Waveguide in MTM

Draki · 31st January 2012, 04:01 PM

Is using a waveguide in MTM a good idea ? ( this one: Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories)
The tweeter is Seas NoFerro-650 with a low fs of 650 Hz and could be crossed at 1.600 - could it cross lower at say 1.400 with the WG?
The mids are 17 cm drivers (Audax hp170MO). With the WG the CTC distance would be abt 32 cm (the WG is 15 cm high), without it abt 27 cm.
Is this increased CTC distance (with the WG) creating a problem versus the benefit of a possibly lower xo point?

Thanks.

bwaslo · 31st January 2012, 04:33 PM

The CTC between the 17cm drivers will be the problem. Below crossover frequency they will interfere with each other at rather small angles from axis.

Draki · 31st January 2012, 04:57 PM

So better not to use WG and try to squeeze the mids as close as possible? What is the advantage of slightly offsetting the tweeter (thus allowing for an even smaller CTC), like the arrangement on the Sunflower?

mdocod · 31st January 2012, 06:31 PM

Offsetting the tweeter helps reduce prominent edge diffraction effects. Equal distance to each baffle edge compounds the effects, whereas having different distances to each baffle means that no 2 baffles can cause equal diffraction. The result is generally flatter response. The waveguide carries out the same purpose but does so even better than just off-setting the driver (no offset required with a wave-guide from my understanding)

I believe that in order to use the waveguide in an MTM, you'd actually have to do something like a WMTMW with little 2" full range drivers as the mids. Then CTC spacing drops to where a 1.6KHZ x-over is more feasible, the bottom x-over would then be somewhere around 500hz.

Eric

31st January 2012, 04:01 PM	#1
Draki diyAudio Member Join Date: Sep 2010	Waveguide in MTM Is using a waveguide in MTM a good idea ? ( this one: Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories) The tweeter is Seas NoFerro-650 with a low fs of 650 Hz and could be crossed at 1.600 - could it cross lower at say 1.400 with the WG? The mids are 17 cm drivers (Audax hp170MO). With the WG the CTC distance would be abt 32 cm (the WG is 15 cm high), without it abt 27 cm. Is this increased CTC distance (with the WG) creating a problem versus the benefit of a possibly lower xo point? Thanks.

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31st January 2012, 04:33 PM	#2
bwaslo diyAudio Member Join Date: May 2006	The CTC between the 17cm drivers will be the problem. Below crossover frequency they will interfere with each other at rather small angles from axis.

31st January 2012, 04:57 PM	#3
Draki diyAudio Member Join Date: Sep 2010	So better not to use WG and try to squeeze the mids as close as possible? What is the advantage of slightly offsetting the tweeter (thus allowing for an even smaller CTC), like the arrangement on the Sunflower?

31st January 2012, 06:31 PM	#4
mdocod diyAudio Member Join Date: Dec 2011 Location: Black Forest, CO	Offsetting the tweeter helps reduce prominent edge diffraction effects. Equal distance to each baffle edge compounds the effects, whereas having different distances to each baffle means that no 2 baffles can cause equal diffraction. The result is generally flatter response. The waveguide carries out the same purpose but does so even better than just off-setting the driver (no offset required with a wave-guide from my understanding) I believe that in order to use the waveguide in an MTM, you'd actually have to do something like a WMTMW with little 2" full range drivers as the mids. Then CTC spacing drops to where a 1.6KHZ x-over is more feasible, the bottom x-over would then be somewhere around 500hz. Eric

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