Question on room effect

[dkelly60]

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]

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]

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

 

[SimontY]

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]

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]

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