smooth enclosure

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http://http://www.stevemeadedesigns.com/board/topic/98191-spl-gains-updates-on-page-16-slot-flares/


different forum, sorry guys but this guy did a bunch of experiments, and gained half a db by adding printing vinyl to the interior of his enclosure (not perfectly either). I'm sure there's something way more efficient, not to mention I don't even know what printing vinyl is.

just curious that's all, half a db is quite a bit when you're extracting all you can.

ps I realize I won't be able to hear the difference. I'm just curious.
 

Rundmaus

Member
2005-08-21 10:46 pm
half a db is quite a bit when you're extracting all you can.

According to the link you posted, the 'spl gain' is 0.4dB. That's 0.1dB less than the reported value for folding the sun visors down. :eek::eek::eek:

All the 'spl gains' listed are of a magnitude that is easily reached by moving the probably cheap, non calibrated microphone when opening/closing the door. And probably well within measurement errors. I wouldn't be surprised if repeating a measurement without changing anything would yield gains or losses in the 1dB range.

The ******** factor rapidly approaches 1.0 here. To be understood as a fraction, therefore complete ********.

Rundmaus

EDIT: ******** := male-cow-excrements

Dear Mods, I NEED THAT DAMN WORD! :rolleyes:
 
According to the link you posted, the 'spl gain' is 0.4dB. That's 0.1dB less than the reported value for folding the sun visors down. :eek::eek::eek:

All the 'spl gains' listed are of a magnitude that is easily reached by moving the probably cheap, non calibrated microphone when opening/closing the door. And probably well within measurement errors. I wouldn't be surprised if repeating a measurement without changing anything would yield gains or losses in the 1dB range.
Exactly right.
In addition, the 55 Hz "burp box" only showed dB results, no frequency graphs.

Additional distortion reads higher, a shiny interior will allow more upper harmonic distortion to bounce through the port.

Flaring the port was a good improvement which would actually make the sub sound better, unlike a shiny interior which would sound worse.
 

turbodawg

Member
2004-02-13 12:51 am
Half a dB is barely noticeable to the human ear.

You guys are funny. The guy in that thread picked up over 10db's from misc small tweaks. Yes, obviously it's an spl application..........that's a "thing" in car audio.

One think I've learned from my projects in home audio, car audio, and pro audio, not every group knows everything and there's things that can be learned and applied elsewhere.
 

Rundmaus

Member
2005-08-21 10:46 pm
Yes, obviously it's an spl application..........that's a "thing" in car audio.

In car audio as 'a technical means to enjoy high quality music while driving in a car', there are "things", surely:

* good frequency response
* low distortion

The importance of SPL is somewhere down at 'sufficently loud, but not ear-damaging'.

For some dumb-*** car audio making rattling oomph-oomph-tzzz noises while passing by, there is only one thing:

* SPL

Guess which one has a place in an audio forum....

Rundmaus
 
In car audio as 'a technical means to enjoy high quality music while driving in a car', there are "things", surely:

* good frequency response
* low distortion

The importance of SPL is somewhere down at 'sufficently loud, but not ear-damaging'.

For some dumb-*** car audio making rattling oomph-oomph-tzzz noises while passing by, there is only one thing:

* SPL

Guess which one has a place in an audio forum....

Rundmaus

Wow, condescending much?
 
anyways, thoughts on how to make an enclosure as smooth, and an non porous as possible?

If you really want smooth and non porous as possible, make it from metal and polish it up. It's already been mentioned before that smooth isn't necessarily the endgame here though, a strong, stiff box will probably do a lot more for you than a smooth enclosure interior, and there is definitely a point of diminishing returns on both fronts. But if you are really serious about this you could make the box out of thick reinforced steel, polish the interior, and brace well in the direction of airflow. And try to keep your ports short, the area of most velocity will be the area with the most losses. (Ports should also be large diameter and flared, which is somewhat of a contradiction to keeping them short, but a good balance can be found wrt enclosure volume and port size.)

If you want to research this on your own, look up Reynolds number and investigate how that applies to audio. You won't get much help on these topics from forums since the car audio guys (like the link you posted) tend to be trial and error more than research, and the home and pro audio guys simply don't care much about friction effects since the gains are fractional and hard to come by - in other words not worth losing sleep over.
 
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