18" in horn for HT

[ßart West-VL.]

My current sub is a BR and I was wondering if the Monacor SPH-450TC can be used at a lower frequency then in a BR?
(http://www.diyaudio.com/forums/subw...ht-sub-stealth-corner.html?highlight=pivoting)
This is a good opportunity for me to learn HornResp, I would like to learn to design horns.
Can someone jump-start me in HornResp with this driver?

I have about 600 litre net to spend, maximum outside dimensions are:

Initial dimensions were wrong!
height 2m 38cm
width 81cm
depth 33cm
These are correct:
height 2m 45cm - 8.038 ft
width 86cm - 2.822 ft
depth 38cm - 1.247 ft

i don't even know what kind of horn is to be simulated, I'm a novice.

Thanks.


[Driver]
Brand=Monacor
Model=SPH-450TC
Manufacturer=Monacor
ProvidedBy=Bart
DateAdded=20121010
DateModified=20121010
Qts=0,25
Znom=8
Fs=20
Pe=1000
SPL=93
Re=7,4
Le=0,0046
fLe=0
KLe=0
BL=32,4
Xmax=0,0129
Cms=0,00022
Qms=2,97
Qes=0,27
Rms=12,7
Mms=0,305
Sd=0,125
Vas=0,48
Dia=0
Vd=0,0016125
no=0,0137
Dd=0
EBP=0
numVC=1
Hc=0
Hg=0
SPLmax=0
SPLmaxLF=0
USPL=0
alfaVC=0
Rt=0
____________________________________

Impedanz (Z)
2x4 Ω
Resonanzfrequenz (fs)
20 Hz
Max. Frequenzbereich
f3-1500 Hz
Empf. Trennfreq. (fmax.)
400 Hz
Maximale Belastbarkeit
2x500 WMAX
Nennbelastbarkeit (P)
2x350vWRMS
Mittl. Schalldr. (1 W/1 m)
93 dB
Nachgiebigkeit (Cms)
0,22 mm/N
Bewegte Masse (Mms)
305 g
Mech. Widerstand (Rms)
12,7 kg/s
Mechanische Güte (Qms)
2,97
Elektrische Güte (Qes)
0,27
Gesamtgüte (Qts)
0,25
Äquivalentvolumen (Vas)
480 l
Gleichstromwiderst. (Re)
2x3,7 Ω/1x7,4 Ω
Schwingspulenindukt. (Le)
2x1,1 mH/1x4,6 mH
Schwingspulendurchmesser
99,3 mm
Schwingspulenträger
Alu
Schwingspulenwick.-Höhe
37,8 mm
Luftspalthöhe
12 mm
Lineare Auslenkung (XMAX)
±12,9 mm
Eff. Membranfläche (Sd)
1250 cm2
Verschiebevolumen (Vd)
1612,5 cm3
Kraftfaktor (BxL)
32,4 Tm
Referenz-Wirkungsgrad (No)
1,37 %
Magnetdurchmesser
220 mm
Magnetgewicht
5,7 kg
Einbauöffnung
Ø 425 mm
Einbautiefe
220 mm
Abmessungen
Ø 460 mm
Gewicht
17 kg

 

[tb46]

Hi ßart West-VL.,

This is a tapped horn from my Hornresp "archive", maybe that'll get you started:

Regards,

 

[ßart West-VL.]

Thanks Oliver,

I have slightly different parameters. Where did you get your parameters?

 

[ßart West-VL.]

I'm lost in the segment numbers, don't really get the feel or visualisation of them.
Where can I find a guick start guide for HornResp?

 

[tb46]

Hornresp Tutorials

Hi Bart,

I don't know if there is a tutorial that addresses the new Wizards, but these two are good:

By lilmike:

Simple Tapped Horn Tutorial using Hornresp

By soho54:

Hornresp for Dum... hmm... Everyone - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

I think my T/S parameters were partially from the manufacturers data sheet, and partially recalculated by Hornresp.

Regards,

 

[epa]

also the help file of hr .
ik volg je bart

 

[ßart West-VL.]

Thanks Oliver and epa, I'll read read!

Hey epa, I was wondering when you would chime in, lol

 

[tb46]

Hi Bart,

You are calling this: "18" in horn for HT". I went on the assumption, that a front loaded horn would just be way too big ("...lower frequency...HT...), and that a tapped horn would be about the maximum size/output compromise. While learing Hornresp you may also want to try the other 1/4 wave resonators and transmission lines that have been popularized on this forum by bjorno, the tapped versions (QWP and T-TQWT), as well as the offset driver enclosures (OD-MLTL and OD-TTL). I'm sure you'll find other names and examples using "search". They will get you lower in a reduced volume with improved group delay.

