Forums
New posts
Search forums
What's new
New posts
Latest activity
Members
Registered members
Current visitors
Log in
Register
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Audio and Video Talk
Acoustics & Room Treatment
What is killing my 900Hz to 2kHz repsonse?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Help Support AVForums:
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="Rick" data-source="post: 545120" data-attributes="member: 17143"><p>What crossover topology is used Butterworth, LR, Cheb? If it's one with the 6db per octave it's not going to be perfectly flat at the crossover point, probably around 3db down is often seen.</p><p></p><p>What I would do is measure the response of the electrical signal to the speaker, then coming out the crossovers, then unit response and only then room response, like an audit trail otherwise it could be just about anything with guesswork you would battle. I have seen capacitor drift from quality/age in crossovers cause this through phase drift, but you say " No matter how much I move speakers or toe them in and out, the dip remains more or less constant. I've checked the speakers as well and that is not the problem. Their response is very flat in that region. " Flat response is fine but are the two speakers exactly in phase?</p><p></p><p>I think some type of phase interaction between left/right or some kind of multipath distortion from reflection. What is the result if you measure left and right running alone?</p><p></p><p>You need a damper like a felt board you can move around the room when measuring. High frequency sound maybe 5khz and above tends to bend or edge diffract around objects, the higher the fz the more the diffraction, but low fz 900hz blasts around in almost straight lines, so ultimately you are probably looking at phase cancellation from parallel objects/furniture/walls.</p><p></p><p>Look at the wavelengths where you experience the problem and measure the room front to back and side to side to make sure you are not an exact wavelength/half/quarter wall to wall.</p></blockquote><p></p>
[QUOTE="Rick, post: 545120, member: 17143"] What crossover topology is used Butterworth, LR, Cheb? If it's one with the 6db per octave it's not going to be perfectly flat at the crossover point, probably around 3db down is often seen. What I would do is measure the response of the electrical signal to the speaker, then coming out the crossovers, then unit response and only then room response, like an audit trail otherwise it could be just about anything with guesswork you would battle. I have seen capacitor drift from quality/age in crossovers cause this through phase drift, but you say " No matter how much I move speakers or toe them in and out, the dip remains more or less constant. I've checked the speakers as well and that is not the problem. Their response is very flat in that region. " Flat response is fine but are the two speakers exactly in phase? I think some type of phase interaction between left/right or some kind of multipath distortion from reflection. What is the result if you measure left and right running alone? You need a damper like a felt board you can move around the room when measuring. High frequency sound maybe 5khz and above tends to bend or edge diffract around objects, the higher the fz the more the diffraction, but low fz 900hz blasts around in almost straight lines, so ultimately you are probably looking at phase cancellation from parallel objects/furniture/walls. Look at the wavelengths where you experience the problem and measure the room front to back and side to side to make sure you are not an exact wavelength/half/quarter wall to wall. [/QUOTE]
Insert quotes…
Verification
Post reply
Audio and Video Talk
Acoustics & Room Treatment
What is killing my 900Hz to 2kHz repsonse?
Top