sub-woofer encloser size problem

[swavvv]

I am created a subwoofer box for 6" 60Watt 8ohm subwoofer, I have subwoofer filter, amplifier. box is shown below diagram, box material is MDF plywood, but cant give real bass effect.

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subwoofer at a bottom & port tube( air hole) at top vertical side

 

[pradeep.g.belchada]

are you given bass reflex port? and waht is the audio o/p rms value of your amp? and which audio ic you used

 

[betwixt]

How thick is the MDF? To work effectively you either have to make the box extremely rigid (maybe 0.5" MDF) or use a reflex port to take advantage of the presure inside the box. Note that if the box is rigid and airtight you would be using half the audio power to compress and expand the air trapped inside it so the efficiency will be very low.

Brian.

 

[swavvv]

i am using 4mm mdf thik which is used commonly used for home theater, and amplifier i am using TDA7265 bridge, which gives 8ohm 50W output

 

[betwixt]

4mm is too thin. MDF is relatively flexible so what you are seeing is the whole box expanding (ballooning) as the pressure inside it changes. The pressure waves from the box itself are aimed in all directions so some will be lost into the surroundings and some will cancel the forward pressure wave you really need. As the box is already built, you could try glueing reinforcement panels to the inside walls and maybe a bracer bar across the sides.

Brian.

 

[swavvv]

ok thanks, but dimensions are ok which i am used?

 

[pradeep.g.belchada]

for 6inch woofer this dimension is very less, increase the width & depth with 10inch width 14inch depth

 

[swavvv]

can you give me a perfect size like home theater subwoofer box?

 

[pradeep.g.belchada]

to get a perfect o/p use the below dimension 14inch hight, 16inch depth, 11inch width, use 1/2inch mdf board
give a bass port of 4inch dia use low pass filter in amp
speaker magnet should be of large size

 

[swavvv]

ok thanks i will check it

 

[swavvv]

sub-woofer enclosure

I have Sub-woofer enclosure, but cant give good performance. enclosure details as follows:

enclosure size: width =8", depth: 8", height:12", MDF size: 8mm

Amplifier : TDA7265 bridge 50W

Port tube : depth 4", diameter 4.4cm

Subwoofer : 6 1/2 " 60W

https://obrazki.elektroda.pl/4969826100_1390114371.jpg
https://obrazki.elektroda.pl/2431739100_1390114375.jpg
https://obrazki.elektroda.pl/3410931200_1390114378.jpg
https://obrazki.elektroda.pl/6123698400_1390114381.jpg
https://obrazki.elektroda.pl/7019984100_1390114384.jpg

 

[betwixt]

I'm no expert in acoustics but my 'gut feeling' is that isn't going to work very well. The bass notes are being squeezed through a gap that may be smaller than the cone movement, hence restricting air flow and it will be more or less omni-directional. You would do better to mount the speaker facing forward and mount an LPF at the bottom. I assume the PCBs are for some kind of display and are not the amplifier itself.

Brian.

 

[chuckey]

As an experiment , remove the base plate and listen to the sound while the box is on its side. I have only ever seen one loudspeaker which did not have a forward facing bass cone, this was an old design (1960s), where the load speaker was in a concrete sewer pipe which stood on end, it had a conical device on top of it to deflect the treble around sideways.
Frank

 

[swavvv]

can you suggest me for 6 1/2" 60W sub-woofer which type enclosure is ok for better performance?

 

[Audioguru]

A little 6" speaker is not used for a sub-woofer. It is a woofer that will play down to about 60Hz. A sub-woofer must play down to about 25Hz.
A sub-woofer uses a larger speaker, 8" is even too small, in a much larger enclosure. The resonance frequency of the speaker must be very low and the enclosure and port should be tuned a little higher than the resonant frequency of the speaker.
Your little box and port are tuned to about 55Hz.

I agree that 4mm MDF is thick paper. Use 3/4" (19mm) material.

 

[swavvv]

i m using this sub-woofer **broken link removed**
also i am using low-pass filter for this, any idea about which size enclosure is ok?

 

[Audioguru]

Your 6.5" woofer resonates at 52Hz so it is NOT a sub-woofer. A sub-woofer resonates at 20Hz to 30Hz.
Its sensitivity is the lowest I have ever seen maybe because its magnet is fairly small. It has a peak at 200Hz in its response so it will sound boomy like a bongo drum. The datasheet for almost every speaker ever made has recommended enclosure sizes but not for the one you found.

Here is a fairly inexpensive 10" Chinese sub-woofer. It resonates at 32Hz and is fairly sensitive. The frequency response is shown in an infinite baffle but its low frequencies will be -3dB at 28Hz with the vented enclosure that is listed.

 

[swavvv]

i am building a home theater, i am observing many home theater which used 5" 1/2 to 10" Sub-woofer. so how i will use 6 1/2" sub-woofer and what is its sizes?

 

[Audioguru]

A little 6.5" speaker cannot be a sub-woofer. Maybe it can be used in a home theater for people who do not know what A REAL sub-woofer sounds and feels like.
Look in Google for Bose Bashing. Bose home theaters use little woofers that they call Sub-Woofers. Boom-boom.

35 years ago I built a sound system for the beach when other people took a boom-box. My woofer had a 4" speaker with a low resonance frequency, a huge magnet and a real rubber surround. Its enclosure was vented and was about 1.5 litres in size. The enclosure and vent resonated at about 50Hz. I added bass boost. Its amplifier produced 6W.
The satellite speakers each had a 3" speaker and their amplifier produced 1.5W per channel.
My sound system sounded fantastic when compared to the crappy sound from the boom boxes.

When I worked for a Pro-Sound manufacturer I bought an 18" very powerful sub-woofer speaker. It is so heavy that I can hardly lift it. I'll sell it to ya.

 

[ALERTLINKS]

https://www.diyaudioandvideo.com/Tutorial/SpeakerBox/

Air-hole is not good. Your dimensions can work. insert a duct of 2 inch diameter and 4.25 inch length. Place the speaker in a corner or experiment to put it where it sounds good in your listening area.
To compute it.
https://www.diyaudioandvideo.com/Calculator/Box/