My Hoe shakin window(s) 149+db daily driver sealed up

Two Digital Design 9518s, with composite cones, carbon fiber dustcaps, and 9900 series flatwound coils powered by a Digital Designs Z2lv amplifier wired at 1.5 nominal / 3 ohms with impedance rise, in a PWK designs box.
Mids and highs are Digital Design components powered of coarse by two Digital Design C4A (4 channel amps)
Alpine CDA-105 headunit with XM, Bluetooth, and flash drive to prevent skipping music.
270+ amp Mechman Alternator (externally regulated) charging 2 PowerMaster D3100 batteries, and 1 Northstar NSB 90 battery. Stock battery under the hood :(
Second Skin Damplifier Pro sound deadener on the ceiling, and Hushmat on all doors.
All old school Stinger King Series RCA cords.
Misc power/speaker wire from DB Link, Stinger, KnuKonceptz, and American Bass.

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Autos & Vehicles

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• z2lv
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• Hushmat
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[philip21786]

Why don't you put some dynamat on the rear doors so they quit shaking?

[audiofanaticz]

@philip21786

LOL

Theres a good 8 cans of greatstuff inside the doors,

On top of a good 6 layers of Hushmat black foil sound deadener, and another 4 layers on the backside of the interior panel.. not much else that can be done, unless I weld them shut :(

[audiofanaticz]

@doza146

Amplifiers are generally tested in a controlled environment usually using a impedance load that never encounters impedance rise.

On top of that some manufactures test test their amps using this dummy load with no impedance rise using a 100hz test tone, which is something no one even plays close to that freq in their car, or competitions for burps since most competitions have a 80hz max or you get dq'ed.

[audiofanaticz]

@doza146

There is impedance rise anytime your subwoofers are being played.

Burps or music, impedance rise is there, and changes from 1 frequency to another.

Subwoofers impednace is a varible and anytime the woofers move, the ohms displayed on a DMM change, even just by pushing on the cone.

So it is very safe to say that if your amp is wired to a 1 ohm load, chances are that amp is never being played at 1 ohm after impedance rise and is never putting out rated power.

[audiofanaticz]

@doza146

If you goto Digital Designs website ddaudio dot com and click on amplifier output testing they tell you how to do it and include a calculator. and step by step directions with pictures :)

[doza146]

@audiofanaticz Aright thanks man now impedance rise usually only happens when your burping rite or can it happen on music to

[audiofanaticz]

@doza146

If your clamp meter and dmm is not true rms meters, you then take your peak watts multiplied by .7 which would then = your rms watts.

.7 is a ruff idea of your amps efficiency rating at 1 ohm which is roughly for most class d monoblocks.

If you want to know your impedance curve, you repeat this step over and over from ruffly 28hz to 50ish hz depending on your tuning.

[audiofanaticz]

@doza146

You need to have a clamp meter, and a digital multimeter.

You clamp the clamp meter around your positive or negative speaker wire comming out of the amp. and set the clamp to measure AC Current.

You take the Digital MultiMeter and connect it to your speaker wire outputs red to pos, black to neg and you set it to measure AC Voltage.

You want to read levels on both meters when you do a burp at your peak freq. You then take the AC voltage multiplied by AC amperage which = peak watts

[doza146]

@audiofanaticz Hey man just a really quick question but how can you tell what your impedance rise is like can you make a video showing how to do that or something

[yamahawildboyz]

wuts this song