Not quite as powerful as i would like

[Howard]

I don't think there's any way in hell that positioning is causing cancellation.

There could be some nulls in the response because of the room, though. Can you try moving one sub into a corner and then the second sub somewhere along an opposing wall? For example, if we're using your diagram, move the green sub to the left corner and the magenta sub close to the midpoint of the right wall.

 

[s44]

Incidentally, have you updated your AVR to the newest firmware?

 

[Rio Rebel]

Subwoofers were created because lower frequencies need more power for the same volume. To get extremely low sounds to be audible, you have to push a lot more air. That means you either have to have a larger speaker (hence the popularity of 12" subs), or more power - and the lower the sound, the more power needed.

Sometimes, you hear a sub do seemingly amazing things despite being in a smaller box. By putting a larger amplifier on an 8" sub, you can get some very acceptable performance. But even then, you generally aren't getting the REALLY low sounds, like the rumble of a fire or the deepest part of an explosion. What you generally get is a very powerful emphasis on the low-but-not-ultralow sounds. In theory, you can make any speaker play low enough with enough power going into it, but in practicality, there are limits to what you can do.

Some people will point to a well-made 8" sub, like Def Tech's SuperCube, and say I don't know what I'm talking about. But those are the exception, not the rule, and you pay handsomely for them...and you still lack some of the ultralows, even with the SuperCube.

You will probably need to spend $250 or more to get what you want. I am very happy with the H100, which can be had for about $250. The subs listed by Yoyo are well reviewed and generally thought to be better than the H100, and I understand that Dayton now makes a 12" designed by Dr. Hsu that is supposed to be a great value in the $200-250 range as well. You can, of course, pay more and get even more performance, but your money is no longer buying more range or volume at that point...more of a tighter, "cleaner" sound.

 

[Noubourne]

Originally posted by: Howard
I don't think there's any way in hell that positioning is causing cancellation.

There could be some nulls in the response because of the room, though. Can you try moving one sub into a corner and then the second sub somewhere along an opposing wall? For example, if we're using your diagram, move the green sub to the left corner and the magenta sub close to the midpoint of the right wall.

Why would you recommend placing the sub in the corner? That's a recipe for creating standing waves. Most advice on sub placement for best results says that your sub should not be an equal distance from any two surfaces - wall/ceiling/floor.

I would agree with your suggestion that they should have different placement - IF he insists on using both - but quite frankly, I'd ditch the second sub as it is unlikely to improve his results. You can't improve your audio system performance by adding a crap sub to the mix, and certainly not without proper calibration and EQ.

I suspect he had both placement and output issues when he started and then added the second sub to try to compensate for it. The placement can probably be fixed with the crawl test. The output issue requires either a better sub - or a more optimal listening space.

 

[Howard]

Originally posted by: Noubourne

Originally posted by: Howard
I don't think there's any way in hell that positioning is causing cancellation.

There could be some nulls in the response because of the room, though. Can you try moving one sub into a corner and then the second sub somewhere along an opposing wall? For example, if we're using your diagram, move the green sub to the left corner and the magenta sub close to the midpoint of the right wall.

Why would you recommend placing the sub in the corner? That's a recipe for creating standing waves. Most advice on sub placement for best results says that your sub should not be an equal distance from any two surfaces - wall/ceiling/floor.

I would agree with your suggestion that they should have different placement - IF he insists on using both - but quite frankly, I'd ditch the second sub as it is unlikely to improve his results. You can't improve your audio system performance by adding a crap sub to the mix, and certainly not without proper calibration and EQ.

I suspect he had both placement and output issues when he started and then added the second sub to try to compensate for it. The placement can probably be fixed with the crawl test. The output issue requires either a better sub - or a more optimal listening space.

I wouldn't ordinarily recommend placing a sub in a corner, but the second sub will help smooth the response even if minimal or no EQ is applied. A second sub can only help matters as long as 1) it's not ridiculously far from the first sub and listening position and 2) it's not extremely inferior. Please see http://www.mehlau.net/audio/multisub_geddes/

 

[CallMeJoe]

If you check the specs, the HK is rated 50 W RMS with all seven channels driven vs. two channels for the Onkyo. Stereo, the AVR254 is 65 W. Any difference you hear is, as others here have said, due to speakers and subwoofer.

 

[Rio Rebel]

And HK rates power much more conservatively than most consumer brands.

 

[vi edit]

Originally posted by: Rio Rebel
And HK rates power much more conservatively than most consumer brands.

