Subwoofer Bottom-out

[mafman]

I have just finished setting up my HT system. I am running a mix & match system comprised of a Marantz SR5500 receiver, Polk r30 fronts, Dahlquist centre and sub and JBL surrounds.

The Subwoofer is a QX-100, self powered 8" polypro. cone and aluminum basket driver, BASH 100 watt integrated amp. Volume is adjustable. I've hooked it up to the Sub Out on my receiver, and directly to the LFE input on the sub.
I've set my amp's crossover to 80, and the adjustable crossover settings on the back of my Sub to about the same. Music sounds great so far.

PROBLEM: During playback of many movies, during more bass-heavy scenes, explosions, etc., I get this disconcerting popping sound from the sub. I'm assuming it's bottoming-out, so I have to adjust volume on the sub to compensate.

I am not a bass-crazy listener, but I do like to listen to movies at moderately loud levels. I feel the sub just can't handle the heavier tracks in some movies and am wondering if I can adjust this or should I just go for a bigger sub (10-12"). Is this frequent? Is it a crappy sub? A friend's Energy 8" sub seems to do fine on these tracks.

Thanks for your HELP!

 

[krzywica]

Is the balance on your reciever set to 0 or do you have it cranked up a bit?

 

[krzywica]

What size is your H/T room?

 

[mafman]

Thanks for responding.

If by balance you mean preset volume adjustments within the amp, yes the sub is at 0db.

the room is rectangular about 300sq feet.

The sub has 2 ports at the back which are about 5" from the wall, sufficient clearance from what I've tried.

 

[krzywica]

I looked at the Dahlquist website, hmmm not very helpfull with the specs huh. Did it come with port plugs? That room is'nt very big you would think that sub would sound pretty good. At what frequ range does it start to sputter out? Maybe you are just asking to much of a 100 watt amp?

 

[Dumar]

... During playback of many movies, during more bass-heavy scenes, explosions, etc., I get this disconcerting popping sound from the sub ...

Does this happen when using your DVD player? Are there some bass management adjustments you can make there?

 

[mafman]

Here are the specs, no port plugs. The does not seem to be the problem, the physical limitations of the driver is what would be making the sound, I presume. In regards to bass management, I've followed instructions to spec. With music, it sounds fantastic, very musical sub. Movies played on DVD are just not as punchy as I like them to be, since I have to keep volume down lower on the sub

here are some specs

- 8" polypropylene woofer with cast aluminum basket
- 1 1/2" voice coil
- 100 watt digital BASH amplifier (200 watts peak)
- Phase control
- Variable crossover control
- 35Hz to 150Hz flat
- Stereo line level inputs
- LFE input
- Front panel volume control
- Brass cone feet
- 13.25"H by 14.25"W by 14.75"D
- 1.26 CUF internal volume
- Weight 37lbs

 

[cownd]

Make sure you are not plugging your sub into a standard power bar. If you don't own a high quality line conditioner, plug it straight into the wall.

 

[3db]

sounds to me like you have a placement problem

Subs of all speakers are the one speaker that is most senstiive to room placement and room interaction. On 1st glance, it would appear that you have the sub in a poor location and your compensating my cranking the sub's volume causing it to overwork. Same thing happened to me with my sub.
So I experimented with room placement and found a sweet spot where the pictures are rattling off the walls, the wife is screaming for me to tuern it down and the sub is barely working.

I seriously suggest you try room placement 1st before faulting the sub. Good luck

 

[Buckeyefan 1]

Subs of all speakers are the one speaker that is most senstiive to room placement and room interaction. On 1st glance, it would appear that you have the sub in a poor location and your compensating my cranking the sub's volume causing it to overwork. Same thing happened to me with my sub.
So I experimented with room placement and found a sweet spot where the pictures are rattling off the walls, the wife is screaming for me to tuern it down and the sub is barely working.

I seriously suggest you try room placement 1st before faulting the sub. Good luck

Agree. Try and get that sub in a corner without pictures or things that rattle. If that doesn't work, you may want to start shopping for a larger sub. Personall I don't think an 8" sub would be adequate - regardless of mfg.

 

[Tex-amp]

Its bottom extension is 35Hz that is why is is fine with music but is bottoming out with HT. Turn the volume down. You're asking too much of an 8" driver and 100 watt amp. Have you used a sound meter and set up disc to calibrate your set up?

