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badboy6120 17th April 2011 07:48 AM

Subwoofer problem
 
Hi everyone
I have a problem with my sub woofer's voice ( kenwood 3012 )
Kenwood - KFC-W3012
in every position of my room I get different bass ( thump )
I want to have a equal bass in every position of my room
I have a cylinder box with below parameters:
Diameter : 30 cm
Height :50 cm

Arty 17th April 2011 09:12 AM

the cylinder box works more or less in a car trunk.
in a room its usualy useless.

You would have to mesure the T/S parameters -or at least obtain some elses mesurements- in order to first make a proper box for it.

Then comes a suitable amplifier, and then the room treatment.
Every room has its own resonances, different characteristics for every room depending on size, furniture, wall /celing/floor materia.
What You can do is place some bass-traps, you can search for those.

So You should start to work a bit on the sub unit first.
Allso, do notice this si not realy a subwoofer driver.
Drivers made as CAR subs are generaly accounting the car's own "room gain", so they are usualy not behaving well below 60 or so hz.
Depending on its parameters it may or may not be suitable at all for anything else than what its ment to be: a CAR sub.

badboy6120 17th April 2011 10:35 AM

Thank you for reply Arty
I have a mosfet amplifier(driver of my sub) with these characteristics:

POWER RATING at 1KHZ with 0.1* THD = 200W/ 8 ohm, 260W /4 ohm
IMD= *0.008*
THD at 200W into 8 ohm *1 KHZ= *0.005*
THD at 200W into 8 ohm *20 HZ....20 KHZ= *0.05*
FREQUENCE RESPONSE [at 50W/8ohm, *0...-3dB]= 1.5 HZ.....125 KHZ
INPUT SENSITIVITY= 1Vrms
ΙΝPUT IMPEDANCE= 48K
SLOW RATE with input filter= 20V/uS
=SIGNAL TO NOISE RATIO [at 1W/8ohm] *99dBA
= DAMPING FACTOR at 8ohm [15HZ...25KHZ] 160

I use this sub for my PC speaker
I tested this sub and ampli in my friend's house(in the drawing room ). but I connected the ampli to my friend's LCD, and it had a wonderful voice (BTW their drawing room is very big beside my room)
I want to build another ampli like this one that I'm using, but I want to connect it to two Mini Sub into parallel.(two 8 ohms that give me a 4 ohms)
you said car's sub is not appropriate for home???? so could you please tell me what can I use for this purpose with this amp?
I use a low pass filter before my amplifier that it's frequency cutoff is 150HZ

purplepeople 17th April 2011 01:37 PM

A quick check with Kenwood shows that your cylinder is almost perfect size for the recommended sealed enclosure.

Kenwood - KFC-W3012

So... I think you have the subwoofer placed in the wrong position in your room. Try moving it to a new location.

:)ensen.

GM 17th April 2011 01:41 PM

Quote:

Originally Posted by Arty (Post 2541203)
You would have to mesure the T/S parameters -or at least obtain some elses mesurements- in order to first make a proper box for it.

Better than nothing: http://www.kenwoodusa.com/UserFiles/...s/kfcw3012.pdf

GM

GM 17th April 2011 01:59 PM

WinISD Pro alpha driver file: http://www.hometheatershack.com/foru...-kfc-w3012.wdr

GM

GM 17th April 2011 02:52 PM

Quote:

Originally Posted by badboy6120 (Post 2541167)
.........in every position of my room I get different bass ( thump )

Based on its published specs, this driver wants a relatively huge, well damped sealed cab of around 13.6 ft^3 net for HIFI and due to its low efficiency its bass output will be modest if not in a corner, especially with only ~280 W available, so some type of high pass 'rumble' filter may be required to protect the driver.

You could heavily stuff your 'one note' car audio alignment cab with lamb's wool or similar to reduce the 'thump' at the expense of a much more rolled off bass, but if you have a high ceiling and/or comfortable with building a folded up TL, then your cab could be extended to a ~105"/268 cm long line or in a somewhat smaller bulk if a new rectangular cross section line of ~ 71"^2/457 cm^2 is built.

Stuff with polyfil or other suitable material as required to get a smooth sounding in-room response down to at least the driver's Fs and a bit lower if there's enough room/boundary gain.

GM

bjorno 17th April 2011 04:40 PM

1 Attachment(s)
Quote:

Originally Posted by GM (Post 2541430)
Based on its published specs, this driver wants a relatively huge, well damped sealed cab of around 13.6 ft^3 net for HIFI and due to its low efficiency its bass output will be modest if not in a corner, especially with only ~280 W available, so some type of high pass 'rumble' filter may be required to protect the driver.

You could heavily stuff your 'one note' car audio alignment cab with lamb's wool or similar to reduce the 'thump' at the expense of a much more rolled off bass, but if you have a high ceiling and/or comfortable with building a folded up TL, then your cab could be extended to a ~105"/268 cm long line or in a somewhat smaller bulk if a new rectangular cross section line of ~ 71"^2/457 cm^2 is built.

Stuff with polyfil or other suitable material as required to get a smooth sounding in-room response down to at least the driver's Fs and a bit lower if there's enough room/boundary gain.

GM

Agree 100% , The driver + cylinder box in post #1: May IMO only sound good in a small bathroom/sauna installation.:rolleyes:

If trying to design a larger ported enclosure,when comparing with a closed box, performance-wise: diminishing returns are apparent ..See the picture.


A simple circuit to make an amplifier with negative output resistance;

http://www.diyaudio.com/forums/multi...tml#post976216

b:)

Arty 17th April 2011 05:18 PM

if You must use this woofer for indoor use..
well probably not the best solution, but here it goes--

The very large sealed damped box approach is I think WAY too big for him..
And this driver is quite not efficient at all. (usual for car woofers, low efficiency, and demanding lottsa powa..)

So, I would choose a 4th order bandpass.
80 liter on the sealed side, 50 at the ported size.
Tune it to 40 hz.

Narrow band yess, cca. 25 to 70 hz only. but at least You gain some efficiency, and the box will be a lot smaller than a sealed one suitable for the task.
This should do it fairly well, but not sure how well will it integrate with the rest of Your speakers.

A nother approach would be a small sealed box, and some electronics.
Sub-Woofer Controller
Not sure if this in efficient driver will be suitable for the task, but i might give thisone a go.

I actualy do not think there are any other setups to make this woofer work properly in a room.
But who knows, while the bandpass box is a STRONG compromise to force it to work more or less acceptible, the other approach may suit You more than You would expect it.


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