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BFD experts!! Please comment on this room response...


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#1 of 21 Abhinandan

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Posted December 29 2003 - 06:38 AM

I'm planning to buy a BFD. Comment on this curve, please! I have HSU VTF-2, which is placed in one of the corners. The SPL values are compensated. The measurements are done with the main speakers off and just the sub on. I think the dip at 45Hz qualifies as a null.
The volume on my sub is at just 1.5 level. I have enough headroom to boost the overall response after EQing.
Posted Image

The compensated SPL values are:
20-->79.5
22-->89.5
25-->87.0
28-->83.0
31.5-->82.0
36-->83.5
40-->84.5
45-->77.0
50-->89.5
56-->91.0
63-->89.5
71-->86.5
80-->86.5
89-->85.5
100-->79.0
111-->79.0

#2 of 21 Jason_Me

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Posted December 29 2003 - 07:33 AM

You could bring everything down to 80 db and have very flat response, though your sub will seem less powerful.

Where are all the Hsu proponents who always claim Hsu subs to have the flattest response? Posted Image I really hope this shows you how asinine those claims have been.
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#3 of 21 Abhinandan

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Posted December 29 2003 - 08:10 AM

Thanks Jason, for the suggestion.
---------------------------------------------------------
Where are all the Hsu proponents who always claim Hsu subs to have the flattest response?
---------------------------------------------------------
I think the peaks and dips are the result of room response. The corner placement might have boosted some frequencies. Correct me if I'm wrong!

#4 of 21 CurtisSC

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Posted December 29 2003 - 08:23 AM

Quote:
Where are all the Hsu proponents who always claim Hsu subs to have the flattest response? I really hope this shows you how asinine those claims have been.

Got to love these kind of antagonistic posts.

Like Abhinandan stated, the peaks and dips are caused by the room...not by the sub. Any room would benefit from a BFD.

That room curve actually does not look too bad to begin with. Have fun with that BFD.
curtis
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#5 of 21 Jason_Me

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Posted December 29 2003 - 08:54 AM

Quote:
the peaks and dips are caused by the room...not by the sub.


Thats my point. Unless you have a room treated to the max, you will not get flat bass without EQ. An anechoicly flat sub will actually have worse in room response then a sub with a shelved response (room gain).
Jason Mertz

#6 of 21 WayneO

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Posted December 29 2003 - 09:12 AM

Which makes a flat response a nice spec on paper...........
If the best advice is "listen for yourself", then why offer your opinion?

#7 of 21 Abhinandan

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Posted December 29 2003 - 09:29 AM

Anyone who can advise on EQing????

#8 of 21 CurtisSC

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Posted December 29 2003 - 10:14 AM

Quote:
Which makes a flat response a nice spec on paper...........

Right...just like for all speakers. But would you rather start out with a flat curve?

Quote:
Thats my point. Unless you have a room treated to the max, you will not get flat bass without EQ. An anechoicly flat sub will actually have worse in room response then a sub with a shelved response (room gain).

I understand the point your trying to make. So what if Abhi's sub had an anochoic peak at 55hz, and then his room gain added to that?

Let's not turn this into a sub brand X vs a sub brand Y.

The bottomline is would you rather start out with a sub with a flat anechoic response or not?



Abhi,

I'd aim for the peak at 55hz. Have you tried moving the sub?
curtis
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#9 of 21 Abhinandan

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Posted December 29 2003 - 10:30 AM

Quote:
I'd aim for the peak at 55hz. Have you tried moving the sub?

Thanks curtis! Unfortunately I don't have much space to move the sub around. As you suggested, I'll go for 55Hz peak. I want to shoot for a house curve. I'll try to flatten out the response and then go for the house curve. How about boosting the dips?

#10 of 21 CurtisSC

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Posted December 29 2003 - 10:40 AM

My understanding is that the proper way is to go after the peaks first, and then see what you end up with.
curtis
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#11 of 21 Wayne A. Pflughaupt

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Posted December 29 2003 - 10:45 AM

Abhinandan,

Quote:
Anyone who can advise on EQing????
There’s really no reason to do that until you get the equalizer.

Also, since you’re getting the BFD there’s no reason to experiment with different locations. That’s an exercise for folks who don’t use an equalizer. Just put it in the corner to maximize output and extension, and the EQ will take care of smoothing response.

Regards,
Wayne A. Pflughaupt

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#12 of 21 Jason_Me

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Posted December 29 2003 - 10:58 AM

Quote:
I understand the point your trying to make. So what if Abhi's sub had an anochoic peak at 55hz, and then his room gain added to that?


Who makes a sub that anechoicly peaks at 55hz? Thats unheard of.

Quote:
Let's not turn this into a sub brand X vs a sub brand Y.


Not trying to argue other brands, just tired of seeing this nonsensical argument in favor of Hsu subs.

Quote:
The bottomline is would you rather start out with a sub with a flat anechoic response or not?


Flat anechoic is an SBB4 (super boom box) alignment. If your goal is maximum output, then thats what you want.
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#13 of 21 CurtisSC

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Posted December 29 2003 - 11:19 AM

Quote:
Who makes a sub that anechoicly peaks at 55hz? Thats unheard of.


Just an example...it could be any peak. Take any peak, place it in a room, and like you stated, the room will have its effects on it. It could make the peak worse...it could make it better. I am saying I would rather start flat.

