MJK Worksheets

[Trapshooter]

Since the MJK modeling worksheets are no longer available, could anyone recommend an alternate product. I simple want to have fun modeling and building a TL.

[hitsware]

http://mywebsite.bigpond.com/dmcbean/

[Taterworks]

Can Hornresp model damping material in a section of the line? I think that's the only place it falls short, for now, unless it's been recently updated to add that feature.

[Bob Brines]

I played with Hornresp a little. It will model MLTL's and BR's quite well except for one glaring exception. There is no provision to move the port up from the bottom of the box. There are some nasty harmonics that appear ~700Hz that are effectively suppressed by proper port location, but Hornresp will not allow this. Also, Hornresp does not include any end effects for the port, so the modeled port will be too long.

As far as damping (the real question), no, Hornresp has no provision for stuffing a line. This is actually irrelevant as long as you have a basic idea what stuffing does, but it makes those pretty plots you see on these forums rather difficult. What you can do is export the data from Hornresp into something like Speaker Workshop and smooth it until you get what you want.

Bob

[GM]

No and not likely to be since the HR sim data can be exported to AkAbak for this type of advanced modeling.

GM

[GM]

Originally posted by Bob Brines
There is no provision to move the port up from the bottom of the box. There are some nasty harmonics that appear ~700Hz that are effectively suppressed by proper port location, but Hornresp will not allow this. Also, Hornresp does not include any end effects for the port, so the modeled port will be too long.

Yeah and was told it's not likely ever to be.

True if the driver is near/at the top, but not an issue if the driver is properly offset and the vent's at the bottom. I have my own math for the offset, but MJK's constants in his CLASSIC TL ALIGNMENT calculator sim well also.

You sure?! I've only done a few BR, MLTL comparisons to MJK's, but they are spot on as best I can tell from the displacement sims. In comparing unstuffed sims, the only major difference I see are in HR's much higher amplitude peaks/nulls which makes their impulse plots somewhat different.

GM

[David McBean]

Originally posted by Bob Brines
Also, Hornresp does not include any end effects for the port.

Hi Bob,

Just for the record - port end effects are automatically taken into account because of the way that Hornresp calculates acoustical impedance.

Kind regards,

David

[Trapshooter]

It's very unfortunate the DIY community lost such a unique resource in the MJK worksheets. For a late comer as myself, I'm stuck using someone elses design. Not being able to tweak or pay around with the software really takes the fun out of it.

[BHD]

Oh, the joy of dishonest people. I was saving up for a copy of math cad since I wanted a licensed version of the software, and then he stopped offering the sheets. I'm just glad I didn't spend the money on math cad only to have him pull the worksheets.

But I understand his frustration. I'd hate it if people were making money off my hard work, especially if I was asking for such a small amount...

Thanks to them, we all do without.

[rjbond3rd]

Although the tool per se is gone, Martin left behind all the knowledge that went into the worksheets, plus the alignment tables for classic TL's (not MLTL's but still incredibly useful).

Also, when we signed up for the worksheets, he had a certain disclaimer that we agreed to, specifically that we understood that a few other tools were also capable of calculating TL's. I think the tools he listed were AJ Horn, Akabak and Augsburger's software:

http://www.aj-systems.de/indexe.htm
http://www.randteam.de/AkAbak/Index.html
http://www.audioxpress.com/bksprods/.../sof-tlwrx.htm

So there are resources out there. Also, it's worth noting that GM came to the same destination empirically, by building and measuring, and is now able to design pretty much in his head.

I also believe that Scottmoose got to a point where he was using another technology to design his enclosures, over and above the worksheets, and I suspect that technology involved a pencil and paper (plus years of study of Olson, Nagaoka, Voigt etc.)

So Martin did not leave us without resources, he just withdrew one particular tool that made it incredibly easy. He certainly did not withdraw the knowledge.