Whats wrong, or right with this picture??

malcolmfraser · 5th May 2011, 07:25 AM

Hello all,

Looking to build the attached design, based off the Tony Gee Nebular.

Will be running nearfield in a small office (hence the need to push into the corners. Will be running off a PP EL84 amp in about 6 months, and right now, off a 20watt SS D class.

Should the driver be mid way between the passive radiators for equal pressure, or as its 'sealed' does this matter?

Whats right or wrong with the current design? Internal volume is 12 litres.

Thanks in advance, Malcolm

malcolmfraser · 5th May 2011, 08:59 AM

OK, so just found one thing wrong!!

Can I mount a passive radiator down-firing?
The PR should never be down-firing, the high Mms will cause the diaphragm to be displaced downward immediately. The spiders will eventually be stretched permanently by this treatment, and the unit will need to be rebuilt.

Source: http://www.aespeakers.com

AllenB · 5th May 2011, 01:12 PM

Yes, it does seem a little unusual. Have you looked around at other designs?

Cal Weldon · 5th May 2011, 03:50 PM

Yes I would be concerned about an up or down firing drone.

18Hurts · 5th May 2011, 04:17 PM

The passives are quite heavy,

My 18" passive has a cone + weights for tuning bending the scales at 1,050 grams. They must be mounted "on edge" to prevent sagging of the suspension from all that weight. It also has a bad effect on tuning since it has to fight gravity and lowers available Xmax.

Arty · 5th May 2011, 05:30 PM

in one direction gravity helps the cone, in the otherone is works against it.
it just makes a whole lot of unpredictable distorsion in tuning.

5th May 2011, 03:50 PM	#4
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	Yes I would be concerned about an up or down firing drone. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

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5th May 2011, 08:59 AM	#2
malcolmfraser diyAudio Member Join Date: Sep 2010	OK, so just found one thing wrong!! Can I mount a passive radiator down-firing? The PR should never be down-firing, the high Mms will cause the diaphragm to be displaced downward immediately. The spiders will eventually be stretched permanently by this treatment, and the unit will need to be rebuilt. Source: http://www.aespeakers.com

5th May 2011, 01:12 PM	#3
AllenB diyAudio Member Join Date: Oct 2008	Yes, it does seem a little unusual. Have you looked around at other designs?

5th May 2011, 04:17 PM	#5
18Hurts diyAudio Member Join Date: Nov 2010	The passives are quite heavy, My 18" passive has a cone + weights for tuning bending the scales at 1,050 grams. They must be mounted "on edge" to prevent sagging of the suspension from all that weight. It also has a bad effect on tuning since it has to fight gravity and lowers available Xmax.

5th May 2011, 05:30 PM	#6
Arty diyAudio Member Join Date: Feb 2011	in one direction gravity helps the cone, in the otherone is works against it. it just makes a whole lot of unpredictable distorsion in tuning.

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