Adjusting new sub - quick and dirty please?

[Sierra Nate]

Several months ago I installed a new Pioneer 4200 NEX head unit , Pioneer GMA 6704 four channel amp and Alpine S in the four doors. I came to this forum because I was getting some serious clipping and followed the advice given and solved that problem through setting the cross-overs in the head unit and not using those setting on the amp.

Of course, the solution rendered me with no bass. So I picked up a cheap Alpine 8 inch powered sub. It filled the void...it was cute...it fit neatly under my back seat right in the middle, installation was easy. Of course everyone on this site said 'don't do it, Nate'. But I was on a budget and lacked the time to do bass the right way.

Well...I blew that sub twice now. It was 200 watts and sounded decent with volume not maxed out. But turn it up on a bassy song and out she went...twice...

OK...this weekend I had some birthday money to spend so I picked up a 13 inch JL Audio TW5v2 and an Alpine MRV M500 mono class D to power it. Man...what a difference in sound quality!

Now I need to understand how to fine tune this thing and also, how to best place it. I have it mounted in a wedge box that fits neatly under the rear seat on the driver's side. Firing up, into the seat. I lifted the seat and hear absolutely no difference in sound with seat up or down.

My problem is I feel like the music is coming from behind me. Before installing this thing it felt like the music was centered in front of me (before this sub, I adjusted the timing using the Pioneer mic to get a starting point and then manually adjusted from there).

All this high fidelity audio stuff is new to me but I follow instructions well.

Where do I start? Is the new sub throwing off my timing and just need to redo the timing now? How do I set the amp LPF? It ranges from 50-400 hz. Crank it all the way to 400 and let the head unit do it's thing? Is firing up into the seat a decent way to fire? I have limited space because I carry a lot of off-road recovery gear and a lot of it is under my seat. Behind the seat means I have to remove the back seat and I'm not even sure I have the space back there for a sub. The box it is in is not ported...just a plain wedge swapped box.

I listen to rock, classic as well as newer stuff. My wife listens to 80s music. My kids listen to swag. When we go camping we listen to country. So ideally I need adjustability but I think adding a RUX knob would accommodate that? No?

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[Sierra Nate]

I am close to finding a sweet spot with these settings. Now it's all about EQ settings?

Am I going the right direction?

I'm not satisfied with the sound but I will say it sounds way better. The bass is big, clean and heart throbbing. But I feel like it is over powering the drivers. If I turn the gain down it just makes the heart pound go away, no real difference in over all sound quality.

I want to say I'm 80% satisfied, but I know it can sound better.

 

[Sierra Nate]

So apparently I'm an idiot when it comes to posting pictures on this site.

So I set the gain to one tick above NOM. LPF is set to 400. Bass EQ set to +8. Crossovers set to 100 with 12db slopes on both high p[*** and low pass.

 

[bandit_kb]

Did you sent your gain by ear or use a multimeter? Trying to make sure you don't damage the expensive sub.

Pics of box? How much space is between the woofer and the bottom of the seat?

 

[Sierra Nate]

I'll get a pic after lunch time. Its a prebuilt box from JL Audio. The grill cover is touching the bottom of the seat. The seat has a cavity underneath it protected by a flimsy piece of material. So the sub is firing into the cavity through that flimsy piece of material. So in effect the grill is approximately 3 inches from the seat foam? The grill is about one inch above the speaker cone? Not sure if that makes sense without a picture.

Short term I plan to use this wedge box the speaker is mounted in but long term I hope to build some custom box with porting of some sort. I hope to find a way to build a transmission line box but space is limited.

I set the gain by ear. I turned the volume all the way up without distortion and then added gain all the way to max and never received any distortion. I backed it down to its current setting because it didn't logically make sense to me to have it set to max. I expected to get some distortion from either the volume or the gain or possibly both.

This weekend I plan to do it with a meter. I've never done that before but there are some good instruction in the search feature I saw yesterday.

. Took a quick break to snap a [pic.

 

[Sierra Nate]

Couple thoughts on the box/enclosure. One...can I open it up and modify it to add some porting? JL says on their site they glue it with tongue and groove. Seems like a sturdy box. If I open it up and add some channels to the passenger facing side and cut a hole there, could I make a make shift t line port of some sort?

Second thought is to remove the back seat and build a new custom box that mounts behind the seat. I have no idea if I have enough space to do that.

 

[BOOMINGRANDPA 5,000+ posts]

set lpf at 100-150hz, turn the 50hz &80hz down to 0 or -1 or2 (if u don't have hp xover on speakers) see if that helps boost the 12.5k to +3-6 that'll help highs (if hu has xover for regular speakers set it at 80hz)

 

[THATpurpleKUSH 5,000+ posts]

The gain setting is way too high on the amp pictured. It's only a matter of time before more speakers/subs are blown, especially with upwards of +6 settings on the EQ. The headunit has 4 volt preouts and the amp accepts up to a 6.5v preout. The gain should be reduced to about 9 o'clock give or take a little bit.

 

[bandit_kb]

I wouldn't mess with the box. Build a new one before trying to make it a ported box. I have seen custom boxes behind the rear seats for every major truck maker. It may not be ideal but it is possible.

 

[Sierra Nate]

The gain setting is way too high on the amp pictured. It's only a matter of time before more speakers/subs are blown, especially with upwards of +6 settings on the EQ. The headunit has 4 volt preouts and the amp accepts up to a 6.5v preout. The gain should be reduced to about 9 o'clock give or take a little bit.

Makes some sense. I thought NOM meant 0 and anything left of NOM would be lowering the gain. OK...first thing to do is turn the gain down.

 

[Sierra Nate]

set lpf at 100-150hz, turn the 50hz &80hz down to 0 or -1 or2 (if u don't have hp xover on speakers) see if that helps boost the 12.5k to +3-6 that'll help highs (if hu has xover for regular speakers set it at 80hz)

LPF is set for 100 on the head unit. Are you saying to set it to 100-150 on the amp also? I made all the other suggestions and it sounds different. I'll try playing some more with those after I turn the gain down.

 

[BOOMINGRANDPA 5,000+ posts]

LPF is set for 100 on the head unit. Are you saying to set it to 100-150 on the amp also? I made all the other suggestions and it sounds different. I'll try playing some more with those after I turn the gain down.

no i thought u said it was at 400hz.. i just saw pick of amp i agree u have gain to high thats your problem, set it about 30% not 60% if u have 4-5v hu..

 

[Sierra Nate]

I used a meter and set the gain. It's almost off. Math formula wants 34.4 v and I got it to 31.6 v. The Bass eq settled ng was at lowest setting when I adjusted the gain. Can I now turn that up? I end up getting 54 v when I turn the bass eq up to half way...after the eq setting was done. It sounds better with bass eq about half way. Not perfect yet but way better than it was. It's moving the right direction.

 

[THATpurpleKUSH 5,000+ posts]

I would keep the EQ flat and move the LPF on the headunit to 80hz and 100hz on the sub amp. The overlap ensures that the headunit is in control and is sending everything below 80hz to the subs.

Increasing bass boost levels and increasing EQ settings alters the signal which leads to distortion and clipping and blown components if you're not careful.

 

[Sierra Nate]