Sub/Amp/Box Opinions needed

[sbuswell]

I am looking for some suggestions to improve my setup. I listen to 90% metal and 10% hard rock/classic rock. I want to get powerful, hard hitting, deep bass especially when the double bass hits. I like my current setup, but I don't love it. Here is what I've got.

Power Accoustik PNX-761 HU w/Axxess ASWC-1

Front: Alpine Type R 6.5 Comp's

Rear: JBL P963 (gain turned much lower than fronts and HPF turned up, I use these for rear fill)

Kicker CVX 12" Sub 4ohm in a 1.8 cubic foot vented box tuned to 36 hertz wired in parallel

XS Power D5100 battery, Big 3, 0 gauge power & ground wire, 5 farad capacitor

JBL GTO1004 Amp for speakers

Hifonics BRX1200.1D for sub

The sub is wired in parallel so the amp should be putting out 900RMS to the sub and its rated for 750RMS, but it doesn't hit as hard as I'd like and being a Kicker sub the SQ isn't the greatest. I have gain turned up 7/10 on the amp, bass eq to 0, LPF set at around 90-100 hertz, everything else at 0. I have remote level controller at around 6/10 and the bass turned all the way up on the HU. It gets loud, but not that loud and I rarely get that rich deep pumping sound I would like when the double bass hits.

What are your opinions of this setup and recommendations to get more out of it through either tuning or swapping out either the box, sub or amp. I really don't want to get all three at least not at once.

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[argenis69 10+ year member]

First of all, of what I heard here, that 5 farad capacitor you have I useless and more harm than good for your system. Second, did you set your gains correctly?, with a dmm or oscilloscope?

 

[sbuswell]

I've been thinking of getting rid of the cap. I got it for free with a wiring kit I bought years ago. Figured it's free so why not use it, but I agree it's not helping me so get it gone. I set the gain by ear, I plan on getting a DMM and doing it that way, but I'm not thinking it needs to be turned past 7/10. I'd rather have some headroom and not risk overheating the amp (even though they are cheap).

 

[argenis69 10+ year member]

I would do the gains with the dmm and test tones first and go from there.

 

[sbuswell]

OK. I will get that done first and report back. Some times it's the simplest things.

 

[mylows10 5,000+ posts]

also a bigger box is needed for that cvx ,your system isnt that bad, but all good systems start with a good hu which you dont have .so new deck ,new box dump the cap and 0 gauge wire

 

[bbeljefe]

Uh...... don't dump the zero gauge wire, btw.

First off, it sounds like your gain is too high but I'm not sure what sort of voltage the head unit provides. However, the crossover should be set at 80 Hz, as there is a lot of bass in metal that occurs at the top of the sub bass region and you've cut it off from your sub. The bass knob should be set full on for metal and other music that's not bass heavy and the bass control on the head unit should not be above flat... especially if you're driving your mids with HU power. If you still don't have enough bass after that adjustment, you can increase it by using the bass boost on the amp but, only in moderation and if you do use it, you need to re-set the gain. i.e. turn it down.

The reason for the changes I recommended is that when you boost the bass at source, you run a much greater chance of clipping the amp and the mids, which will almost surely make an otherwise (possibly) clean signal dirty.

I would get hold of the manual for your head unit and check the line level output voltage. If it's 2 volts your gain may be okay but if it's higher than 2 volts, you're clipping the sub. Gain is not a volume control for the amp, it's a sensitivity matching device. Once it is set to match your head unit, it should never be reset unless you adjust the bass boost on the amp.

As for the box, it's a bit small and tuned a bit high for sound quality but given your musical taste, it shouldn't be a large part of the problem.

 

[sbuswell]

Uh...... don't dump the zero gauge wire, btw.
First off, it sounds like your gain is too high but I'm not sure what sort of voltage the head unit provides. However, the crossover should be set at 80 Hz, as there is a lot of bass in metal that occurs at the top of the sub bass region and you've cut it off from your sub. The bass knob should be set full on for metal and other music that's not bass heavy and the bass control on the head unit should not be above flat... especially if you're driving your mids with HU power. If you still don't have enough bass after that adjustment, you can increase it by using the bass boost on the amp but, only in moderation and if you do use it, you need to re-set the gain. i.e. turn it down.

