Go Back   Home > Forums > >

Multi-Way Conventional loudspeakers with crossovers

Do you dampen a Uframe?
Do you dampen a Uframe?
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
Old 23rd July 2015, 07:25 AM   #1
mrkennyk is offline mrkennyk  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Yonkers,NY
Do you dampen a Uframe?
Default Do you dampen a Uframe?

Do you need to add dampening to a Uframe?

Kenny
  Reply With Quote
Old 23rd July 2015, 09:22 AM   #2
AllenB is offline AllenB  Australia
diyAudio Moderator
 
AllenB's Avatar
 
Join Date: Oct 2008
Do you dampen a Uframe?
I've just built a u frame but I don't know if it's the same kind of u frame as you.
  Reply With Quote
Old 23rd July 2015, 06:01 PM   #3
norman bates is offline norman bates  United States
diyAudio Member
 
norman bates's Avatar
 
Join Date: Nov 2003
Location: iowa
Hmm.

You mean the walls from vibration or filling it with fluff ?
  Reply With Quote
Old 23rd July 2015, 09:33 PM   #4
mrkennyk is offline mrkennyk  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Yonkers,NY
Do you dampen a Uframe?
Filling the box. Tried using bonded poly to foam a tube(not blocking the back of the speaker), but was not sure if that is a correct application. There are little actual detailed build threads around and the published info is gray in regards to stuffing.

Kenny
  Reply With Quote
Old 24th July 2015, 10:37 AM   #5
john k... is offline john k...  United States
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
First, let me be sure we are talking about the same thing. In my designs a U-frame is basically an open ended tube with a driver mounted at one end. If you want it to operate as a quasi-cardioid the tube must ne damped (or stuffed) correctly to reduce the quarter wave resonance and to achieve the correct delay. Quasi-cardioid frequency range will typically be from Dc to a frequency 1/2 octave, or a little more, below the quarter wave resonance. If undamped the U-frame will operate as a dipole at low frequency (well below the 1/4 wave resonance).

Details can be found here NaO U-frame
__________________
John k....
  Reply With Quote
Old 24th July 2015, 01:05 PM   #6
mrkennyk is offline mrkennyk  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Yonkers,NY
Do you dampen a Uframe?
John K, thank you. I will reevaluate what I did.

Kenny
  Reply With Quote
Old 25th July 2015, 09:53 PM   #7
dlr is offline dlr  United States
diyAudio Member
 
Join Date: Mar 2005
Location: Canton, MA
Default Cardioid vs. dipole question

John, what's your position on a dipole vs. quasi-cardioid now? I seem to recall you saying something to the effect that you're not so enamored of cardioid. I ask because I've had two 10" XLS drivers on the shelf for several years and am thinking of building a pair of subs with them. I've always liked the idea of cardioid woofers.

Dave
  Reply With Quote
Old 26th July 2015, 08:40 AM   #8
Jag768 is offline Jag768  Netherlands
diyAudio Member
 
Join Date: Apr 2009
Location: the Netherlands
I have built cardioid subs based on a combination of a monopole and dipole sub. I couldnt find an advantage of cardioid compared to monopole in the <100hz region.

I have also built cardioid tops using a damped u frame, which works quite well.
  Reply With Quote
Old 26th July 2015, 02:12 PM   #9
dlr is offline dlr  United States
diyAudio Member
 
Join Date: Mar 2005
Location: Canton, MA
Thanks for the links. I'm going over the thread and some of the info at Merlijn Van Veen's site linked by weltersys. I have downloaded his spreadsheets to check out. Very interesting, it provides some additional perspectives.

Dave
  Reply With Quote
Old 27th July 2015, 04:31 PM   #10
john k... is offline john k...  United States
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Hi Dave,

I don't check in very often these days. I still like the quais-cardioid, damped u-frame woofer but there are +/- compared to a dipole woofer. Given the same overall effective separation, correctly damped the U will be about 6dB more efficient than the dipole. But getting the damping right is an issue, particularly without measurements. Both radiate the same acoustic power, about 4.7dB less than a monopole at the same SPL. The Room modes aren't that much of an issue to me. I looked at both and the best I can conclude is that they are different and each behave differently as you change placement and orientation. Lastly, the dipoles lack the ability to pressurize a room. Whether you view that as a + or a - depends on what you are after I guess. Over all I would say that for woofers the dipole is just a lot simpler to build and for that you give up efficiency. But remember, I'm olt talking about below 100 Hz here.
__________________
John k....
  Reply With Quote

Reply


Do you dampen a Uframe?Hide this!Advertise here!
Thread Tools

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
Dampen transformer endbells? pjanda1 Tubes / Valves 13 22nd January 2013 08:25 AM
Do lighter cones of a given size dampen and settle quicker? asberrys Multi-Way 19 13th July 2012 04:05 PM
Is it possible to dampen a partially microphonic 12ax7? DrStrangelove Tubes / Valves 8 5th May 2011 12:19 AM
Dampen metal cone resonance: How much is enough? gary f Multi-Way 33 14th February 2009 04:53 PM
JBL E140 suited for OB Uframe sub ?? Buhl Subwoofers 3 19th December 2005 09:50 AM


New To Site? Need Help?

All times are GMT. The time now is 09:22 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki