Tuesday, September 29, 2015

New Folded Bass Horn - Preliminary Testing

Even before completing the folded bass horn construction, I decided to borrow one of the KLH model CL-3A series-wired crossovers from the Sound Transformer and connect the corner midrange horn, folded bass horn, and Magnavox tweeter to one channel of a Lepai 2020A amplifier.  Here is a video of "Slow Burn" by Betty Fox Band through this setup:

Monday, September 28, 2015

New Folded Bass Horn - Even More Progress

 
The next two panels are rectangles to enclose the second section of the horn.  The horn throat is on the right in this photo.
Folded Bass Horn - Next Two Panels
Folded Bass Horn - Next Two Panels
 Here is another view from the end opposite the throat.

Folded Bass Horn - Next Two Panels
Folded Bass Horn - Next Two Panels

 It is necessary to make small rectangular sides for the "turning" region of the first horn folds.  One is visible in front and the other in the back of the assembly.


Folded Bass Horn - Small Rectangular Sides
Folded Bass Horn - Small Rectangular Sides
 Here is a triangular jig on top of the cover temporarily placed over the end opposite the throat.  The purpose of the triangle is to help to establish the angles for cuts on panel edges.


Folded Bass Horn - Cover And Triangular Jig
Folded Bass Horn - Cover And Triangular Jig
Here is a look down into the first fold showing short braces in place to secure four panels from vibration.

Folded Bass Horn - Small Braces
Folded Bass Horn - Small Braces
Here are two more side panels installed to establish the contour of the third horn section after the second fold.  The final flare core sides are in place making the "roof" at the top.

Folded Bass Horn - Two More Side Panels and "Roof"
Folded Bass Horn - Two More Side Panels and "Roof"
And here are two additional side panels fastened onto the assembly to enclose the third horn section.

Folded Bass Horn - Two Additional Side Panels
Folded Bass Horn - Two Additional Side Panels
I had no problems carrying this folded bass horn from the barn attic through the doorway into the adjoining listening room.  Here is the bass horn assembly with side panels attached to the "roof" and a baffle over the throat end.  There is an eight-inch bass driver attached over the throat for preliminary testing.

Folded Bass Horn - Preliminary Testing
Folded Bass Horn - Preliminary Testing
 Here is another view with the driver removed to show the square throat opening in the center.

Folded Bass Horn - Preliminary Testing
Folded Bass Horn - Preliminary Testing
I disconnected my Klipsch Short Horn from the right channel in my listening room and set up the folded bass horn in the corner just to see how it might sound.  The bass is very deep, tight, and solid even though the horn construction is still incomplete!

Check out the video at New Folded Bass Horn - Preliminary Testing.



Tuesday, September 22, 2015

New Folded Bass Horn - More Progress

Here is the folded bass horn progress for today.  First, I made three of the panels illustrated below.  Two are for this horn and the third is for use as a pattern later on.  The rectangular cutout provides a "key" for locating the panel and allows the side of the throat section to "feather" to the horn width.


Here is the throat section with four side panels glued on and clamped with sheetrock screws.  These four panels provide the sides of the next horn section.  I applied construction adhesive to the butt seam between each panel pair.


Here is another view looking into the horn throat.  Tomorrow, I will enclose the first fold by fastening a panel over the top of each half of the second horn section.


The next installment is at New Folded Bass Horn - Even More Progress.

Monday, September 21, 2015

New Folded Bass Horn - Progress

The inspiration for the New Folded Bass Horn project is the Klipschorn, designed by Paul Klipsch about seventy years ago.  The goal is a folded bass horn with lighter weight, wider frequency range, more accessible driver assembly, and versatility as bench seating and display shelving.

Yesterday, I cut some parts for the New Folded Bass Horn out of a 4' x 8' sheet of plywood.  I am starting with the throat construction of the horn first because it will not be accessible after the horn is completed.  Here is the throat, consisting of a central spacer web with two sides.

New Folded Bass Horn - Throat Construction
New Folded Bass Horn - Throat Construction
After assembling the horn throat, I set up the plywood sheet outside and cut out the next four panels for the next flare.  I used the throat assembly as a jig to check and refine the dimensions of the next four panels.  In the photo, upper left, is the horn throat assembly.  One panel is visible to the left of the circular saw.  I use the 4' straight edge and small clamps as a guide for cutting panels.  I am using a plywood blade with small teeth to minimize tearing up the plywood edge.


New Folded Bass Horn - Cutting out panels
New Folded Bass Horn - Cutting out panels
Finally, I set up the throat assembly for further assembly.  Here is a panel in position.


New Folded Bass Horn - Panel in position
New Folded Bass Horn - Panel in position
I use sheetrock screws to fasten the panels together while the glue is drying.  It is a little tricky maintaining the assembly square and free of distortion.  It helps that the plywood sheet is quite stable and flat to begin with.  All four panels are now glued and fastened.  This is a view looking into the horn throat.  You can see the end of  the center spacer inside the horn throat in the following picture.

New Folded Bass Horn - Looking Into Horn Throat
New Folded Bass Horn - Looking Into Horn Throat
 Here is the opposite end of the assembly, showing the center spacer extending about two inches beyond the side panels.


New Folded Bass Horn - Looking At Opposite End
New Folded Bass Horn - Looking At Opposite End
 Here is another view with the assembly set on the throat end.  At this point, the first 25 inches of the bass horn to the first fold are fully assembled.  There will be more to come as additional 25 inch lengths are added one at a time.


New Folded Bass Horn - Another View
New Folded Bass Horn - Another View
You will find more progress on this project at New Folded Bass Horn - More Progress.

Wednesday, September 9, 2015

Sound Transformer Midrange Horns Get New Paint

Here are some images of the midrange horns with a coat of  black paint:

Sound Transformer Midrange Horns With New Coat Of Black Paint
Sound Transformer Midrange Horns With New Coat Of Black Paint


Sound Transformer Midrange Horns With New Coat Of Black Paint
Sound Transformer Midrange Horns With New Coat Of Black Paint

Sound Transformer Midrange Horns With New Coat Of Black Paint
Sound Transformer Midrange Horns With New Coat Of Black Paint

 
Now for some listening tests!