# Help tunning Amp for an 8" sub



## marito17 (Oct 16, 2004)

I had a 300 Watt RMS Crunch Series amp installed in my 2004 Pathfinder. At this time, I'm only feeding an 8" Cerwin Vega HED-D802 Sub which does not sound good at all. I installed the sub on the rear right side panel compartment so this may be the cause of the bad sound.

I'm trying to tune the AMP and I need some help. I only have channel 1/2 feeding the AMP. Channel 3/4 is not being used at this time.

I have the switch in the ALL BASS section. But I need help with the following settings:
LEVEL (I guess this is the volume or amount of power correct?)
HPF ?
LPF ?
BASS BOOST (Should this be at the max level?)

I'm only looking to add some bass and I would like to set it high at the amp level settings, and lower the bass level in the dash radio settings.

I have picture but it's not too clear in the link below

http://home.bellsouth.net/p/PWP-mmontag

Thanks,

Mario


----------



## Punkrocka436 (Jul 8, 2003)

Level- this is the gain....turn the music on and slowly turn this dial up until you hear the subs start "slapping" and then turn it down about 1/8 turn

HPF- High pass filter, you dont need to worry about this with a subwoofer

LPF- Low pass filter, set this to about 80 hz

Bass Boost- This will give you 18 dB of bass boost at 40 hz. If you want sound quality, i would suggest leaving this at the minimum setting, because every freqency will be the same, and then you will have a super loud 40 hz note. If you want the sub to be loud as shit, by all means turn it up


----------



## Azgrower (Oct 1, 2004)

I doubt the amp is giving its rated power to the sub. This can affect the sound quality as well. What type of box and what cubic feet of air space is it in? If the box is too big, it will not sound correct either.


----------



## marito17 (Oct 16, 2004)

Azgrower said:


> What type of box and what cubic feet of air space is it in? If the box is too big, it will not sound correct either.


The pathfinder has a small compartment in the rear right cargo area. I removed the cover and installed the 8" sub attaching it to the plastic door. I also installed some of that cheap white particle board to remove vibrations. The sub is not kicking at all. I wanted to installed RE8" but when I went into the installation shop, the guy did the cheap install using a cerwin vega he sold. I would guess the space is about 1' x 0.4' x .8' of space. There is also a small air vent on the inside of the panel that allows the sub to breath air. This is what I get for trying to save some cash. A custom fiberglass enclosure would take me days of work and at least $100 in materials.

I used to have the same crunch amp installed with a 10" Hifonic sub on a cylindrical box that sounded amazing. The 10" sub did not fit in the tight space so I had to go with an 8". I also wanted to save space in the cargo area so I tried to side enclosure and I'm not too happy so far.

I'm thinking in purchasing a RE8 for about $60 bucks and testing the sound just to make sure it's not the crapy speaker and not the enclosure.


----------



## Matt93SE (Sep 17, 2003)

is that enough airspace for that 8" sub?
the hole itself is on.y 0.32 cu ft, and then when you count the thickness of the walls on the box itself, you can't be using much more than about 0.2 cu ft of airspace behind that sub. I've venture to guess that's your first and most obvious problem.


----------



## Azgrower (Oct 1, 2004)

From the sound of it, you didnt add a box, its kinda in the cargo area (I know this storage area, thats where I am fiberglassing a box for a 8" sub too!). But that storage area is not sealed, so therefore thats the problem. I would try to at least seal it somehow better, maybe like add 2 layers of Dynamat (or alternatives) all around the inside to keep the area as sealed as possible. Also, build a MDF baffle for the sub to keep vibrations down and help seal the "box". If you just added it to the plastic cover, thats not very sturdy at all. So thats your problem. 

My box will have 0.250 cu ft of air space when done, and the sub requires 0.215, so after the woofer is in there, I should be damn close. I am also using a RE8" and I would say that it is a quality speaker, prolly better than the CV (CV only made on good sub....Strokers). I takes 0.215 ft^3 to for SQ.


----------



## Azgrower (Oct 1, 2004)

So you mounted the sub on this cover correct? And it sits in this cargo area correct? See the air vent? What you did was create a ported enclosure and not a sealed enclosure. Ported enclosures are touchy in that you need to have specific calculations on ports (where the air "vents" out) and inside air space....Your amp can be tuned better yes, but your MAIN problem is the fact that the sub is not in a box, or the right enclosure.


----------



## marito17 (Oct 16, 2004)

I will work on sealing the enclosure and adding some carpet pad or some other think insulator between the compartment door and the panel walls. I will also have to remove the 2 screws that are used to seal the enclosure door. They vibrate and it kills the sound.

What is Dynamat and where could I get this stuff? I'm thnking in building an MDF box that will fit inside the enclosure. It will reduce the overall box size inside, but it will seal the enclosure. What should I wrap the MDF with to avoid vibrations between the MDF and the plastic panel? I'm thnking in using some kind of spray adhesive and glueing thin carpet padding to the MDF to cushion the wood against the plastic panelling and the door. Just a thought. THe Dynamat stuff might work better if I knew what that was.

I played with the amp settings and it's sounding better.

Thanks,

Mario


----------



## Azgrower (Oct 1, 2004)

Carpet padding will not do a damn thing but make a mess of the enclosure! Dont do it!

Dynamat, Second Skin, Fat Mat, Brown Bread, RaamMat = sound deadener (foil type with tar based center sadwiched with foil on one side, and adhesive on other) Its used to add mass and the benefits are they help dampen vibrations. Check Ebay and type in Dynamat!

You wont even have enough room if you went with a full MDF enclosure, even if it were 1/2" MDF. What I plan on doing is a simple fiberglass back and side walls with a dual 1/2 MDF baffle (the second baffle is for recessing the sub to sit flush with the first). This way you can affectively get about 3/16" of thickness to the fglass and still be as strong as the 3/4 mdf for that enclosure (partly because its not free standing enclosure and will be reinforced by the cargo area itself. I am not sure what I want to do with the cover yet, maybe I will add a nice looking grille cover and Duramix it in with the plastic, sand and re-texture the entire cover, then use some HD Velcro to hold it onto the MDF, or use some speaker grille pop rivets to fasten it onto the MDF baffle. Dont know that part yet. I am gonna actually start my enclosure tomorrow, and I am adding some sound deadener to the inside of the cargo area first then glass the mold. I can snap and post some pics, but here is a shot of my Silverado's door panel with some Raamat 60 (2 layers), all the other products look similar.


----------

