Part of audioXpress Speaker Focus edition in September 2017, this article by Don Keele, Jr. reminds us of how things evolved in speaker design, revisiting a subwoofer project that uses an Electro-Voice 30W 30" woofer from 1975! In "True Bass in a Large Space," Keele writes, "Getting true bass in a small place is quite easy and straightforward today, but back in 1975, it was not!"
Part of
audioXpress Speaker Focus edition in September 2017, this article by Don Keele, Jr. reminds us of how things evolved in speaker design, revisiting a subwoofer project that uses an Electro-Voice 30W 30" woofer from 1975! In "True Bass in a Large Space," Keele writes, "Getting true bass in a small place is quite easy and straightforward today, but back in 1975, it was not!" Inspired by Thomas Perazella's DIY article, "True Bass in a Small Space" (audioXpress, February 2017), Keele describes an equivalent solution from 1975 that provides about the same response and acoustic output but using a high-efficiency low-excursion 30" driver mounted in a massive 76 ft3 vented-box driven by a 60 W amplifier, with a total system weight that exceeds 800 lbs!
Don Keele, Jr. writes, Thomas Perazella’s
audioXpress article “True Bass in a Small Space” described a $900 very high-performance subwoofer system using a low-efficiency high-excursion 18” driver mounted in a 4 ft3 closed box driven by a 1,200 W DSP plate amplifier, with a total weight of only 115 lbs. The system was capable of radiating several acoustic watts down to 30 Hz.
![](https://cdn.xingosoftware.com/audioxpress/images/fetch/dpr_1,w_300,h_462,c_fit/https%3A%2F%2Faudioxpress.com%2Findex.php%2Fassets%2Fupload%2Fimages%2F1%2F20180214170449_Photo1TrueBassDonKeeleWeb-.jpg)
After reading that article, I was reminded of my time at Electro-Voice (EV) in the early 1970s when I designed the EV TL bass box line and specifically a very-large vented-box design called the TL303 for the EV 30W 30” driver. This article describes an equivalent solution from 1975 that provides about the same response and acoustic output, but used a high-efficiency low-excursion 30” driver mounted in a massive 76 ft3 vented-box driven by a 60 W amplifier, with a total system weight that exceeded 800 lb!
At the time, the direct-radiator enclosure design theories of Neville Thiele and Richard Small were new and Ray Newman and I and many others at Electro-Voice were at the forefront of encouraging the industry to use the then-new Thiele-Small (T-S) driver parameters for designing vented-box (bass reflex) loudspeaker enclosures.
After reading Perazella’s description of the low-efficiency high-output subwoofer system, I wondered how the vintage 1970s 76 ft3 vented box design with the low-excursion 60 W EV 30” driver might stack up against this latest competition. This article compares the two units using detailed simulations and analysis and comes to a somewhat surprising conclusion.
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This article was originally published in audioXpress, September 2017