Secrets Benchmark Product Review Klipsch RT-12d Subwoofer Part I December, 2006 Ed Mullen




● Bass Reflex through Passive Radiators

● Drivers: One Active 12" Front-Firing, Two 12" Passive
    Radiators on the Sides

● MFR: 19 Hz - 120 Hz ± 3 dB

● Amplifier: 800 Watts RMS BASH
● Adaptive Room Correction (ARC) with Included

● Connections: RCA Inputs and Outputs, USB 2.0

● Dimensions: 18.75" H x 24" W x 21.75" D

● Weight: 71 Pounds

● MSRP: $1,999 USA, in Cherry or Black Ash




Founded in 1946, Klipsch Audio Technologies (Klipsch) has become one of the leading manufacturers of speakers for audio and home theater use, and is a popular choice with audiophiles and home theater aficionados around the world.

Since the year 2000, Klipsch has introduced more new products than at any other time in its 60 year history. Klipsch manufactures floorstanding, bookshelf, and architectural speakers, powered subwoofers, center channels, and surround sound speakers.

The RT-12d is one of their latest, and largest subwoofers.

General Product Description

The RT-12d packaging solution was well-engineered and protective of the subwoofer. Additional items in the shipping container included a plug-in microphone (for the auto-EQ feature), a detachable power cord, and the Owner's Manual with serial number label.

The Owner's Manual is presented in no less than seven languages, and is well-written, comprehensive, and detailed, with excellent photographs and diagrams explaining proper control usage and all aspects of operation.

Corner placement is easy with the triangular shaped cabinet. Dimensions are roughly 19" H x 24" W x 22" D, and the subwoofer weighs about 71 pounds. Floor interface is handled by heavy-duty rubber feet. The amp connections are in the rear, while the amplifier itself is internally mounted on the cabinet bottom. The digital interface control panel is top-mounted for easy user access. The cabinet interior features one brace with a cut-out for the woofer magnet.

The three grilles feature an injection-mold plastic lattice framework that can withstand a collision with a running dog or child; owners with active households will appreciate this. The grille grommets are rubber allowing them to damp vibration and flex if someone accidentally leans on the grille tops while connecting or adjusting the subwoofer.

The RT-12d is available in two finishes – cherry or black ash wood veneer. The review model came finished in black ash. Fit and finish on the review model were great, with no surface flaws and tight seams and tolerances.

Woofer and Passive Radiator Description

This subwoofer is a bass reflex alignment, with a 12" front-firing active driver, and dual side-firing 12" passive radiators. The woofer is an overhung voice coil design, with dual spiders featuring woven opposing tinsel leads, a double stacked magnet with vented pole piece, a cast basket frame, and that famous copper-colored Cerametallic™ cone with a high-excursion rubber surround. The passive radiators use similar cones, surround, spider, and cast basket components. The woofer is attached to the cabinet with machine screws and recessed nuts – a nice touch.

Digital Control Panel and Amplifier Description

The top-mounted digital control panel is so convenient it makes you wonder why other manufacturers didn't include this feature long ago. The keypad features up/down push buttons to scroll through the menu, and left/right push buttons for adjusting each setting. There is a center push button to store and recall settings or to lock the keypad.

Digital Control Panel Features:

Memory Presets (Music, Movies, Night, User1, User2)
EQ Mode (Flat, Depth, Punch)
Room Correction (auto-EQ)
Low-Pass Filter Frequency (40-120 Hz)
Low-Pass Filter Slope (18, 24, 36, 48 dB/octave)
Low-Pass Filter Bypass (LFE Mode)
Phase (0-180 degrees variable)
Panel Brightness (4 intensity settings)
Power (auto-on with standby or always-on)
Demo (two 12-second demos)
Keypad Lock
System Info Settings

While I certainly applaud the flexibility of the adjustable frequency and slope of the Low-Pass filter, most owners will probably use the digital bass management circuit (which imposes a Low-Pass filter on the subwoofer) in the surround sound processor (SSP). The "Lowpass Off - LFE Mode" setting on the RT-12d is appropriate in this case.

The Depth EQ setting boosts the 30 Hz region, and the Punch setting boosts the 55 Hz region. As one might suspect, the Flat setting uses no EQ. Refer to the In-Room Frequency Response section of this review for FR charts showing each EQ Mode settings. My goal for subwoofer reviews is to always obtain a flat frequency response at the listening position so I didn't use the Depth and Punch settings, but they might appeal to some listeners looking to add a little flavor to the bass mix. Regardless, I would recommend the Flat setting prior to engaging the auto-EQ Room Correction routine.

The Auto-EQ Room Correction (Called Adaptive Room Correction or ARC by Klipsch) utilizes a microphone (placed at the listening position) and generates a sine sweep from 15-120 Hz over about 55 seconds. The software attempts to smooth the frequency response by attenuating peaks in the response using a parametric equalizer. I tried the Auto-EQ at several different subwoofer locations and listening positions, and found it an accurate and useful feature. I deliberately introduced room nulls at certain sub/mic locations in an attempt to trip up the software, and it consistently ignored true nulls rather than vainly trying to boost them - thus passing this test with flying colors. Refer to the In-Room Frequency Response section of this review for a before/after FR chart showing the operation of the Room Correction routine.

Amplifier Features:

Digital BASH (800 watts continuous)
Clipping, Thermal, and Overload Protection
Detachable Power Cord
Power Switch (rocker)
IR Sensor (for remote control – codes available at the Klipsch website)
USB Port (PC interface for advanced users)
Mic Input (for auto-EQ feature)
Low Level L/R RCA inputs
Low Level L/R RCA outputs (unfiltered)

During subwoofer break-in with sine waves, I noticed a small air leak from the USB port. I could not detect this air leak during normal music/movie listening sessions, nor do I believe it negatively affected the performance of the subwoofer. The USB port allows more advanced users to access additional menu options in the Room Correction software. Proprietary Klipsch software is required for your PC in order to use this capability. Included below is a screen shot of the software showing the PEQ parameters used to modify the frequency response shown. Contact Klipsch Technical Support for more details if you are interested in using this advanced PC software.

Click Here to Go to Part II.

© Copyright 2006 Secrets of Home Theater & High Fidelity

Go to Table of Contents for this Issue.

Go to Home Page.


About Secrets


Terms and Conditions of Use

Our Vault pages may have some display quirks. Let us know if we need to take a look at this page or fix a bug.
Connect with us
  • Instagram
  • Google+
  • YouTube
  • LinkedIn
  • Pinterest
Secrets "Cave"