Regards,

 

[GM]

FYI, a driver’s cab loading BW is defined by Flm = Fs*Qts/2 and Fhm = 2*Fs/Qts, though for Prof. Leach’s horn design routine, use Qes and of course it’s best to use measured specs.

With the understanding that the further below the driver’s upper mass corner [Fhm] the desired gain BW extends the less peak power handling is available; this driver’s low Fs, Qts means a very wide usable horn loading BW, so with its fairly high power handling capability, horn loading to below Fs is viable, though its high Vas means a relatively large cab.

GM

 

[ßart West-VL.]

What does BW stand for?
Flm= 20*0.25/2= 2.5
Fhm= 160

I tried to measure T&S parameters but ATB-PC Pro doesn't measure below 12hz, so it couldn't determine the lower impedance peak or something like that.
Even if it did work suddenly, then it would be even worse with the added mass.
I gave REW a go but didn't figure out enough to use it properly...

 

[seanny]

BandWidth

 

[ßart West-VL.]

Thanks.

Just sliding back and forth.
When changing radiation angle, the graph is very different.

 

[epa]

hi bart i use arta>limp
its free
al you need is a good low impedance meter(or make one) and some weights.

btw if you got~600 ltrs your sim should be aprox 450~500 ltrs

 

[epa]

something like this?

this could be ~55x47x225 bxdxh.
can you specify sizez?

 

[tb46]

Hi Bart,

I noticed a few things about your simulation in Post #12:

- the L34 dimension should be at least 1/2 the driver frame diameter for the driver to fit into the box,
- S1 does not have to be larger than Sd, it could be even as small as 1/2Sd (not quite sure about this, but that's how I interpret some of bjorno's simulations),
- in the Speaker Wizard, setting S2 and S3 to Auto makes things easier
- I recommend you keep the segments at Par,
- if you are simulating at higher power than reference (e.g.: 1W/1m) try to keep the maximum displacement in the Filter Wizard at or below Xmax (in my example about 300W/8Ohm).

Regards,

 

[ßart West-VL.]

I'm struggeling on here, lol.
Thanks for the help guys, much appreciated!
The space that I have to put the sub in is:
height 2m 38cm - 7.808 ft
with 81cm - 2.657 ft
depth 33cm - 1.083

Just downloaded Arta and the help files.
I will check in HornResp and see what Oliver is talking about, great stuff. I like the graphs.

It's 21:30 here, time for a movie with the prototype BR sub.
Can't be all thinking and no fun, right?!

 

[epa]

this one is exactly the outside dimensions you gave

olivers sim has a wider bandwidth,i just don't know how to fold that one in the given dims

 

[ßart West-VL.]

Didn't have time to learn about horns properly and 'hupla', epa has a 'ready to build' solution... incredible...
Now my motivation is gone to learn HornResp...Thanks a lot...

lol
I'll sure play around with the numbers in your HR sim but there isn't much room of course, the maximum dimensions are fixed.
Just want to see if the top end can be extended without loosing the low end.

I see you used quarter space instead of eighth space, why is that?

How thick is the wood in your drawing?

 

[ßart West-VL.]

OMG, I made a stupid error, sorry about that!

When I wrote the dimensions I already kept in mind the thickness of the boards and bracing, so the dimensions that I can use for the outside of the box are bigger.
I realized this when I saw the volume was only 430l instead of the 600l that I came up with.

I hope you aren't too disappointed, epa.

OK, I checked this twice to be sure:
height 2m 45cm - 8.038 ft
width 86cm - 2.822 ft
depth 38cm - 1.247 ft

One thing I was wondering about is, the depth behind the driver, is there enough room? I mean, for the venting.

 

[GM]

An end loaded tapped horn is limited to ~three octaves and ~two octaves for an off-set driver or inverse tapered one [T-TQWT], so yes, you 'rob Peter to pay Paul' within these limits as you shift its mean BP tuning [(Fl*fh)^0.5] up/down.

Here’s a ~three octave TH Vs its inverse ~two octave T-TQWT equivalent in 600 L net/522.78 cm path-length, which clearly shows the theoretical BW limits and extreme tuning difference, power handling capability.

GM