ago, with the xover at 50 hz and 24dB with the level set by the RS meter. But I want to set up the PEq, so I may need the precision of the option by Kijanki, and I as I have a 64 bit PC close enough to work, I will probably try that. (My smart phone is only a cheapie Samsung.) Thanks again. |
I have a PCE 353 which I used to set up a pair of Wilson Benesch Torus Infrasonic Generators with their outboard amp/crossovers. https://www.pce-instruments.com/us/measuring-instruments/test-meters/decibel-meter-kat_162375.htm You only need to match the sub bass drivers to your main speakers 1kHz level using an appropriate test tone found on many reasonably priced CD demo discs. Use your ears to fine tune to taste. It is not as difficult as many lead you to believe. I hope this helps! |
Kijanki all that is wonderful but now you need a very high resolution way of digitally creating mirror images of the curves then EQ on top. It takes at least a 64 bit system. The best way is with a digital preamp with room control and the ability to modify curves such as the Anthem STR and Trinnov Amethyst. |
I'm with Erik on this one. The are a lot of hand held dB meters on the market. I keep one on my coffee table. I have room control and getting all that stuff out is a PITA. With the hand held I get an answer just by flipping the switch. Using a dB meter to set up subs is difficult. You would need to impulse test very driver and graph the results. Using say white noise my not produce equal levels between the drivers. The best way to do this is turn the subs up until they are obviously too loud then start dropping the volume a little at a time until the sub just disappears. If the sub does not disappear you have a phase/time alignment problem or just bad subs. I like my subs aggressive. I use a curve that is up 6 db at 18 Hz dropping to 0 dB at 100 Hz. This produces the air behind that kick drum strike which is very realistic. Check out a small jazz club. Brittany Howard's new album Jaime uses a bass drum without any damping what so ever. You can feel that bass drum head shake producing a glorious boom instead of a thud. |
I got UMIK-1 (USB microphone) https://www.minidsp.com/products/acoustic-measurement/umik-1 Then I downloaded Room EQ Wizard (free program): https://www.roomeqwizard.com/ When you enter microphone serial # it downloads calibration data. It contains two text files - dB corrections at different frequencies for directional (microphone pointing forward) and omnidirectional (microphone pointing up) modes. It allows to automatically sweep frequencies and record chart, but it works only if you can connect computer to your system (I use computer for playback anyway). |
Skip the meter. Play music with good bass at the volume level you care about the most. Because the perceived loudness of bass is volume dependent, while meters are not. Also the level you get with a meter is only good at whatever frequency is playing. Your ears on the other hand will balance and average it all together. Meters cannot do this. So play music, make very small adjustments, and repeat until satisfied. Which btw will not happen with "a" sub. The day you get four though, watch out! Bliss! |
I’m willing to bet a new calibrated USB mic is more accurate as well then a radio shack old style one. specially used. Oh, they are good, but also kind of a PITA to use. I mean, I have 2. Still got to drag out the stand, the cable and the software. I mean, if you are making speakers or attempting to measure the decay rate of the room, USB mic is the way to go. If you just want to say calibrate a HT system or integrate a sub, the cheap one I suggested is the way to go, and they actually DO have better range in Hz compared to the SPL meters and with the calibration file are really good. Of course, none of these will come with OSHA certs. :) |
+erik_squires I'm willing to bet a new calibrated USB mic is more accurate as well then a radio shack old style one. specially used. or just the app one may be enough for your purposes. that said you can get professional quality ones form various places that supply the film-studio-recording industry. you may get one from an industrial safety equipment sales place as well. |
Old Radio Shack sound level meters are easily purchased on Ebay. https://www.ebay.com/p/1300619695 B |
Absolutely. Use a $20 calibrated mini-mic: https://amzn.to/2XxZ4bl Requires a normal headphone/mic plug on your phone. I use AudioTools on Android. You go to the manufacturer’s website, and copy the calibration file to your phone. Best, E |