Welcome to John Pomann's Web Pages:
This is the way-station where you can find links to my pages. This site will remain stable, even though the locations of the individual pages may move. Therefore, I ask that you please link here (or store this page in your "favorites") if you want to reliably reach me or get back to my work. This site was updated on 12/25/01.
You can E-mail me at: firstname.lastname@example.org
Active Crossovers for DIY Speaker Builders:
(http://www.snippets.org/filters/crossover.htm or http://www.t-linespeakers.org/pomann/crossover.htm)
Here you will find lots of info on active crossovers, and a very flexible kit designed for speaker builders, or anyone interested in active filters. Thanks to Dave Dlugos (Planet10) for hosting this link.
A Simple Quiet Preamp (http://www.snippets.org/filters/preamp.htm)
Other Pages: coming soon.
News / Looking for.....
1) Active Crossover Testimonials Page: Many of you sent me photos and graphs of your completed work. Unfortunately, do to my bad organiztion I have lost many of them. The ones I have saved may be viewed at:
http://www.t-linespeakers.org/pomann/testimonials.htm If you want your work posted here, please send it to me.
2) I am always looking for new music. I like Blues, some Jazz, some New Age, and Instrumental pieces. Some examples: Ronnie Earl and the Broadcasters, Billy McLaughlin, Al Di Mieola. All recommendations appreciated.
Recommended Audio/Electronics Reading
BASIC, hands-on electronics: Radio Shack's Getting Started in Electronics, by Forrest Mims (1983). Very simple, very good, very cheap. Weak on equations, strong on 'gut understanding'. Covers MANY important areas for the hands-on beginner.
Op amps, filters, components: Complete Guide to Active Filter Design, OP AMPS, and Passive Components, by Z. H. Meiksin (1990). Simple, but all equations there, and simplified whenever possible. Newer op amps are better than the ones he talks about.
Hands-on audio projects: Enhanced Sound - 22 electronic projects for the audiophile, by Richard Kaufman (1988). Keeps things simple; useful and interesting audio projects.
See Erik Brewster's Active vs Passive crossover discussion at: http://home.inreach.com/ebrewste/cross.html
See Rane Corp's website for TONS of quality discussion of active crossovers, grounding and awesome App Notes: http://www.rane.com/
**See Foote's (advanced and awesome) discussion on Sallen-Key filters: http://www.t-linespeakers.org/filters/Sallen-Key.html
Additionally, I've learned a lot from databooks (National Semiconductor, Burr Brown, etc.). Lots of them are now on the web:
See B-B's data sheets: http://www.burr-brown.com/ This is the link to download the pdf of the OPA2134 op amp data sheet: http://www.burr-brown.com/download/DataSheets/OPA134.pdf
Search the application notes or data sheets @ National Semiconductor: http://www.national.com/
See Matt Tucker's page active crossover at http://kahuna.sdsu.edu/~tucker/diyaudio/xover.html.
See Alex Megan's DIY active crossover work at: http://www.soton.ac.uk/~apm3/diyaudio/AXO.html.
See Luc Henderieckx's page at http://users.pandora.be/airborne; His page shows a rigorous and detailed application of active filters, complete with spreadsheets, response curves, and more.
See a DIY Test Mic Kit: http://www.gti.net/wallin/preamp.htm
Look at the OT Tech Articles at the Transmission Line Speakers Page: http://www.t-line speakers.org/
True Audio has a spreadsheet to calc values for a 'Linkowitz transform' circuit: http://www.trueaudio.com/
Check out this Architectural Loudspeaker System, and great Audio Electronic Schematics, at Paul's site: http://www.linkline.com/personal/phorn/audio/rss_schematics.html
See Tons more Audio Electronic Crossover Links, compliments of the Transmission Line Speakers page: http://www.t-linespeakers.org/xolinks.html
For those very new to Basic Electronics, see: http://library.advanced.org/16497/ (recommended by Greg Worrel)
A cheap, many-function multimeter: http://www.web-tronics.com/webtronics/my-65.html (found by Greg Worrel)
Want to check an advanced power supply created by a 'seasoned tweeker' who uses my kit? Please see Greg Robert's work at: http://communities.msn.com/DIYElectronics
Want to check out a similar commercial kit?: Marchand Electronics Inc. Although more expensive and less flexible, you should check them out before buying from me.
Special Thanks to: contributing members of the Bass List http://www.diyloudspeakers.org/ , and all other sites I link to.
Some of My Favorite Info-Rich DIY Speaker Links
http://www.snippets.org/ldsg/idx.htm The Loudspeaker Designer's Selection Guide. Mandatory Reading.
http://www.spiceisle.com/audiodiy/ Brian Steele's Subwoofer DIY Page
http://www.silcom.com/~aludwig/contents.htm Art Ludwig's page (rigorous experimental work)
You can E-mail me at: email@example.com