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

End correction factor question
End correction factor question
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
Thread Tools Search this Thread
Old 18th March 2008, 02:50 AM   #1
Newbomb is offline Newbomb  United States
diyAudio Member
Join Date: Feb 2008
Default End correction factor question

I have a sub plan finalized, but the ECF for the port is a bit of a question. Construction is to be 11/16" plywood.

This sub is only 7.25 inches high (42" d x 34" w). The vent is square, internal on one side, and 33 1/8" long - along the 42" side.
One side of the vent is the long (42") edge of the enclosure, the top and bottom of the vent have a single extra 11/16" piece of plywood (to reduce vent volume).

So, internal vent dimensions are 5 3/8"w x 4 1/2" h X 33 1/8 l. Logic says I should approximate by adding 1/2 the width (5 3/8"), but the height only has an extra 11/16" of room due to the one extra layer of plywood. Should I compensate for this?

If someone has time on their hands, what would be the tuning frequency of this enclosure be if the volume were 100 liters. This, after driver (Dayton rss265hf) and bracing and vent are accounted for. I am aiming for 21 Hz, and my calculations come to about 21.3 Hz.

Finally, this is important, as a 1 Hz error could give me a bump of ~ 1 dB right near a room mode.
  Reply With Quote
Old 18th March 2008, 06:45 PM   #2
Svante is offline Svante  Sweden
diyAudio Member
Svante's Avatar
Join Date: Feb 2004
Location: Stockholm
Calculating the port length of this port exactly is hard. I'd do a bit of simple calculations just as you have done, build it and measure the result. If the Helmholtz frequency is not close enough to what you wanted, the make some adjustments.
Simulate loudspeakers: Basta!
Simulate the baffle step: The Edge
  Reply With Quote
Old 18th March 2008, 09:19 PM   #3
Wayne Parham is offline Wayne Parham  United States
diyAudio Member
Wayne Parham's Avatar
Join Date: Feb 2004
Default Electro-mechanical parameters

I would suggest doing impedance measurements at various power levels. This will confirm not only your Helmholtz frequency but also the amount of electro-mechanical parameter shift and how that affects overall performance.

I am concerned about any application that requires electro-mechanical parameters to stay put. The problem is they don't. It's always good to do things that reduce parameter shift, but you can't completely remove it. If you can make your system be tolerant of changes, it will be more robust and will sound better as a result.
  Reply With Quote


End correction factor questionHide 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
Power Factor Correction - PFC with MC34262 luka Power Supplies 19 24th November 2013 02:37 AM
Power factor correction Stefano Pass Labs 3 12th July 2008 01:58 PM
Power Factor correction daly41k Pass Labs 4 30th June 2007 11:28 PM
Power Factor Correction Narcisse91 Power Supplies 16 30th September 2006 04:04 PM
Port Correction Factor??? mathman Multi-Way 5 17th April 2006 03:53 PM

New To Site? Need Help?

All times are GMT. The time now is 06:09 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio