Cabinet/Driver Resonance Tweaks for SDA-1Cs
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PolksTillIDie
Posts: 98
I've heard in this forum and elsewhere about resonance deadening of SDA drivers and cabinets. Specifically, using Dynamat X-treme on driver baskets and lately, using Sonic Barrier behind the midwoofers in two four-inch strips.
Does anyone know specifically what frequencies I'm treating by these tweaks? Will I get a smoother, flatter frequency response characteristic of modern loudspeakers from these changes?
Does anyone know specifically what frequencies I'm treating by these tweaks? Will I get a smoother, flatter frequency response characteristic of modern loudspeakers from these changes?
Polk SDA-1Cs with RD0194-1 upgrade tweeters, SoniCaps, Clarity PX, Gimpod boards, Cardas BPs, Erse inductors, Canare 4S11 IC; Yamaha Aventage RX-A1080; Yamaha M-80; Yamaha C-80; Yamaha CD-S1000; Sony UBP-X800M2; Technics SL-1400 with Ortofon 2M Bronze PnP; Vincent Pho 701; PS Audio Dectet; AudioQuest Red River ICs; WAudio PCs; RapcoHorizon High Def High 413-Strand 10AWG Speaker Cable; Auralex Isolation Pads
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You will get less distortion. You don't want the speaker baskets to be energized at all because that is going to find its way back to the cone and interfere with its movements that should ONLY be from the primary musical signal.
You can't stop that energization from occurring but you can reduce the amplitude of those vibrations greatly and make them die out sooner (reduce ringing) with a material like Dynamat Xtreme which is actually a constrained layer dampening material because of the aluminum skin. Does it change the resonant frequency? I'm sure it does but I'm not sure if it raises or lowers it. That's not the primary goal.
You will hear drums like tom toms and congas like you never did before the mod. The tone will be different and there will be faster rise and decay times. At least that was my experience. So it is in those frequencies that the primary improvement lies I believe.
So I don't take heat for a long winded explanation (too late probably) the effect of the Acoustical Foam material behind the MW is to absorb some of the backwave that would've had a chance to reflect off of the cabinet walls and back on the rear of the cone which will produce distortion as well, reducing clarity.
My Armacell Foam mod inside the baskets does something similar but works at a closer distance to diminish the reflections from inside the basket.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Specifically, using Dynamat X-treme on driver baskets and lately, using Sonic Barrier behind the midwoofers in two four-inch strips.
Black Hole 5 is better than Sonic Barrier.
To answer your question, it cleans up the mid-range frequencies.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
