Ridiculously "stiff" sub !! what is the point? - Page 2 - diyAudio
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Old 9th September 2007, 02:50 AM   #11
anatech is offline anatech  Canada
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Hi Mikey p,
For a car, most boxes are too small with an 8" woofer in them. A sealed enclosure then becomes a good alternative if you are after sound quality. If you want a high order box to win SPL events, then I am way out of my element.

-Chris
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Old 9th September 2007, 02:51 AM   #12
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Perhaps these were actually part of a large lot of transducers specifically designed to turn ocean tidal energy into electric power and got shipped by accident to a car stereo shop? That could account for the 1/4 inch thick rubber surround.

or...

Maybe this is the device the man stands on when he is about to be launched out of a circus cannon. Again, a shipping error.
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Old 9th September 2007, 03:02 AM   #13
JinMTVT is offline JinMTVT  Canada
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ahhaha you guys are funny

Seriously, i am pumping an estimate of 1500W in 1 of those stupid driver, and i can even get past 60-70db of output for anything under 60-70hz

that has to be ridiculously low efficiency here

Still didn't get 1 reason why those things should exist at all....

i'll try and get some time to remove one of the driver out of the shitty box later on just to see what it is supposed to be
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Old 9th September 2007, 03:21 AM   #14
anatech is offline anatech  Canada
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Hi JinMTVT,
Quote:
Still didn't get 1 reason why those things should exist at all....
Simple. It's a parent's dream (more the neighbours maybe).

This driver will absorb all this power and give low sound output, although it may have great "snap". All that juice and no one stays awake.

It is entirely possible that it's a messed up recone or experiment. Could be rejects from off shore manufacturing. Does it really matter, they will be hard to sell unless you make it clear there are no refunds.

-Chris
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Old 9th September 2007, 03:34 AM   #15
OzMikeH is offline OzMikeH  Australia
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Do your have a really big variac?
They're obviously junk so why not see how much power they can actually handle at 50 or 60Hz.
In short bursts of course. Don't just burn them out. See if they can get any decent excursion across mains voltage.

Be careful

Any pictures?
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Old 9th September 2007, 03:34 AM   #16
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Quote:
Originally posted by anatech
Hi JinMTVT,
Does it really matter, they will be hard to sell unless you make it clear there are no refunds.

-Chris

Yes it appears those drivers will be hard to move.

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Old 9th September 2007, 03:39 AM   #17
JinMTVT is offline JinMTVT  Canada
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Bah i'll probably try and convince some punks around here that they require "THE" amplifier to actually make sound ..

lol ...what would be needed to send some direct 120v from the wall through them ?
transfo ? i don't have a variac
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Old 9th September 2007, 04:03 AM   #18
OzMikeH is offline OzMikeH  Australia
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120V into 8 ohms = 15 amps = 1.8 kilowatts
120V into 4 ohms = 30 amps = 3.6 kilowatts.

A 15 amp, 60 volt transformer would me more appropriate. Perhaps a large welder wound up to maximum?

Very dangerous! I was joking.
I doubt you'll have a 15 amp outlet, let alone a 15 amp isolation transformer. Look at the size of the wires in a 15 amp mains extension cord - is the voice coil that big? what about the wires from the terminals to the voice coil?

think of the element in an electric oven, now shrink that element into something the size of the voice coil with the same heat output.

The sub would take about 2 seconds to catch fire, then you have 120V on the chassis. Death!

Similar care should be taken with the outputs on your big amplifier. Music can kill with enough power.

Perhaps the rubber surround was more compliant but it was treated with some inappropriate polish.

Edit: with a 100% efficient amplifier (impossible) 1 kilowatt requires 72 amps at 13.8 volts. In the real world we're talking at least 120 Amps per kilowatt of amplifier.
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Old 9th September 2007, 04:34 AM   #19
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Quote:
Originally posted by theAnonymous1
Volfenhagen
12" Dual Voice Coil Car Sub Model: ZX-4712

Manufacturer's Specs (Based on 1 Voice Coil):
Fs = 30 Hz
Vas = 56L
Qes = 0.614
Qts = 0.526

TS measured with LMS (Free Air & Delta Mass-120g)
(Based on 1 Voice Coil)
Fs = 44.3 Hz
Vas = 31.4L
Qes = 3.79
Qts = 2.56

Absolutely ridiculous. Never encountered anything so stiff before. Judging from the thick rubber surround, seriously doubt it can be broken in. Tried emailing but unable to get through Faxing them on Monday regarding discrepancy.
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Old 9th September 2007, 05:08 AM   #20
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car woofers are used by kids that havent got a clue what they are doing or how things work. 9 time out of 10 they are mounted to a board and the back fires into the trunk. The only cabinet they see is the cabin and the trunk.

In these days of 5000+++ watt class D car subwoofer amps traditional woofers dont last long. Kids are into max volume, and who cares about distortion. half the time they crank it up well well WELL into distortion anyway. These ar enot audiophiles here guys.

Car stereo compititions are well into the 170+ db range. i think the record is over 180 actually.

Even most 1000 watt rated pro audio subwoofers wont handle anywhere near 1000 watts down around 20-30hz. maybe a couple of hundred at best.

SO, a super stiff suspension makes sense when there is no back box and it will be seeing 5,000watts plus clipping. and they will.
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