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paulspencer 26th October 2005 12:57 PM

Comments on bass horn sim in horn response
 
2 Attachment(s)
Comparison of Adire Koda Mk1 (not sure of all params unfortunately) and Tang Band W8 740C.

The darker line is the Tang band and the grey is the Koda 8"

The Tangband has 150w but the Koda has 100w, which does not concern me as both have plenty of SPL

There will be some eq for the TB to get the peak down which will make excursion acceptable, but since the koda is already flat, I've given it less power; it would have a highpass to control excursion.

Which is better?

Keep in mind that I will eq with ultracurve

The koda is flat at the bottom end but is more difficult to eq on the top end.

Anyone have advice on what to look for with sims? I'm finding it a bit hard to know if what I see is a good thing or not!

paulspencer 26th October 2005 01:00 PM

2 Attachment(s)
excursion

Rademakers 26th October 2005 06:06 PM

Some more questions first:

Can you post a view of the input window as well? A lot of information is in there. Furtermore, what's the Xmax of both the units, what is your intended frequency range (30ish?) and how are you most likely going to load the cabinet into space?

Do the dimensions mentioned (100 x 60 x) in the other topic apply to this horn?

Mvg Johan

simon5 26th October 2005 06:10 PM

Hey Paul !

I think you can do better than that, there's serious ripple in the passband, what's the frequency you want to use the horn? I'll try to do better for fun, maybe it's the driver making it hard?

Good luck!

paulspencer 26th October 2005 06:33 PM

Johan, they both have an xmax of about 12mm

corner loaded (most likely)

40 - 120 Hz ideally

I don't really need lower than 40 since my subs take over down there, but it just so happens that they seem to get down to 30 Hz! I'd actually rather they were smaller, or that the response was smoother, or that they don't need corner loading, than have 30 Hz extension.

100 x 60 x 40 would be a good size I could live with, although doing some work on cad I found it hard to work with those dimensions! It seems easier to design when it is square. I want to avoid greater than 90 degree bends.

Simon,
If you have ideas how to get it flatter I'm all ears. However, I notice that even the lab horn isn't that smooth, and yet when I've tried modelling it, I could get it smoother, and Danley could have easily done that as well. So I ask why he didn't. Obviously there is more to it, so I'm trying to learn some of the rules of horn design. With sealed and vented boxes, we have a better idea of how the response should look, but in this case I'm not so sure.

simon5 26th October 2005 07:04 PM

Due to your size limits, I can't improve your design much.

To be flat 3 dB, I need about 3.2 meters long and 6600 square centimeter of mouth hehe!

You'd get around 130 dB at 150W imput and stay under the 12 mm Xmax limit with a back chamber of 8 liters.

paulspencer 26th October 2005 07:15 PM

Actually I'm getting it much flatter by starting with the Hypex designer and working backwards. It gives me a smaller throat and a larger mouth and slightly shorter horn. I can cut back on the mouth area, reducing it to 40 x 60cm while still getting reasonably flat.

s1 40
s2 2400
hyp 375
vrc 4.5L

When I work through the same process with the Koda driver, it now doesn't look as good, as it has a sharp and narrow peak in excursion around tuning, whereas it is easier to tame the excursion on the TB.

simon5 26th October 2005 07:21 PM

Well, to respect your old 1000x600x450 limit, I did s1:220 s2:2700 CON:250

You get your old 5 dB response but only 3 peaks instead of dozen of them. It would fit in your enclosure, mouth would be 600x450.
VRC:8 LRC:10 TAL:0 FR:0 VTC:0 ATC:0

EDIT: Since you've got displacement left where dips are, you could even EQ the two dips up instead of EQing the three peaks down.

Rademakers 26th October 2005 08:00 PM

Just some thoughts:

If you don't need 30 Hz, I wouldn't go there even if they can, as it's much easier to get a flat response in the given size for a 40 Hz horn. Especially when 1/8 th space isn't what you want ideally.

I think S1 could be made between 55 and 110 cm2 without problems for the cone, if it's stiff (enough). This could enhance the response much over a 220 cm2 throat.

The Labhorn was designed to be used in a stack of 4 or 6, so it doesn't needs to be flat on it's own. High powerhandling resulting in high SPL-levels and especially low distortion where the more important design-factors.

In the beginning of the horn it isn't problematic to have folds which have more than 90 degree bends. In the end it's prefered to have it smooth however. You could take a look at the Punisher design as it's a clever fold (like some of the Tuba's).

There are definitly speakers that make it easier to get a flat response.

Wkr Johan

MJK 26th October 2005 08:50 PM

From the plots, your horn looks more like a TL. The peaks in the SPL and the nulls in the displacement plots are probably good indicators of quarter wavelength standing waves.


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