MarkAudio CHP-90 Enclosure Options

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#202
emc71 said:
I think that a folded TL would be the best for me for the CHP-90 but I also think I would need some help to do it!
Any practical suggestion on how to proceed?
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Hmm, based on the following IME, an inverse tapered one is best overall since its 'system' specs (Qts + Rs) 'naturally' requires a large/long vent for max power handling in a BR alignment:

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
Click to expand...
 
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#203
GM said:
Hmm, baserat på följande IME, är en omvänd avsmalnande en bäst överlag eftersom dess "system"-specifikationer (Qts + Rs) "naturligtvis" kräver en stor/lång ventil för maximal effekthantering i en BR-uppriktning:

FYI/FWIW, IME och bevisade till min tillfredsställelse när jag "proofed" MJK:s MathCad-designprogram mot några av mina egna Tower/Column-justeringar från "way back when", den ventilerade TL (closed pipe)-inriktningen (aka MLTL) sträcker sig från ~0,312 - 0,624 Qts verkar tekniskt bra nog, dvs från Keeles 6:e ordningens assisterade basreflex till hans Extended Bass Shelf (EBS) justering.

Medan "sweet spot" (medelvärde) är ~0,4412 Qts, är en "nära nog" enkel riktlinje:

~0,403, Vb = Vas, Fb = Fs (konstant avsmalnande MLTL)

< ~0,403, Vb = < Vas, Fb = > Fs (omvänd avsmalnande MLTQWT)



Qts' = Qts + eventuellt tillagt seriemotstånd (Rs): http://www.mh-audio.nl/Calculators/newqts.html
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If you have time.
Can you make a hornresp txt file for me. Make me understand. Please.
 
#204
GM said:
Some copy/pasted info I've posted over the years in one form or another:
Margolis-Small's HP 67/97 & 41C calculator program if wanting all the math for vented, sealed: http://www.aes.org/e-lib/browse.cfm?elib=3902

T/S max flat:

net volume (Vb) (L) = 20*Vas*Qts'^3.3

box tuning (Fb) (Hz) = 0.42*Fs*Qts'^-0.96

Find its net Vb, then its i.d. area (CSA); driver vertical location + offset + bottom plate thickness sets i.d. height

The vent/horn terminus opening causes a downward shift, hence the distances are further down than a closed box's 1/5, 1/3rd, etc., but both the driver and vent should be at a vented pipe's odd harmonics. You can figure it out using Hornresp's
'path' slider in 'chamber' or just use these as proven audibly 'close enough':
Z = (L)x ~ 0 (top), 0.217, 0.349, 0.424, 0.561

Of course the first one doesn't apply to any ~zero area [CSA] terminated pipe/horns and if your desired ear seated/whatever driver height doesn't line up close enough to your design, suggest you change the alignment tuning [pipe's length] by adjusting Fs to get it to line up with one of these offsets.

Vent offset only, depending on box HxWxD ratio: Z = (L)x ~0.651, 0.714, 0.848, 0 (bottom)

I only use/recommend ~0.75"/1.8 cm no void plywood or similar, so no need to brace beyond basic vertical, horizontal + driver brace, so just the 'outline' of Dave P10's bracing schemes, but until we reach concrete weight, can't go wrong with his if the extra woodworking isn't a big deal like it always was for me and others with severely limited build timeframes.
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Addendum:

https://www.diyaudio.com/community/threads/markaudio-chp-90-enclosure-options.391468/post-7178128

https://www.diyaudio.com/community/threads/markaudio-chp-90-enclosure-options.391468/post-7180005

https://www.diyaudio.com/community/threads/markaudio-chp-90-enclosure-options.391468/post-7180042
 
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#208
Hmm, made me go back and look at this and found a potentially very confusing error (bold)! 🙁

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
Click to expand...
 
#210
OK, I don't know how to make it easier other than go back to this box formula (20*Vas*Qts'^3.3) and make (3) sims in WinISD/whatever with all the same specs except one has a 0.403 Qts, one with 0.38 Qts and one with a 0.42 Qts and compare to what I posted concerning Vb, Fb where < = less than and > = more than
 
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#211
GM said:
OK, I don't know how to make it easier other than go back to this box formula (20*Vas*Qts'^3.3) and make (3) sims in WinISD/whatever with all the same specs except one has a 0.403 Qts, one with 0.38 Qts and one with a 0.42 Qts and compare to what I posted concerning Vb, Fb where < = less than and > = more than
Click to expand...
I start with formula 20*Vas*Qts'^3.3
Qts 0.364 original. Vb 14.24 l
Qts 0.380 give me Vb 16.41 l
Qts 0.403 give me Vb 19.93 l
Qts 0.420 give me Vb 22.80 l
 
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#215
A large straight transmission line (kinda short with no mass loading).

Seas_FA22RCZ_in_Open_Speaker_Cabinet.jpg


dave
 
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#220
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