On 22/03/2012 17:31, TonyL wrote:
Some time back I posted in here regarding lack of a sweet spot when using a
pair of IPL transmission line speakers. I never did resolve the problem and
just lived with it...until now. I've just bought a pair of Behringer B2301
near field reference monitors and the difference is astounding. I'm hearing
high resolution and detailed images both spatially and acoustically with
these speakers. Which makes me wonder...IPL speakers are quite high spec and
I would not have expected so much difference, especially with my ancient
ears. I haven't done any proper A/B tests. The speakers are not even in the
same room, for example. But there must surely be a problem with the IPL
units.

IPL speakers come in kit form...is it possible that I have gotten incorrect
phasing to one or more drivers? The bass drivers are correct...is there an
easy way to check the others without disassembling them (a chore)? Any other
ideas/suggestions?

You're supposed to be able to tell by placing the speakers face to face,
swapping the connections to one, and playing a mono source.
So one driver pushes while the other pulls, and there is little output.
If one midrange is inverted, there will be lots of output.
I never tried it myself. It might not work for HF where the wavelength
is short.

--
Eiron.

Eiron wrote:

You're supposed to be able to tell by placing the speakers face to
face, swapping the connections to one, and playing a mono source.
So one driver pushes while the other pulls, and there is little
output. If one midrange is inverted, there will be lots of output.
I never tried it myself. It might not work for HF where the wavelength
is short.


Yes, that is exactly how I determined that the bass drivers were correctly
phased. But I agree that this might not work well with the midrange and hf
drivers.

The way I checked the polarity of mine was to half-wave rectify a sine wave
and using that as a signal source, play it and then, using a microphone,
check on a 'scope which way up was the flat bit. It took a certain amount of
messing about with the EQ on the microphone mixer to get a clear image, but
it worked fine in the end.

S.

"TonyL" wrote in message
...
Eiron wrote:

You're supposed to be able to tell by placing the speakers face to
face, swapping the connections to one, and playing a mono source.
So one driver pushes while the other pulls, and there is little
output. If one midrange is inverted, there will be lots of output.
I never tried it myself. It might not work for HF where the wavelength
is short.


Yes, that is exactly how I determined that the bass drivers were correctly
phased. But I agree that this might not work well with the midrange and hf
drivers.

Hey Serge, sounds good. Any asymmetrical signal source would do, I guess.
Thanks.

Serge Auckland wrote:
The way I checked the polarity of mine was to half-wave rectify a
sine wave and using that as a signal source, play it and then, using
a microphone, check on a 'scope which way up was the flat bit. It
took a certain amount of messing about with the EQ on the microphone
mixer to get a clear image, but it worked fine in the end.