Single sheet TH challenge

[Djim]

Originally Posted by 4pyros

OK then make S1 and S2 smaller? Why did you open up the S1 area again? Andy

Andy, grey lines "old" situation, red lines my suggestion. However, it's not accurate yet for a final drawing. The total volume of S1, S2 until the first bend wont change that much and that's more important then a correct visualisation. I expect changes (positive) in the upper part of the bandpass.

[tb46]

Hi Djim,

I'll attach a revised drawing of the original SS15 horn path, and a .xls file with the data point (had to rename the .xls file as .txt to get it uploaded, to use: change the extension back to .xls).

Regards,

[4pyros]

Oliver; It does not look like you moved the path lenght out to the mid point of the long lines going into the corners. Was thare a reason for that? Andy

[epa]

Originally Posted by tb46

Hi Djim,

I'll attach a revised drawing of the original SS15 horn path, and a .xls file with the data point (had to rename the .xls file as .txt to get it uploaded, to use: change the extension back to .xls).

Regards,

hi oliver i like the mod in this post
not only the path is longer but it also stiffens the back pannel..
that and 2 deflectors in the last 2 corners ,you do not need bracings(except the flappy ends) imo.
regards erik

[kenpeter]

A few questions and assumptions of mine that might be misguided:

The most limiting factor is the mouth size? Which is restricted by
the total internal volume available to expand toward that size.

Maximum internal volume for a given amount of side area is a cube?
Though this assumption does not account for area used by internal
baffles and bracing, maybe a cube makes this worse?

What of the floor? Can it be a "side", would that be a legit cheat?

I've never built any tapped horn, but did build a Karlson K15 once.
Thats definitely tapped, hybrid of too many things to say for sure
why it behaves as it does, and almost exactly 1 sheet. Effective,
but not sure how it compares against a horn of that same 4x8??

[Xoc1]

Jbell post 12

BTW -- leaving out the bottom panel and saying "just sit it on the floor" is cheating.....

[tb46]

Hi 4pyros,

Responding again to your question in Post #583: "Can you get it to bend at S3?" I changed the flare from S2 to S3 to an even 3degrees, and then started into the same angle as your driver mounting board, that will do it, no major change in Hornresp:

Regards,

[tb46]

Hi 4pyros,

Post #623: "...does not look like you moved the path lenght out to the mid point of the long lines..."

Because soho54's method does not use the long lines in the corners, and he has done a lot of testing comparing simulations to actual tapped horns, so I'm sticking with his method for the overall corner length.

Regards,

[Xoc1]

Djim
I added 3 extra lines to the corner sketch, making 7 in total - the extra line that you want to add at the beginning of the bend seems wrong to me as this line is before the corner actually starts.
I should explain that when I sketch in the lines to measure the corner, that the first line is perpendicular to the previous centre line, before this point in my opinion the expansion is linear.
The last line through the corner is perpendicular to the outside wall as this is the shortest distance.
I have attached some screengrabs of what I have done so far for you to appraise. Is this what you are trying to acheive?
I am busy at the moment, and will continue to be for the next 3 months so it may take some time to get back to you.

I have based my dimensions on the PDF files in posts 74 & 82 by TB46
Can anyone confirm that these are the most accurate drawings of the SS15 as it stands?

As for modifying the ss15 it is very tricky to improve on what JBell has done with 1 sheet of timber.
You could shorten the 8" mid panel a little to get a more linear expansion (at the expense of the path length)
You could lengthen the baffle to make the last corner more smooth.
but that makes it a ss & a bit more 15

I found JBells explanation of the shape that he was trying to acheive very interesting. The expansion of the horn then emulates a parabolic shape.
I am trying to develop that idea by sketching the unfolded path of a TH with an expansion based on a segment of an elipse
Regards
Martin

[Djim]

Thanks Martin for dropping by and I didn’t post you since I saw your absence around here, the man must be busy...

I do have a comment on the middle path route which you can see in my next post as an answer to Oliver his post. Yes! The idea of 7 reference points you are showing is exactly what I am after. I know my graphics are bad because I don’t have the right progs or skills so I only can use my bad eyes and unstable hand and use straight line as guidance (and most time I work with old fashion pen & paper). I use the same dimension from post 82 since it’s in metric numbers.

I know it’s tricky to change this SS15 concept but maybe there are small possibilities that can improve here and there a dB or something. Also I think there are possibilities with less known factors. But indeed it is very difficult to stay within the one-sheet-challenge. Sometimes experience gives more opportunities then just predictions simply because not all parameters are represented in HornResp. To name a few:
1.) Dropping of BL force in conjunction with excursion
2.) Absorption trough panels
3.) Air mass changes along the path (especially around ‘non gentle’ bends, I am looking in other areas to find more solid info on this matter)
4.) Imperfections of data (still looking for accurate measurements of 3015LF parameters)

Jbells goal of his parabolic was indeed very interesting to see lined up to the ‘roll-out’ from Oliver. Like I said before I was following your post with great interest since the horizontal representations or roll-outs do show more information that the visual of the cab. That’s why I need accurate roll-outs and along a (metric) scale. Anyway, thanks for responding and don't stare to much on those reports. Especial in the next three months when weather is changing