Visaton B200 in Alpha TL

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Andrewbee

My acquiring of a pair of JX150 did not pan out (i was planning on TL subs with them) and I now am the owner of a pair Visaton B200’s (thanks Dave).
So, since I wanted to try TL’s for the first time I took a re-read of the Alpha TL by Rick Schulz and it just so happens that he recommends a Qts of .5 to 1.0 and the B200’s are .75 so......
Now I would like someone to double check my work. I used the published T/S specs from Visaton and its Qts .75 / FS 40Hz / Vas 102L (6224 cu in)
I decided on a F0 of Fs X 1.4
I will be using Poly as stuffing as that is easily available and easy to work with.
This is what I got.
F0=56
Length = 58 inches
Z= .273
Alpha= 1.693
Sx= 225
Stuffing 1.0Lb/ cu ft.
So, do those numbers look right?
So I am think about a box with internal dims 11.5” X 19.5” with the speaker mounted on the wide side.
Since the terminus is at the bottom, how high should it be off the ground? Is 2” sufficient?
Anything I”m missing?
I am really planning on using the B200’s on O.B’s but I need to try a TL.
I need another pair of speakers as much as I need a hole in my head but I suppose I do not suffer from this madness anymore than anyone else around here!

Thanks

Andrew

GM

Greets!

Using the formulas from the 8/03 AudioXpress article, I get:

L = 56.299"
CSA = 268.143"^2
alpha = 1.432
Z = 0.275
Dp = 1.5 lbs/ft^3

When I use 1.0 lbs/ft^3 density in mine I can't see any difference between the two in a sim, so whichever one works for you and increase density if it doesn't sound 'tight' enough.

FWIW I calc 0.321"/0.323" min. for yours/mine assuming 19 mm material thickness.

GM

Andrewbee

Thanks GM,

I used the same formula but admit to "eyeballing" it on the charts as they were a bit small on the copy I got but my numbers are good enough for government work, at least they are similar to yours which I will use. Hope to start on them on the coming weekend.

Any opinion as to the height off of the ground for the legs? I was thinking about 2 inches as being sufficient.

Andrew

GM

Greets!

I wondered if that's what you did. Since I calc'd ~5/16" min., 2" is fine.

GM

Thanks again

Andrew

planet10

Paid Member
Andrew,

You successfully skirted today's hurricaine?

dave

Andrewbee

Yes, Thanks,
Thats why I was kind of antsy while in Florida, I knew it would not hit home but it was big enough to be of concern. I flew out on Friday night and it was a smooth ride home. Unfortunately the people of Pensecola are'nt as lucky.
At least I got my shopping done from Planet 10 so I was coming home with goodies

I listened to just one of the B200's this P.M. just in my hand and playing an mp3 through the "puter" and it is quite a clean sound. I did a quick comparison with a RS 40-1272 and while the RS had a bit more output and bass it was not as clear, and this with 20mW of power.

Andrew

Tyimo

Hi!

Could you tell me where can I find infos about the Alpha TL design-theory?
I would like to understand and try it too.

Thanks!

tyimo

Tyimo

Thanks a lot Dave!!!!!!

Greets:

Tyimo

GM

Greets!

FWIW, here's my latest Alpha TL Excel WS.........

GM

Attachments

• alpha tl v1.zip
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Tyimo

Hi GM!

How can I adjust the driver Sd parameter? Or I needn't it?

Greets:

Tyimo

GM

Greets!

'Sd' isn't a speaker cab design criteria, so nothing to adjust.

GM

Tyimo

Thanks GM!

I need to read again the article..... :-(

Tyimo

planet10

Paid Member
Tyimo said:
I need to read again the article..... :-(

Martin uses Sd as a convienient, but confusing unit of area) measurement. He started doing this because a classical line was always generated around the Sd of the driver. Turns out that Vas is the parameter of interest.

I will often just pick a convienient size for Sd to make it easier to do cross-section math in my head.

dave

Tyimo

Thanks Dave!

I see.

Tyimo

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