DiyMobileAudio.com Car Stereo Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
96 Posts
Discussion Starter · #1 ·
I'm currently running my best tune yet, which sounds 'good'.
I turned on a tone generator and stepped through 10hz at a time, and found 5-6 frequencies between 20hz and 1000hz where the left side perfectly disappears.
Is this a comb filter? A nearside null?
Given that the response as a whole sounds pretty good to me, I was surprised to hear such drastic cancellations.
How do I address this?

Ford Fusion
Factory head unit
Helix mini
Highs: CDT Unity8+
Mids: Stevens SA-6
Xover: 400hz
 

·
Registered
Joined
·
1,983 Posts
What are the frequencies and does the result change with a change in listening position?
 

·
Registered
Joined
·
96 Posts
Discussion Starter · #3 ·
What are the frequencies and does the result change with a change in listening position?
165, 230, 450, 544, etc.
Yes, position absolutely matters.
6" left or right and the cancellation disappears.
I'm at the edge of my understanding here, but doesn't that sound like phase cancellation?
Would adjusting delays by a few ms one way or another move the point of cancellation away from my head?
 

·
Registered
Joined
·
619 Posts
::: Bump :::

Giving this thread a bump, 'cause really interested in learning the answer......
 

·
Registered
Joined
·
3,890 Posts
165, 230, 450, 544, etc.
Yes, position absolutely matters.
6" left or right and the cancellation disappears.
I'm at the edge of my understanding here, but doesn't that sound like phase cancellation?
Would adjusting delays by a few ms one way or another move the point of cancellation away from my head?
The cancellation doesn’t disappear, it will move frequency’s slightly, if you’re lucky when you listen the dips cancel with peaks from different reflective surfaces it’s why location is more important than aim for the most part… but aim can also influence reflections somewhat…
 

·
Registered
Joined
·
1,983 Posts
165, 230, 450, 544, etc.
Yes, position absolutely matters.
6" left or right and the cancellation disappears.
I'm at the edge of my understanding here, but doesn't that sound like phase cancellation?
Would adjusting delays by a few ms one way or another move the point of cancellation away from my head?
Yes - this is cancelation and it can be from direct or reflected sources. It's the reason we can't have nice sound in cars. If you delay one side then you start to get comb filtering at other frequencies based on the distance from the source and comb filtering repeats at regular intervals throughout the frequency coverage of the source.

Sent from my SM-G965U using Tapatalk
 

·
Registered
Joined
·
3,890 Posts
Yes - this is cancelation and it can be from direct or reflected sources. It's the reason we can't have nice sound in cars. If you delay one side then you start to get comb filtering at other frequencies based on the distance from the source and comb filtering repeats at regular intervals throughout the frequency coverage of the source.

Sent from my SM-G965U using Tapatalk
Adding the correct delay removes comb filtering not adds it
 

·
Registered
Joined
·
1,983 Posts
Adding the correct delay removes comb filtering not adds it
I meant to indicate that adding delay to an already time aligned driver creates comb filtering thereby making it the incorrect delay for the distance. You are correct in that adding the correct delay removes comb filtering by making the sounds arrive at the same time (assuming no head transfer function variables.)
 
  • Like
Reactions: dumdum
1 - 8 of 8 Posts
Top