Does distance from door change midbass?

[The Camry]

I made a mdf baffle today. Dropped my speaker in it. installed it in the door. Lost all my midbass.

took it out. Put my plastic baffle back in. Got midbass back //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Biggest difference is. Mdf bracket leaves the speaker about 3/4 of an inch from flush with metal. and the plastic bracket holds the speaker 2-3 inches from the metal. Could the speaker being a distance from the chamber of the door, be causing me a gain in midbass and vice versa?

or did i just screw up and prob leave space between the mdf bracket and the door and have a little air escape. It couldnt have been much.

Can that really cause that much of a difference???

Plastic bracket ^

Click to read more...

 

[winkychevelle 10+ year member]

Put foam around the speaker to seal it to the plastic door panel

 

[hispls 5,000+ posts]

More likely it's how tight things are. Most folks use modeling clay or other substances to COMPLETELY seal off the front from the rear of a midrange.

 

[The Camry]

Well thats what my plan was. That was my next step but it sounded so horrible from the mdf that i just threw the plastic bracket back on. Didnt want to go through the effort of sealing it with clay and then having it sound terrible, and then having to take it all off.

 

[Umbra]

I can tell you the mid bass comes largely from the enclosure, or lack thereof. My component speakers were seriously lacking in midbass, until I fully treated the doors. Now the midbass is easily 5-10x stronger.

I had followed a bunch of guides. @keep_hope_alive has done a bunch of build logs, I think the one I spent the most time studying was an old Accord build log. Here's a newer one with improved strategies for the door:

http://www.caraudio.com/forums/car-...14-accord-sport-sq-build-keep_hope_alive.html

 

[keep_hope_alive Premium Member]

the gap between the speaker and the door panel is the culprit. the door panel is the speaker front baffle in most cars. midbass from the rear of the cone cancels with midbass from the front of the cone when the speaker isn't sealed to the door panel (or if the doors are fully sealed).

 

[The Camry]

Hm, Alright ill make another bracket and glue them together tomorrow. Try it again. Should help.

 

[keep_hope_alive Premium Member]

weatherstripping foam around the front of the speaker basket to seal against the door panel is what you need as well.

 

[The Camry]

OK thank you!

You seem to be the guy to chime in on every thread which btw im very greatful for. So i have a few question on different things.

What db should i make test tones? -3 -6? Is there a easy way to make a test tone or a site you know with premade mp3s.

What is the safe zone for playing with mid/tweet crossover point. Like 3 to 5 k?

What have you noticed about different crossover points? Are some things more pronounced or what exactly makes crossover points important for mids/highs.

is there a way to know what your tweeter is capable of. Spec sheet on my tweeter says 2-23k. Hertz ET 26.5 but obviously you never play the extremes, whats a safe buffer?

If for now i run half active. Mids LP at 3.5khz active at 24 db slope. Tweets 3.5 khz Hp on passive x-over at 12db slope. How exactly does that roll off point matter? Im having a hard time visualizing and grasping the concept of different speakers attenuating frequencies. Will i end up missing some frequencies?

Sorry to ask so much, Just curious and i like to learn as much as i can.

 

[keep_hope_alive Premium Member]

asking questions is great and that's why forums are here.

i only use test tones for setting gains. if i need to evaluate crossover points i use pink noise and an RTA. you can get RTA apps for your phone (Audio Tools for Apple or Audio Tool for Android).

each tweeter has a recommended frequency range and the crossover slope determines what safe ranges are. steeper slopes let you play lower.

the woofer is a major player in determining the best crossover point. it will roll-off due to being off-axis. if it rolls off above 3kHz then you'll need to push the crossover point on the tweeter lower to match. as you force a tweeter to play lower it will distort sooner.

a shallow slope takes longer to attenuate. the slope is literal - 12dB down when you are an octave lower (octave is halving or doubling of frequency).

check out these graphs

http://www.rane.com/note160.html

Crossovers

 

[The Camry]

How exactly do i use an RTA? just run the woofer only, in full range mode and see at what frequency sound starts to drop im assuming?

i know you cant look at the frequency response curves the manufacture give you because thats only 1Watt at 1 meter and it changes drastically when you install it in a car.

Where it starts to attenuate is where you cross the tweeter and woofer. going higher if it sounds better to my ear but never lower than that point.

Am i on the right track?

 

[keep_hope_alive Premium Member]

play the woofers full range, one at a time, and note roll-off. it may be different left vs right but left should be worse (from driver's seat). use natural roll-off as the crossover point - both high and low.

frequency response curves from the factory are useless once you have them installed in a car door.

 

[The Camry]

So 3k looks gold which is exactly where the passive crossover is set...

 

[keep_hope_alive Premium Member]

ideally, you'd use an EQ to tame 800-2500Hz 1/3 octave bands to match up with the adjacent bands and try again. then you could adjust the crossover point over a wider range which gives more control.

 

[The Camry]

On another note. If i sit in the front seats. certain frequencies hurt my ears. Could be those 800-2500Hz being too high. Though when i was sit in the backseats. That ear hurting goes away instantly. Its buttery and beautiful sounding. Why is that or rather...could be an off axis vs on axis response. Something being too peaky?