Dissapointed With Sub

[Johny Bravo]

Alrighty, got a fusion sub connected to a fusion 2 channel amp (bridged) and then thats connect to my head unit. Not at all happy with the bass im getting from the sub. The sub is in a sealed box and stuck in the boot facing the rear seats in my R31. I'm barely getting any more bass then i do from my speakers connected to my 4 channel amp.

Any way i'll give you the stats.

Fusion Sub:

Max Power: 400W

RMS Power: 200W

Freq Resp: 21Hz - 3kHz

Impedance: 4 ohms

Sensitivity: 90dB

Fusion Amp:

Max Power: 300W

RMS Power: 180W @ 4 ohms

Freq Resp: 10Hz - 40kHz

Turning up the gain, fidling with everything on the amp, fiddling with the settings on the head unit ( i can control the cut offs for what frequencies it sends to the amp) and stuff. I'm not very happy with the result.

I grabbed an amp that wouldn't over power the sub and blow it and i figured that it would underpower it too much, or am i greatly wrong?

Only thing i can think of is that the amp isn't seeing enough power from the battery? Yet the four channel amp ( 50W RMS per channel for my 4x 55W RMS 3 way speakers) is doing a superb job.

Should i go grab a multimeter and have a poke around? any suggestions? I've checked all my wiring and everything seems all ok.

Cheers

Kurt

Edited January 25, 2011 by Johny Bravo

[BlackR32]

sounds like you haven't bridged the amp properly at this stage... unless you have and I didn't read it...

If you are running off ONE of the 2 channels you won't be pushing much power to the sub.

To fix if this is the case..

Use the possitive from one channel and the neg from the TOHER chennel... thus doubling the power and providing better response.

Let us know if this helps.

H

[Johny Bravo]

sorry. should of mentioned that. it is bridged. And i've bridged it properly.

[BundyBear]

Kurt

Dissapointing Bass can be from several things,

1) you said the amps bridged OK, I'm assuming the subs are in parallel and not in series ,check the phase of both subs ( if one is reversed it will work against/cancel out the other sub.

2) the box, if the box is not stiff enough to withstand a couple of hundred psi of air pressure you'll loose bass, so NO air leeks (check round the subs, the wiring, and the edges of the box), also if the box is chipboard or even 12mm MDF it's flex with the bass, resulting in a disapointing output (my last box for 2 12" was 2 laminated layers of 18mm MDF with a fibreglass layer inside to reduce leaks and stiffen the flat bits)

3) getting bass from the boot, try opening up the path from the boot to the cab, ie remove backseats, parcel shelf etc. Something might but baffeling the subs

4) Power. start by checking the battery voltage with the system running 2/3's, watch the meter for a min or 2 then compair to the sub, if you see more then a Qtr volt drop, you might have power cabling issues.

If your loosing Voltage( and therefore wattage) you'll need to find where. Possiblities are:-

Main Power lead

Ground from amp to chasis

Ground from Batt to Chasis

Ground from Alternator to Chasis/Batt

Dodgy Battery

Most of the grounds are easy to check, just stick the meter on each end of the cable on question ( use the 2V Setting), you should get like 0.2V or simmilar ( this is the voltage lost to the cable)

The main cable is usually longer than the meters leads, but these can be extended easly with thinish wire, as the meter draws very minimal current, again the voltage drop should be very small

5) Subs may need to be 'Worn in', sounds a bit BS but they do openup after a dozzen hours of use

6) Tune. Even a good system not tuned well will sound off, unfortunatly it takes a lot of skill, experience and a good ear to do propperly. If everything else checks out a tune by a pro might just make the grade!

7) reserved for anything else I 4got

Let us know how you go

Cheers

Bundy

Edited January 25, 2011 by BundyBear

[Johny Bravo]

I'm only running one sub, the box probably isn't the best so i think i might reline the inside of the box with something or at least seal the joins. Pulling the seat down doesn't make much difference, it's still poor.

I do intend to get a tune but i guess i will wait till i've worn the sub in, its probably had less then 1hr on. Guess i'll go get my self a multimeter and have a poke around, if there's anything wrong there i'll find it.