The reason for the changes I recommended is that when you boost the bass at source, you run a much greater chance of clipping the amp and the mids, which will almost surely make an otherwise (possibly) clean signal dirty.

I would get hold of the manual for your head unit and check the line level output voltage. If it's 2 volts your gain may be okay but if it's higher than 2 volts, you're clipping the sub. Gain is not a volume control for the amp, it's a sensitivity matching device. Once it is set to match your head unit, it should never be reset unless you adjust the bass boost on the amp.

As for the box, it's a bit small and tuned a bit high for sound quality but given your musical taste, it shouldn't be a large part of the problem.

My speakers are powered by a JBL GTO1004. The sub frequency on my HU is set at 80hz, on my amp it's between 90-100 so that should be fine, if a little high right? anything over 90 or 100hz won't play. The pre-amp voltage is listed at 4V. Not sure if it's a true 4V and I don't it is. What size box would you recommend and would a sealed enclosure be a better choice? CVX's list sealed enclosure sizes between 1.0-4.6 cubic feet which is a really wide range. I would imagine a smaller sealed box would be better than larger, maybe larger ported box?

 

[sbuswell]

Also I have the HPF on my 4 channel set higher to eliminate a lot of the bass coming out of the F&R speakers so the sub can take over that roll as it should.

 

[bbeljefe]

My speakers are powered by a JBL GTO1004. The sub frequency on my HU is set at 80hz, on my amp it's between 90-100 so that should be fine, if a little high right? anything over 90 or 100hz won't play. The pre-amp voltage is listed at 4V. Not sure if it's a true 4V and I don't it is. What size box would you recommend and would a sealed enclosure be a better choice? CVX's list sealed enclosure sizes between 1.0-4.6 cubic feet which is a really wide range. I would imagine a smaller sealed box would be better than larger, maybe larger ported box?

If you don't trust your head unit's line out voltage, why trust its crossover? Just curious...

It doesn't matter that the sub crossover is set to 80 at the source. If you have it set higher at the amp, that's where the bass is crossed over. So if you're set to 100 on the bass amp and 80 on the front stage amp you're cutting a considerable amount of the fast hitting midbass contained in metal and hard rock out of the system. The way to set crossovers is to have them set at the same frequency and because of the natural roll off, the bass and mid/high stages will blend with one another and nothing will get cut or left out. In the end, if your head unit crossovers work well, then there's no need to use the ones on your amps. If they don't work well, turn them off and use the ones on the amps but, I wouldn't use two different active crossovers. And about the mids... if you'll turn the bass down on the head unit, you won't need to set the mid amp's crossover so high. They should be perfectly fine playing 80Hz and up, as long as they're not being blasted with a boosted bass signal.

As for the line out voltage, I don't know what makes you suspect it's not a true 4 volts but I wouldn't assume anything without actually checking. Even if it's only 3 volts, your gain is still set too high and the end result will be cooked coils in your sub. For a 4 volt line, the gain should most likely be somewhere around the 9 'oclock position.

The enclosure should probably be 2-2.5 cubic feet and I never recommend sealed, save when there are serious space constraints or when the sub has a very low EBP. Your sub has a high enough EBP and you have enough space for a proper ported box and that's what will sound the best and get the loudest in your vehicle. Kicker recommends 1.75 to 2.25 for the 12 in vented enclosures and if you'll notice, the smaller box is called "compact" and the larger, "deep bass". This is because larger boxes improve low end extension. They can also help to smooth out acoustical peaks that are common in ported boxes. In sealed boxes, there are no acoustical peaks and low end extension is atrocious at best, but making them larger helps. But as I said before, the box is the last thing you should worry about. You need to get the system set properly before you'll be able to tell if the box isn't good enough for what you listen to. Personally, I think it's fine.

 

[sbuswell]

thanks for the advice. I will work on it some more today.