Using a second speaker as a passive radiator/controlling with circuit on terminals - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 28th October 2002, 01:53 PM   #1
alvaius is offline alvaius  Canada
diyAudio Member
 
Join Date: Feb 2002
Location: Toronto
Default Using a second speaker as a passive radiator/controlling with circuit on terminals

I was playing around on the weekend with my dual-woofer speaker system. I had the bottom speaker disconnected while doing some frequency tests. I shorted the bottom speakers terminals together so it would not flap around so much and screw up some results I was testing for. That led me to think about changing the resistance between the terminals on my unconnected speaker. Which I did, and I found I could play around with the system frequency response at the low end by doing this. Of course, I started adding caps, etc. ... you get the picture.

I could not find any similar posts to this. Has anyone tried this or played around with this? No doubt it is common, but it was new for me.

Alvaius
  Reply With Quote
Old 28th October 2002, 02:40 PM   #2
Bill F. is offline Bill F.  United States
diyAudio Member
 
Bill F.'s Avatar
 
Join Date: Nov 2001
Location: SW MI
Never tried it, but it sounds like a cool idea to me!

Seems to me you could do some lower end EQ with notch filters, etc. on the passive.

Or how about using it for MFB?

Bill
  Reply With Quote
Old 28th October 2002, 03:09 PM   #3
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Default Re: Using a second speaker as a passive radiator/controlling with circuit on terminals

Quote:
Originally posted by alvaius
That led me to think about changing the resistance between the terminals on my unconnected speaker. Which I did, and I found I could play around with the system frequency response at the low end by doing this. Of course, I started adding caps, etc. ... you get the picture.
I just want to understand one basic part of the picture. The unconnected speaker was reconnected to the amp before the resistors and caps you put on it had any effect, right?

I know it seems obvious that it would be reconnected, but if the speaker is acting as an unconnected passive radiator, I imagine it is sending current through it's wires as it moves, and who knows-passive components could possibly, concievably, maybe, perhaps have an effect on the frequency response.

Just want to make sure.
  Reply With Quote
Old 28th October 2002, 03:53 PM   #4
jag is offline jag  United States
diyAudio Member
 
Join Date: Aug 2002
Location: TX
From the Shiva White Paper :

But the most important benefit for dual voice coils is flexibility for the T/S parameters. One can actually
“dial in” a desired Qts of the driver, by resistively loading one voice coil and actively driving the other.
This configuration, which we call Resistively Damped Operation (RDO), uses the second (undriven) voice
coil as an electromagnetic brake. In essence, the resistance across the second coil will determine how
strong the brake is. The smaller the resistance, the stronger the brake.
RDO affects the Qts of the driver by decreasing the Qms of the driver. The RDO brake acts to damp cone
motion, as if the suspension was considerably stiffer. However, as it’s an electromagnetic brake, the Fs is
NOT affected (as it would raise if the suspension components – the surround and spider – were stiffened).
  Reply With Quote
Old 28th October 2002, 08:27 PM   #5
alvaius is offline alvaius  Canada
diyAudio Member
 
Join Date: Feb 2002
Location: Toronto
For clarification, the second speaker is NOT connected to the amplifier. It is disconnected, but between its terminals, I started putting in resistors and caps, and soon inductors..... sort of a tunable passive radiator.

On one post of motion feedback, I think the issue may be delay between the main speaker and the passive unit, but heh, you never know.

Alvaius
  Reply With Quote
Old 28th October 2002, 10:46 PM   #6
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
This is a fairly old trick that gets rediscovered annually.

It works great. First, because the two drivers are identical,
it gets tuned perfectly no matter what you do.

From my experience, variable resistance is the way to go.
Values as high as 100 ohms or so have a fairly dramatic
effect on the damping of the "passive" radiator, and you
can tune it to taste.
  Reply With Quote
Old 29th October 2002, 01:37 AM   #7
diyAudio Member
 
Circlotron's Avatar
 
Join Date: Jun 2002
Location: Melbourne, Australia
Attaching an adjustable negative resistance might do interesting (or dissapointing) things.

GP.
__________________
Best-ever T/S parameter spreadsheet.
http://www.diyaudio.com/forums/multi...tml#post353269
  Reply With Quote
Old 29th October 2002, 06:40 PM   #8
PedroPO is offline PedroPO  Portugal
diyAudio Member
 
PedroPO's Avatar
 
Join Date: Jan 2002
Location: Lisbon,Portugal
Send a message via ICQ to PedroPO

Alvaius,

You shine a light on my path!

I also have a dual woofer speaker (infinity delta50)

That sounds a great idea!

what is the actual sound diference (without measurements)?
__________________
Pedro Oliveira
  Reply With Quote
Old 30th October 2002, 01:15 AM   #9
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
"Attaching an adjustable negative resistance might do interesting (or dissapointing) things."

Or even a small lamp.

Eric.
  Reply With Quote
Old 30th October 2002, 01:50 AM   #10
diyAudio Member
 
Join Date: May 2001
Blog Entries: 5
There's a good article in an old TAA titled, "The Not Quite Passive Radiator". The author experimented with several passive elements between the terminals.

Also, I believe one of Sonus Faber's speakers employed a similar technique and obtained very good low frequency response from a monitor-sized speaker.
  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
Passive radiator Chris8sirhC Subwoofers 4 5th August 2008 06:49 PM
Passive Radiator Fazorcat Subwoofers 42 10th May 2006 08:05 PM
passive radiator ??? Ahmad_tbp Multi-Way 20 29th March 2005 08:44 AM
Passive Radiator For ESS qdoc Multi-Way 0 8th July 2004 06:06 AM


New To Site? Need Help?

All times are GMT. The time now is 12:17 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