Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th October 2012, 06:41 PM   #131
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Quote:
Originally Posted by Vadim View Post
Yes, I understand and I agree that you can do without a baffle, as long as you are willing to live with rather high roll off. I wanted to use 10-inch drivers for my mid-range, so at most I needed to place the crossover around 500 Hz and my baffle can support that. You probably are using 8-inch drivers.

Erik, I wonder if you could describe your PC-based crossover in some detail. I would like to know what software you are using and what are the computer requarements? Also, - how many channels are possible? Am I to understand that you are running multiple SPDI/F outputs out of your PC? Can you do AC-3 5.1 format? I just might go the same route. Thank you.
At my listening distance, RD-75 is flat to 200 Hz even with no baffle. I XO at 180 Hz. The real attraction with the RD-75 is that you can make a 2-way.

I am using 21" woofers in large H-baffles together with the RD-75.


My PC XO is based on a midi routing software called "Console", which can be used as a host for VST-plugins. I use a high-quality parametric EQ plugin for both XO and EQ. Such a system can do multi-channel, provided you have enough outputs. A three-way 5.1 system will require 16 channels. Some pro-audio interfaces can support that through AES-3 or ADAT interfaces. How powerful the computer needs to be depends entirely on what EQ plugins you will use. Some are quite CPU-intensive, and some are not.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 12th October 2012, 09:43 PM   #132
diyAudio Member
 
Join Date: Oct 2011
Smile Questions

Hi StigErik I have a few questions I would like to ask you. I just ordered the Bohlender Graebener RD75, they should be here in a week. My questions are at what frequency on the top end do I need to start EQing from. I know it's 12dB at 20khz but were does compensation start at. Also at what exact frequency do you need to compensate with a notch filter and how wide of band, I guess that is the Q. I am using a active crossover Marchand xm44, so not digital. I need to order the frequency modules for this crossover. Thanks alot.
  Reply With Quote
Old 17th October 2012, 11:15 AM   #133
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Main EQ points that I use are:
20 kHz, +10 dB, Q=10
5800 Hz, -4,5 dB, Q=1.6

Note that the 5800 Hz EQ may not be correct in every case, as the baffle shape and size changes the response peak to a certain degree. To be sure you should have them measured.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 17th October 2012, 08:31 PM   #134
diyAudio Member
 
Join Date: Oct 2011
I was wondering if you could change the q figures into frequency response for me. I don't know how q works. Is a q of 10 one octave. Also if I give you a baffle width of 20 inches could you calculate the notch filter frequency for me, I don't have any measuring software or hardware and probably won't for another 6 months.
  Reply With Quote
Old 17th October 2012, 08:55 PM   #135
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Q is the inverse of octave width. Q=1 is one octave. Q=10 is 1/10 octave.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 19th October 2012, 06:04 PM   #136
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Oooops... the EQ values I posted was wrong!
Correct values:
20 kHz, +10 dB, Q=2.5
5800 Hz, -4,5 dB, Q=1.6

Like to add that the 20 kHz EQ is really not necessary. I cant hear 20 kHz.....
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 20th October 2012, 02:04 PM   #137
diyAudio Member
 
Join Date: Jun 2009
Quote:
Originally Posted by StigErik View Post
Q is the inverse of octave width.
For which definition of bandwidth? With the usual -3dB points it's

Quote:
Originally Posted by Robert Bristow-Johnson
The relationship between bandwidth and Q is
1/Q = 2*sinh(ln(2)/2*BW*w0/sin(w0)) (digital filter w BLT)
or 1/Q = 2*sinh(ln(2)/2*BW) (analog filter prototype)
You can find the Bristow-Johnson cookbok here.

Most software implementing digital filters takes analog values as input and uses the same definitions as Bristow-Johnson. So generally one wants the analog translation for converting from Q to bandwidth in octaves to find the values to plug into the UI:
BW=2/ln(2)*asinh(1/(2*Q))
  Reply With Quote
Old 20th October 2012, 09:03 PM   #138
diyAudio Member
 
Join Date: Oct 2011
Smile Double check

Stig Erik are these frequencies correct. A notch filter frequencies of 5800hz wit a q of 1.6 gives me a starting frequency of 3625hz and an ending frequency of 9280hz. Is that correct? That seems like pretty big range for a notch. Just figured I'd double check. Thanks alot StigErik.
  Reply With Quote
Old 21st October 2012, 06:39 AM   #139
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
This is how such a notch looks like in a parametric EQ.
Attached Images
File Type: png notch.png (54.7 KB, 451 views)
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 25th October 2012, 12:13 AM   #140
diyAudio Member
 
Join Date: Oct 2011
Will the notch be more than 4.5db when installed on a baffle instead of the round overs you used on your drivers.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Waveguide loaded MT dipole? mayhem13 Multi-Way 14 3rd August 2010 01:13 PM
OB MTM w/ Dipole Waveguide thadman Multi-Way 12 10th February 2010 07:56 PM
75 degree waveguide, any good reason? dantheman Multi-Way 16 3rd January 2010 03:52 AM
BG-75 / ATC planar dipole construction auplater Multi-Way 8 5th February 2007 02:00 AM
open baffle bass-dipole-what amp felixx Multi-Way 20 13th December 2006 06:53 AM


New To Site? Need Help?

All times are GMT. The time now is 02:14 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2