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

Open baffle step compensation on fullrange adds distortion
Open baffle step compensation on fullrange adds distortion
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 30th June 2020, 08:23 PM   #1
flo777 is offline flo777  Canada
diyAudio Member
 
Join Date: Jun 2018
Default Open baffle step compensation on fullrange adds distortion

I followed the design by Rudolf in post #13 below to build a pair of small open baffle speakers
Small open-baffle?

For the baffle step circuit, I could not source a 3.3mh inductor, so I used a 2.4mh instead in parallel with a 12 ohm resistor.
(photo attached)

Adding this to the fullrange driver creates a lot of distortion in the low frequencies (similar to voice coil rubbing).
I tried adding hot glue on the coil, but did not help.
Does anyone know what the issue could be?
Thanks in advance
Attached Images
File Type: jpg ob.jpg (137.7 KB, 207 views)
  Reply With Quote
Old 30th June 2020, 08:29 PM   #2
kaos is offline kaos  United States
diyAudio Member
 
Join Date: Dec 2005
Location: Los Angeles
Could be coil saturation, try an air-core inductor.
  Reply With Quote
Old 30th June 2020, 08:33 PM   #3
planet10 is offline planet10  Canada
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Open baffle step compensation on fullrange adds distortion
Small baffle, small driver, bu\ig lift in the bass will certainly mean a big hit on how loud you can go before running out of excursion, so more LF distortion would be expected as you turn up the wick.

dave
__________________
Stay safe. Stay home. Respect the 2m bubble.
  Reply With Quote
Old 30th June 2020, 09:07 PM   #4
flo777 is offline flo777  Canada
diyAudio Member
 
Join Date: Jun 2018
Thanks for the tips.
The saturation current is rated at 3A.
The LF distortion also occurs at very low volumes.

Last edited by flo777; 30th June 2020 at 09:20 PM.
  Reply With Quote
Old 1st July 2020, 12:00 AM   #5
kaos is offline kaos  United States
diyAudio Member
 
Join Date: Dec 2005
Location: Los Angeles
The core may be rated for 3 amps at 100 KHz but go down to 50 Hz and it could easily saturate at 20 mA. If you have a scope, signal generator, power amp and power resistor (5 ohms will work) it's easy enough to check if the core is saturating at lower frequencies. Connect the equipment in series in an appropriate manner and connect the scope probe across the resistor, when the core saturates you'll see a step in the sine wave. Use Ohm's law to solve for the current that saturation occurs at.
  Reply With Quote
Old 1st July 2020, 01:41 AM   #6
perceval is offline perceval  Taiwan
diyAudio Member
 
perceval's Avatar
 
Join Date: Feb 2014
Location: Taiwan
I tried the cheap inductors like those, along with the cheap capacitors you can get for pennies...

They are ok to test if your calculations were correct, but they introduce a lot of sound distortion and modulations.

Get audio grade stuff and your problems will disappear.
  Reply With Quote
Old 1st July 2020, 07:30 PM   #7
Juhazi is offline Juhazi  Finland
diyAudio Member
 
Juhazi's Avatar
 
Join Date: Mar 2007
Location: Jyväskylä
Coil and resistor type have nothing to do with your problem!

Rudolf's small baffle speakers were sitting on a desk/table which works as extra baffle, and still response below 100Hz drops like stone. The driver very easily must work too hard and it reaches mechanical excursion limit (Xmech) easily and starts clonking. Even before that there will be rubbing noise from coil/magnet gap in many cases

Click the image to open in full size.

Guru tells more about it here Tech
Click the image to open in full size.
__________________
Radikal aktivist AINOgradient speaker project
  Reply With Quote
Old 1st July 2020, 09:04 PM   #8
flo777 is offline flo777  Canada
diyAudio Member
 
Join Date: Jun 2018
Thanks for the responses.
The inductors are 2.4mh at 15 khz. However, it did not read any value at 1 khz. Maybe the inductors are the problem here?
  Reply With Quote
Old 1st July 2020, 09:27 PM   #9
flo777 is offline flo777  Canada
diyAudio Member
 
Join Date: Jun 2018
Maybe something wrong with the inductors, can someone please explain?
1.3mH at 200 kHz
2.3mH at 15 khz
?58H at 1 kHz
Attached Images
File Type: jpg 200khz.jpg (566.7 KB, 105 views)
File Type: jpg 15khz.jpg (604.1 KB, 103 views)
File Type: jpg 1khz.jpg (581.2 KB, 11 views)

Last edited by flo777; 1st July 2020 at 09:34 PM.
  Reply With Quote
Old 2nd July 2020, 01:15 AM   #10
perceval is offline perceval  Taiwan
diyAudio Member
 
perceval's Avatar
 
Join Date: Feb 2014
Location: Taiwan
Quote:
Originally Posted by Juhazi View Post
Coil and resistor type have nothing to do with your problem!
Just sharing my experience on the topic... yes it does.

Using the kind of inductor posted, I get all sorts of sound artefacts while doing a sweep in REW in the lower to midrange.

If I use a real air-core inductor, the artefacts go away.
 

Reply


Open baffle step compensation on fullrange adds distortionHide 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
Baffle step compensation.. how important is it? nannoo Multi-Way 64 17th March 2014 04:23 PM
When to use baffle step compensation? tmblack Multi-Way 28 6th December 2008 12:39 PM
Short TL as Baffle Step Compensation m@ Multi-Way 0 10th March 2008 09:07 AM
Baffle step compensation formula? bart_dood Full Range 4 8th July 2006 10:50 AM
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 11:47 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki