3x8" in a TL

[wingman]

Oops! These are fields you fill in on MJK's Mathcad worksheets to plot a sim. I just assumed that you were using Mathcad, or at least the demo version available at his website, to 'see' the predicted response various folks are suggesting. I see Tim has explained them. FYI, 'eta', the little symbol MJK started using on his later WSs is the Greek symbol for the letter 'h', which translates to the letter 'e' in English. I do not have a clue why it is used to describe a point along a line. I assume it has something to do with the Greek's early plane geometry notations.

WRT containing stuffing, attaching a net made from bug screen cloth or similar open weave material across the cab at the desired point works well. Do not stretch it tight though or it can 'hum' loud enough that the stuffing does not damp it down enough.

Tim,

Did you send the WSs?

GM

Thanks !

i will download MJK's Mathcad worksheets.
new software is always cool

 

[GM]

No, I played around with them this morning but didn't get them into an e-mail. I started with the dims I sent to you for my bipole FE103E and ran it for a single driver with the CSA halved. I found that I also needed to halve the port radius to get a good (similar) response graph.

Maybe no need to now that I know a bit more. If you halve the Vb, then you need to halve the vent area to get the same FR (except for the difference that Le makes if a value is used), assuming you adjust the driver's Vas, Sd, BL, and Re to one driver. This means you have to reduce the vent radius by SQRT(1/2), or 0.707x.

Try this and let us know if it solves this conundrum.

GM

 

[Timn8ter]

Maybe no need to now that I know a bit more. If you halve the Vb, then you need to halve the vent area to get the same FR (except for the difference that Le makes if a value is used), assuming you adjust the driver's Vas, Sd, BL, and Re to one driver. This means you have to reduce the vent radius by SQRT(1/2), or 0.707x.

Try this and let us know if it solves this conundrum.

GM

Yep, that's it. Thanks.

 

[wingman]

What about this : se attach file

Will it be a bad idé ?

How can i cal. one big port so i do not need 3 small

 

[wingman]

What about this : se attach file

Will it be a bad idé ?

How can i cal. one big port so i do not need 3 small

a littel help thanks

 

[GM]

I've never done a three driver layout, but it might be the 'Hot Ticket' for getting a good balance between baffle loss and room gain, so I look forward to a review.

Anyway, here's one way:

D2 = D1*SQRT(Dt)

L2 = L1/SQRT(Dt)+(D2-D1)/2*0.732, which assumes that one end is flanged, ie. terminates on a baffle.

This also assumes that the Vb for one driver is multiplied by Dt to get the new Vb. Since this usually results in a non standard pipe diameter, then to find the ~correct length of the next largest standard size:

L2 = L1*(D2^2/D1^2)+(D2-D1)/2*0.732

where:

D2 = new diameter

D1 = present diameter

Dt = number of drivers

L2 = new length

L1 = present length

GM

 

[planet10]

I have not received any of your e-mails, I don't know why

It could be your @ao; account... i have a lot of problems sending emails to aol accounts (you and woody seem to get them).

GM, Thanx for reminding me of Martin's horn paper, that it was up got lost in the recent chaos around here

dave

 

[wingman]

I've never done a three driver layout, but it might be the 'Hot Ticket' for getting a good balance between baffle loss and room gain, so I look forward to a review.

Anyway, here's one way:

D2 = D1*SQRT(Dt)

L2 = L1/SQRT(Dt)+(D2-D1)/2*0.732, which assumes that one end is flanged, ie. terminates on a baffle.

This also assumes that the Vb for one driver is multiplied by Dt to get the new Vb. Since this usually results in a non standard pipe diameter, then to find the ~correct length of the next largest standard size:

L2 = L1*(D2^2/D1^2)+(D2-D1)/2*0.732

where:

D2 = new diameter

D1 = present diameter

Dt = number of drivers

L2 = new length

L1 = present length

GM

Thanks !

i hope to start build today ! Just need the wood, but i think i know where to get it !
I will review it when done.

I think that i will pair i all with at vifa xt25, i will mod xt25 first

 

[GM]

I think that i will pair i all with at vifa xt25, i will mod xt25 first

Mod how?

Anyway, FWIW, while I agree that using the same brand is a 'safe' choice IF you use whatever tweeter the manufacturer suggests as a good match/XO, Dan Wiggins (Adire Audio) posted this recently and if I were to go budget priced point source tweeter 'hunting' I would choose from his 'short list' since he does extensive testing and I don't. Last, but not least (for me), he and I share the same lack of interest in Vifa tweeter performance (judging solely by this list). As always though, YMMV:

The "short list" is the Hiquphon OWII, Peerless 2978 (really low budget, but great SQ even for an old driver), Morel MDT30S, Morel MDT44, and the ScanSpeak 9500. Of that list, the Peerless and MDT44 have the "in" IMHO, because not only are they very good performers, and prices attractively, but are also video shielded. The Hiquphon is a great driver, too, and would be my top choice for non-video shielded use.

GM

 

[wingman]

Mod how?

Anyway, FWIW, while I agree that using the same brand is a 'safe' choice IF you use whatever tweeter the manufacturer suggests as a good match/XO, Dan Wiggins (Adire Audio) posted this recently and if I were to go budget priced point source tweeter 'hunting' I would choose from his 'short list' since he does extensive testing and I don't. Last, but not least (for me), he and I share the same lack of interest in Vifa tweeter performance (judging solely by this list). As always though, YMMV:



GM

Sten Duelund from denmark use xt25 in his "hifi4all" speaker

An externally hosted image should be here but it was not working when we last tested it.

i´ll try to find more pic. at wirte it all down in english !