Unibox and Zaph's BAMTM

[bobhowell]

I have been working on proficiency in Unibox so I have plugged data on the speakers I have built and plan to build. Now I am confused!!

I found I had a corrupted file 5 days back and got a new copy of Unibox. Now I get different data on Zaph's BAMTM than he got. I built it with 35L and using the specs from PE's site it projects a Qtc of .739. Zaph projected a Qtc with 28L, of .660, using his T/S parameters I assume.

This seems too far out to lay off on normal variations. To obtain a Qtc of .707 it proposes a 56L box. I keep going back over my input, but see no error.

Which do I believe and/or do I have another corrupted file?

I am using this in Office 2003.

Thanks for your thoughts

Bob

[ThomasW]

It's impossible for us to know what's happening unless you post some attachments showing us your sim. The entire file itself is to large to post as an attachment. But you can post screen shots of the data entry areas using a program like MWSnap3.

That's how I posted the shots seen in this thread.

http://www.htguide.com/forum/showpost.php4?p=301386&postcount=10

[understandin]

Use the specs on Zaph's site.

http://www.zaphaudio.com/6.5test/compare.html

[bobhowell]

I will try to post screenshot.

[bobhowell]

More

[ThomasW]

I used his T/S parameters and get this .....

[ThomasW]

I played around with a lower Qtc, can't get his box size, but it's no where as large as yours.

[bobhowell]

I understand the drivers vary somewhat, so the difference is no surprise, but I would think the parameters given as PE specs. would be a better guess of mine, bought this summer than his from a year or more ago. Also, I did not expect the difference to be so great and cause such a significant discrepancy in volume.

Anyway, I guess I must test mine with WT3 to know the answer to the correct parameters.

Also, I could have a bad Unibox file again.

The speakers sound great, but I am leary of my efforts to customize with Unibox sims. You would have to test the woofers to get reasonable results.

Thoughts?


Thanks

Bob

[HareBrained]

OK, first Bob doesn't have the "FR affected by Le, Le2, Re2" checkbox selected (K24).

You're using different Rs values. This has a significant impact on the parameters, especially the "Standard Design" Vb. And since this is a passive design, I would suggest a minimum value of 0.5.

Bob, check to see if the Analysis ToolPak and Analysis ToolPak-VBA are selected in "Add-Ins..." in the Tools menu. Not sure if it matters with Unibox, but it can't hurt.

I think you're misquoting the BAMTM data. There's no way a pair of DA's in a 1cf cabinet would ever have a Qtc=.653. I believe this data was from his "options" section where he's referring to the 2cf box sealed. He states in the main text that 1cf is a compromise between size and a reasonable Qtc, and 0.653 is much better than "reasonable".

[bobhowell]

Here is what I assumed was the Qtc. I might be off. Not sure how to read many of his graphs.

BTW, What is RS, that I have off. Can't find it in Unibox.

Thanks for helping

Bob

I am refering to the lable in the top left corner.

[jkrutke]

Here is what I assumed was the Qtc. I might be off. Not sure how to read many of his graphs.

Congrats and thanks, you found an error on that page.

SE's calculated Qtc for 2 woofers in a 28 liter box (14l each) is about .79. The predicted response curve and F3 you show is correct for that condition however.

.66 Qtc is likely for a 2 cubic foot sealed tower. The data is shown on there because SE has a glitch that the current calculated box is not shown until the data is cleared and re-run. I probably ran that curve right before the shown model and the old data is still there.

[jkrutke]

Fixed.

[bobhowell]

Thanks for helping me figure this out. I am considering building a new, more stylish speaker box for the BAMTM. I would not want to lower the sound quality, so I see I must stay above my current volume of 1.2ft^3.

Also, your comments on choice of box size, now make more sense. The 2 ft^3 size puzzled me until now. Especially as so many discussions showed people building the larger size.

Bob