Question on room effect

dkelly60 · 22nd June 2003, 12:34 AM

With a transmission line design what is the effect of the seperation between driver and line opening? The driver is often 4 or 5 feet above the floor but the opening may be nearly on the floor. Does this create any step in response?

GM · 22nd June 2003, 01:27 AM

properly designed/stuffed, there will be very little coming out of the vent at any amplitude that's far enough out of phase to be an issue.

GM

mikee12345 · 22nd June 2003, 09:03 PM

normaly at resonance -

the Port is making the most output,and the driver is hardly doing much..thats what i read anyway on a site..

www.quarter-wave.com

SimontY · 22nd June 2003, 09:55 PM

Most transmission lines seem to use the *in-phase* line output to bolster the main output. The response will definately be boosted by the floor.

The only pair of 'lines I've heard were terribly affected by the room, just like any 'proper' speaker.

dkelly60 · 23rd June 2003, 12:34 AM

The floor effect is what I was thinking about. If the driver is say 4 feet of the floor and the opening at floor, floor effect will have more impact on the outlet than on the driver. If the outlets contribution is only at the tuned frequency won't this cause a sudden step in output relative to most of the bass coming from the driver? Or is the output from the outlet going to be broad enough to integrate well?

SimontY · 23rd June 2003, 09:14 AM

I think the t-line's output will be fairly broad, maybe more so than a port(???) but room modes don't operate over a broad-band. If the speaker's output is strong at the resonance mode of floor-ceiling and the line exit is right at the floor you will get some peaky bass. Do these speakers have plinths to sit on? The small bit of height may help 'tune' any boom away.

Crucially, do you know your room dimensions? If the height and width or length are the same and the speakers have strong bass (as I believe TLs typically do) the result could be a disaster. This can only be made worse by having the exit right next to the floor.

I may be slightly out with this, can anyone explain better?

-Simon

22nd June 2003, 12:34 AM	#1
dkelly60 diyAudio Member Join Date: Jul 2002 Location: Australia	Question on room effect With a transmission line design what is the effect of the seperation between driver and line opening? The driver is often 4 or 5 feet above the floor but the opening may be nearly on the floor. Does this create any step in response?

22nd June 2003, 01:27 AM	#2
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	properly designed/stuffed, there will be very little coming out of the vent at any amplitude that's far enough out of phase to be an issue. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

22nd June 2003, 09:03 PM	#3
mikee12345 diyAudio Member Join Date: Nov 2002 Location: NZ	hm normaly at resonance - the Port is making the most output,and the driver is hardly doing much..thats what i read anyway on a site.. www.quarter-wave.com

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22nd June 2003, 09:55 PM	#4
SimontY diyAudio Member Join Date: May 2003 Location: Sheffield, North England	Most transmission lines seem to use the in-phase line output to bolster the main output. The response will definately be boosted by the floor. The only pair of 'lines I've heard were terribly affected by the room, just like any 'proper' speaker.

23rd June 2003, 12:34 AM	#5
dkelly60 diyAudio Member Join Date: Jul 2002 Location: Australia	The floor effect is what I was thinking about. If the driver is say 4 feet of the floor and the opening at floor, floor effect will have more impact on the outlet than on the driver. If the outlets contribution is only at the tuned frequency won't this cause a sudden step in output relative to most of the bass coming from the driver? Or is the output from the outlet going to be broad enough to integrate well?

23rd June 2003, 09:14 AM	#6
SimontY diyAudio Member Join Date: May 2003 Location: Sheffield, North England	I think the t-line's output will be fairly broad, maybe more so than a port(???) but room modes don't operate over a broad-band. If the speaker's output is strong at the resonance mode of floor-ceiling and the line exit is right at the floor you will get some peaky bass. Do these speakers have plinths to sit on? The small bit of height may help 'tune' any boom away. Crucially, do you know your room dimensions? If the height and width or length are the same and the speakers have strong bass (as I believe TLs typically do) the result could be a disaster. This can only be made worse by having the exit right next to the floor. I may be slightly out with this, can anyone explain better? -Simon

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