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Old 26th September 2005, 11:53   #61
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Navin

I can integrate a 15" Subwoofer in a sealed box can play down to 14Hz...with the front components. You will feel as if the bass is coming from front speakers and there is no subwoofer in the car. As i have mentioned earlier its all about the driver and enclosure quality.

In low bass drivers and enclosures reducing the size helps in integration as you have mentioned.

Lot of people dun care for the integration. They think they have bought a subwoofer they should hear it.
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Old 26th September 2005, 13:09   #62
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a 15" would have a Vb that is too big. My perogative was a sub that left room for my son's bike.
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Old 26th September 2005, 13:10   #63
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Given the Vb I had the 12" subs I tried did not work. Given a big enough box any good sub can be integrated.
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Old 26th September 2005, 13:19   #64
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We have subs that can play in box as small as 0.5 cuft (the driver barely sits inside) and they disappear completely. You cannot install a subwoofer in a smaller enclosure than that...and that will leave more than enough room for your son's bike :-).
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Old 26th September 2005, 13:22   #65
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A 12" in 0.5 cu. ft? Wow! this I gotta hear. I would use 2.
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Old 26th September 2005, 14:39   #66
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Quote:
Originally Posted by navin
A 12" in 0.5 cu. ft? Wow! this I gotta hear. I would use 2.
Check out the Hi-Energy series HX300D from the Hertz website. Go to the Technical section for downloading the technical pdf. Very nice Subs...
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Old 26th September 2005, 16:41   #67
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yup but the Fs is high and hence the f3 isn 15 liters is 55Hz. while sealed boxes do roll off slowly 55Hz is quite high given that I am XOing my subs at 80Hz. I would love to hear them before I let paper specs influence me.

any chance of seeing them in Mumbai. Pleeease. :-)

BTW 1 part of me wanted to see them perform better (the part that is always seeking better products)

1 part of me wondered if a 12" woofer could really produce deep bass (-3b sub 40Hz) in 10-15 liters. thank god you guys are still within the boundaries of acoustical physics as i know them. I am not outdated yet.

Last edited by navin : 26th September 2005 at 16:45.
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Old 26th September 2005, 19:24   #68
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Quote:
Originally Posted by navin
any chance of seeing them in Mumbai. Pleeease. :-)
Navinji, what is the power available in your car for the sub... or better, which amp are you using. And I assume this is in an Octavia
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Old 26th September 2005, 21:17   #69
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Navin you are right...but see that the driver is very sensitive at 97dB. And if you run the sub at 600 Watts RMS (the rated power) the rolloff will be taken care of and the sub will play louder at lower frequencies.

Even the Image Dynamics IDQ range needs very small box IDQ 12 can play easily in 0.55cuft volume (20Hz -3dB in car, 50Hz Free Space)

the other recommended enclosures for IDQ 12 are :
0.85cuft volume (16Hz -3dB in car, 43Hz Free Space)
1.00cuft volume (14Hz -3dB in car, 40Hz Free Space)

These subwoofers are like "Turbochargers" extract more bass from small box
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Old 27th September 2005, 10:51   #70
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I am using my own home made amp for the subs. My subs are 8" tubes (2 of them) run stereo and tucked into either side of the trunk. this way I have a large part still available for baggage.

the amp delivers 40-45W rms, 0.01%, 20-20k, 4 ohms/1mh load. I use a reactive load to test my amps as vey few speakers are purely resistive. It was made in 1986 or 87 using Hitachi MOS FETs. Now imy brain cant remember much of the details from so far back but it does good work with subs. I assume (from it's power supply ratings that it would deliver about 80-100W rms into 4 ohms if 2 channels are bridged). Ihave not tested the amp into 2 ohms bridged (your sub's 2 coils in parallel is 2 ohms).

Lets see 97db @ 600W = 152db! GEEZ I dont want anything near that! I dont exceed 95db in my car. Usually closer to 85db average.

Also at 40Hz (I expect the sub to cover 40-80Hz atleast) 600W rms (maybe even 60W) may run it out of Xmax. Not that I intend running it that loud anyway.

I dont have the pdf of the sub in front of me but I think the Xmax was 10mm so that means Xmech would be about 20mm.

1. what do these subs cost?
2. The sub has a displacement of about 2.5-3 liters so in my 15 liter box it will really get only about 12 liters. I dont think I can afford much bigger than a 15 liter box.

now you are getting me excitred. me think....

i could build box that looks like tube out of 3mm SS or treated MS. damp box with 1.5mm lead sheet on the inside. cover box with resin bonded fiberglass rovings and pluther (syntetic leather).

let me see how big a box i can dig up and then we'll take it from there. this might take time.
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Old 27th September 2005, 11:33   #71
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The sub will not run out of its mechanical limits at 60 watts, when installed in enclosure and it will take the RMS power. Though in free air without any baffle it can happen that too only on a test tone of a particular frequency.
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Old 27th September 2005, 16:15   #72
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what i meant to say...."The amount of acoustic output is limited by the amount the driver can travel (Xmax). Equation (O3) shows acoustic output () with respect to displacement (X)." from this link http://www.arcavia.com/kyle/Equations/Closed.html

also see....
http://www.bcae1.com/speaker.htm
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Old 28th September 2005, 10:49   #73
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You are right...amount of acoustic output is dependent on travel of cone as well as size of the cone.

The drivers need less power in IB than ported and sealed box for reaching a specific acoustic output. Needs maximum power in sealed boxes.

As the enclosure gets smaller the demand of power by the driver increases.
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Old 28th September 2005, 11:04   #74
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You mean to say that the sub will take 600W rms in a 0.5 cu. ft. box and not run out of excursion? the 80Hz crossover would be before the amp so the whole 600W of the amp would be in the sub and it would be uproducing only freq. below 80Hz.

lets 1st consider thermal / electrical capability.
I've seen a few big subs but they were big is size too (30" in fact) that would take 110V (8 ohms) at 50hz but a 12" that can take 600W (2 ohms)?

110V at 8 ohms = 1500W = 13.75A! at 50Hz. It was made by Altec.
600W at 2 ohms = 17.32A! 8.6A per coil! that is a huge ammount of current assuming the amp can deliver this.

Now this is the electrical/thermal load. Xmax limits should be reached well before this.
Xmax calculations are a bit more complex and require a spreadsheet. but 10mm Xmax is not huge so my guess is that the sub will not handle 100W or 60W at 30Hz or 40hz even in a small box without complaining (Xmax limits reached).

Last edited by navin : 28th September 2005 at 11:09.
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Old 28th September 2005, 11:12   #75
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We are running ID IDQ12 in 0.8 Cuft Sealed enclosure with 400 Watts RMS Tru Tech Amplifier. At 0dB on Clarion Headunit the sub is getting 400 Watts. And there are no signs of strains on the subwoofer.

The crossover is 3rd order 80Hz. If we mount this sub in IB it will never be able to take 400 Watts.

The amps can deliver that much of power. The sub rated at 600 Watts RMS installed in 0.5 cuft enclosure, absolutely sealed (you cannot push the cone in) will take that power. Because of tremendous pressure of trapped air from behind.
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