Enclosure to Tangband W8-1772

[Hoffmeyer]

Hello there.

At my job I have been so lucky as to receive a pair of Tangbang W8-1772 for evaluation purpose.
http://www.tb-speaker.com/detail/1230_04/w8-1772.htm
I must say that they look a million.
Thus far we've only tested them in 16l sealed enclosures, the size based on simulation made in WinISD Pro Alpha.

The treble is well-balanced, neither over-analytical nor absent,
the midrange is still a bit hard, but I think it's just a matter of breaking it in, but there is a good speech-intelligibility. No tendency to shout or being nasal.
Bass is of course lacking, and this is where I need advice from You, since I only have experience with TL's and sealed enclosures for Hi-Fi, and none of these are suitable for this fullrangespeaker ;-)

There are many other ways to make bass, deep'n clean, like horns and various ML and quaterwave-styles, and a lot of You who are a lot more experienced than I to se which design will suit this speaker the best, and help with the math!

My evaluation of the speaker will of course be sent to Tangband, together with descriptions of the enclosures used, since they delivered the speakerunits, but the proprietary rights to any design comming from this forum will of course belong to this forum.

Is there anybody out there..........
who are willing to give a hand?

[hm]

Hallo Hoffmeyer ,

i made a double horn study and plan to take the TB8"
as the front driver,
if you need easy math calculation for expo horns, tell me.

[Hoffmeyer]

Hi hm.

Thank You.
That looks beautifull.
Unfortunately we only have 1 pair of speakerunits, and not 2 pairs, as required for this design.
I really like Your designs at Your homepage.
Facinating.

[hm]

hello,

thanks,
the indirect driver could be a
Visaton BG20, or the pioneer,
cheap and if no invers montage,
it might be a need of a 6 dB
at 500- 1000 Hz

[dzzmiller]

Horst, if you finish that design and are willing to share, please post it.

[Hoffmeyer]

Hello again hm

Originally posted by hm
[B]if you need easy math calculation for expo horns, tell me.]

Easy math would be nice, but there are a few issues I'd like to adress before we start our pocket calculators and XLS spreadsheets, just in order to understand the choises being made

-First issue is a chamber behind the speaker.
I've read somewhere that it will act as a low-pass filter to the horn, filtering out frequencies that can cause phase cancelations.
Is this true, and if so, how is it calculated.

-Second issue is the calculations of the horn it self: size of the hornthroat, expantion rate, area of the horn mouth.
I'm very well aware that the amount of bass, and the bass extension depends of these parameters, but are these things solely determined by math, or do experience play a part as well?

-Third issue is the hornmouth, or rather in wich direction it shall radiate, backwards, downwards or forwards.
What are the pro's and con's??
Please tell me if I'm wrong, but when facing backwards it will use the wall, or corner, behind it to enhance the output from the hornmouth, but also making the speaker more sensitive to where it is placed in the room.
When facing forward You'll hear everything that comes out of the hornmouth, good and bad!
Facing downwards can't just be a design issue, but is it a way to take pro's, and not the con's from the others??

[hm]

Hello,

1:
look my TUBA and a Sat horn for example,
more important for Basshorns, look my use of softfibre
you can reduce frequencies over 100 Hz.
a simulation is the best way to get the right size.

2:
if you take physically optimum you need 5,9 sqm for
40 Hz = not realistic, in living room is the lenght and flare rate important and the flare rate must be one oktave below the wished lowest frequenz.

3:
i use softfibre, so i like the direkt variation.

But for helping, it is better you tell us what a horn you will built and which driver.

If you know what you will construct, my easy math are:

Calculation of expo horns

If you have AH, AM, l,
k still lacks the flare rate:

ln (AM / AH) / l = k

so you can see the surface
each point out (Al):

INV ln (l * k) * AH = Al

l m, AH + AM + AL in square meters

By Al e.g. m in width and divide
you have the distance in meters

AH = Horn throat
AM = Horn mouth
k = flare rate
l = length


Lengths and flare rate VALUES

K VALUES:
0.37 ~ 10 Hz
0.55 ~ 15 Hz
0.7 ~ 19 Hz
0.9 ~ 25 Hz
1.1 ~ 30 Hz
1.3 ~ 35 Hz
1.48 ~ 40 Hz

About an octave above k plays the horn,
if the length matches. At BL horn lengths
over 3.4 m, you get a suck out
below 100 Hz

4/lamda lengths VALUES
3.4 m ~ 25 Hz
2.8 m ~ 30 Hz
2.4 m ~ 35 Hz
2.1 m ~ 40 Hz
1.7 m ~ 50 Hz
1.4 m ~ 60 Hz

[Scottmoose]

if the length matches. At BL horn lengths
over 3.4 m, you get a suck out
below 100 Hz

Only if they're not impedance matched down to Fo.

[hm]

No,

all BLH have that suck out, but most over 100 Hz,
at 3,4 m it is below 100 Hz,
make aj horn simus, you will see.

[Scottmoose]

Er, no offense, but what BLHs have you been looking at?

1 very rough back loaded horn 25ft long (7.62m). I've made no attempt at all to refine or reactance annul it -heck, it's only an exponential, rather than a ~optimal hyperbolic. Even so, I might be going blind, but I can't see a suckout below 100Hz. Come to that, I can't see a suckout above 100Hz either.

In fairness, I agree, the more you compromise the impedance matching at cutoff, the more response aberations you will get, but it's complete nonsense to say 'all BLHs have a suckout below 100Hz.' They don't.