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Old 26th February 2008, 23:48   #76
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Default Hanging over the EDGE with Philips Dynamo Amp + Subwoofer 12". Please help me out

Dear Mods,
Please bear with me as i am in diverse condition as i am facing some problems with the brand new subwoofer and amp that i purchased. i am having some issues with the enclosure design and ratings of AMP and Subwoofer.
Please Merge my earlier thread from page no 4 to this thread so that i get my problem noticed by the audio gurus. the link is below. pics on page no 5.


http://www.team-bhp.com/forum/product-discussions/33816-philips-dynamo-amps-4.html

Last edited by amit_mechengg : 26th February 2008 at 23:49.
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Old 27th February 2008, 09:52   #77
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i'd seriously advice you to ditch the HU and get a mp3 player, since these cassette thinggys cause a lot of quality loss. I was using one of these things earlier, and now after changing the HU, there is a world of difference. Especially with a sub, these cassette adapters will have a muffled kind of sound.
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Old 27th February 2008, 18:20   #78
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is my enclosure the culprit? i have posted the pics. it has 2 air vents.
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Old 27th February 2008, 19:53   #79
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Quote:
Originally Posted by amit_mechengg View Post
is my enclosure the culprit? i have posted the pics. it has 2 air vents.
Basically, your sub and enclosure are not made for each other. Unfortunately, in the absence of the T-S data for the Philips sub, even Navin or LBM will not be able to design an enclosure for you.

What you should now try is an empirical method:
* Most common subs (like Pio etc.) sound decent in a single-ported box of 1-1.2 cft
* Measure your box and calculate the internal volume in cft (subtract 1.5" from each of the external dimensions, assuming 0.75" wall thickness)
* Close one of the ports tightly with waste cloth
* (Painful process) Put a few bricks into the box to reduce the internal volume and check if the performance is better. Experiment with the number of bricks till you get an acceptable performance
* Subtract the volume of the bricks from the original internal volume; this should be the volume of the box that you should use
* Ask your dealer for a box whose internal volume is closest to that figure
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Old 27th February 2008, 19:55   #80
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I agree completely. I used one of these with an old cassete HU and 500 rs wala fake pioneer speakers and still the cassette adaptor was the weakest point in the setup.


Quote:
Originally Posted by JayD View Post
i'd seriously advice you to ditch the HU and get a mp3 player, since these cassette thinggys cause a lot of quality loss. I was using one of these things earlier, and now after changing the HU, there is a world of difference. Especially with a sub, these cassette adapters will have a muffled kind of sound.

Last edited by adityamunshi : 27th February 2008 at 19:56.
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Old 27th February 2008, 20:10   #81
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Originally Posted by adityamunshi View Post
I agree completely. I used one of these with an old cassete HU and 500 rs wala fake pioneer speakers and still the cassette adaptor was the weakest point in the setup.
but the cassette adaptor is a gud one . its not the china made 350 Rs one. its Maxcon make who are manufacturer of quality adaptors, cables, tv parts and other electronic parts.
it has a Original Sony Audio head. it gives no humming or hissing sound. the quality is simply great.
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Old 27th February 2008, 20:14   #82
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Quote:
Originally Posted by DerAlte View Post
Basically, your sub and enclosure are not made for each other. Unfortunately, in the absence of the T-S data for the Philips sub, even Navin or LBM will not be able to design an enclosure for you.

What you should now try is an empirical method:
* Most common subs (like Pio etc.) sound decent in a single-ported box of 1-1.2 cft
* Measure your box and calculate the internal volume in cft (subtract 1.5" from each of the external dimensions, assuming 0.75" wall thickness)
* Close one of the ports tightly with waste cloth
* (Painful process) Put a few bricks into the box to reduce the internal volume and check if the performance is better. Experiment with the number of bricks till you get an acceptable performance
* Subtract the volume of the bricks from the original internal volume; this should be the volume of the box that you should use
* Ask your dealer for a box whose internal volume is closest to that figure
Sir i will right away go down to my mark and measure the dimensions of the box accurately. the dimensions might help u to guide me .due to lack of my knowledge i choose the bigger box which the dealer claimed is the best for my woofer. alas i ended up in shudder rather than punch of the woofer.
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Old 27th February 2008, 21:12   #83
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i measured the dimensions of the box. the length is 24" i.e 62 cms , the Width is 13" it approx 25cms and the height is 12" ie approx 21 cms.
the air ducts dia is exactly 45 cms. there are 2 such ducts. the length of the pipes in duct is approx 6".

Please gurus calculate the volume from the data above and please tell me what is to be done.
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Old 27th February 2008, 23:54   #84
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Quote:
Originally Posted by amit_mechengg View Post
i measured the dimensions of the box. the length is 24" i.e 62 cms , the Width is 13" it approx 25cms and the height is 12" ie approx 21 cms.
the air ducts dia is exactly 45 cms. there are 2 such ducts. the length of the pipes in duct is approx 6".

Please gurus calculate the volume from the data above and please tell me what is to be done.
that is 1.57 cuft, 44.5 liters.

you can close the ports and try to reduce the internal volume it will help a lot.
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Old 27th February 2008, 23:55   #85
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Quote:
Originally Posted by amit_mechengg View Post
is my enclosure the culprit? i have posted the pics. it has 2 air vents.
That is not a issue I am using two ports also. But it depends on the sub and tuning freq box volume.
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Old 28th February 2008, 00:02   #86
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Quote:
Originally Posted by low_bass_makker View Post
that is 1.57 cuft, 44.5 liters.

you can close the ports and try to reduce the internal volume it will help a lot.
do u mean i should put some solid matrials like bricks or wooden blocks etc to reduce the volume? then i have to open the component and then put in this materials.
44.5 litres? is it too big for me? mine is a 12" sub 250 RMS driven by 125 RMS amp.
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Old 28th February 2008, 00:03   #87
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Quote:
Originally Posted by low_bass_makker View Post
That is not a issue I am using two ports also. But it depends on the sub and tuning freq box volume.
]

sir i dint get the meaning of tuning freq box volume.
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Old 28th February 2008, 21:06   #88
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is 1.57 cubic feet/ 44.5 litres too big for a 12" woofer. i went to 3-4 audio installers in pune. they all were saying that the box is fine and more the size more will be the effect. i told them 10 times that for every woofer there is recommended size. but according to their practical knowledge they are saying that it is sounding ok and box is also appropriate size.
also smaller boxes with them had 2 ports.

how to test guys?
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Old 29th February 2008, 10:40   #89
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Box size depends entirely on the T/S specs not on the diameter of the woofer (although smaller woofers usually require smaller boxes). So unless we have the T/S specs it is difficult to predict the optimum box size.

Keep in mind that thanks to the transfer function of automobiles (and road noise) a slightly undersized box (with it's resultant hump in hte mid bass) is often prefered.
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Old 29th February 2008, 10:43   #90
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Quote:
Originally Posted by amit_mechengg View Post
is 1.57 cubic feet/ 44.5 litres too big for a 12" woofer. i went to 3-4 audio installers in pune. they all were saying that the box is fine and more the size more will be the effect. i told them 10 times that for every woofer there is recommended size. but according to their practical knowledge they are saying that it is sounding ok and box is also appropriate size.
also smaller boxes with them had 2 ports.

how to test guys?
Amit, they are in the business of gobar gas, hence they need / recommend large enclosures. Don't entertain a bhains with a been - the dealer wouldn't even begin to understand specs and data-sheets! For them bhhhooom-bhhhhooom is "aila, kya jhakass bajela hai", for you - NOT!!!

Ignore all that, take LBM's advice. Either try the brick-filling method (no additional cost) or get a new smaller box (if it has 2 ports, close one).
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