njtripface

I just recently installed a POLK GNX104 10" Sub w/ an ALPINE MRP-F200. I have the 3/4 channels bridged (one positive from 3rd channel and one negative from 4th channel) -- is this correct?

I'm using an KDC-MPV701 head-unit also.

The AMP picture follows with the adjustable GAIN / Bass Boost / Filter Adjustment. There are also other adjustments that you can see.

The sub is producing sound, but seems not to be "hitting" very hard at all. If I up the volume, I can feel some thumping coming up from the door panels, but that doesn't seem correct. I haven't played to much with the settings on the AMP, because I'm really unsure what is correct to produce a better sound.

Can anyone provide any insights on this? I really appreciate the help, since I'm so new at car audio.

--John

mgiang7

hmm it might be a gain problem which you can adjust. it might also be a wiring problem with the subwoofer. do you have the specs for the subwoofer? specifically number of ohms for the resitance?

WLAURENT

The GNX104 is a single voice coil 4 ohm sub. The Alpine MRP-F200 delivers 100 watts bridged into 4 ohms. You should still get some decent bass with 100W, but 200W would be better.

You might try playing around with the gain to your sub channels. I am not familiar with the KDC-MPV701, but assume it has a sub out capability which allows you to adjust the output to the amp on the deck also.

njtripface

Thanks for the information guys.

You both mention adjusting the Gain on the AMP. Any tips to this, do I just keep adjusting it till I hear a good sound being produced?

The wiring should be good, but I'll check it again. I bought an Amp wiring kit, wire kit for the sub, and wire for the speakers themselves (2 front / 2 tweeters).

Also, bridging channels, what is the method of doing this?

-- Here are the specs of the SUB -- Polk Audio GNX104 10" 4-ohm Component Subwoofer

Impedance 4 ohms
Frequency Response 18 - 0.4k Hz
RMS Power Range (Watts) 50-175
Peak Power Handling (Watts) 400

--- AMP specs -- Alpine MRP-F200

RMS Power Output -------- (Watts x Channels) 40 x 4
Frequency Response -------- 20-20k Hz
Peak Power Output (Watts x Channels) -------- 180 x 2
Power at 2 Ohms (Watts x Channels) -------- 50 x 4
Bridged Power (Watts x Channels) -------- 100 x 2
Minimum Impedance Bridged -------- 4
Minimum Impedance Unbridged -------- 2



Thanks for the help guys.

--John

TepEvan

Make sure for channel 1/2 the filter is set to HP (for high pass) and for 3/4 the filter is set to LP (for low pass)

This will allow only highs and lows (respectively) to be passed to each channel. Set it with the bass boost off first, see how it sounds. bass boost is usually a good way to make your sub sound ugly if your gains are set too high (but that may not be a problem with only 100 watts). Also, make sure the headunit is set for a flat response (0 bass - 0 treble).

The way to effectively set gains:
-turn the gains down to nothing
-make sure the headunit is set for a flat response (0 bass - 0 treble)
-turn the head unit volume almost all the way up (if it goes up to 32, set it to around 29)
-adjust the gain on the fronts until the sound starts to distort, then back off a little bit (so there is no distortion).
-repeat the above step with the subwoofer (which is a lot harder to sometimes hear if a sub is distorting)... try to listen if it is bottoming out.