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subwoofer placement (1 Viewer)

Brian_cyberbri

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What is this 50%, 75%?
So at the main listening position if it's 100dB, it will be 50dB 1ft further from that, and 25dB a few feet further?

Where are you getting your "physics"?

And how do you apply your so-called "physics" to corner placement where a sub can be 8-15' away?



I suggest you at least TRY a subwoofer, not even the MBM, nearfield behind your couch before you make assumptions. Dr. Hsu has always been an advocate of nearfield placement. I assume he knows what he's talking about. Mid-bass impact is greater at nearfield as well, whether it be to the side or behind the listening position. Which is the concept behind the MBM.

And I myself have tried a subwoofer behind the couch with great results (aside from integration with the mains, which was due to bad speakers and a fixed 100hz crossover at the time - I have since upgraded all of my equipment). The SPL wasn't any different across the three seats as it is when the sub is put in the corner.

With the sub in the corner, I have measured the response in the three seating positions on my couch. Bass traps help keep it more uniform, but there is still a big difference moving to either side of the center position.
 

Arthur S

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Hi John

You don't have to defy the laws of physics to achieve 120db+ at the listening position when you have a 12 inch light weight purpose built driver in the MBM in a pretty good sized cabinet with a 350 watt BASH amp. I would add the MBM to my pair of HSU VTF-3HOs + Turbos if my living situation allowed for it.
 

JohnRice

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Brian, sorry if this comes off as glib, but that very question demonstrates a complete ignorance of what is being discussed. Decibel measurements are logarithmic. 50% of 100 dB is not 50 dB. It is 97 dB. Learn some fundamentals before contesting scientific fact. Even if you take into consideration theoretical "perceived" sound pressure, half of 100 dB is sometimes considered to be "perceived" as 90 dB. Sound pressure is halved when distance is increased by the square root of 2. These are physical, scientific absolutes.

Nearfield placement means sitting close to the sound source. If that primary position is 2.5 ft from the sound source, that means moving only 1 foot further away (2.5 x 1.4 = 3.5) is a reduction in sound pressure of 50% (or 3dB). Moving to 5 ft away is a reduction to 25% of the primary position, or a reduction of 6dB. This has nothing to do with absolute output, has nothing to do with the maximum capabilities of the sub, it has to do with the balance between the other speakers and the sub constantly changing, radically, with a small change in listening position, since the other speakers are not nearfield.

Now, if the same sub is 15 feet from the prime listening position, but only 12 feet from a more peripheral position, the difference in sound pressure from the sub between those positions is small. Only about 1dB. Yes, the sub has to output higher levels to reach a given pressure at the main position. Yes, there is more to deal with regarding standing waves. Yes, I have freaking typed those facts over and over. I am trying to spell out all the factors to consider. I am not attempting to ignore those which don't fit my idealized view of the cold, hard physics of sound reproduction.

Now, nearfield positioning could be a great way to go with multiple subs, or with someone who sits in one place and never moves, or someone who is only concerned with maximum bass reproduction and completely unconcerned with how the bass blends with the other channels. I have no idea why Dr. Hsu advocates this approach, but considering the severely incomplete arguments being made in its favor, I suspect there are critical factors he is pointing out which are being ignored.

Furthermore, I have tried so many subs in so many different placements, I can't even begin to enumerate them. I have discussed it with many people more experienced than either of us. I have even spoken to Dr. Hsu personally on the phone back when he was just starting the company, before he changed the name from Definitive Research. I don't know how many different placements I have been every bit as sure of as you are now, only after decades of experimenting, to conclude that with one sub, front, corner loaded is typically the best situation, ALL factors considered.

My apologies to the OP. This has gone far off topic. I probably have said all I have to say. I still think setting up cables to positions 2 & 3 is the best choice, if only foor flexibility.
 

Brian_cyberbri

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I know 6~10dB means half/double the perceived loudness. And you have to double the # of drivers, or watts, to get 3 additional dB. Yes.

But why say "output will drop 50~75%" when you meant "(perceived) SPL"? The output is still the same, but the SPL at the listening position changes.

Let's just leave it as you disagreeing with Hsu. ;)
I still say, as I did in the previous post, you should try the MBM in the application it was designed for before totally discounting it.
 

familyguy

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thanks for all the advice. i bought one 25 foot subwoofer cable and i plan to use it for spot #2. its gonna be a while until i buy the sub but i plan on installing the cable soon. thanks again
 

Arthur S

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I completely agree with Brian cyberbri...and with all due respect to John Rice...how many subwoofers has Dr. Hsu designed?...how many patents do you suppose he has?...how many pending patents do you suppose he has?...and again...with all due respect...how many subwoofers have you designed and patented? No hostility or aggression intended. Thank you for contributing to this thread.

PS I think that 120db+ from the MBM at the listening position is enough to handle moving a couple of feet from the sweet spot. The MBM is $450 plus shipping for existing HSU customers...again, no hostility or aggression directed towards anyone.
 

JohnRice

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The MBM isn't actually intended as a subwoofer, it is a Mid-Bass Module, so I don't even know why it has been brought up here.

Once again, maximum output is not the point. Maintaining balance between all speakers is. And, Dr. Hsu is not the end all and be all for information about subs. Les Paul has stacks of patents on music instruments, but that doesn't mean he is the greatest at actually using them.
 

Arthur S

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Hi John

The MBM was a huge hit at the High End Show in Las Vegas...the MBM has everything to do with subwoofers...if you really want to know how much it has to do with subwoofers...you might want to get one for less than 30 days and see what 120db+ actually sounds and feels like.
 

JohnRice

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Arthur, do you happen to know what the maximum SPL of the MBM is? I haven't been able to find it and thought you might know.
 

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