You also need to turn the crossover on the sub all the way up. A crossover it not a brick wall but a gradual overlapping fade from sub to speakers. You are double processing/filtering the crossover with both the receiver and the sub.

 

[mazersteven]

If you are going to change subwoofers, take a look at Definitive Technology's SuperCubes. www.definitivetech.com
If you are on a budget, take a look at these subwoofers. SVS Subwoofers www.svsubwoofers.com

 

[3db]

Its not over extending onthe really deep stuff; 25 Hz

an lower becuase it can't push those frequencies anyway. Its over extending on the the frequencies it can push; hence the popping. Its over extending because your pushing it too hard because You've probably have the sub set in a room position relative to you such that you are not getting very much bass ; a null

 

[RJB]

Correct me if I'm wrong but I believe the general rule is that if you let the amp do the bass management, as indicated in the original post - x-over set to 80db, you should turn the subs internal x-over off or "subwoofer direct" as some manufacturers call it.

There are lots of articles on bass management on this site that are very educational...

 

[shokhead]

8" is to small for a true sub. OK for added bass but not the deep,loud stuff and not LFE.

 

[RLA]

Hello
Have to agree with the other member's 8" 100 watt sub in a 300-sqft room is way to small And just because the manufacture claims it has a low frequency cut off of 30Hz does not make it A real figure at any usable SPL level.

I would look for a high power long excursion 12" like the Axiom EP-600 or a high power 15" Subwoofer for that room. You can never have enough subwoofer and you gain headroom by having more rather than less

http://www.axiomaudio.com/epicenter600.html

 

[WooHoo]

Correct me if I'm wrong but I believe the general rule is that if you let the amp do the bass management, as indicated in the original post - x-over set to 80db, you should turn the subs internal x-over off or "subwoofer direct" as some manufacturers call it.

There are lots of articles on bass management on this site that are very educational...

I agree with RJB. Setting the crossover on the sub to 80 and the crossover on the amp to 80 is a problem.

 

[mafman]

Thanks for the info guys, I agree, the sub is probably fine for music, just not big enough for any real LFE. I will be looking to upgrade to a 12" tomorrow!

 

[warnerwh]

Thanks for the info guys, I agree, the sub is probably fine for music, just not big enough for any real LFE. I will be looking to upgrade to a 12" tomorrow!

Be careful! Just because a sub has a 12" driver doesn't mean diddly. There's alot more to it than driver size. Many 12" drivers in subs I've seen are very poor imo. Buy used if you have to but buy quality and you'll be happy you did. You're better off with the 10" Rocket sub like reviewed here than many 12" subs. Don't just run out and buy something at the store. Do some research here and on the net. Subs can make or break a home theater system. Specs that most manufacturers give btw are bogus or let's just say they give themselves the benefit of the doubt. There's alot of very good buys in subs and a good one can be had for 4 or 500 if you know what you're doing. Lots of junk at Best Buy and Circuit City compared to what can be had from HSU, VMPS, AV123, M&K and others. Also subs are often offered in kits to save money. These are easy to put together and offer good value. In case you're not familiar, a place called audiogon.com has ads for quality used gear and of course Ebay does too. Sell your little sub and add some money and your home theater experience will improve immensely. Good Luck

 

[mafman]

Well, since the place where I got it will probably allow me to upgrade with little or no penalty, I was going to go with the Dalquist's bigger brother

QX 300S

12 " polypropylene woofer with cast aluminum basket
- 1 1/2" voice coil
- 300 watt digital BASH amplifier (600 watts peak)
- Phase control
- Variable crossover control
- 22Hz to 150Hz flat
- Stereo line level inputs
- LFE input
- Front panel volume control
- Brass cone feet
- 15.5"H by 15.5"W by 17.75"D
- 2.12 CUF internal volume
- Weight 53lbs.

OR the 10", i"m not sure which yet.. 10 " polypropylene woofer with cast aluminum basket
- 1 1/2" voice coil
- 200 watt digital BASH amplifier (400 watts peak)
- Phase control
- Variable crossover control
- 28Hz to 150Hz flat
- Stereo line level inputs
- LFE input
- Front panel volume control
- Brass cone feet
- 14.25"H by 14.25"W by 15.75"D
- 1.95 CUF internal volume
- Weight 44lbs.