$325 Lab 12 based PA tapped horn ~ 35Hz extension

Art,
Thanks for the tip. Any suggestions for placement of the keystone in relation to the driver? Or keystone cutout area?
The Keystone exit area should be similar to the predicted area to start with.

The aspect ratio seems to be related to path length vs cabinet height and width, examples of a 2x10" (26.5 x 22.5 x 15 inch deep) and the 18" (26.5 x 45 x 22.5 inch deep) below.

Relationship to the driver? "It depends".
The 18" (or 2x12") have the drivers and the upper portion of the exit in the upper half of the cabinet, the 2x10" in the lower half.

That said, I experimented with a lot of shapes and sizes with both, each required a different compromise.

One tip, listen to each change before saving the test result, early on I had one test that the upper response looked much better (a dip had filled in) turned out it was a pipe clamp resonating against a panel :rolleyes:.

Hope you have a lot of clamps!

Art
 

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Hi m R g S r
Looking at your fold in Post 8 it looks like the S3 corner where you have positioned the reflector the reflector panel is too big, and is causing a restriction. Also it looks like the centre panel in the first corner after S2 could benefit from being a bit longer - but of course I could be seeing distortion due to the photograph. Fairly sure that the reflector corner is a bit tight though. Are you planning to fit a castor on that corner?
Regards Xoc1
 
I want to use casters, which is the purpose of that reflector panel. Once I get the casters I can mock up and make that panel as small as possible just enough to fit the casters.

It did appear to me that it was causing a slight restriction so I already thought of making that panel smaller.

Do you know if there is a minimum area which should be maintained around the turn in order to not restrict?
 
If I remember correctly the center panel is 22.75"

I could add an inch to that and take an inch off the bottom of the left panel, closest to the reflector. That would reduce the restriction there...
That wouldn't hurt, as the middle panel first turn looks to be oversized.
As a rule of thumb I have just tried to make the area an even expansion from beginning, to middle to around the corner- the caster turn was almost doing that already.

One suggestion to keep the caster panel from punching through when hitting ramps, use 45 degree angles on the caster panel so there is maximum wood overlap when in the tilt back position.
 
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Awesome! Thank you
I could shorten the panel and if I need to I can add a small reflector to the opposite side.
Although I thought the reflectors were more for bracing and upper response...but I could be wrong.
I do, however, want to keep bracing at a minimum to keep weight down.
Internal panel width is only 13.5", so bracing isn't as critical as in a 21" internal width horn.
 
I would not worry about adding reflectors - They were added to the TH18 design during development because of other members requests for perfection -
Only much later did it become apparent that even Mr Danley did not think they were necessary.....:rolleyes:
Some might add a single reflector, say to the top right hand corner in your fold as this stops the opposing panel walls in two directions from being parallel.
Others might equally say that this just adds weight and reduces volume!:headshot:
 
I would not worry about adding reflectors - They were added to the TH18 design during development because of other members requests for perfection -
Only much later did it become apparent that even Mr Danley did not think they were necessary.....:rolleyes:
Tom had mentioned sometime in the latter part of last century how faired corners had reduced output level in his folded horn designs, guess you were late to that party ;).
 
Also made a 12" mouth for now as opposed to 13.5". Mouth testing will be done as Art suggested, for different shapes and sizes.
For testing I'd suggest not building any portion of the front panel so you can experiment with various height openings- you may find the exit should be taller than you have drawn.

It does not appear you have changed an important detail (learned from many failed cabinets that were a real PIA to repair) of part "E" mentioned in post #28, a picture included this time:
 

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Here is the updated sketch / layout....

imageijrc.jpg


New Hornresp coming in a min...,

Bad news, can't fit it all on one 4x8 sheet. So I most likely won't waste $ on two 4x8 MDF sheets, ill just build the test cabinet from (2) 3/4" Baltic Birch sheets and hope it works out!

A. 29 1/8" x 13.5"
B. 30" x 13.5"
C. 24 1/2" x 13.5" (subject to change with the keystone / different mouth size)
D. 21 7/8" x 13.5"
E. 13" x 13.5"
F. 28" x 13.5"
G. 23 7/8" x 13.5"
H. 9" x 13.5"
I. 16 3/4" x 13.5"
J/k. (Side Panels) 30" x 38"
 
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