PeterSt
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« Reply #4 on: September 26, 2013, 10:08:35 am » |
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The smaller the room, the better it works. Think of this :
First of all disregard standing waves. They will technically be there, but not noticeable. All you may notice is a small dip at the "room length". So not even peaks, but a dip yes. For example, when your room is 7 meters long, there will be a dip at 344 (assumed speed of sound) / 7 = 49Hz. The story is much longer because each frequency will imply such anomalies, but the frequency which just fits in the room length is the most profound. Will you perceive this dip ? I can't tell. Mine is at 29Hz for 12 meters but not much music plays there. But also : open an opposite door when possible, and the dip goes away (room gets longer). Notice that this is also pressure related.
Next, it should be obvious that the larger the room, the more difficult it will be to let all behave as well. So, now I am talking about the frequencies up to a rather crazy high range which you will still perceive as individual "vibes". And what I discovered : when you feel the woofer's vibes, you will hear them just the same. That good it is. (imagine that you can't feel 250Hz as "vibrating" anymore (goes too fast) so at that stage you won't hear it anymore either as single up-downs) Remark : Yes, I am by now talking about the *higher* frequencies still perceived as vibrating; that is in the end way more difficult than the lower ones. It, for example, creates the flagiolette like sounds a cello can play.
What I try to say is that at the same SPL (Sound Pressure Level) in the listening seat, the larger room is way more difficult to keep all "tight" than the smaller room. This is because in the larger room all more spreads (you might compare headphones for the super-small room ?).
But compare Bert's room and with the speaker positioning he applies these days (a bit not the best hence most easy if you ask me, but alas, this story is just about that) : So, speakers are maybe 4 meters from the listening position (behind that a wall) and with fairly rough "tuning" all works very well. Notice that in -dBFS terms Bert won't play as loud as I do, but this is because his room is (m3) so much smaller. Same SPL is reached sooner in the smaller room than in the larger. Now :
With the rough tuning and all working in the smaller room, the larger room needs far more precise tuning. This seems a bit (up to a lot) of blahblah, but in the end it comes down to the standing waves principle again. All this principle (mind you, of mine - this is not general knowledge) is only about more preciseness. In this case this is literally about less bumps and dips in the frequency response, which is a mixture of an evenly tuned bass section compared to the mid, and (which leads to) a better crossover; A bit technical, but when the XOver ain't 100%, in the XOver area the bumps and dips emerge (this area spreads from 124Hz to 570HZ in this case).
All this unevenness is not so much of a problem close by (not that you won't perceive this as anomalies within itselve !) but the point is : they spread. and the further they spread the more "wide" they get and the more difficult it will be so perceive all in "tight" fashion. Besides this, the more widely spread "anomaly" will reflect on walls, and assumed the reflections are audible, they again more wide reach your ears (this really can be compared with ringing which implies a smiliar frequency domain problem, never mind it is in the time domain). In the small room, where the SPL level is such that reflections won't bounce extra-loud, it is the only (?) difference that the anomaly isn't as wide at bouncing at the wall, as it is not as wide for the direct beam (as talked through above). Again, I think you can compare with headphones.
Loooong story short : Once you get this working for the large(r) room, and I most certainly did, for the smaller room it will only work for the way better. However, when all is right there won't be a difference for the larger and the smaller room. Both should work equally well (now).
Regards, Peter
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