Cheers for the reply

Kurt

[t_revz]

i was right into stezzas back in the day. followed some advice given to me and it turned out to be correct atleast in all my cars. by putting the sub facing backwards in the boot into the corner was better. by facing it away you get and echo off the surface its facing which made it louder. in the corner it has 2 sides to reflect off and was better again. aparently driving one into spare tyre well is meant to be better again. still sounds like you need a tune tho to get the most out of it. keep frequency to 80-90hz and adjust gain for volume. if gain is at max and still not loud enough then amp is too small or set up incorrect. dont turn frequency up to get more out of it as mid range noise can sound crap through a sub. dont turn bass settings on head unit right up. try to keep it fairly even across the eq and adjust amps to get correct volume then tweak eq later to suit the style of music you listen to. 300w amp shouldnt pull that much power from the battery so if you see big power drops then something is wrong for sure and check the connections bundybear mentioned. new sub should be quite punchy but little soft for the deep stuff. 10 hours should loosen it up. but it will require a little extra grunt to break it in. a good box is a worthy investment. get some marine ply from bunnings and knock one up if yours isnt strong enough, if it has any old screw holes then seal them up

[BundyBear]

Kurt

If posible, dismantle the box and 'liquid nail' n screw them, silicon and similar on the inside of the seams will soon fail, cause the pressure is +'ve and -'ve ( a 3-4 inch strip or FRP ( fibre glass) works well.

leaks in joints, screew/wire holes will loose heaps of bass.

spinning the box round will get some gains but only in the 2-3dB range from what I found ( I built 6 or 7 'test' boxes 4 my last car, just to try different angles and directions[The best setup varys from car 2 car]) ended up pointing back and slightly up, Lots of Dynamat in the tailgate helped, as did a 2/3 baffle above/behind the box, the other option I found thet can work well is putting the box at the back of the boot, facing forwards ( Some Subs Seem to like a bit of free-air infront of them)

From memory it takes around 7-8 Meters for a Bass wave to 'mature', the interesting part is if you walk round the car with the stereo on, you should notice the most bass 2-4M infront of the car, thats the sweet spot, where the bass wav has fully matured, confirming the bass is indeed being reflected forwards

Not a personal fan of ply for boxes but with a fusion sub he should be fairly right, just get the thickest stuff they got

EDIT: I got loads of info from a book called 'the loudspeaker design cookbook', covers just about everything without needing the phd

borrowed from the Public library, very handy

Edited January 26, 2011 by BundyBear

[KezR33]

Buy a better sub. Fusion sucks. 200rms is pathetc.

[Johny Bravo]

That was my thoughts Kez, but the speakers are great! I'll just do what i can to improve them and be done with it. Was blasting the sub yesterday and today and it seems better then i remember. Oh well it will do. I think i might put some better sound deadning inside the box after i seal all the edges with something.

Cheers for the feedback.

Kurt

[BundyBear]

Yea Fusion gear is a bit average, but 200W rms is far from pathetic (although I doubt most of Fusions Power figures)

I think sealing the box will be half ya battle,

There are proper sound-deadening 'pads' that go behind the sub in the box now and give good results ( might end up costing more the a quality sub though)

cheers

Bundy

[Nanogrip]

I think you have to "break in" the sub for a while before you can blast it.  To break it in, you have to play the sub at low volumes for a total of... I forgot how many hours, but 40hrs popped into my head.

If the sub box had leaks, then you can hear whistling or fooshing noise, too small of a box will also hinder it.  Type of box also affects how the sub gives you bass so see if your box is right for the sub.  Ah, also the bass frequency, if it is set too low, then you won't hear it, but feel it of course.  Try setting it to a more punchier bass to see if it helps, such as in the 80Hz or higher.

[Johny Bravo]

Gonna retune it this arvo, should make some difference, been playing it a bit the last three days and it seems to be getting better. I'll get hold of some stuff to seal the inside edges and i'll layer the inside with sound deadner later down the track.

The box is the right size for the sub, i made sure of that when i purchased it.

Cheers fulla's will let ya know how i go.

Kurt

[GTRPowa]

Stop.

Turn the sub around and face it backwards.

Go.

