|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
173.80.184.112
In Reply to: RE: not offset ? posted by tomservo on October 02, 2015 at 13:36:08
I've got a BP4 with a folded rectangular vent which could benefit from a trap to reduce a ~210-220Hz peak - would a 3"ID piece of pvc be able to null it?red trace is the BP4 in question
Karlson Evangelist
Edits: 10/02/15Follow Ups:
Hi Freddyi
The big red peak is an organ pipe resonance, this happens at the 1/2 wavelength, the lowest frequency a pipe or duct open at both ends will resonate at.
The easy way around these with a bp speaker is to use a passive radiator instead of a port as they have no pipe resonance.
If you can get inside the cabinet, you could use another duct or pipe with a closed end to make an absorber at that frequency. I put several of those inside the DTS-10 cabinet at work which do this job.
What you would want to do is attach a pipe with a closed end to the port at it's mid point, make the length a bit more than 1/4 wavelength at the peak frequency. If possible, make it so that you can trim the length based on it's effect on the peak (trial and error measurement). A 2inch diameter plastic water pipe ought to be about right.
Hope that helps
Best,
Tom
Danley Sound Labs
thanks Tom - I might be able to poke a stub pipe "sideways" into the vent -- -Oops! there's a brace in the vent- I'm kinda crippled plus the front chamber is difficult to access.a passive radiator would have been cool.
Geddes used to employ an external vent with lengths "Pan - piped"
Will this fix work with a right angle elbow? What happens if the resonator is placed in the rear chamber? Should any damping be used in the pipe?
here's the rear chamber
Karlson Evangelist
Edits: 10/03/15 10/03/15 10/03/15
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: