My subs sound awful...

[avs20 10+ year member]

Here's the deal. I just built a big fiberglass enclosure/amp rack. Inside the enclosure are two .75^3 sealed boxes. I'm using 2 JBL W10GTi's, inverted wired to 3 ohm.

I'm running each sub off of a phoenix gold tantrum 1200.1

I set the gains with a DMM for 900 watts each.

The bass is not punchy at all. I've wired them in phase and out of phase, and cant tell a huge difference. With the gains set with a DMM, there wasnt that much bass. I have my HU xover set at 80hz. What should I set the xover on the amps to? Ive played with everything on the amps to make it sound better, and I havent accomplished anything other than time wasted.

Any ideas?

System specs:

2 JBL W10GTi's

2 PG Tantrum 1200.1

1 JL 450/4

2 .75^ft boxes(with polyfill)

1/0 wiring to dist block

1/0 ground wire

4 gauge wire to all amps

Click to read more...

 

[squeak9798 5,000+ posts]

If you have the subs inverted, then you need to take the cone area into account....which means that your box is actually bigger than .75cuft by the amount of cone displacement. If you want "punchy" (i.e. peaky) bass, then you need to aim for a Qtc around .9-1.0......I don't have a box program here at work, but I'm going to guess that you need to make your box a little smaller. Get a box program and punch in the numbers and see where your Qtc is.

 

[avs20 10+ year member]

Even if the boxes are 1^3....should they still sound 'boomy'?

 

[squeak9798 5,000+ posts]

Bigger box = smoother sound

Smaller box = peaky, punchy sound

 

[avs20 10+ year member]

So should I put some wood in my current boxes, and take out the polyfill, and see what happens?

 

[squeak9798 5,000+ posts]

Exactly. Be sure you know how much displacement the wood has when you put it in (i.e. measure it and determine how much cubic foot it displaces) that way you can tell what size enclosure is right for you.

 

[OLD_SCHOOL 10+ year member]

maybe it's because i am not familar with JBL subs but how to wire 2 subs @ 3 ohms

and make sure you hole is not so small that the cone/spider is smashing against the box.

also the differance of .25 cubic feet sould not make THAT huge of diif erance in audabile sound in a sealed box.

or maybe i misunderstand you definition of crappy

does crappy equal old grandma walking farts

or does crappy equal they sound like subs are supposed to only i want much tigher and accuate bass

cause .25 cuic feet could make that kind of differance... some what

 

[DFW40 10+ year member]

a 4 by 4 post that is 27 inches long will take up .25 cubic feet. You can get one of these and cut it into small pieces to throw in the box. If you say that it sounds awful then that makes me think that there might be another problem incolved. Unless you were just being overly drammatic with "awful".

 

[avs20 10+ year member]

By awful, I mean the boxes seem backwards. In rap songs they are very bassy, but during rock songs, with tighter bass, they arent tight at all. More like 'rumbling' than anything. My ported boxes sounded better than these sealed boxes, by far. Another thing....I have to use the bass boost on the amps to get something that sounds like bass, or it doesnt sound like I have 2 10's behind me.

I dont know what it could possibly be. I dont think .25ft^3(if that) will make them sound better. Im stumped.

Old_school, each sub has dual 6 ohm coils, wired in parallel. They each have their own PG T1200.1

 

[thismightbepat 10+ year member]

Sorry if you've already stated this, but if you have them inversed did you take into account that u have to reverse the polarity of the wiring (wire the negative wire to the positive terminal, positive to negative)?

 

[DFW40 10+ year member]

Is their anyway that you wired them in "series" or screwed up the phase on one speaker or amp output. Have you tried putting the subs in the box, not inverted but regular style, playing on at a time?

 

[avs20 10+ year member]

Each voice coil has a plate on it connecting them together. So both +'s are connected to each other and both -'s are connected to each other. I then run a wire from each voice coil to the amp. One to the + and one to the - .

I have not tried them in the box mounted normally because they will barely fit, if at all.

 

[DFW40 10+ year member]

Did you say that these were fiberglass boxes or sealed MDF boxes within a fiberglass outer enclosure.

 

[thismightbepat 10+ year member]

well i think that may be your problem, when u invert the subs, everything has to be reversed, the positives from the amps have to connect to the negatives on the subs.

 

[avs20 10+ year member]

Yes, these are sealed boxes in a fiberglass enclosure. And I have wired them out of phase and normally. Out of phase sounds a little bit better, but either way, they dont sound very good.