Quote:
Flat anechoic is an SBB4 (super boom box) alignment. If your goal is maximum output, then thats what you want.

Maximum out put does not mean good bass. You may want maximum output, but others may want clean and accurate bass.
curtis
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#14 of 21 Jason_Me

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Posted December 29 2003 - 12:38 PM

Quote:
Just an example...it could be any peak. Take any peak, place it in a room, and like you stated, the room will have its effects on it. It could make the peak worse...it could make it better. I am saying I would rather start flat.


Starting flat will give you a peak when you stick the sub in a room. If you want in room response to be flat, then you need a shelved response. The room gain will then fill it out, and you will have a flat curve.

Quote:
Maximum out put does not mean good bass. You may want maximum output, but others may want clean and accurate bass.


I think your confusing me with yourself. Posted Image
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#15 of 21 CurtisSC

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Posted December 29 2003 - 12:47 PM

Quote:
Starting flat will give you a peak when you stick the sub in a room. If you want in room response to be flat, then you need a shelved response. The room gain will then fill it out, and you will have a flat curve.


OK...I am a little confused at what you are trying to say. If you start with a shelved response, placing it a room will make it flat? Do you have an example of a shelved response that was made flat when placed in a room?
curtis
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#16 of 21 Jason_Me

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Posted December 29 2003 - 01:08 PM

I think the guys at Adire can explain it better then me.

Quote:
The room has a tremendous effect on the low-frequency performance of any loudspeaker system. This effect is generically referred to as room gain, although it is actually composed of two parts: boundary gainand pressure-vessel gain.

Boundary gain arises from the driver operating not in free space but in a constrained space. That is, the
driver is typically referred to as operating in 4p space free air, but ½p space in-room. Each boundary cuts the total “space” in half. Thus the floor boundary cuts the space to 2p, the side wall cuts the space to p, and the rear wall finishes reducing the space to ½p (also referred to as eighth space).

Pressure vessel gain comes from the fact that, below a certain frequency, the room no longer supports standing waves; that is, the room is too small to contain a full wavelength. Contrary to legend, this does NOT mean the room cannot “reproduce” such waves! Rather, it means that the room is completely and
uniformly pressurized by the input signal (we can’t call it a wave, since it’s not a full wave). This results in a gain in acoustic pressures in the room that grows as the frequency decreases (more gain for lower frequencies). Note that this effect is the primary reason one can get tremendous bass levels within a car; the gain starts at a very high frequency, thanks to the small size of the pressure vessel (car interior).

We model and use both of these effects when determining the typical in-room performance of a system. Our models are based upon application of accepted physical principles, as well as confirmation with empirical measurements in several different rooms. The curve we use for estimating room gain is:


As you can see, such a room and placement within the room can provide 10 dB of gain at 20 Hz. In
addition, the total gain starts well above the typical crossover point (above 300 Hz).



You'll have to check out the PDF to see the chart.

http://www.adireaudi....plications.PDF
Jason Mertz

#17 of 21 CurtisSC

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Posted December 29 2003 - 01:24 PM

Thanks Jason,

I respect Adire's opinions. Dan Wiggins is a highly respected subwoofer/speaker designer, as is Hsu. But what is in that paper does not compare different subwoofers in the same location.

The Hsu subs have been tested by various professional reviewers to have super flat response, that is not nonsense, it is simply a fact. Hsu also understands in detail how room interactions affect bass performance, more so than almost anybody. Dr. Hsu is considered one of the most knowledgable people when it comes to giving advice on how to properly place and set up a subwoofer in room.

Hopefully we can agree that bass performance not only depends on quality of design but on room characteristics, placement options, and setup.

By the way...Adire also advertises "flat anechoic response" for its subs.
curtis
Manhattan Beach, California

#18 of 21 Jason_Me

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Posted December 29 2003 - 01:38 PM

Quote:
I respect Adire's opinions.


Those aren't opinions, room gain is a proven fact.

Quote:
The Hsu subs have been tested by various professional reviewers to have super flat response, that is not nonsense, it is simply a fact.


Just curious if this was flat in room, or anechoic?

Quote:
Hopefully we can agree that bass performance not only depends on quality of design but on room characteristics, placement options, and setup.


Agreed.

Quote:
By the way...Adire also advertises "flat anechoic response" for its subs.

They have different alignments for different needs. If you read the white papers you'll see the EBS (extended bass shelf) is recommended for flat in room response.
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#19 of 21 CurtisSC

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Posted December 29 2003 - 02:35 PM

Quote:
Those aren't opinions, room gain is a proven fact.

Yes...room gain is fact...never said it wasn't. The paper does have opinions in it.

Quote:
Just curious if this was flat in room, or anechoic?


Anechoic, but more clarification would be needed from the likes of Aczel, Nousaine, Ferstler, Deutsch, Hardesty, etc who all test FR in a different manner and who all noted the very flat/extended response of the Hsu subwoofers.

Quote:
They have different alignments for different needs. If you read the white papers you'll see the EBS (extended bass shelf) is recommended for flat in room response.


OK...that is fair. What is the Rava?...which seems to be Adire's top seller
curtis
Manhattan Beach, California

#20 of 21 Zack_R

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Posted December 29 2003 - 04:07 PM

I reccomend you re-measure with your main speakers on. This will more accurately represent the type of eq adjsutment you will need.


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