otto88 said:
Suns don't have a "transient response" per see. They have one, of course, but being LF limited its always very slow to rise and rings out a long time. All subs will do this. And again, you have to consider ALL of this in context of room modes. The modes ring out far longer than any sub. So in the end if the total room response is smooth the net result will be a smooth "impulse response". Its a big mistake to consider any LF source out of the context of the room that its in, which has to also include all the other sources. At LFs, the room and all of the sources become one system with the sources being dominated by the room.
Dr Geddes,
Very interesting thread, as always!
Perdone me my english is poor so I am not confortable to read tons of
AES papers so maybe I am sure missed something.
If I have well understood, Welti's approch "solve"95% of problem below 80Hz.
But what about the (even) more important 100/300Hz range?
What is your "medicine" for it ?
Cheers,
Paolo
Very interesting thread, as always!
Perdone me my english is poor so I am not confortable to read tons of
AES papers so maybe I am sure missed something.
If I have well understood, Welti's approch "solve"95% of problem below 80Hz.
But what about the (even) more important 100/300Hz range?
What is your "medicine" for it ?
Cheers,
Paolo
It's also necessary to consider the type of music being produced. I do agree the there is very little percussion type instruments that have very low frequency content. Nor do many people have listened to these type of instruments live. However, if one wants to reproduce these kinds of instruments in a more accurate manner, the initial impact and the following timbre should be alligned as closly as possible. If not, then the sound image will shift. Normally when room modes or other form of resonance take effects, you will feel the sound source changing from the front to no aparent image source.gedlee said:
Send me a soundfile and I'll show you that your idea of low frequency perception is completely wrong.
The drum in your example shows a transient part when the stick hits the drumhead. The frequency of that sound is nowhere near the low frequency range. That makes the drum localizable. The low frequency part of the drum sound takes some time to build up after the first hit.
Best, Markus
The drum in your example shows a transient part when the stick hits the drumhead. The frequency of that sound is nowhere near the low frequency range. That makes the drum localizable. The low frequency part of the drum sound takes some time to build up after the first hit.
Best, Markus
inertial said:
I have found the room modes get bunched up pretty well towards the higher end of that 100-300Hz band. Rooms usually shift from being modal to reverberent in this range.
There is one exception: Floor bounce. Tower speakers or speakers on stands often have a notch in the lower midrange causesd by self-interference from floor bounce. It's usually around 100Hz to 200Hz, depending on speaker height. And it isn't usually mitigated by carpeting, as some might think. Sound absorbtion isn't good at that frequency because the carpet and pad aren't nearly thick enough, not even close.
This can be solved with the same sort of approach that the multisub approach uses. In fact, you'll never see floor bounce from a line array for that very reason. You can also smooth the notch when blending a woofer with a midrange, if the midrange is crossed over low enough. They're stacked vertically on the baffle, so their vertical offset smoothes the notch by "filling it in". Likewise, a "sub" that's placed fairly close and crossed over high enough will do it, provided they are positioned with vertical offset.
If you're running two-way speakers and have them on stands, try placing two subs on the floor, near the mains. Low-pass them a little higher than you might normally, so they blend in the range where floor bounce is. Then you might put one or two other subs further away to smooth modes at lower frequency.
The problem is floor bounce usually occurs at frequencies where wavelength is somewhere between 5 feet and 10 feet, which is why the self-interference problem happens when the speaker is raised off the floor a couple feet. It's a 1/2 wave cancellation notch. So the radiator has to be spread out over a couple feet in the vertical dimension, and even the largest direct radiators are a little small for that. Better to have a couple of them offset in the vertical.
First of all, I don't think it's legal to just copy files like that.markus76 said:
Second, the point is exactly that the impact makes the drum localizable, however, the following waves are also localizable in live situation. But when room modes are excited, the the following drum rumble cannot be localized. This is a listening experience totally dependent on preference. How can you use data to prove what another person hears or cannot hear?
Hi Wayne,
I understand your point but agreed only partial.
If you are familiar with room's simulators ( yes you have said this previously) you sure know that floor is not the only issue.
There are six walls, you can virtually add one at time and see the difference in your listening position. A caos!
When you have added all the six walls, the influence of the only floor
is not so rilevant .
I am referring at european rooms, not very large, very solid walls and
listen triangle about 2 metres.
In this scenario, i always see peaks and dips in the midbass zone and basic measurement semms comfirmate this. Problems in the 80-300Hz zone. ( of course there are big problem also below 80 Hz)
It is easy listenable with normally a lack of punch, no body, no weight , very bad sound .
This is a very typicall performance in our "small" european rooms ( to say 20-25 square meters), not sure how much different can be in yours americans rooms .
I know simulators makes big simplifications respect real conditions, but something is interesting to my eyes .
So the question remain IMHO, who takes care of the 80-300Hz?
Cheers,
Paolo
I understand your point but agreed only partial.
If you are familiar with room's simulators ( yes you have said this previously) you sure know that floor is not the only issue.
There are six walls, you can virtually add one at time and see the difference in your listening position. A caos!
When you have added all the six walls, the influence of the only floor
is not so rilevant .
I am referring at european rooms, not very large, very solid walls and
listen triangle about 2 metres.
In this scenario, i always see peaks and dips in the midbass zone and basic measurement semms comfirmate this. Problems in the 80-300Hz zone. ( of course there are big problem also below 80 Hz)
It is easy listenable with normally a lack of punch, no body, no weight , very bad sound .
This is a very typicall performance in our "small" european rooms ( to say 20-25 square meters), not sure how much different can be in yours americans rooms .
I know simulators makes big simplifications respect real conditions, but something is interesting to my eyes .
So the question remain IMHO, who takes care of the 80-300Hz?
Cheers,
Paolo
soongsc said:
Now I know where your misunderstanding comes from. A loudspeaker is not an instrument! It can't recreate the original soundfield at your ears. If you want that, then look for dummy head recordings or wave field synthesis. A speaker for stereo or multichannel sound reproduction in a home listening room just needs to reproduce the original, which is NOT the original venue but what was heard in the control room where the recording was created.
Best, Markus
Wayne Parham said:
Oh certainly, for the primary notch that's true. Perhaps I should have been more clear: "Floor BOUNCES". While it's most apparent at one frequency, there are effects at multiples thereof. So if your primary bounce is at 150Hz, then at 300Hz, 450Hz on could expect an issue as well, and here, a half wavelenth can fall within the variance of size between a 15" and a 6.5".
Oh, and while the vertical dimension spread is valuable to combat floor bounce when the subs are close to the speakers, in the multisub setups we're discussing it's going to be spread via the lateral/depth variations fairly effectively.
One interesting technique I've played with is a "bed" of acoustic foam under a speaker, cutting out some of the "down and forward" energy that contributes to floor bounce. Obviously this is only effective when thick, but can really help clean up the mids, when done appropriately. It also typically looks quite horrible.