TH or T-TQWP or ????

[NWCgrad]

I have been looking into building a new enclosure for a Maelstrom-X 18 gen II sub driver I already have. There are a few 18" driver based TH builds (such as Ricci's Gjallerhorn and mdrakes over at HTS [http://www.hometheatershack.com/foru...l-x-18-a.html]). Ricci was kind enough to send me the plans for the Gjallerhorn and right now I would go with this design.

However, I stumbled across this thread http://www.diyaudio.com/forums/subwo...deep-help.html by justint where bjorno recommended a T-TQWP over the TH and Don Price was able to rapidly produce drawing and cutsheet.

I assume this would work for other drivers but can find little information. To adapt the design up to the 18" Mal-X driver - I assume it is more than just widening the cabinet. I downloaded hornresp and failed miserably at trying to model a horn. I am attaching the imput parameters from the mdrake build.

USAGE: The sub will be used with 4 sealed LAB-12's, so it will be used only to augment below 50Hz. Looking to fill in from 15 Hz and up for HT. I also listen to a lot of classical music and lod school heavy metal from the late 60s early 70s.

TIMELINE: I am currently stationed overseas (22 months until I return to US from Cambodia), so I am wanting to finalize a build now as the driver has been discontinued and information about - and DIY community experience with - the driver will be significantly less in 2 years.

The T-TQWP build looks much easier than a TH and would not require finding a CNC shop.

I would greatly appreciate any assistance from the resident experts.

[DrDyna]

I'd probably input the hornresp parameters exactly as bjorno has them in post #10, then enlarge the cross section areas until it'll fit your 18, and then gradually make it longer until the sim looks good (or doesn't, lol)

I'm no expert though, but I'll be following this thread pretty carefully as I've wanted to build a pair of T-TQWP/T using monster 18" woofers for a while now.

[bjorno]

FYI:

Here's an example:

b

[epa]

beet me to it b.
i was thinkig a straigh pipe 700 sq cm
like this one

[NWCgrad]

Thank you DrDyna, bjorno, and epa. Looking at the data provided by bjorno it looks like the enclosure would be 12.25 cu ft and would have an F3 of 16 Hz (w/ 4th order HPF as 12 Hz). That seems very good to me, my sealed build using the driver has a calculated F3 of 33 (Qtc = 0.623).

The enclosure shown by epa looks to be a straight forward build.

How do I calculate the operating limits of the design (SPL, freq resp curve, cone excursion, etc)? I appologize for my ignorance using Hornresp, I am used to WinISD and Jeff Bagby et al's Woofer Box programs.

Thank you again! I look forward to seeing where this design goes.

[NWCgrad]

Been reading all morning on the multiple hornresp help guides. A lot of info to digest....

How does a T-TQWP differ from a TH? Looking at the diagram from epa and one on the web by CowenAudio (Tapped Horn Experiments) I do not see a lot of difference - except the inner "baffle" is straight vice slanted.

In the hornresp parameters from bjorno, there are data for S1 (1182), S2 (1149.26), S3 (626.74) and S4 (594). I think this is sq cm, but am not entirely sure. I cannot visualize these 4 sections in the diagram by epa, looks like there would only be two. What am I missing?

Am I correct that since the model has ANG = 2.0 x Pi “half space” and represents the sub in an open field and compared to in an open field (open field in bjorno’s model) the response will model smoother with more extension when next to a wall (1.0 x Pi), or in a corner (0.5 x Pi). According to what I read that to get the same performance in an open field, you'd need 4 of the horns stacked together.

I am trying to learn as I go, but there is very little info that I can find on T-TQWP.

Thanks for the continued support.

[epa]

Originally Posted by NWCgrad

Been reading all morning on the multiple hornresp help guides. A lot of info to digest....

How does a T-TQWP differ from a TH? Looking at the diagram from epa and one on the web by CowenAudio (Tapped Horn Experiments) I do not see a lot of difference - except the inner "baffle" is straight vice slanted.

In the hornresp parameters from bjorno, there are data for S1 (1182), S2 (1149.26), S3 (626.74) and S4 (594). I think this is sq cm, but am not entirely sure. I cannot visualize these 4 sections in the diagram by epa, looks like there would only be two. What am I missing?

Am I correct that since the model has ANG = 2.0 x Pi “half space” and represents the sub in an open field and compared to in an open field (open field in bjorno’s model) the response will model smoother with more extension when next to a wall (1.0 x Pi), or in a corner (0.5 x Pi). According to what I read that to get the same performance in an open field, you'd need 4 of the horns stacked together.

I am trying to learn as I go, but there is very little info that I can find on T-TQWP.

Thanks for the continued support.

they are the same principle.
the tqwtp starts with a bigger cross section and ends smal,with a th horn its the other way around.
and then you have something in between wich is a straight pipe.qwp
tqwtp has a wider bandwith lower sensivety,and the th the other way around.

0.5 pi is corner loaded
1 pi is agains the floor and wall.(you can use this for indoors)
2 pi is on the floor (outside)
4 pi is free hanging

cross section are sq cm so s1=5cm*20cm = 100

keep at it your getting there

[NWCgrad]

Been working more with hornresp and modeled the Mal-X driver with both bjorno's and Ricci's Gjallerhorn parameters. Not sure if Ricci's accurately reflect his design as he did a lot of the work in Akabak and indicated that the HornResponse approximation is only a rough approximation of the Akabak script.

Is there a way I can add HPF and LPF in hornresp?

Looks like either design would be pretty good, but I am looking to get the best performance possible out of the driver - and lack the skills required to design it on my own.

Thanks for continuing support on this project!

[NWCgrad]

Here are the inputs:

[epa]

gjallerhorn is verry big,but its a great sub.
bjorno moddels is much smaller.
have you found the loudspeaker wizzard(in tools tab)
there you can use the sliders and see fr change realtime.
note , the volume of a real box is much more then hr predicts in the schematic