Dave's Speaker Pages

Mensicus Audio has provided a dedicated sub-forum at their site for WinPCD, a Windows application program patterned after Jeff Bagby's very successful Excel spreadsheet, the Passive Crossover Designer (PCD). WinPCD is compatible with Jeff's session files and uses an identical schematic scheme with minor additions. It also largely emulates the design methodology so that PCD users should be able to work with it without much difficulty. Go to the links farther down for more information.

My pages are mostly from the empirical aspect. I started this site as part of a discussion on the Madisound Discussion board back around 2000. It just kept growing as I found new topics that were of interest to me. I never expected that it would expand as it has. It remains only a hobby for me.

Writing software has become my current passion with regard to speakers. Links to the them are in the first section below. Several programs are available. These are Windows native programs and are free for anyone to use. They should run on anything from XP to Windows 10.

The General Articles section contains a web-based version of an article of mine published in Speaker Builder magazine (ONE:2000) included. It describes a method for determining relative acoustic offset for drivers when mounted on a baffle.

The diffraction section shows the predicted and measured impact of baffle edge diffraction on the driver raw response as well as an extensive set of measurements of baffles with felt applied for diffraction reduction.

One page on CAD software deals with phase error due to an inaccurate CAD model. An example using CALSOD is extensively documented. A second page deals with the Hilbert-Bode transform and the effects which can occur when the CAD model does not have enough range, as when the high end rolloff of a tweeter is too high for the measurent system.

One of my early forays was Tweeter Tweaks. This section shows all details of adding wool to the pole piece vent, but not just any wool. I found, quite by accident, a product which is very useful for tweeters. It is used to stuff the pole piece vent and has absolutely no negative effects, although moderate density cotton, such as that found in aspirin bottles, seems to be nealy as effective. The cotton used is clean and much more consistent in density. I wholeheartedly recommend either of these for tweeters for which access to the pole piece vent is possible. Some tweeters either prevent access and/or they already have a good filler from the manufacturer. Examples of the latter are the Vifa XT-25 and the Scan-Speak tweeters (probably all of them). I also have a section that shows results of the testing of changing rear-chambers.

The models section shows a couple of the electrical and acoustic models used to represent a driver and/or system. It is one frequently used in CAD software.

The raw measurements pages are now for those taken on what I call my "quasi-IEC" baffle. Raw measurement text files either exported from LAUD v3.0 or CALSOD (with Hilbert phase using CALSOD) may be downloaded by anyone interested. Be aware, though, that they will only be quasi-anechoic (no baffle effects), so you won't get what these show. You'll have to post-process them for baffle diffraction. Tweeters will have significant baffle effects, midranges will vary, smaller ones having more effects. Woofers will have baffle step loss, but little if nay other diffraction effects. These files must be considered as useful more for some testing and learning than for any final designs. The files can be imported into the tools at the FRD Consortium or other software such as the Passive Crossover Designer to get approximations. Some users have taken it the extent of designing from scratch using this method, but it takes some experience to get reliable results. It's always best to use actual measurements if possible.

10 Sep 2019: MusicAndDesign, a web site created by John Kreskovsky, closed as of 1 Sep 2019. His contributions to the speaker building knowledge of both amateur and professional alike have been significant. His site contained a wealth of technical information with emphasis on dipole physics. I found it invaluable as a learning and reference site. My dipoles were designed using his dipole spreadsheet. I felt that this resource should be made readily available, so with John's permission I created an archived copy in a subdomain. I've added links to software and special instructions that he provided at his site. Links to them can be found below.