Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

Baffle compensation for nearfield measurement
Baffle compensation for nearfield measurement
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 6th May 2016, 05:35 PM   #1
lup31337 is offline lup31337  Romania
diyAudio Member
 
Join Date: Nov 2010
Default Baffle compensation for nearfield measurement

I'm trying to do a near-field measurement using ARTA (for the bass driver). Following the tutorial on their manual and I stumbled upon something I don't understand.

After the measurement is complete, they are suggesting to make some sort of baffle compensation, before we scale the curve to far-field. There is an option called " LF box diffraction" where you enter the dimensions of the baffle. As an effect, the low frequencies are lowered by few db.

I understand that the near-field measurement ignores baffle gains, room gains etc. In a far-field measurement all of these would be present. But I am also aware that baffle gains only apply to high frequencies.

If there are no gains for low frequencies, what am I compensating ? And if there were partial gains, shouldn't the low frequencies go up, to compensate for the lack of baffle gain ?
  Reply With Quote
Old 6th May 2016, 06:18 PM   #2
bwaslo is offline bwaslo  United States
Old guy with soldering iron
diyAudio Member
 
bwaslo's Avatar
 
Join Date: May 2006
Location: Portland, Oregon!
Baffle compensation for nearfield measurement
When you measure nearfield, the mic doesn't see the effect of LF flowing toward the back, it sees the response as if all the propagation is coming only forward from an infinite baffle. To correct for that, the LF part of the curve needs to be reduced, to simulate the LF pressure loss that actually exists around the box when seen from a more practical listening distance.
__________________
[W9MJE] Horn spreadsheet SynergyCalc/; SmallSyns SmallSyns;
Crossover design Xsim; Depot diffusor super-easy diffusors
  Reply With Quote
Old 6th May 2016, 07:03 PM   #3
sreten is offline sreten  United Kingdom
R.I.P.
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Compared to near field a driver in farfield only has baffle loss.
There is no baffle gain, as nearfield is equivalent to an infinite baffle.

For higher frequencies there is no loss as the speaker front is
big enough to be similar to half space, infinite baffle response.

When the speakers transitions to full space lower down there
is an eventual 6dB loss in output compared to half space.

rgds, sreten.

Last edited by sreten; 6th May 2016 at 07:06 PM.
  Reply With Quote
Old 6th May 2016, 07:08 PM   #4
lup31337 is offline lup31337  Romania
diyAudio Member
 
Join Date: Nov 2010
Now I get it!

Since near-field "sees" the speaker on an infinite baffle, all frequencies gain 6 db.

In reality it is a finite baffle and only the high frequencies get the boost. So I need to decrease the LF to match reality.

Thanks guys !
  Reply With Quote
Old 6th May 2016, 08:33 PM   #5
sreten is offline sreten  United Kingdom
R.I.P.
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Except all drive sensitivities are specified into half space.
(Think about it, it is the only sensible engineering option).
There is no 6dB gain, only loss compared to half space.

rgds, sreten.

Last edited by sreten; 6th May 2016 at 08:35 PM.
  Reply to this post

Reply


Baffle compensation for nearfield measurementHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Open baffle or no baffle for nearfield full range monitors? mdevelde Full Range 33 14th December 2019 02:33 PM
Open Baffle Nearfield balance Multi-Way 19 24th January 2019 11:36 AM
nearfield measurement vs listening position measurement pointless?? charlie2 Multi-Way 21 5th November 2015 05:15 PM
How To Modify Linkwitz' Stereo Mic For Nearfield Measurement? kelticwizard Multi-Way 22 12th February 2007 07:11 PM
Baffle Step Compensation Khron Multi-Way 4 16th April 2006 08:23 PM


New To Site? Need Help?

All times are GMT. The time now is 03:53 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki