15PR400 transmission line?

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GM

GM

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Joined 2003
Qts'

Periodically posted:

FYI/FWIW, IME and proved to my satisfaction when 'proofing' MJK's MathCad design programs against some of my own Tower/Column alignments from 'way back when', the vented TL (closed pipe) alignment (aka MLTL) range from ~0.312 - 0.624 Qts' seems technically good enough, i.e. from Keele's 6th order assisted bass reflex to his Extended Bass Shelf (EBS) alignment.

While the 'sweet spot' (mean) is a ~0.4412 Qts', a 'close enough' simple guideline is:

~0.403, Vb = Vas, Fb = Fs (constant tapered MLTL)

< ~0.403, Vb = < Vas, Fb = > Fs (inverse tapered MLTQWT)

< ~0.403, Vb = > Vas, Fb = < Fs (expanding taper MLTQWT/MLhorn)

Qts' = Qts + any added series resistance (Rs): http://www.mh-audio.nl/Calculators/newqts.html
 
A

AudioGeek

Member
Joined 2004
GM said:
Quickie ~42 Hz Fb max flat MLTQWT
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ok so total hornresp beginner here. I DL the program and imported the txt file into the software. Not sure how to go from the numbers and the schematic diagram to the actual dimensions of said enclosure. I can for sure do some homework and look at tutorials. Just wondering if you can point me in the correct direction?

Thanks!
 
GM

GM

Member
Joined 2003
'con' (cm) are the distances from the top (i.d.) to the driver center to the vent center to the bottom (i.d.), so as HR notes, its axial length (HR only 'understands' round) is 122 cm, so it's up to you to decide its width x depth dims.

S1 - S4 are the cross sectional areas (cm^2) at the 'con' points

Ap, Lpt is the vent area, vent length, so assumes a typical ~3/4" thick panel

If wanting to fold it, use Brian's nifty program.
 
GM

GM

Member
Joined 2003
AudioGeek said:
Hmmm... is that in Hornresp or in the spreadsheets? For the life of me I cannot figure out how to get the info from Hornresp into the spreadsheets to determine how the enclosure would look like. So sorry. lol.
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DL the HR record file to the HR Import folder, then in HR: click File/Import/HR Record to choose it, then 'open' and it auto loads as a new record for you to save, etc. as you please.
 
GM

GM

Member
Joined 2003
profiguy said:
That usually means it has a short VC and compromised in the xmax department? I would think that is not so conducive to a TL design unless one would be ok with limited LF dynamic range.
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My response was based solely on explaining why it has such a flat wide range response. ;)

That said, like any box alignment it depends on the needs of the app, so if one has a high output impedance tube amp, the lower/flatter the driver's impedance the better overall from an SQ POV.

For box loading in general, it only loads to the driver's upper, lower mass corners, so as you note, just depends on how much gain/dynamic headroom one desires over this relatively narrow BW.
 
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