Do I have too much port area?

[eliotz28 10+ year member]

I have 2 dayton ho 10 subwoofers in a 1.35 cu ft enclosure tuned to 28hz. My port is a piece of 4 inch pvc about 29 inches long. My issue is when playing low frequency's I have little to no output the subs are moving but there's very little sound. 50hz is loud 40 hz is half as loud 30hz is almost no output. Do I not have enough port area to properly load the subs? I really cant figure out whats going on.

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[Jeffdachef 5,000+ posts]

I have 2 dayton ho 10 subwoofers in a 1.35 cu ft enclosure tuned to 28hz. My port is a piece of 4 inch pvc about 29 inches long. My issue is when playing low frequency's I have little to no output the subs are moving but there's very little sound. 50hz is loud 40 hz is half as loud 30hz is almost no output. Do I not have enough port area to properly load the subs? I really cant figure out whats going on.

So i'll need a few things

Whats your box's length x width x height

Where is your sub firing in your trunk/house/SUV/truck?

Where is your port firing?

Whats your amplifier's subsonic filter settings?

whats your head unit model number or How are you getting your signal.

 

[eliotz28 10+ year member]

Whats your box's length x width x height

Its a wedge enclosure bottom depth 10 inches top depth 6 inches 14 inches high 32 inches wide these are approximate measurements. the port is external, fires out the side and has 2 bends a 45 out the side and then a 90 down towards the corner.

Where is your sub firing in your trunk/house/SUV/truck?

sub are behind the rear seat of a crew cab chevy firing forward

Where is your port firing?

port fires into the corner/floor on the passenger side subs are on drivers side

Whats your amplifier's subsonic filter settings?

turned all the way down to 15hz

whats your head unit model number or How are you getting your signal.

pioneer avh x3800bhs

 

[BOOMINGRANDPA 5,000+ posts]

yeah I was gonna ask about ss filter so that ain't it but u should set it higher than 15., fast check of your box the #'s look right.. could it just be box is to small to play very low?, could 1 12 be better in that size box?

 

[Jeffdachef 5,000+ posts]

Whats your box's length x width x height
Its a wedge enclosure bottom depth 10 inches top depth 6 inches 14 inches high 32 inches wide these are approximate measurements. the port is external, fires out the side and has 2 bends a 45 out the side and then a 90 down towards the corner.

Where is your sub firing in your trunk/house/SUV/truck?

sub are behind the rear seat of a crew cab chevy firing forward

Where is your port firing?

port fires into the corner/floor on the passenger side subs are on drivers side

Whats your amplifier's subsonic filter settings?

turned all the way down to 15hz

whats your head unit model number or How are you getting your signal.

pioneer avh x3800bhs

Yeah its not enough airspace more than anything. Even when you are tuned low, with lower airspace it shifts the frequency response to the higher notes.

You have to account for how much space the sub takes up as well, not just the port are right around 1 cube tuned to 32~33hz. could be less depending on how much bracing you've done. Essentially you have a close to ideal spl burp box if you shorten the port and tune higher lol. For musical lows, you might want a bit bigger than what dayton's box recommendations call for.

 

[eliotz28 10+ year member]

Im pretty confident I have 1.35 after displacement the box has a small tumor on the side (for lack of a better word) for a little extra airspace. the sub displaces .08 cu a piece. I thought my problem was my head unit but switched to the 3800bhs and there was no change. General consensus on diyma is .66cu ft tuned at 30 hz is ideal for these woofers which was a big part of my reason for choosing them. When playing low test tones I noticed there is almost no air moving in the port compared to the higher tones even tough the woofer is moving.

 

[staan]

.08 cu ? or .8

 

[eliotz28 10+ year member]

.08

 

[Jeffdachef 5,000+ posts]

Im pretty confident I have 1.35 after displacement the box has a small tumor on the side (for lack of a better word) for a little extra airspace. the sub displaces .08 cu a piece. I thought my problem was my head unit but switched to the 3800bhs and there was no change. General consensus on diyma is .66cu ft tuned at 30 hz is ideal for these woofers which was a big part of my reason for choosing them. When playing low test tones I noticed there is almost no air moving in the port compared to the higher tones even tough the woofer is moving.

You can step down to a 3 inch port 16 inches long if you want it musical but as of now, torres calculator and your results dont lie, you built a box not properly tuned to deep lows. Your port per cube is on the higher side and your airspace is on the low side. This is basically a burp box format. If you want to keep the 4 inch port, you need much more airspace. If you want to keep the same box, you need a smaller port.

It cant be 1.35 cubes after displacement, thats completely impossible because your port itself takes up ~ 0.25 cubes of displacement(assuming your port thickness is extremely low) and your net airspace is 1.44. Not sure what you are using to calculate but you might want to switch programs.

2x2x3.14x29= 364.24/1728 = .21 thats with no port thickness accounted for. plus .16 from subs.

 

[eliotz28 10+ year member]

You can step down to a 3 inch port 16 inches long if you want it musical but as of now, torres calculator and your results dont lie, you built a box not properly tuned to deep lows. Your port per cube is on the higher side and your airspace is on the low side. This is basically a burp box format. If you want to keep the 4 inch port, you need much more airspace. If you want to keep the same box, you need a smaller port.

It cant be 1.35 cubes after displacement, thats completely impossible because your port itself takes up ~ 0.25 cubes of displacement(assuming your port thickness is extremely low) and your net airspace is 1.44. Not sure what you are using to calculate but you might want to switch programs.

2x2x3.14x29= 364.24/1728 = .21 thats with no port thickness accounted for. plus .16 from subs.

My port is complely external.

Do you think I will have port noise with a 3 inch aero port? the subs have a low xmax (12mm) but i was worried about port noise so i went with the 4 inch.

its interesting what you said about this being a burp box design because this thing is loud as fuxk at higher frequencies

 

[Jeffdachef 5,000+ posts]

My port is complely external.
Do you think I will have port noise with a 3 inch aero port? the subs have a low xmax (12mm) but i was worried about port noise so i went with the 4 inch.

its interesting what you said about this being a burp box design because this thing is loud as fuxk at higher frequencies

I missed that. I'd still try to shoot for a bit more airspace if you want lows from the sub. If you want to experiment, try shoving 1.2 lbs of poly fill in the box and see the frequency shift.

 

[eliotz28 10+ year member]

I missed that. I'd still try to shoot for a bit more airspace if you want lows from the sub. If you want to experiment, try shoving 1.2 lbs of poly fill in the box and see the frequency shift.

Thanks for your help.

I think i will try the polyfill and a 3" aero port. Im already %40 over daytons recommendations. they recommend .47 cuft ported lol.

 

[Jeffdachef 5,000+ posts]

Thanks for your help.
I think i will try the polyfill and a 3" aero port. Im already %40 over daytons recommendations. they recommend .47 cuft ported lol.

Recommendations is just a starting point and thats in home theater. In a vehicle its completely different due to cabin gain. Due to how small of a cabin a truck is, it doesnt allow for the waveform to develop like it would in a trunk or suv. Hence your higher peak. In order for you to plauly low, youll need a much bigger box tuned lower to shift your peak down lower. Hence you build the box not only custom tailored for the sub but for the vehicle acoustics as well. Something a lot of the home audio guys cant grasp because they are spoiled with a big room with good acoustics.