Channel: John Heisz - Speakers and Audio Projects

Category: Howto & Style

Tags: how tomakingi build itwoodworkingdiymakermakejohn heisz

Description: I'll say up front that my experiment wasn't exhaustive enough to prove the metamaterial doesn't work. Since I didn't see a notable improvement, that only suggests that it may not work. There could be other factors that I didn't explore that could change that. Here's a link to the paper I took the design from: rolfbader.de/wp-content/uploads/2020/05/Bader_MetamaterialWall_Preprint.pdf More about my system: I have all of the music I listen to on the computer and there isn't any streaming or internet in my listening room. I don't have a turntable or vinyl records and I don't play CDs. I use the digital out (optical) directly from the computer. This goes into the MiniDSP 4x10 that does all of the crossover processing. There are three amps: - the one I made drives the 4 infinite baffle subwoofers individually (4 channels). - the Yamaha 7.1 HTR is set to multichannel input and drives the midwoofer, midrange and tweeter on both open baffle speakers (6 channels). - the Onkyo receiver drives the two 15" woofers in the open baffle speakers (2 channels). This all active system gives me precise control of all of the speakers and the overall response in the room. In every way it is superior to a passive crossover system, when you know how to set it up. The recording: I did the stereo recording in two sessions, the left channel first with the microphone pointed at that speaker, and the the right channel with the mic pointed at that speaker. In both cases only one speaker was on - the left or the right. Using this method I was able to get a stereo recording using a mono microphone and also avoid the comb-filtering problems there would be with a stereo microphone recording two speakers at the same time. Our brains have some tricky software to deal with that comb-filtering, but a microphones do not. I took those two recordings and combined them into a single stereo file and that's what was playing in the video. I then used the original sound file that I downloaded from YouTube's sound library and put that directly into the video for comparison. The music I chose has good stereo separation, good dynamic range and most important is that it's neutral and less likely to annoy some people. This test was to show two things: first that a treated room doesn't sound "dead". In fact the treated room was the very reason why I was able to make such a clean recording. Second was to give a fairly accurate idea of what these open baffle speakers sound like. My EQ settings for normal listening are a bit different than what I used here - I bump up the bass slightly - but changed it to flat response to try to match the original music as closely as possible. The microphone isn't anything special, it's a fairly low cost Umik-1 used for measurement and it was set up in my normal listening position about 7 feet away from the speakers. The closer the mic is to the source the better (cleaner and more accurate) it will be, but I wanted this to be as close to "what I hear" as possible. I even left the chair in place, and moving that might have made a slight improvement. Even with all of those compromises I think the recording turned out pretty good. Not a perfect match for the original, but like I said in the video, that's very difficult to get. Try something like this yourself in the place you normally listen to music - it's an eye-opening experience if you truly enjoy high quality sound reproduction. You can help support the work I do in making these videos: Project plans for sale: ibuildit.ca/plans Join the ibuildit community on Loacals: ibuildit.locals.com Support this channel on Patreon: patreon.com/user?u=865843&ty=h #diyspeakers #johnheisz #audio My "Scrap bin" channel: youtube.com/c/IBuildItScrapBin My main channel: youtube.com/user/jpheisz Website: ibuildit.ca Facebook: facebook.com/I-Build-It-258048014240900 Instagram: instagram.com/i_build_it.ca