Adjusting Amps For Dummies (Me) Long

[2therock 10+ year member]

I'm over my head here. Please throw me a line?

I hope I can take advantage of your expertise with this one long message? Maybe others here can lean from your answer.

I have a Alpine CDA-7894 head unit. I can turn off the internal amp. It has all sorts of adjustment tweaks available. (See Below).

I have an Alpine 5 Cahnnel 40 x 4 RMS (Benchmarked @ 50+ Continus), 120 X 1. 75 X 4 X 180 MAX Amp with a few adjustments.(See Below)

I have Cerwin Vega HED Series 6.5" Components (Front) and Cerwin Vega HED Series 4x6 Plates (Rear). They max at 100Watts.

And JL Audio's lovley little 8.1 micro sub aimed at the floor under the rear seat of my Chevy 2k2 Ext Cab.

My Alpine AMP only has 3 Gain knobs (1 of them is for the sub channel), a LP filter knob, 2 HP Filter switches, a bass boost switch and a LP Filter knob.

The Alpine CDA-7894 radio has cross over settings in the menu. Here They Are:

Bass Center Frequency (Selectable) : 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 130Hz, 150Hz, 180Hz

Bass Level Control Range : ±14dB at 60Hz (2dB steps)

Bass Width Adjustment (Q) : 4 Choices (1= Wide, 4=Narrow)

Crossover Type : Independent HP/LP (2-Way) Analog

High Pass Crossover Frequency (Selectable) : Off, 80Hz, 120Hz, 160Hz

Low Pass Crossover Frequency (Selectable) : Off, 80Hz, 120Hz, 160Hz

Treble Center Frequency (Selectable) : 10.0kHz, 12.5kHz, 15.0kHz, 17.5kHz

Treble Level Control Range : ±14dB at 10.0kHz (2dB Steps)

Here is a question. My Cerwin Vega Components and plates have fixed cross overs on them! Will these defeat my radio cross over controls? Will they be butting heads? Do I select the HP filters to "On"?

Here is my amp specs.

• Max Power (EIAJ) 75W x 4 + 180W (4ohm; Stereo) 180W x 2 + 180W x 1 (Bridged 4ohm

• 14.4V RMS Continuous Power 4ohm; Stereo (0.08% THD) 40W x 4 + (0.3% THD)120W x 1(4ohm 2ohm; Stereo (0.3% THD) 50W x 4 + (0.3% THD)120W x 1(4ohm Bridged 4ohm; (0.3% THD) 100W x 2 + 120W x 1

• S/N Ratio 100 dBA

• Bass Engine©

• Bass Boost

• 18dB LP (50-200Hz) & 18dB HP (80Hz) Crossover

• 18dB LP (50-200Hz) & HP (80Hz) Crossovers

• 4 Volt Input Capability

• STAR Topology & Duo-B Circuitry

• Darlington Bi-Polar Outputs

• MOSFET Power Supply

Please suggest where you would start at.

I told you guys I was a newbee. I am pulling my hair out trying to keep figure out how to get the best of what I have.

I do know that one needs to set the gains first. Turn them down, the radio up, increase the gain untill there is minimal distrition, then take the gain down until it smooths out?

Talk to me Cuzz!

2therock

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[richie1 10+ year member]

i heard that u really shouldnt mess with the gain. im almost positive that the filter for the component set does all that hp lp stuff without help from the amp of equalizer or what have you. the filter takes out all of the noise and distortion basically so if you have a component set and say an amp with a built in crossover, the component sets filter does all of the work.

 

[2therock 10+ year member]

The crossovers that come with your Cerwin Vegas are pre-set but they only crossover the mid and the tweeter. The low point of the mid comes from your amp or head unit.

If possible, defeat one of the crossovers (either on the head unit or amp). If you can't, try and set them to the same frequency. Anytime you add crossovers together, the slope adds. For example, if you have a the head set to 90 Hz (high pass) at 12 dB per octave and the amp at 90 Hz (high pass) at 12 dB/Octave, your speakers will see a 90 Hz high pass signal at 24 dB per octave. This can be good most of the time (the steeper the slope the better) but sometimes you want a more shallow slope. Listening tests will determine this.

If the crossovers aren't set up to the same frequency, then the slope cascades. For example, if the head is set at 100 Hz and the amp is at 80, the head starts to roll things off and then the amp does again so you get a cascading affect, this is not good so like I said, try to set them to the same frequency.

As far as the Q setting goes, this adjusts the width of the frequency you are boosting on the bass EQ. For example, if you want to boost 45 Hz with a high Q (2-4), the EQ will focus on 45 Hz (tighter bass). If you set the Q to a low setting (.3 or something like that), the bass will be louder, but probably boomier and not as accurate.

I hope this helps you out.