Speakers based on Beyma 15XA38ND

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#21
I recommend an inverse tapered TQWT, which can't correctly be calculated in WinISD. If you want to try, use Hornresp's Loudspeaker Wizard. Otherwise, if bjorno/whoever doesn't beat me to it, I'll sim one as time permits.

GM
 
#23
Zoef said:
Thanks!
Click to expand...

You’re welcome!

OK, for a ~198 L TQWT tuned to ~Fs, the path-length = 191.1 cm with a 1394 cm^2 closed end area tapering to a 440 cm^2 open end and a 66.7 cm driver offset. Damp to ‘taste’ with whatever stuffing material you prefer.

Between its medium low Qts and high Vas wanting a ~ Vb = Vas [~358 L] to have a strong bass down to Fs after damping, expect it to be more of a strong mid-bass, lower mids alignment.

After figuring all that out, I realized that when I posted earlier I was thinking about a different brand/model driver alignment from another thread, so while these are nice designs, they require complex folding to fit in your space, so we’re back to the too short, small ~198 L MLTL tuned to Fs that only needs a single fold:

Path-length = 100 cm
Cross sectional area [CSA] = 1982 cm^2
Driver offset = 21 cm
Vent offset = 80 cm
Vent dia = 12.7 cm
Vent length = 6 cm

I line the top, one side, back with 1” acoustic fiberglass insulation, but many folks prefer to stuff with polyfil these days, so whatever type/quantity sounds best to you with the object being to only damp it just enough to keep it from sounding hollow as any more just starts rolling off the bass too much.

GM
 
#27
GM said:
You’re welcome!

OK, for a ~198 L TQWT tuned to ~Fs, the path-length = 191.1 cm with a 1394 cm^2 closed end area tapering to a 440 cm^2 open end and a 66.7 cm driver offset. Damp to ‘taste’ with whatever stuffing material you prefer.

Between its medium low Qts and high Vas wanting a ~ Vb = Vas [~358 L] to have a strong bass down to Fs after damping, expect it to be more of a strong mid-bass, lower mids alignment.

After figuring all that out, I realized that when I posted earlier I was thinking about a different brand/model driver alignment from another thread, so while these are nice designs, they require complex folding to fit in your space, so we’re back to the too short, small ~198 L MLTL tuned to Fs that only needs a single fold:

Path-length = 100 cm
Cross sectional area [CSA] = 1982 cm^2
Driver offset = 21 cm
Vent offset = 80 cm
Vent dia = 12.7 cm
Vent length = 6 cm

I line the top, one side, back with 1” acoustic fiberglass insulation, but many folks prefer to stuff with polyfil these days, so whatever type/quantity sounds best to you with the object being to only damp it just enough to keep it from sounding hollow as any more just starts rolling off the bass too much.

GM
Click to expand...
To be sure, since you said you had the wrong drivers in mind.... the tqwt i posted will not work?
Having a hard time working out how/what to draw.

You advise a mltl of 198l ?

Sent with tapatalk from a lazy chair......
 
#28
Only WRT to initially recommending an inverse tapered TQWT. Your driver works fine in a MLTL based on published specs and should be a much easier build.

I gave you my thoughts on the custom designed BLH and don't know how to make them more clear, sorry.

GM
 
#30
Check out these designs:

Caveman 15 - TQWT with 15XA38Nd

Sweden's No Frills Audio Introduces The Caveman Loudspeaker | Ultra High-End Audio and Home Theater Review

Wizard High-End Audio Blog: No-Frills-Audio Caveman 15

www.audioexcite.com Sweetspot Stockholm 2013

Inner Magazine - Stockholm Highend Mässä 2013 - Part III

Monitor 38 - 125L with xo 1200Hz (the highest I'd go!)

Monitor 38 (download the prospect for cabinet drawings)

Beyma XA38 von Oliver P.

Blog with various simulations (BR, sealed, LWT etc)

DIY Audio Blog: August 2013
 
#33
As turns out, this will be a long term project. A while ago i bought some (huge) volti horns with b&c compression drivers for a real bargain. So currently i'm building pair of jamborees.
When this will continue i don't know. But it's still in my mind.........
 
#40
Hi!
I'm resurrecting this thread if you don't mind...!


I'm also contemplating a speaker build with the Beyma 15XA38ND, much inspired by hifisucks' builds, and I have a few questions if I may:


In a 182 liter Arden-style cabinet tuned to about 45Hz I can only only get the bass down to about 50Hz before it starts dropping off (simulation in Boxsim). Is there a trick to extending the bass, or won't the 50Hz be a problem?


Will a Tannoy GRF-style back-loaded horn offer better bass? With that design I'm a bit worried about the ghosting effect of the mid-range through the horn.


I've also tried laying out an Onken-style cab, but the Onken-Excel-Sheet doesn't seem to "like" the TSP of the driver...


Is there an easy way of getting usable TSP for the mid / tweeter section of the driver? Apart from actually buying one and masuring it?


I do have a full DSP setup, but the aim would be to build a traditional crossover!


Cheers

Es
 
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