Preliminary info about a TQWT to build

[giralfino]

Hi all,
I would like to build a TQWT or a TL speaker using 2 Vifa MG14WK09-08 per speaker in a MTM configuration. Ideally an enclosure like this one: TQWT-

I have a couple of questions:

1) Are a couple of Vifa MG14WK09 drivers suitable to a TQWT alignment? Driver parameters can be found here: http://www.parts-express.com//pe/pshowdetl.cfm?&PartNumber=297-360&DID=7]Vifa Mg14wk09-08 5-1/2" Woofer 297-360
My preliminary measurements show however a higher FS and lower Qts. Assume spec data.

2) I know that there are MathCad Worksheets available for a small fee from MJ King, however the biggest problem I have is to justify the MathCad license cost just for running those worksheets. I have found a couple of free programs that could run the worksheets but don’t know for sure because I wasn’t able to run the demo worksheet with them. The demo worksheet is a .mcd file.

The first program is MathCad Prime Express (available here: PTC Mathcad Express | PTC). It needs a .mcdx file. I was able to convert the .mcd to a .xmcd trough a trial version of MathCad 15 but I wasn’t able to convert the resulting .xmcd into the .mcdx needed by Prime, I suspect the problem is in the locked area of the demo worksheet. Can someone try this conversion with a non locked MJ King worksheet?

The second program is SMath Studio (available here: SMath Studio - official web site). I’m not able to import the .xmcd worksheet into SMath Studio. I don’t know if the problem is the locked area or maybe a not fully compatibility between the MathCad file and the functionalities built into SMath Studio. Can someone try SMath Studio with a non locked MJ King worksheet?

Thanks in advance
Ralf

 

[giralfino]

No one cares to try a quick-and-dirt simulation for me?
Specs of the Vifa driver are:
Le: 0.72 mH
Re: 5.60 ohm
Fs: 45 Hz
SPL: 87 dB 1W/1m
Vas: 13.8 L
BL: 6.2
Sd: 80 cm2
Qms: 1.99
Qes 0.35
Qts: 0.30
Xmax: 3.5 mm

Thanks

 

[GM]

Greets!

Troel’s simple pipe horn wouldn’t be my first choice unless it was a large one such as a BIB alignment: http://www.diyaudio.com/forums/full...ose-fostex-craft-handbooks.html?highlight=bib

MJK has an old free demo version that works and I gather it’s what most folks use, it just won’t allow you to save any designs you do, so would need to be saved as a WORD doc or similar if you want to keep a record of it: http://www.quarter-wave.com/Back_Door/MathCad_Explorer.zip

Sorry, can’t help with the other programs.

GM

 

[giralfino]

Troel’s simple pipe horn wouldn’t be my first choice unless it was a large one such as a BIB alignment: Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

What would you suggest? Would be a folded constant section line better?

MJK has an old free demo version that works and I gather it’s what most folks use, it just won’t allow you to save any designs you do, so would need to be saved as a WORD doc or similar if you want to keep a record of it: http://www.quarter-wave.com/Back_Doo...d_Explorer.zip

I have that free demo, but it doesn't permit to modify the driver T/S parameters as this area is locked, so I can't model my driver. This is the reason why I was asking someone to provide a preliminary result, just to be sure it is a viable design.

Using MathCad Explorer is a PITA because it can't save files, so I'd have to re-insert the modified values every time I start again.

Thanks, Ralf

 

[GM]

Probably, but don’t have time right now to do any sims.

WRT using MJK’s software, it’s full function except for the inability to save one’s results. Since the driver’s specs field is locked, it’s because you haven’t paid for the various worksheets to load into it, which are completely unlocked AFAIK, allowing them to be modified, added to, rearranged, etc..

You’re welcome!

GM

 

[GM]

Simple MLTL:

H = 55"
WxD = 56"^2
tweeter centered 19.25" down from top
3" diameter x 3" long vent 44" down from top

All dimensions approximate and inside [i.d.].

The sim assumes a 1 ohm series resistance for wiring, etc., minimal damping and is approximate since I can't show the minor averaging of the pipe's 1/4 WL action going on due to the drivers being above, below the tweeter location a bit.

GM

 

[giralfino]

Thanks GM,
it is reassuring that it can be done. I'll invest some $ on the MJK worksheets.

Ralf

 

[GM]

You're welcome! Please document here whatever you decide to build, it may eventually help someone else.

GM