AV Rant #737: Interview with Todd Welti on Subwoofers
We are proud to present our interview with Todd Welti, Distinguished Engineer at Harman International Inc., and the author of the whitepaper, Subwoofers: Optimum Number and Locations, which is the primary topic of our discussion today. We hear about Todd’s background, and his current setup at home. Then we dig into Todd’s subwoofer research, getting clarification about audience location, subwoofer locations, time alignment, and level matching. We tackle notions about Full Range speakers, “stereo bass”, and crossovers.
Then we expand our discussion to tackle non-rectangular and open rooms. Various ways of addressing such rooms, including CABS, the Geddes approach, and Sound Field Management. That leads to some discussion of ARCOS. And some final, practical simplifications and clarifications before finishing up with some of Todd’s more recent research and modelling of a large number of different rooms and subwoofer and seating locations.
Our thanks to AVRant Listener Joe K. for putting us in touch with Todd. And a huge thank you to Todd for being so generous with his time, and for presenting so much amazing information!
Links:
– Subwoofers: Optimum Number and Locations: https://www.harman.com/documents/multsubs_0.pdf
– Audio Engineering Society (AES) Convention Paper 8748: Optimal Configurations for Subwoofers in Rooms Considering Seat to Seat Variation and Low Frequency Efficiency: https://www.aes.org/e-lib/browse.cfm?elib=16490
– Low-Frequency Optimization Using Multiple Subwoofers (includes mentions of avoiding nulls, mode canceling, and Sound Field Management: https://audioroundtable.com/misc/Welti_Multisub.pdf
– Controlled Acoustic Bass System (CABS) “Double Bass Array”: https://vbn.aau.dk/ws/portalfiles/portal/62729209/LF_sound_field_control.pdf and https://www.aes.org/e-lib/browse.cfm?elib=14642
– Earl Geddes multiple subwoofer approach: https://mehlau.net/audio/multisub_geddes/
– Multi-Sub Optimizer Software: https://www.andyc.diy-audio-engineering.org/mso/html/index.html
– History of Multi-Sub & Sound Field Management: https://www.audioholics.com/room-acoustics/history-of-multi-sub-sfm
– JBL ARCOS (Adaptive Room Correction and Optimization System): https://www.jblsynthesis.com/about/arcos.html
– Additional Harman whitepapers: https://www.harman.com/audio-innovations (you can find the graphics that Todd mentions near the end of the podcast here. Look for “Optimal Configurations for Subwoofers in Rooms Considering Seat to Seat Variation and Low Frequency Efficiency: Color Plots”)
– Our YouTube video version (this link will take you straight to the portion when Todd begins showing his graphics & diagrams): https://youtu.be/BZtRNVG078A?t=3283
– Room EQ Wizard: https://www.roomeqwizard.com/
– Cross-Spectrum Labs individually calibrated microphones: https://cross-spectrum.com/
– Rob’s 12 Step Guide: http://avrant.com/a-12-step-guide-to-setting-up-dual-subwoofers/
Todd’s contact info:
– Twitter: https://twitter.com/todd_welti
– email: todd.welti at Harman dot com
– Todd’s AES Member Profile: https://www.aes.org/member/profile.cfm?ID=682293182
- Check out the AV Rant YouTube channel to watch our show videos.
- Download Tom’s FREE superhero-themed ebook Bob Moore: No Hero.
- Visit Tom's website for download links as well as links for the two full-length follow-ups - Bob Moore: Desperate Times and Bob Moore: Hostile Territory.
- Check out AVGadgets.com where Tom is the new Editor-in-Chief!
- Download Tom's NEWEST book, Touch of Pain from Amazon now!
Podcast: Play in new window | Download
Subscribe: RSS