Breaking in sub's is a past time for general subs. While it could spark an argument on a moot point, it's not what's causing you your shit bass in this instance. Often it's phasing mate, sometimes turning the sub around, move it left/right/back/forward is all you need. Serious, top end systems, have adjustable phasing on every speaker to ensure you get hit with the right frequencies at the right time.

You can always test voltage at the amps terminals, but if you're using more than a 12 gauge cable with that setup, again it's not the cause of the shit bass.

Cross the sub over at around 70-80Hz, because of the shallow Q on the crossover, you'll still hear 160Hz coming out at 80Hz setting.

Now if your headunit has a high pass filter (take all bass out of the speakers) then use it. If it doesn't, my trick is to turn the amp right up (dont use bass enhancers, just turn the gain to max) - Then at the headunit, turn your sub to max, then start lowering your "Bass" in the headunit. This will kill all bass in the speakers (which if they arent phased with the sub, can cencel most of the bass from the sub) and just give you bass from the sub.

[Johny Bravo]

Didn't do anything this arvo. But will get onto it. Cheers for the feedback.

Kurt

[conan7772]

I'd put a capacitor in for sure with all that power.

Made a huge difference in my car.

My headlights used to dim to the music before, not anymore.

The bass immediately was cleaner, smooth and punchy.

Also, are all your power cables nice and thick 8-10mm , not to mention speaker cabling should be 3-4mm min.

Edited January 29, 2011 by conan7772

[t_revz]

i dont think a cap is the solution to this. his amp is only 300w. ive ran my 750w + 700w amps at full stick for years, and while the lights dipped it still packed a punch. i think a cap is overkill. decent power cables and the amp will see enough power

[Johny Bravo]

its got nice thick cables for the power, can't remember the gauge, im thinking 4? dunno. just bought some aero pro wiring kits from repco. i might try some thicker cables from the amp to the sub though, the speakers are doing fine as they are.

Still haven't done anything yet though. I will one day though.

Cheers

[GTRPowa]

An 8ga kit would even suffice for that amp setup. And cap won't make a difference with that sort of steup either. Same with T_Revz, I'm running a 1000W Mono Alpine without a cap.

If you run thick cabling, (1ga, 2ga, 4ga) you'll see your light's dimming because the cables have less voltage drop under high loads, which means the voltage drop hits the battery, and alternator. Some people run too small of a wiring kit, their light's won't dim, but the voltage drop is still there at the amp, just the cabling takes the difference in voltage instead, which heats it up. I'm running 50mm2 cable, which is between 1 and 2ga, because I want minimal voltage drop at the amp. Make sure your ground cabling is the same size as your power cable. And if you're using 1ga, 2ga, 4ga, you'll want to upgrade the size of the chassis earth that leads from the negative battery terminal to the body of the car. Not that I've seen it myself, but I hear if you don't do this you can cause a type of feedback in the alternator, which will kill the reg.

You can test the seal for your sealed box by pushing the cone of the sub in (not hard, just push it the normal travel it would move while in use) then let go. It should come back out slowly like it's under a vacuum. The quicker the cone comes out, the less sealed the box it. My sub takes a good 3-4 seconds to come out. Anything taking more than 1-2 seconds, consider it sealed to the point where it's not causing the issue.

Have you turned the sub around yet? Do something. lol

[Johny Bravo]

Car is at the mechanics today. I've got nightshift tonight, so i'll have a quick nap tomorro morning and do some investigating for ya's during the day. Was thinking i pull the sub out, remove the cotton ball sound deadner ( really thin shit thats rubbish), you something like silicon (whatever product i need) to seal all the inner edges and then i'll stick some dense sound deadner in there. Any recommendations on the sealer and deadner?

[S4LVA]

How much was the sub and amp? If you after some cheap budget bass maybe sell the fusion stuff on gumtree or something and get this set from JB.

http://www.jbhifi.com.au/car-sound-gps-navigation/sub-woofers/cadence/600-watt-sub-amp-combo-sku-52575/

They did that pack for $220 for me so you should be able to get something similar. I downgraded from an Earthquake 15" DBXI-D in my old crappy commodore to the cheap cadence pack in my skyline and Im more than happy with the bass,

I wasnt after much bass im running the little amp about 3/5 of the way up and its enough for me. You can listen to it at jb youll be pretty impressed for $220 Sub and amp.