D-MAN Posted June 3, 2005 Share Posted June 3, 2005 We had an ongoing argument sometime ago in which some of you failed to agree with me (ahem!). Here is something from JBL to back up my side where I said that you can't actually get 40Hz waveforms to express in an undersized room. Post follows. DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted June 3, 2005 Author Share Posted June 3, 2005 Excerpt from a pdf post that I first saw on the AudioAsylum website. This is in 3 parts, and its a worthwhile read. I will get the link info and re-edit below. DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted June 3, 2005 Author Share Posted June 3, 2005 Here's the web link: Link DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted June 3, 2005 Author Share Posted June 3, 2005 This excerpt is from another article on the same site, but the point is the same. Boss! The room! The room! - what did I tell you? DM Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 3, 2005 Share Posted June 3, 2005 Very sure. That in no way shape or form supports what you were saying in that it is impossible to reproduce a wave that has a wavelength that is longer then your rooms length. That article is just saying you can't hear the bass reproduction of the speaker alone without the influences on its amplitude response of the room too. That is of course true as was noted last time around. It is also true that that happens well above the bass range too. It just gets progressivly easier to treat that at higher frequencies because it is easier to absorb shorter wavelengths then longer wavelengths. E-mail the guy that wrote that article and he will tell you your supposition that it isn't possible to reproduce a wave that is longer then your room is not correct. Buy some measuring equipment and you will see that that is not correct. Look at measurment I made last time around of the 75 foot wave in my 16 foot long room.... Shawn Quote Link to comment Share on other sites More sharing options...
sunnysal Posted June 3, 2005 Share Posted June 3, 2005 shawn in right, the articles do not support your position from last time, they do clarify room modes, etc. They are interesting articles non-the-less. tony Quote Link to comment Share on other sites More sharing options...
Erukian Posted June 4, 2005 Share Posted June 4, 2005 Darn you for posting the links! I just went through a sleepless night just to read pretty much every PDF on the HK site. I'll make up for ths sleep when i'm old I guess, What i'm about to say is from what I've concluded, i'm by far no audio engineer, so feel free to correct me. While I try not to take all new information as gospel when I read it, their testing in the 2nd paper of the series rotating the speakers is REALLY interesting. but i think somewhat inaccurate for horn designs that sort of beam out a nice sweet spot. Horns would also completely change how sound bounces around a room. If i put my head above the speaker while it's playing, the tweeter is SO much quieter than say a ribbon or common dome tweeter. Also If you sit in the middle of the room. All you really need is good dampening behind you with horns because their so much more directional (this is especially the case if you want to prevent the highs from sounding tinny) From my experiences though, and going back to the topic, to get a 20-40Hz waveforms to 'express' in my 12x13x8 room, i have to set up about 4 parametric equalizers fighting and working with room modes to get a nice flat response. -Joe Quote Link to comment Share on other sites More sharing options...
hjones4841 Posted June 4, 2005 Share Posted June 4, 2005 Hmmm... my room is much smaller that a 16hz wavelength (22' x 12.5' x 8'). What, oh what is my SPL meter reading when I put a 16hz tone to my Velodyne FSR18 and why, or why do my walls, doors and furniture inside and outside the room vibrate??? Quote Link to comment Share on other sites More sharing options...
rebel7sleg Posted June 4, 2005 Share Posted June 4, 2005 It would seem that you have him there.... Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 4, 2005 Share Posted June 4, 2005 Same here; I get a pretty strong (-4 dB), but inaudible, 16 Hz tone out of my room that is 16' x 18' x 20' x 21' with a 5' x 24' hall off of it (it's hatchet-shaped). That max. dimension calculates 26 Hz. Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 4, 2005 Share Posted June 4, 2005 Had to find the file I uploaded last time around.... My room is a little over 16' deep. If I pump a 15hz sine wave through my subs in my room (which is very well sealed up) this is what the instruments say is being reproduced in my room. A 15hz wave is around 75' long which is obviously much longer then my rooms longest length. But just as obviously it could be reproduced within my room. Shawn Quote Link to comment Share on other sites More sharing options...
