low (22Hz) port tuning in real world trunk applications

[Rashaddd 5,000+ posts]

If I had the space, I'd either port these at 35hz ish or at 20hz ish, and It'd be a hell of a hard choice.

Once you experience serious pressure at the 15-20hz range, it can be very addicting and pleasing, and porting at 20hz would just be ridiculous down there compared to 30-35hz

 

[Immacomputer 10+ year member]

You must have a weak *** front stage //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

It's not too loud but it can get louder than what my ears want to hear without running out of steam. I'm running two AA poly mids and Seas neo tweeters active off of an Avionixx amp that does about 110rms a channel.

 

[MikeyB 5,000+ posts]

I was listening to a blues song the other day that had a constant foot tapping against an old wood floor. There was a nice resonance that dug down very deep and it made my car cabin area appear to be much larger due to the apparent low resonance of the floor. That subtle content (I believe it was from like 18-21hz or so?) added detail that I was not able to get from listening to the track with my headphones that only get down to around 30hz before starting to crap out.

Thats what Im talkin about!^//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[mlstrass 5,000+ posts]

It's not too loud but it can get louder than what my ears want to hear without running out of steam. I'm running two AA poly mids and Seas neo tweeters active off of an Avionixx amp that does about 110rms a channel.

that should be able to keep up no problem then. I run 2 AA mids per door with Alpine tweets now, ran Vifa's for a long time and tried the Neo's also. I've metered at 149 and my front stage keeps up no problem.

I only push 45watts to each mid and around 50 to the tweeters.

Active is SO nice isn't it. Being able to tweak things the way you want and try out new speakers anytime. How low you crossing the mids?

 

[Immacomputer 10+ year member]

that should be able to keep up no problem then. I run 2 AA mids per door with Alpine tweets now, ran Vifa's for a long time and tried the Neo's also. I've metered at 149 and my front stage keeps up no problem.
I only push 45watts to each mid and around 50 to the tweeters.

Active is SO nice isn't it. Being able to tweak things the way you want and try out new speakers anytime. How low you crossing the mids?

Well when I say "keep up" I mean that the output stays consistent and balanced with the mids/highs. The problem is that my ear-pain tolerance is much lower for the higher frequencies and so with them at full tilt, I want them no louder but I could keep cranking the sub all day. That removes the balance and even though I can hear the mids and highs just fine, it's just not balanced anymore and its peaky from about 100hz and below. If I had to guess at random without being on a TL, I would say it only does around 135-137 full tilt in the bass range getting about 100 watts. Nothing crazy but my front stage can't do 135dBs across the spectrum!

I have the mids crossed over at 125hz @ 12dB/oct due to some nasty rattles I get if I cross over any lower. The sub gives itself away though since I have it crossed over at 100hz @ 18dB/oct. It sounds much better if I cross them over at 63 @ 12dB with the sub at 40 @ 6dB but I loose a ton of output because I can't turn it up without my doors pissing me off. They can get down that low but I just can't handle listening to it at high volumes like that.

 

[Haunz 10+ year member]

I suppose someone should mention that there isn't much point tuning to 20hz if your sub has an FS of 35hz... //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[mrogowski 5,000+ posts]

Absolutely. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[Immacomputer 10+ year member]

I suppose someone should mention that there isn't much point tuning to 20hz if your sub has an FS of 35hz... //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Well, I wouldn't worry about the FS as much as I would worry about Q values. It's more than possible to get a speaker to play well below its free air resonance and it is possible to lower its resonance by the enclosure but you wouldn't be using a standard ported enclosure. You would have to move into the mass loaded transmission line realm... that would still involve tuning in the 20hz range so it's applicable. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[MikeyB 5,000+ posts]

^ This guy knows his stuff //content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif

 

[mcsoul 10+ year member]

^ This guy knows his stuff //content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif

x2.

I'm going to have to show my stupidity and ask if taking out

my 6x9's and leaving the holes open creates a quasi-6th-order

bandpass effect resulting in a peak starting around 50 Hz and

peaking at 100hz? Thus skewing my flat response I planned

so carefully for.

 

[helotaxi 5,000+ posts]

Like I said the RIGHT tuning for the sub. Everyone here is talking in generalities. But for a frequency to mean anything it has to be in relation to a given driver and enclosure volume. A high tuning for one driver might be just right or even too low for another.

The cabin gain of the car is going to generate a response peak. Nothing you can do about that other than go with a low Q sealed enclosure that fully relies on the cabin gain to bring the low freq response back up to reference level. Tuning a ported sub for a flat free-air response though doesn't exacerbate that peak. Mistuning the enclosure resulting in a response peak free air and then adding in the cabin gain over accentuates the frequencies right around the peak. IMO the overall sound that you're left with is annoying. The subs only really play a very small range of freqs and those are overrepresented.

 

[helotaxi 5,000+ posts]

x2.
I'm going to have to show my stupidity and ask if taking out

my 6x9's and leaving the holes open creates a quasi-6th-order

bandpass effect resulting in a peak starting around 50 Hz and

peaking at 100hz? Thus skewing my flat response I planned

so carefully for.

Think about that one for a second. The imagine the effect of a 1/32" long port... The car itself has an effect, but that is to boost the lower frequencies with the level of boost inverse to the frequency.

 

[mcsoul 10+ year member]

Think about that one for a second. The imagine the effect of a 1/32" long port... The car itself has an effect, but that is to boost the lower frequencies with the level of boost inverse to the frequency.

Have you ever LP'd at 60Hz or less? How does that sound?

I would imagine a lot is missing in many bass notes.

Edit:

Thank you for your input into this thread, I've learned a lot.

 

[audioholic 5,000+ posts]

Have you ever LP'd at 60Hz or less? How does that sound?I would imagine a lot is missing in many bass notes.

You SHOULD LP your subs at 60hz, if you have the setup to allow it. That being strong enough misbass to allow authoritative presence down to 60hz. That is exactly what everyone should be striving for. Its the exact recipe for 'up front bass'. But far too many people think 60-120hz is SUPPOSE to eminate from your subwoofer.

 

[iamamp3pimp 5,000+ posts]

it sounds really nice in my car

subs lp @ 40 HZ and the mids crossed at 60 hz

sounds great.

not very loud though