The Subwoofer DIY Page
Horn Folding Spreadsheets
22 May 2022

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 in 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: 4.6  - 02-APR-2021
This workbook can be used to design a tapped horn with a "THAM" style fold.  I used an earlier versionof this workbook to design my POC2 tapped horn. The spreadsheet allows for the design of both single and dual-expansion tapped horns. 

boxplan-mht

BOXPLAN-MTH
Current Version: 3.2 - 02-APR-2022
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. 

boxplan-alt

BOXPLAN-MTHALT
Current Version: 3.1 - 08-MAR-2018
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.

boxplan-ss 

BOXPLAN-SS
Current Version: 9.7 - 21-SEP-2021
This workbook can be used to design a tapped horn with an "SS"style fold.

boxplan-vbslot 

BOXPLAN-VBSLOT
Current Version: 2.3 - 08-JUN-2021
This workbook can be used to design a sime slot-loaded vented subwoofer. This new version of the workbook uses Hornresp's new "Offset Driver / Offset Vent" model, in an attempt to show the impact of the driver and vent locations on the frequency response.  Make sure that you download the latest version of Hornresp before you use it.

BOXPLAN-ODOV
Current Version: 0.3 BETA - 02-APR-2021
This workbook can be used to simulate a speaker with an offset driver and offset vent on the baffle, the purpose being to determine the best locations for both, by observing the simulated impact on the out-of-band resonance modes in the vent's response.

BOXPLAN-Othorn

BOXPLAN-OTHORN
Current Version: 3.3 - 30-MAR-2021
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.

 

BOXPLAN-WBIN
Current Version: 3.3 - 08-MAR-2022
This workbook can be used to design a simple "W-bin" type of front-loaded horn. 

  BOXPLAN-CYCLOPS
Current Version: 3.1 - 19-MAY-2020
This workbook can be used to design a "Cyclops" type of tapped horn with straight segments (the last section is flared however).   

  BOXPLAN-ROAR
Current Version: 1.0 - 22-JAN-2020
This workbook can be used to design a "ROAR" type of tapped horn. The workbook contains optimization and export routines. 

  BOXPLAN-SPLANAR
Current Version: 0.4 (beta) - 09-NOV-2018
This workbook can be used to design a planar type of compound horn. The workbook contains optimization and export routines. 

  BOXPLAN-TL1
Current Version: 1.8 - 31-MAY-2020
This workbook can be used to design a straight TL, using a fold that is very popular with the car audio crowd. 

  BOXPLAN-TL2
Current Version: 1.3 - 01-JAN-2021
This workbook can be used to design a straight TL, using a better fold than the TL1 fold as it allows for much more flexibility in positioning the driver at a useful offset down the line.

boxplan-mltl 

BOXPLAN-MLTL
Current Version: 2.8 - 07-SEP-2021
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 an earlier version of this workbook to design my "Boom Unit" subwoofer and my "POC6" PA bass unit.

  BOXPLAN-MLTL2
Current Version: 0.2 (beta) - 13-MAR-2022
This workbook can be used to design a mass-loaded transmission line (MLTL) style vented subwoofer, with a folded vent. 

  BOXPLAN-MLTL3
Current Version: 1.3 (beta) - 06-JUN-2020
This workbook can be used to design a mass-loaded transmission line (MLTL) style vented subwoofer, with a straight vent. 

  BOXPLAN-SFTH
Current Version: 0.4 (beta) - 21-NOV-2021
This workbook can be used to design a simple TH with one fold.  This is probably the simplest way that a TH can be designed, and is best used for home audio builds as the box can end up being pretty tall.

BOXPLAN-SFTH2
Current Version: 0.6 (beta) - 06-FEB-2021
This workbook can be used to design a simple TH with two folds, similar to the SFTH fold.  Like the SFTH fold, this is best used for home audio builds as the box can end up being pretty tall, though the extra fold in the design does provide for some flexibility in the box dimensions.  

  BOXPLAN-TQWT
Current Version: 0.1 (beta) - 08-FEB-2019
This workbook can be used to design a simple mass-loaded Tapered Quarterwave Tube with one fold.  Like the SFTH fold, this is best used for home audio builds as the box can end up being pretty tall.  

BOXPLAN-MWTH
Current Version: 0.3 (beta) - 15-APR-2019
This workbook can be used to design a tapped horn that uses the same fold used in the "Microwrecker" tapped horn.   

BOXPLAN-BP6S
Current Version: 1.2 (beta) - 17-AUG-2019
This workbook can be used to design a series-tuned 6th order bandpass system. It also includes an additional feature that allows you to import an existing 6th order bandpass Hornresp sim as a target.

