ML-TQWT port direction : down/forward?

Jim McPherson · 2nd June 2004, 12:24 AM

What if any difference does port direction make when building an ML-TQWT? I'm finishing up a new design and was ready to cut frount facing ports when I came across the "solo" :http://diyaudio.8m.com/Solo/solo.html where the port fires downward. Would the down firing port do anything to quell the ripples in the midrange inherent to TQWT's?

-Jim

Jim McPherson · 2nd June 2004, 06:26 PM

Any ideas?

-Jim

Timn8ter · 2nd June 2004, 08:06 PM

I'm not aware of port direction making a significant difference. I'm curious about why you feel that mid-range ripples are inherent. Most of the TLs I've heard have the best mids around. The mid-range is usually controlled by driver placement and stuffing.

GM · 2nd June 2004, 08:17 PM

No. Assuming the vent is in the lower 5th of the cab, placement is for looks/convenience. Bottom exit is nice if they sit on carpet as it attenuates port noise somewhat, allowing a smaller/shorter vent. If on a hard surface, the distance can be adjusted to further mass load the vent, either allowing for a shorter than predicted one or 'pumping up' the bottom end some. Ditto rear firing.

GM

Jim McPherson · 2nd June 2004, 09:14 PM

The "inherent" ripples idea comes from the modeling (Martins) / RTA's I've seen compared to comparable to straight up bass reflex enclosures. Sure stuffing helps, but it seems like "cheating". I was hoping to get by with as little stuffing as possible.

Thanks for the suggestions. I think I'll try a downward firing port.

-Jim

2nd June 2004, 12:24 AM	#1
Jim McPherson diyAudio Member Join Date: Jun 2004 Location: Maryland, USA	ML-TQWT port direction : down/forward? What if any difference does port direction make when building an ML-TQWT? I'm finishing up a new design and was ready to cut frount facing ports when I came across the "solo" :http://diyaudio.8m.com/Solo/solo.html where the port fires downward. Would the down firing port do anything to quell the ripples in the midrange inherent to TQWT's? -Jim

2nd June 2004, 08:17 PM	#4
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	No. Assuming the vent is in the lower 5th of the cab, placement is for looks/convenience. Bottom exit is nice if they sit on carpet as it attenuates port noise somewhat, allowing a smaller/shorter vent. If on a hard surface, the distance can be adjusted to further mass load the vent, either allowing for a shorter than predicted one or 'pumping up' the bottom end some. Ditto rear firing. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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2nd June 2004, 06:26 PM	#2
Jim McPherson diyAudio Member Join Date: Jun 2004 Location: Maryland, USA	Any ideas? -Jim

2nd June 2004, 08:06 PM	#3
Timn8ter diyAudio Member Join Date: Jul 2003 Location: Seattle, WA	I'm not aware of port direction making a significant difference. I'm curious about why you feel that mid-range ripples are inherent. Most of the TLs I've heard have the best mids around. The mid-range is usually controlled by driver placement and stuffing.

2nd June 2004, 09:14 PM	#5
Jim McPherson diyAudio Member Join Date: Jun 2004 Location: Maryland, USA	The "inherent" ripples idea comes from the modeling (Martins) / RTA's I've seen compared to comparable to straight up bass reflex enclosures. Sure stuffing helps, but it seems like "cheating". I was hoping to get by with as little stuffing as possible. Thanks for the suggestions. I think I'll try a downward firing port. -Jim

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