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Triticum Agricolam

Port compression and optimization

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tuned


CURRENT SYSTEM:

  • Alternator:
    1. Stock alt on mids/highs
    2. Isolated DC Power 270 SP - Charging @ 16.8v
  • Batteries: (2) XS D1400s
  • Power Cable: Double Runs of 1/0 KNU Kolossus Fleks
  • Headunit: 80-PRS
  • Sub Amp: DC 5.0k
  • Subwoofers: 2 RE MT 15s /PSI dual .7ohm recones
  • Subwoofer Enclosure: 9.1cubes @ 32hz - brutal.
  • Mids & Highs Amp: CT125.4
  • Active Components:
    • Mids RE XXX 6.5c
    • Highs - 3 RE XXX tweeters per side(A pillar)
  • Noise Control: Damplifier Pro all over the cab.

Build Log

If you do business with me please leave feedback here: FEEDBACK THREAD

 
Highest Legal Score: 151.0 db
Highest Musical 30 Second Average: 151.6 db

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Have a way to measure excursion?

Would be nice to show people this difference in excursion with different amounts of port area (above tuning of course).

All he would need is a ruler on the wall, a laser and a piece of reflective tape..(and a camera to film it, or slow shutter speed on the camera)


Thinking is the root of all problems...

You ALWAYS get what you pay for.

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Great tests! Very interesting read.

Always love the work you do. Tuned in! Keep it up man!


Fi Team 18's (4)
Crossfire 16k
Crossfire 400.4 & 800.4
Pioneer AVH-X491bhs
140ah cmax
CES 320's (2)

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So you're saying that tuning at 20 or 50 doesn't make a difference in output below 80hz?

Output above 80 Hz. A 50 Hz tuning it getting close enough it would probably have a effect but 30 Hz vs 40 Hz isn't going to make hardly any difference above 80 Hz.


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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Have a way to measure excursion?

Would be nice to show people this difference in excursion with different amounts of port area (above tuning of course).

All he would need is a ruler on the wall, a laser and a piece of reflective tape..(and a camera to film it, or slow shutter speed on the camera)

There is an even easier way, just make a wedge micrometer:

wedge-micro.gif

This would be cool to test. I'll have to make a micrometer and put the sub back in the box.


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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So you're saying that tuning at 20 or 50 doesn't make a difference in output below 80hz?

As already stated, above 80 Hz.

I hear so many times "I need to tune higher so I can get the higher bass".

More than likely the system has a large peak in the output just above tuning so that all that is heard is the peak, which gives the idea that the upper bass is missing. The proof here would be that upper frequencies do not roll off based on tuning frequency.

The correct idea would be to design a system that didn't have such a large peak in the response.


Current system:

1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s

Previous systems:

2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz.

1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz.

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Is it not true that our ears can begin to localize sounds somewhere around 80hz - 100hz?

If that is true why would you ever want to have your sub covering frequencies up that high?

I cross mine at 63hz typically.


That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals.

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...More than likely the system has a large peak in the output just above tuning so that all that is heard is the peak, which gives the idea that the upper bass is missing. The proof here would be that upper frequencies do not roll off based on tuning frequency.

The correct idea would be to design a system that didn't have such a large peak in the response.....

This x 1,000,000.

The hard part is most of the higher power subs out there have such stiff suspensions its just about impossible to tame their peak in output, especially once cabin gain is added into the mix. Another solution would be to use EQ to tone the peak down, but that comes at a lot of output. Everything is a trade off.


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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Is it not true that our ears can begin to localize sounds somewhere around 80hz - 100hz?

If that is true why would you ever want to have your sub covering frequencies up that high?

I cross mine at 63hz typically.

Yeah it's somewhere in that range. You want flat response to extend past your crossover frequency though. Otherwise the output will drop off too fast and you won't have as smooth of a transition between your subs and mids and you might want. Crossover frequencies aren't a hard cutoff, they are a gradual decline.

I try to run my subs up as high as I can. I want to be just under the point where I can start to tell the sound is coming from behind me. The higher you run your subs the less hard your mids and to work, which reduces distortion and let you run more power if you so desire.


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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