BOXPLAN-BP6S2
Current Version: 0.4 (beta) - 17-JAN-2021
This workbook can be used to design a series-tuned 6th order bandpass system with an alternate layout.

BOXPLAN-BP6P
Current Version: 1.2 (beta) - 17-AUG-2019
This workbook can be used to design a parallel-tuned 6th order bandpass system. It also includes an additional feature that allows you to import an existing 6th order bandpass Hornresp sim as a target.

  BOXPLAN-BP6P2
Current Version: 0.1 (beta) - 13-DEC-2020
This workbook can be used to design a parallel-tuned 6th order bandpass system with an alternate layout, similar to the "Paraflex" designs.

BOXPLAN-CUBO
Current Version: 1.1 (beta) - 12-JAN-2020
This workbook can be used to design an optimized "Cubo" tapped horn.

  BOXPLAN-POC7
Current Version: 1.2 (beta) - 19-MAY-2020
This workbook can be used to design an optimized "POC7" tapped horn.

  BOXPLAN-SHINSON
Current Version: 0.6 (beta) - 08-FEB-2021
This workbook can be used to design an offset front-loaded horn, using a folding scheme provided by Scott Hinson. It's still a work in progress.

BOXPLAN-PARAC
Current Version: 0.6 (beta) - 22-MAR-2021
This workbook can be used to design a Paraflex "Type C" design. It's still a work in progress.  Version 0.6 (beta) includes support for Hornresp's new "PH1" sim model.

BOXPLAN-PARAA
Current Version: 0.8 (beta) - 22-MAY-2022
This workbook can be used to design a Paraflex "Type A" design. It's still a work in progress. Version 0.5 (beta) includes support for Hornresp's new "PH1" sim model.

BOXPLAN-PARAC2E
Current Version: 0.1 (beta) - 27-FEB-2021
This workbook can be used to design a Paraflex "Type C2E" design. It's still a work in progress.

BOXPLAN-PARAH
Current Version: 0.1 (beta) - 13-FEB-2021
This workbook can be used to design a simple parabolic offset sealed horn.

BOXPLAN-BP4SLOT
Current Version: 0.2 (beta) - 12-JUN-2021
This workbook can be used to design a simple parabolic offset sealed horn.

  BOXPLAN-DRIVERS
Current Version: 0.2 (beta) - 21-FEB-2021
This workbook can be used to display Hornresp's driver database in a simple table, allowing for easier review and manipulation. The workbook also allow you to export the driver database to a different folder.    

In Development:
These workbooks that are flagged as "beta" should be considered as still under development, so expect a few bugs. Panel dimensions should be checked closely, for example. If you use them and come across any bugs, please report them to me thanks, using the message thread listed at the top of this page

General Instructions:
These are general instructions to follow when using the BOXPLAN workbooks.  Note that some of them do have some steps that should be specifically followed when using them.

  1. Enter the physical dimensions, the t/s parameters and if available the semi-inductance parameters for the driver that you want to use in the "Driver" spreadsheet in the workbook. You can also use the "Load Driver" option to load the parameters for any driver currently stored in Hornresp's database.

  2. Enter the physical dimensions of the box that you want to use in the "Design" spreadsheet in the workbook.

  3. Enter the thickness of the wood that you plan to use to build the box in the "Design" spreadsheet in the workbook. In some of the workbooks, you can select different thicknesses for different panels.

  4. In some of the workbooks, you can adjust the depth of the baffle inset, or the position of the driver on the baffle. Do this if necessary.

  5. Under Hornresp parameters, enter the cross-sectional area of the sections or their lengths where allowed to do so.

  6. If the workbook has an Optimize button, hit it until all the numbers in red read "0.00". The layout of the box is now optimized. If it does not have an Optimize button, adjust the lengths of each panel and the expansion angle or angles until the expansion graph is smooth and all numbers in red read "0.00" or very close to zero.

  7. Under "Filename", change the desired location of the export file. The default location for HornResp is "C:\Hornresp\Import". and click on the "Export" button.

  8. In Hornresp, select "File..Import..Hornresp Record" and import the file you created in Step 7

  9. In Hornresp, select "Tools..Loudspeaker Wizard" to bring up the Loudspeaker Wizard, and review the simulated response of your design by selecting "Power" from the pulldown menu.

  10. To adjust your design, change any of the options available to you on the "Design" spreadsheet, hit the "Export" button and press F6 to quickly update the sim in Hornresp. Repeat this step until you get a result that you like.

  11. Take the panel dimensions from the "Panel Dimensions" section of spreadsheet, cut the panels, build your box and enjoy. If available, use the "Guides" sheet in the workbook to assist with the layout of any internal panels in the box.

Brian Steele
22 May 2022