Couple Amp Questions

[ctmaudi 0]

I have a Cadence ZRS-C65 with two SA-10 D2s.

When setting the gain, do I go by the impedance the subs are wired to (2ohm), or what they actually measure at when I test the wires with a DMM (2.7ohm)?

Also, when voltage drops does the power drop, or does the amp draw more to keep power where it should be? My electrical isnt up to par at the moment (all stock), so I sit 13.8v idle, and drop to high 12s when the amp reads ~30v. So if thats 450w at 2ohm, which would be 32amps if it stayed at 13.8v. Since it doesnt, and drops to about 12.8v, does that mean it draws 35amps instead to make the 450w, or does it continue to draw 32amps and only put out 410w?

And when figuring efficiency, thats added to what its sending out correct? So if an amp is 1000w and 80% efficient, it takes 1200w from the charging system, and produces the 1000w to the speakers right?

Trying to figure if Ill need a HO alt, or if battery upgrades will be enough. Only going to push 1000w to the subs, and 200w to front stage. 110amp stock alt, 2007 Nissan Altima 2.5S. The cheapest HO alt for my car is $500, which I really dont want to have to spend lol.

Edited February 25, 2011 by ctmaudi

[jonbearsmt 919]

if you have low power.. you make less power... no way around that... it takes power to take power...

thats very weak idle... i would bo the big three, and replace the under hood cell with something bigger...

for 1200 watts you dont need a bigger alt..

just some back bone (bigthree) and a nice run of wire 0 gauge prefered and a nice sized battery.

[///M5 2,833]

DMM does NOT measure impedance, but resistance. HUGE difference. Use the published impedance spec for the driver.

I would also argue against using a DMM to set your gains, in particular since you are in a low voltage situation. Without a distortion analyzer you are going to be clipping until you solve your voltage woes.

If you want help you'll have to describe the electrical setup of your install in much more detail.....

[ctmaudi 0]

DMM does NOT measure impedance, but resistance. HUGE difference. Use the published impedance spec for the driver.

I would also argue against using a DMM to set your gains, in particular since you are in a low voltage situation. Without a distortion analyzer you are going to be clipping until you solve your voltage woes.

If you want help you'll have to describe the electrical setup of your install in much more detail.....

Stock 07 Altima 2.5s, 110amp alt, stock 550CCA battery. Both were tested yesterday by the dealership to be fine. The battery produced 536CCA and voltage is 12.44. No load 13.85V, loaded 13.7V, 43mV ripple.

Using 1/0 kicker hyper flex from battery back to amp, 300amp fuse ~8in from battery. 1/0 kicker for ground, not the best ground but not that bad either, its a bolt under the rear bench seat. Going to change it when I get in there to take the rear speakers out and build a shelf under the rear deck. Subs and remote are wired with 8awg wire.

Used a 60Hz -3db test tone, measured a little over 30v so far. Not using the 4chan I have yet (DSC-480), waiting for my comps to get here.

I am going up to knu in a bit to pick up wire for Big 3 and some other stuff. I should have gotten an HC600 today, but the guy messed up the shipment and have to wait for it to be resent.

Edited February 25, 2011 by ctmaudi

[sefugi 166]

I beleive you to be on the right track, complete the Big3 and recheck the voltage.

[ctmaudi 0]

I feel like a huge idiot right now. It was dark out when I first set my amp up, and it was pushed far back in the trunk. I thought the LPF was from 30hz-250hz, it was 50hz-250hz. I had it set too high. Set it correctly to the 80-90Hz range, and I also didnt have the HU up high enough. For some reason I thought it only went to 30, but it goes to 35. So I was using volume at 23 instead of 28. I set the HPF for the fronts to 90Hz and the LPF on the HU for the sub to 90Hz.

Now its set to 34v, idles 13.88, drops to 13.5 or so. With max AC and brights on, sits about 13.7, drops to 13.35. Gains are about 2/3 of the way up instead of 3/4 like they were.

Once I get the battery and big 3 done, Ill try to get the 1000w Im aiming for, and add in the 4chan. Got to fix some trunk rattles too.

Edited February 25, 2011 by ctmaudi

[ctmaudi 0]

My amp has two settings Ive never seen before. One is Bass EQ, Im guessing thats just another name for bass boost?

The other is Bass Focus.

I always keep bass boost off, so I just left those down all the way. Anyone know what they do, or if I should even mess with them? I have bass boost level 1 and Sub +5db on the HU (KDC-X794).

Also, Ive never had an amp with a bass nob before. Does that change the gain, or bass boost of the amp?