sub response
 

I have a 10" alpine type R 2ohm dvc powered with mrd-m605 at 4ohm. so it's getting 400wrms and sub rated at 300wrms. I'm using 4awg from battery to distor block and 8awg from distro to amp as well as 8awg ground. ground wire is about 1 meter going under a huge bolt under my rear seat. sub is in a sealed tube enclosure estimated at a about 0.6cu/ft

The problem is when I turn up the volume I hear the speakers play more loud and clear but the sub volume stays the same at some point (after about 60% volume) kinda like flat spot. I can hear the speakers scream but the sub is not getting loud enough to keep up with the speaker volume.

Prime suspects in my opinion either the ground and power (short one from distro block) cable must be 4awg or the box design needs to be revised. I made some calculations and I can make a regular box either ported or slotted (recommended by alpine) with about 1cu/ft for the space I have.

Need some opinions please

I also had the same issue. Conveniently, I was getting a port box anyways as well as heavier gauge wire. My issue went away.

What are you using for a HU? Some factory HU's limit the bass frequencies at higher volume.

What is the gain setting at on the sub amp?

Alpine CDA-9857 is the HU. 2 volt pre-outs. I set the gain to 1V on the amp. frequency is about 45hz. subsonic filter turned off. and I raised the db level to about 12 (max is 16).

at early stages of my setup about 2 months ago when I ran my sub from my stock bose via LOC and running off my 4ch bridged (getting about the same 400wrms) the sub got very loud and was overpowering my stock everything else. but now it's the other way around. :dunno:

is there a device that would bump the 2v pre-out to maybe 4-5v?

Think line driver. There have been discussions about them here, good info.

Not sure if the low voltage is exactly your problem. I had 9853 deck with 2v outs and I had no problem and I can't notice any difference when I switched to 9835 with 4v outs.

I'll upgrade to 4awg and see what happens

Yes you can, use a line driver and there has been a few sub output issues on a couple of the Alpine units in the past as well as most other manufactures. I just sold Chromey one to try out and the amp and sub combo came alive and he has a Alpine hu. Just try a cheap one first to see if its the issue. If you need one let me know but PM Chromey and ask about the difference.

I had sub output issues with my 9835. I tried a PG PLD-1 I had laying around and it didn't do a thing to help. No matter how I tuned that thing nothing helped.

are there any issues with sound quality when using a line driver? or is it about the same as having a higher volt pre-outs on the hu? in terms of signal quality

Pretty much the same thing as having a high voltage preout deck.

There's been many a fine sounding system with less than 2v of preout juice.