ygmn Posted June 4, 2005 Share Posted June 4, 2005 To hear something you just need to get in the way of the sound wave.... Our ears are not large enough to have a 100 hz wave fit in them...but we can hear the tone.... We hear due to special little hair like nerve thingys in our inner ear being vibrated by ear drum...and this sends signals to brain which then tells other parts of brain what we heard.... To hear anything...it has to be within the audible range of your hearing and the sound wave tickle your ears.... Where you are has nothing to do with it,.... You could be in a closet...and as long as the sound wave hit your ear you would hear it... Have headphones on...(small room huh)...and play low notes...you hear it... PEACE Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted June 4, 2005 Share Posted June 4, 2005 Shawn: I'm curious about what you're using for a signal generator. I have a vintage Eico that's used mainly for HF radio applications, and was just wondering what your using for these much lower (audio) frequency response tests. Thanks, Erik Quote Link to comment Share on other sites More sharing options...
hjones4841 Posted June 4, 2005 Share Posted June 4, 2005 Here are low freq MP3 files - part of a group that another forum member posted (don't remember who.) Trrrrrrryyyyyyyyyy iiiiiiiittttt yyyyooooouuuuullllll liiiiiikkkkkee iiiit! And if you can't hear these in your room, get a better subwoofer. bass.zip Quote Link to comment Share on other sites More sharing options...
sfogg Posted June 5, 2005 Share Posted June 5, 2005 Erik, "I'm curious about what you're using for a signal generator." I actually tend to use a couple different things. For most testing I have a HP 3325a Function Generator. I also have a couple of function generator programs for my laptop which I use mostly for dual frequency testing. For a computer a decent free function generator is at: http://marchandelec.com/fg.html Shawn Quote Link to comment Share on other sites More sharing options...
Erukian Posted June 5, 2005 Share Posted June 5, 2005 it's not a bad idea to download NCH Tone Generator, drag your laptop/computer into the music room and hook up your PC and then generate some tones. At least you'll be able to do any frequency you want, with white/pink noise, sine waves, square waves, etc etc. -Joe Quote Link to comment Share on other sites More sharing options...
D-MAN Posted June 6, 2005 Author Share Posted June 6, 2005 Yeah, I read all of that stuff too, pretty interesting. I agree that "getting in the way of the soundwave" is quite true, providing it doesn't "turn around" on you... The problem is when the waveform reflects back onto its original path, in particular when the listening place is positionally less of the wavelength which is typically the case. Now you are listening to a compound waveform because of the overlying reflection. Now THAT'S what I said before, and I said it pretty clearly. You can't hear an unaltered uncolored (re: TRUE) low frequency waveform in a room shorter than the wavelength being produced or the modes take over and that is what you hear. DM Quote Link to comment Share on other sites More sharing options...
formica Posted June 6, 2005 Share Posted June 6, 2005 ---------------- On 6/3/2005 6:24:09 PM D-MAN wrote: We had an ongoing argument sometime ago in which some of you failed to agree with me (ahem!). ---------------- Really? ---------------- "Most rooms boom ... It is not possible to listen to the TRUE" (as in UNMODIFIED) "bass output from a loudspeaker unless in an anechoic space." ---------------- ---------------- "The graphs show the PROFOUND effects of room resonances at frequencies up to about 300Hz" ---------------- Both quotes say exactly the point others have been trying to explain; In those frequency ranges you are listing to BOTH the room and the speakers simultaneously. The wave exists and is audible... Room effects are an interesting science, and I think you'd benefit from some additionally research in the area. It would also explain some additional differences you'll find between a regular horn loaded enclosure and a corner loaded one. There is more to it than just using the walls to extend to mouth of the horn. I think the time has come for you to invest in some testing equipment (test mic and preamp) and a software RTA that will allow you to measure both your room and your creations... Rob Quote Link to comment Share on other sites More sharing options...
formica Posted June 6, 2005 Share Posted June 6, 2005 ---------------- On 6/6/2005 12:33:03 PM D-MAN wrote: I said it pretty clearly. You can't hear an unaltered uncolored (re: TRUE) low frequency waveform in a room shorter than the wavelength being produced ... ---------------- Not sure about the "clearly"... but that's basically what we are all saying, so everyone is in agreement . Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 6, 2005 Share Posted June 6, 2005 The article also points out something many already know. That the Klipsch horn loaded speakers sound fantastic outside. I love bringing my corns and/or Las outdoors whenever I get the chance. They sound way better when you get 30 to 50 yards away, and especially at night. In fact, better than in any room I ever had them in. Quote Link to comment Share on other sites More sharing options...
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