First let me tell about my system. The car is a 98 Saturn SL2 with a stock 85 amp alternator, stock front battery, and an Optima Yellow Top in the trunk. The car was running for the tests. The amp is a US Amps USA 800. The sub is a 15" Stroker in a 3 cube box tuned to 45 Hz (I know it isn't ideal but it is all I have to work with ). It is wired up to present a .9 ohm nominal load on the amp. The deck is a Panasonic G-Shock series deck with a 4 volt output. Not sure on the model number off hand. The deck had its bass on 0 for the tests. For reference the deck goesd up to volume 40. The line driver is a RW Audio LD6.8MS"burp" capable of 11.6 volts RMS of unclipped signal. The measurments were taken with the gain wide open like it would be for competitions. The disk is track 50 of the new DB Drag Volume 5 cd. All measurments taken at 50 Hz tune.

I took measurements at certain volumes on the cd player with and without the LD. The voltage represents the max voltage since my DMM doesn't have an RMS feature. Let me just say that there is a noticable difference in volumes as you can see from the numbers. I have converted the numbers to watts but the RMS value is not correct due to impendance rise so I am using the .9 ohm value just for comparisons sake. Here is the formula I am using to determine wattage also.

Speaker A/C voltage * .707
Square that number
Divide by the final ohm load (in this case .9 ohms)

Here are the numbers I got

Without LD

Volume 5 = 0 volts = 0 watts RMS
Volume 10 = .6 volts = .2 watts RMS
Volume 15 = 2.4 volts = 3 watts RMS
Volume 20 = 8.4 volts = 39 watts RMS
Volume 25 = 27.6 volts = 423 watts RMS
Volume 30 = 77.8 volts = 3362 watts RMS

With LD

Volume 5 = 2.7 volts = 4 watts RMS
Volume 10 = 9.3 volts = 48 watts RMS
Volume 15 = 30.4 volts = 513 watts RMS
Volume 20 = 81.4 volts = 3680 watts RMS

I stopped at those respected volumes because the sub was moving quite a bit and I still need to compete with it The measurments without the LD were taken first. That way if there was any voltage loss or battery drain it would happen to the measurments taken with the LD.

As you can see there was great improvement over the "4 volt" preout of the Panasonic. There was no audible distorion in the sub either. Unfortunately I did not get to measure voltage or voltage drop while the amp was playing.

I would recommend this to anyone competing in SPL. If anyone has any questions about my LD or the tests email me or contact me on the chat programs.

One thing to keep in mind though. If your nominal impedance was .9 ohm, during a burp your impedance was probably ("in reality") much closer to 1.5+ ohms.. So your wattage specs may not be entirely accurate.

But for this test, that really shouldnt matter much.. There was clearly a gain in output voltage.

Nice!

I knew it would boost the wattage up early, but since I didn't have the subs to test the amp to its max volume it is hard to say what the actual gain in wattage is wise when the deck is maxed out.