How to Design Loudspeakers without Performing Measurements

[dlr]

Re: How to Design Loudspeakers without Performing Measurements

Jeff,
I think this is one of those tomato, toe-matt-oh cases, either way works. I recommended the same offsets in the slides (slide 13), but personally feel its better if the actual frd file contains the delay offset. This replicates what you would get from real measured files.

The user can then still dial in additional delay via the PCD to see the lobe move over various vertical angles.

Dave

I don't know how much difference it makes in typical cases, but I agree with Jeff because I believe it's the more accurate model if one is going to examine the off-axis.

dlr

[DDF]

Re: How to Design Loudspeakers without Performing Measurements

canadians rock.

No, we Kick Axe, and I have the t-shirt to prove it!

[DDF]

Re: How to Design Loudspeakers without Performing Measurements

Dave,

Thanks, this looks excellent, but I do have a question. Why advise the user to "add a small amount of delay" using the Response Modeler to adjust for the woofer's offset and not enter any Z-offset in PCD? First, how much is a "small amount of delay" that would make for an accurate adjustment? Leaving the driver as minimum phase and adding in offsets in the Passive Crossover Designer has two significant advantages: First, it is much more accurate in establishing the correct amount of delay, as -.020 to -0.024 Meters works well over a wide range of small woofers. Second, once entered, the designer now can model the interaction of the drivers on different vertical and horizontal axes, which is a powerful piece of information in the design process as well. I personally feel this is a much better approach and similar to the one we grew up with using CALSOD.

Jeff B.

Jeff,
I think this is one of those tomato, toe-matt-oh cases, either way works. I recommended the same offsets in the slides (slide 13), but personally feel its better if the actual frd file contains the delay offset. This replicates what you would get from real measured files.

The user can then still dial in additional delay via the PCD to see the lobe move over various vertical angles.

Dave

[Jeff B.]

Re: How to Design Loudspeakers without Performing Measurements

Hi all,
I've created a presentation explaining the usage of the free speaker design programs that Charlie Laub is kindly hosting on his site. The presentation illustrates a design method for those with without access to measurement equipment, and is geared towards users not yet intimately familiar with the programs. Also included are a number of design tips, tool usage tips, an introduction to *.frd files, and pointers to driver databases.


The programs include:

• Unibox - Excel Program for modeling the response of closed, vented, passive radiator and bandpass loudspeaker boxes
• BoxyCAD - Excel application for planning loudspeaker box construction including cut list and sheet goods estimation
• Baffle Diffraction and Boundary Simulator – Excel application for modeling the effects of baffle and room response
• Frequency Response Modeler - Excel application for manipulating FRD files in many ways
• Passive Crossover Designer - Excel application for designing passive crossovers and equalization
  
  and tools from the FRD Consortium
  
  
• Baffle Diffraction Simulator
• SPL Tracer - a utility for loading a picture file of a frequency response and automating the process of tracing over that response to create a FRD (Frequency Response Data) file for later import into other Acoustic Design Programs

You can find the presentation on Charlie's site (thanks Charlie), where most of the tools are also hosted:

http://audio.claub.net/software.html

Also included is a 12Meg zip file which illustrates step-by step an example design with these programs, including all the necessary .frd and .zma files.

This was originally created for the Ottawa Winter 2011 DIY meeting, and I hope you also find them useful.

Dave Dal Farra
Ottawa, Canada

Dave,

Thanks, this looks excellent, but I do have a question. Why advise the user to "add a small amount of delay" using the Response Modeler to adjust for the woofer's offset and not enter any Z-offset in PCD? First, how much is a "small amount of delay" that would make for an accurate adjustment? Leaving the driver as minimum phase and adding in offsets in the Passive Crossover Designer has two significant advantages: First, it is much more accurate in establishing the correct amount of delay, as -.020 to -0.024 Meters works well over a wide range of small woofers. Second, once entered, the designer now can model the interaction of the drivers on different vertical and horizontal axes, which is a powerful piece of information in the design process as well. I personally feel this is a much better approach and similar to the one we grew up with using CALSOD.

Jeff B.

[theLinks]

Re: How to Design Loudspeakers without Performing Measurements

Thanks Jeff, Charlie and Dave! And the rest who give back to this hobby!
Tim

[[email protected]]

Re: How to Design Loudspeakers without Performing Measurements

canadians rock.

[donradick]

Re: How to Design Loudspeakers without Performing Measurements

Thanks Dave!

Exactly what I need at this time.
Maybe you could have the mods put this into a permanent link in the "Designing Speakers" thread.

[DDF]

Hi all,
I've created a presentation explaining the usage of the free speaker design programs that Charlie Laub is kindly hosting on his site. The presentation illustrates a design method for those with without access to measurement equipment, and is geared towards users not yet intimately familiar with the programs. Also included are a number of design tips, tool usage tips, an introduction to *.frd files, and pointers to driver databases.

The programs include:

• Unibox - Excel Program for modeling the response of closed, vented, passive radiator and bandpass loudspeaker boxes
• BoxyCAD - Excel application for planning loudspeaker box construction including cut list and sheet goods estimation
• Baffle Diffraction and Boundary Simulator – Excel application for modeling the effects of baffle and room response
• Frequency Response Modeler - Excel application for manipulating FRD files in many ways
• Passive Crossover Designer - Excel application for designing passive crossovers and equalization
  
  and tools from the FRD Consortium
  
  
• Baffle Diffraction Simulator
• SPL Tracer - a utility for loading a picture file of a frequency response and automating the process of tracing over that response to create a FRD (Frequency Response Data) file for later import into other Acoustic Design Programs

You can find the presentation on Charlie's site (thanks Charlie), where most of the tools are also hosted:

http://audio.claub.net/software.html

Also included is a 12Meg zip file which illustrates step-by step an example design with these programs, including all the necessary .frd and .zma files.

This was originally created for the Ottawa Winter 2011 DIY meeting, and I hope you also find them useful.

Dave Dal Farra
Ottawa, Canada