The Subwoofer DIY Page
Horn Folding Spreadsheets
last updated: 02 November 2017
The Subwoofer DIY Page

Folding a new bass horn design or adjusting the dimensions of an existing design to meet a specific requirement can be somewhat of a challenge and prone to error.  To make the process easier and to avoid errors as much as possible, I've created a number of different Excel workbooks that can assist with the folding process. All of them should be considered as "works in progress" as I'm continually adding new features and of course fixing the odd bugs that I come across, so always make sure to check here for the latest version before using any of these workbooks.  Some of them I've actually used to design and build my own subwoofers (the best way to confirm that the workbook in question works), and in those cases I've included a link to the project sin question.  If you have any questions about the spreadsheets, please post them to the DIYAudio Subwoofers forum using the provided link below, thanks!

http://www.diyaudio.com/forums/subwoofers/171747-spreadsheet-folded-horn-layouts.html

boxplan-tham BOXPLAN-THAM
Current Version: 3.4
This workbook can be used to design a tapped horn with a "THAM" style fold.  I used an earlier version of this workbook to design my POC2 tapped horn. The spreadsheet allows for the design of both single and dual-expansion tapped horns.  The workbook contains optimization and export routines.  To use it, you'll need to enter the driver and desired box dimensions, then hit the "Optimize" button until the error cell reads zero (or keeps oscillating around some small numbers). Then update the file location and driver parameters at the bottom of the spreadsheet and use the "Export" button to export a file which you can then import into Hornresp for further analysis.
   
boxplan-mht BOXPLAN-MTH
Current Version: 2.2
This workbook can be used to design a tapped horn with a "MTH-30" style fold.  The MTH-30 fold is an easy one to do, but it only supports single expansion designs, which does limit its use a bit.  The workbook contains optimization and export routines.  To use it, you'll need to enter the driver and desired box dimensions, then hit the "Optimize" button until the error cell reads zero (or keeps oscillating around some small numbers). Then update the file location and driver parameters at the bottom of the spreadsheet and use the "Export" button to export a file which you can then import into Hornresp for further analysis.
   
boxplan-alt BOXPLAN-MTHALT
Current Version: 1.3
This workbook can be used to design a tapped horn with an alternate version of "MTH-30" style fold, where the mouth is placed on a different side of the box. The MTH-30 fold is an easy one to do, but it only supports single expansion designs, which does limit its use a bit.  Currently the workbook does not contain any optimization and export routines.  To use it, you'll need to manually enter the driver box and panel dimensions that you'd like to use, along with the expansion angles, then modify them until the "Err" values are as low as possible.  The horn's expansion is displayed as a guide.  Once you have completed this, copy the displayed Hornresp parameters to your Hornresp sim for the horn.
   
boxplan-mltl  BOXPLAN-MLTL
Current Version: 1.2
This workbook can be used to design a simple mass-loaded transmission line (MLTL) style vented subwoofer, with the vent placed at the narrow end.  I used this workbook to design my "Boom Unit" subwoofer. The workbook contains optimization and export routines.  To use it, you'll need to enter the driver, and desired box dimensions, then hit the "Optimize" button until the error cell reads the lowest number possible. Then update the file location and driver parameters at the bottom of the spreadsheet and use the "Export" button to export a file which you can then import into Hornresp for further analysis.
 
   
boxplan-ss  BOXPLAN-SS
Current Version: 6.3
This workbook can be used to design a tapped horn with an "SS"style fold, and include cone compensatin if necessary. I used this workbook to design my my POC3 tapped horn and POC4 tapped horn. The workbook does not currently contain optimization and export routines.  To use it, you'll need to manually enter the driver box and panel dimensions that you'd like to use, along with the expansion angles, then modify them until the "Err" values are as low as possible.  The horn's expansion is displayed as a guide. Once you have completed this, copy the displayed Hornresp parameters to your Hornresp sim for the horn.
 
   
boxplan-ss  BOXPLAN-SS (with optimization)
Current Version: 7.1
This workbook can be used to design a tapped horn with an "SS"style fold. This version of the workbook contains optimization routines, and a number of bugs existing in v6.3 have been corrected. I suggest using this workbook if you don't plan to or need to include cone compensation in the actual path.  Tho use it, you'll need to enter the driver dimensions, the desired box dimensions and the desired values for S1 and S5, then hit the "Optimize" button until the error cell reads zero. Then update the file location and driver parameters at the bottom of the spreadsheet and use the "Export" button to export a file which you can then import into Hornresp for further analysis. 
   
boxplan-vbslot  BOXPLAN-VBSLOT
Current Version: 1.3
This workbook can be used to design a sime slot-loaded vented subwoofer. The workbook does not currently contain optimization and export routines.  To use it, you'll need to manually enter the driver box and panel dimensions that you'd like to use. The workbook then provides relevant details such as net box size, vent length and cross-sectional area.
 
   
BOXPLAN-Othorn BOXPLAN-OTHORN
Current Version: 1.3
This workbook can be used to design a tapped horn with a "Othorn" style fold.  The spreadsheet allows for the design parabolic (default), conical or exponential expansion, the latter two being approximated by parabolic segments. A simulation of the actual Othorn produced by using this workbook shows a frequency response that is very similar to that measured for the Othorn. The workbook contains optimization and export routines.  To use it, you'll need to enter the driver dimensions, desired box dimensions, desired values for S2 and S5, then hit the "Optimize" button until the error cell reads the lowest number possible. Then update the file location and driver parameters at the bottom of the spreadsheet and use the "Export" button to export a file which you can then import into Hornresp for further analysis.

 

 

 

 

 

 

Brian Steele
02 November 2017