Jump to content



Sign up for a free account to remove the pop-up ads

Signing up for an account is fast and free. As a member you can join in the conversation, enter contests and remove the pop-up ads that guests get. Click here to create your free account.

Photo
- - - - -

Need solutions for flattening frequency response....


This topic has been archived. This means that you cannot reply to this topic.
5 replies to this topic

#1 of 6 OFFLINE   Jeff_Wi

Jeff_Wi

    Stunt Coordinator



  • 53 posts
  • Join Date: Sep 13 2004

Posted October 19 2004 - 04:26 PM

I recently ran some frequency sweeps using Spectrum Lab and a Radio Shack spl meter.

http://pg.photos.yah...lbum?.dir=/8848

Can someone recommend what is the best approach to reducing the nasty bump centered at 80Hz? I have read about the BFD being good for this, but what about broadband eq, such as a 31-band eq? I have tried multiple xover settings and phase settings. The problem is actually coming from my mains, in conjuction with the room properties

#2 of 6 OFFLINE   MingL

MingL

    Stunt Coordinator



  • 214 posts
  • Join Date: Mar 26 2003

Posted October 19 2004 - 04:36 PM

The free way is to adjust the x-over on the sub to a lower value.

At 80Hz, it may be the case that both the subs and mains are active at the same time and they are reinforcing each other (thats probably why 80hz is approx 6dB higher)

Maybe try crossing over at 60hz or 70hz and things may just measure better.

#3 of 6 OFFLINE   Jeff_Wi

Jeff_Wi

    Stunt Coordinator



  • 53 posts
  • Join Date: Sep 13 2004

Posted October 19 2004 - 05:57 PM

Well, actually the xover is set to the lowest of 40Hz. I measured the response of the sub only and the true slope is at about 70Hz -3db. By the way, can anyone see my graph? It was there at first, I think. Now it isn't.

#4 of 6 OFFLINE   MingL

MingL

    Stunt Coordinator



  • 214 posts
  • Join Date: Mar 26 2003

Posted October 19 2004 - 06:26 PM

Don't see it now.

Could you post the graph of the subs alone, mains alone and the sub+mains superimposed on the same graph? Its easier to see things this way sometimes.

#5 of 6 OFFLINE   Jeff_Wi

Jeff_Wi

    Stunt Coordinator



  • 53 posts
  • Join Date: Sep 13 2004

Posted October 19 2004 - 06:50 PM

Ok, finally got the graph to work. As soon as I get a chance, I will do a comparison graph.

#6 of 6 OFFLINE   Mark Seaton

Mark Seaton

    Supporting Actor



  • 600 posts
  • Join Date: Oct 10 1999

Posted October 20 2004 - 03:59 AM

First try setting the crossover for the mains up at ~80Hz. Then measure again.
Mark Seaton
Seaton Sound, Inc.