Not enough "out" outside?

[Mos Fetish]

When measuring outside, how much room do you need out there to justify the effort?

I have a driveway that is 5 metres wide and extends 50 metres across to the other side of the street. On both sides, give or take a few gaps, are partly-bushy wooden fences.

Do I essentially have a very long outdoor room, and is it worth it? Do I need to be facing into a very wide backyard to get any outdoor benefit?

[bjorno]

Mos Fetish

Read this artice it may help:

http://stereophile.com/reference/405time/

b

[roddyama]

What exactly are you trying to accomplish?

[Mos Fetish]

I'll rephrase: does the proximity of driveway "sidewalls" negate the effect of having 50m of open space in front of the speaker and infinity (the sky) above?

Am I just best to measure inside using nearfield + farfield?

[planet10]

The longer the 1st reflected path is, the lower in frequency you can accuartely measure.So you want to place the speakers to increase the time....

dave

[ente]

... here you will find some information

http://www.xlrtechs.com/dbkeele.com/...ld%20Paper.pdf
http://www.listeninc.com/files/pdf/AESFreeField.pdf
http://www.fesb.hr/~mateljan/arta/Ap...d-Rev03eng.pdf

Regards
Heinrich

[Svein_B]

I guess the grond reflection will be dominant one also outdoors, possibly reduced by soft grass?

I have read that some place the spakers outdoors flat on the ground for measurements (=halfspace ?)

Depending on measurement method, low frequency noise could be a problem outdoors.

Speaking without practical expertice in outdoor speaker measurement

SveinB

[Mos Fetish]

Originally posted by ente

http://www.listeninc.com/files/pdf/AESFreeField.pdf

At the bottom of page 12 of that document, the author says to scale the output of the port relative to the surface area of the woofer(s).

(the graph illustrating this is Figure 20 in the appendix)

He says to do this BEFORE the nearfield low frequency response is scaled to match the farfield response.

Why scale the port response relative to the woofer(s)? The port's output is as legitimate as the woofers. It is what it is. Why scale it at all? Why not just sum the responses of the woofer(s) + port, and then scale them relative to the farfield response.

I assume he means by scaling that if you have a port with half the surface area of the woofer, then you scale the response by half (-6db?)? What if you have two woofers in a cabinet: do you take their COMBINED Sd for the calculation?

Thanks in advance for your help :-)

Mos

[Cloth Ears]

Originally posted by Mos Fetish
I'll rephrase: does the proximity of driveway "sidewalls" negate the effect of having 50m of open space in front of the speaker and infinity (the sky) above?

Am I just best to measure inside using nearfield + farfield?

I thought that when measuring outside, you laid the speaker on its back (preferably in a hole with the baffle level with the ground) and suspended the mike over head to avoid ground reflections - getting a 2ð measurement. Not that I've done this...

[Mos Fetish]

Originally posted by Cloth Ears

I thought that when measuring outside, you laid the speaker on its back (preferably in a hole with the baffle level with the ground) and suspended the mike over head to avoid ground reflections - getting a 2ð measurement. Not that I've done this...

Yeah, I've read about that and it seems like a good idea, although digging a hole is probably a bridge too far :-)

Just laying the speaker on it's back will cause the ground to act like a huge wall behind the speaker. That would be good for measuring the effect of baffle step. But, in my case, I'd still have problems because of the width of my driveway. The fences would still make for uncomfortably close "sidewalls".