50+ Hz sounds like ***

[hatedonmostly 5,000+ posts]

So last weekend, I finished the blowthrough in my truck. I was running only two of four subs for a while since I had a sub that blew. When I had the two installed, the SQ was incredible, the response was near flat and played down to the mid 20's to the 60's no problem at all.

Now that I have all four subs installed, the high end (50+) sounds like ***. The lows are killer, but it sounds so horrible that I can't listen to anything that has notes that high. I don't know why adding two subs would do that.

However, here's the part that has me baffled the most. When playing low notes, the subs move normally and have plenty of excursion. When playing the higher notes, the subs appear to be out of phase, instead of going out, they go in. //content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif

The subs are RE Audio RE 12's, which have a "optimal" ported box size of 1.5 cubes @ 35. Each of my subs have 1.5 cubes and the enclosure is tuned to 33. I don't see why the box would be too big, or the tuning would be too low to have such a negative affect.

Amp settings are:

SSF set to ~20 Hz

LPF set to ~80 Hz

I shouldn't have to tell you guys that I have the gain set correctly and the bass boost off. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

This one has got me pretty baffled. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Click to read more...

 

[I Like Waffle]

subs ****

 

[power-fanatic07 5,000+ posts]

Sounds like it's tuned too low, probably something like 26-30 hz and when you tune that low it cuts off the high side response that most songs have.

 

[Digital Designs 10+ year member]

Is the box you put the 2 in tuned different or a different size than the box you have all 4 subs in?

 

[hatedonmostly 5,000+ posts]

Sounds like it's tuned too low, probably something like 26-30 hz and when you tune that low it cuts off the high side response that most songs have.

I thought by tuning lower you'd get a flatter response? I think it actually might be tuned considerably lower than 33, now that I think about it.

Is the box you put the 2 in tuned different or a different size than the box you have all 4 subs in?

Two separate chambers, it's a clamshell.

 

[hatedonmostly 5,000+ posts]

up once more before i start studying

 

[l7runner 10+ year member]

make sure they are all wired in phase...you can use a 9 volt battery

 

[Johnny Law.Lulz 5,000+ posts]

lulz. I guess i have a chance tobe louder still.

 

[hatedonmostly 5,000+ posts]

make sure they are all wired in phase...you can use a 9 volt battery

They are all in phase.

lulz. I guess i have a chance tobe louder still.

//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[power-fanatic07 5,000+ posts]

lulz. I guess i have a chance tobe louder still.

You started a build log with no pics of any kind. He wins

 

[hatedonmostly 5,000+ posts]

You started a build log with no pics of any kind. He wins

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[T3mpest 10+ year member]

I'm only going to say this one more time on this forum before I swear to god I will build a thread and post it in big letters.. PLAYING A SUB ABOVE TUNING DOES NOT REDUCE IT's OUTPUT!!!!!!!!!!!!!!!!!!! Below tuning a sub and port are out of phase with one another hence a 24db/octave roll off. Above tuning, the port isn't being excited since your no longer near the resonance frequency of the air mass. The sub acts as a sealed box of the same internal volume.. You can tune a sub as low as you want and still have it play higher notes. Below tuning is the issue, above nothing happens. Shit my home sub is tuned to 16hz ffs and I run it up to 80hz with no problems lol I've let it play tone as high as 1.2k just messing around, no issues.. Anyway there is a lot of cabin gain down low so it's pretty easy to have a low tuned box simply have far too much low end for your midbasses, or even your subs keep up at 80hz+. I think that's where the myth of playign above tuning originates. That and the fact that newbs assume that since a sub doesn't behave properly above tuning, it must not behave properly above it either.

Anyway how much port area do you have? I've heard of this happening one other time and most people said it was too much port area, although I'm disinclined to beleive that's the case necessarily. Anyway, check your box for air leaks and double check your phasing on all the woofers as well as your wiring. That would be where i woudl start at least. Also you said it's a clamshell, so that means the subs are facing one another? Try disconnecting one side of them fi you can and see if it still does it. You might be getting some wierd loading from the subs facing each other.

Also try and verify your box tuning anyway. Download tones and look for your minimum excurison point. Get a set of tones say 25-50hz, as many as you can and play each tone recorded at the same volume and at the same hu level. The tone that makes the sub move least is your actual tuning frequency. You should see increased excurison below this point. (turn you ssf off to do this and don't go stupid on your volume knob. Start with 45hz or so, get the sub moving enough to be able to gauge how far it's going, then keep going down from there in frequency and compare. Also, you can then check and see at what frequency your subs start to act strangely

 

[hatedonmostly 5,000+ posts]

I'm only going to say this one more time on this forum before I swear to god I will build a thread and post it in big letters.. PLAYING A SUB ABOVE TUNING DOES NOT REDUCE IT's OUTPUT!!!!!!!!!!!!!!!!!!! Below tuning a sub and port are out of phase with one another hence a 24db/octave roll off. Above tuning, the port isn't being excited since your no longer near the resonance frequency of the air mass. The sub acts as a sealed box of the same internal volume.. You can tune a sub as low as you want and still have it play higher notes. Below tuning is the issue, above nothing happens. Shit my home sub is tuned to 16hz ffs and I run it up to 80hz with no problems lol I've let it play tone as high as 1.2k just messing around, no issues.. Anyway there is a lot of cabin gain down low so it's pretty easy to have a low tuned box simply have far too much low end for your midbasses, or even your subs keep up at 80hz+. I think that's where the myth of playign above tuning originates. That and the fact that newbs assume that since a sub doesn't behave properly above tuning, it must not behave properly above it either.
Anyway how much port area do you have? I've heard of this happening one other time and most people said it was too much port area, although I'm disinclined to beleive that's the case necessarily. Anyway, check your box for air leaks and double check your phasing on all the woofers as well as your wiring. That would be where i woudl start at least. Also you said it's a clamshell, so that means the subs are facing one another? Try disconnecting one side of them fi you can and see if it still does it. You might be getting some wierd loading from the subs facing each other.

Also try and verify your box tuning anyway. Download tones and look for your minimum excurison point. Get a set of tones say 25-50hz, as many as you can and play each tone recorded at the same volume and at the same hu level. The tone that makes the sub move least is your actual tuning frequency. You should see increased excurison below this point. (turn you ssf off to do this and don't go stupid on your volume knob. Start with 45hz or so, get the sub moving enough to be able to gauge how far it's going, then keep going down from there in frequency and compare. Also, you can then check and see at what frequency your subs start to act strangely

Yeah, I always though playing below tuning was the issue but in reality I play below tuning fine and above is where I have issues...

I have two chambers at 3.0 cubes each. The port is 13.5x3, so 13.5 sq. in. per cube. Sounds reasonable... No air leaks anywhere as far as I can tell, I'll check phasing again but like I said, it plays anywhere below 50 fine, but above that there is issues, which is odd.

Here is a picture. They aren't facing directly at each other or anything...

Before, when I didn't have issues, only the two left subs were playing. I will try disconnecting just one side. But if that's the case, what can I do? //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Cool, I'll try this.

 

[hatedonmostly 5,000+ posts]

Any more suggestions?

 

[T3mpest 10+ year member]

Try placing something in line with your port that extends further out than the port itself does, just as an experiment. It may lower your tuning slightly, but it may stop your subs from being overloaded, or move the frequency that it occurs out of your needed bandwidth.