Yeh, they'll usually say something like 50w +30w on demand. They rate the baseline, many others rate peak use.

 

[cheesehead]

Originally posted by: kgokal

Originally posted by: Rubycon
If rumbling lows tickles your fancy you don't want a polk subwoofer.

Any recommendations in the $200's?

Yes.

Find a used professional rackmount power amp - an old Mackie for preference, but anything (like my $50 Audio Centron 1600) will do.

Buy a subwoofer driver. For about $130, you can get a Dayton RSS270 12" sub, which is pretty good.

Then spend the remaining $20 on a sheet of MDF to build the box. Adding some pillow batting can help to reduce internal resonances.

 

[cheesehead]

Originally posted by: Rio Rebel
Subwoofers were created because lower frequencies need more power for the same volume. To get extremely low sounds to be audible, you have to push a lot more air. That means you either have to have a larger speaker (hence the popularity of 12" subs), or more power - and the lower the sound, the more power needed.

I'm just a hobbyist, but I think you've got only half the story.

The efficiency of a speaker - how many dBs it makes per watt - is directly linked to the moving mass (voice coil, cone, and suspension.) Tweeters often have tiny domes with nearly no mass at all, making 97dB/1w possible.

However, moving mass is inversely linked with the resonant frequency of the woofer. Between their heavy cones and gargantuan coils the average speaker has quite a lot of mass, and as such a very low resonant frequency. A speaker with less mass but the same excursion and power handling would have a higher resonant frequency, and not produce the same deep bass.

However, if you have a truly gargantuan driver - say, one of those 18" B&C units - you can have your cake and eat it, too. You'll still have a huge coil and heavy cone, but because the cone is much larger, you move more air with each stroke. Of course, these drivers cost a huge amount of money, but one could always dream....

Originally posted by: Rio Rebel
Sometimes, you hear a sub do seemingly amazing things despite being in a smaller box. By putting a larger amplifier on an 8" sub, you can get some very acceptable performance. But even then, you generally aren't getting the REALLY low sounds, like the rumble of a fire or the deepest part of an explosion. What you generally get is a very powerful emphasis on the low-but-not-ultralow sounds. In theory, you can make any speaker play low enough with enough power going into it, but in practicality, there are limits to what you can do.

You can get response down to 20hz - lower than the majority of $500+ subwoofers - out of a pair of Beyerdynamic DT770s with tiny little drivers.

Noise is roughly a function of SPL = air volume * frequency. Tweeters need only move tiny amounts of air 2,000 times per second, wheras subs need to move huge amounts of air 20 times per second.

The problem with 8" subs is that it's generally easier and cheaper to make a 10" sub that moves a little than an 8" sub that moves a lot. As such, the latter are generally quite pricey, as bargain-oriented manufacturers would use the more cost-effective 10" driver every time.

 

[Noubourne]

Originally posted by: HowardI wouldn't ordinarily recommend placing a sub in a corner, but the second sub will help smooth the response even if minimal or no EQ is applied. A second sub can only help matters as long as 1) it's not ridiculously far from the first sub and listening position and 2) it's not extremely inferior. Please see http://www.mehlau.net/audio/multisub_geddes/

In this situation, I think it's bad advice to tell him to put it in the corner.

It's also blatantly obvious that he has nothing to measure FR with - not even a Radio Shack SPL meter - much less the equipment that Dr. Geddy recommends for use in calibrating a multiple sub setup.

Also, Dr. Geddy's opinions on the subject are not exactly accepted in the industry - and I'm not saying his methods don't work, but they certainly are not an industry standard - or even widely employed among any population of enthusiasts, custom installers or otherwise. In fact, he's pretty much alone in his opinions at this point. Also, he employs varying crossovers to accomplish his goals (among other things), with the subwoofers DESIGNED from the ground up to handle specific frequencies.

The OP hasn't invested as much in his entire system as he would have to invest in the recommended FR measurement equipment recommended by Dr. Geddy. He's using a couple of HTIB subs and isn't even quite sure what each of them is capable of - much less designed for.

You're applying highly specialized and advanced custom installation methods to a situation that calls for some of the most basic trial and error testing (the crawl test). The advice does not match the problem posed by the original poster.

I think he should start with the crawl test with one sub, and then move on from there. If someone asks you what is 2+2, you start by applying basic math. Only if they are unsatisfied with the result of "4" should you launch into a discussion of advanced existential philosophy. That's just my 4 cents.