Electronic Bass Augmentation Devices

Sub Harmonic Synthesis

manufacturer name description comments cost
dbx 120A sub-harmonic synthesizer they claim it fueled the disco era, sampling range of 54-110Hz (for 27-55Hz synthesis), seperate crossover, pro inputs/outputs only (1/4") $200
Audio Control Phase Coupled Activator Series 3 (PCA) sub-harmonic synthesizer selectable sampling range 50-100Hz and 30-70Hz (for 25-50Hz/15-35Hz synthesis), seperate crossover, RCA inputs/outputs only. product discontinued $250
Audio Control Epicenter sub-harmonic synthesizer automotive 12V version of the PCA. cool/flashing EPICENTER logo tracks The Bass. discontinued (list was $200) $140

Graphic Equalization

manufacturer name description comments cost
Alesis MEQ-230 30 bands 1/3 octave EQ (25Hz to 20kHz) two channels in one rack space!, tiny/stiff sliders, NOT constant Q, short throw sliders, (1/4" and RCA inputs/outputs) $220
Audio Control Richter Scale Series 3 1/2 octave bass graphic equalization (6 bands) calibrated mic, warble source and meter, seperate crossover $300?
Audio Control Bijou THX 1/6 octave for bass (20Hz - 80Hz) 1/3 octave for fronts 80-800Hz + surrounds?, constant Q, short throw sliders $995
DOD SR4321Q and SR231Q 31 bands 1/3 octave EQ (20Hz to 20kHz) mono or 2 channel, constant Q, short throw sliders, pro inputs/outputs only (XLR, 1/4") $199, $299
Rane ME60 30 bands 1/3 octave EQ 2 channel, constant Q, (pro and RCA inputs/outputs) $575

Parametric Equalization

manufacturer name description comments cost
Marchand BASSIS WM-8 2 band parametric for bass they claim it is an inverse Q speaker compensator, like a LPF with adjustable Hz and Q and dB gain, but it really is just a bass parametric EQ. Might have a crossover built in. Available as kit. $400
Rane PE17 5 band parametric EQ If desired all bands can be configured for bass 10-200Hz pro inputs/outputs only (XLR, 1/4"). Fantastic product. Recommended! $400
Rane THX44 2 parametric bands for bass (20Hz - 80Hz) 1/3 octave for fronts 80-800Hz + parametric, constant Q, short throw sliders. discontinued $1200

Compressor / Limiters

manufacturer name description comments cost
Behringer Composer dual compressor / gating / limiter dual channel, standard compressor stuff, pro inputs/outputs only (XLR, 1/4") $110
dbx 166XL dynamics processor dual channel, noise gating / compression / peak control / +, pro inputs/outputs only (XLR, 1/4") $250
dbx 266XL dual compressor / gate dual channel, standard compressor stuff, pro inputs/outputs only (XLR) $150


manufacturer name description comments cost
Crown K2 the ultimate bass amplifier 2 channel: 475W into 8ohms, 800W into 4ohms, 1250W into 2ohms, bridged mono: 2500W into 4ohms, 1600W into 8ohms, damping factor of 4400 at 50Hz, cool running class D fan-less design, completely sealed chassis, does run warm to the touch but it doesn't get hot!, 38 pounds, pro inputs (1/4", XLR). Fantastic product. Recommended! $1550
Sabine SDA-102 speaker delay line .9 - 999.98ms delay range, 20bit DA and AD conversion, level controls, 1/6 rack space size, pro inputs/outputs only (?? maybe) $365

Spectrum Analyzers (RTA)

manufacturer name description # of bands bandwidth LEDs per band pink noise generator comments cost
Audio Control SA 3052 1/3 octave realtime analyzer 30 25Hz - 20kHz 9 yes each LED can be 1,2,3 or 4 dB. (9dB - 36dB window) can store and average up to 6 measurements. product discontinued $1,100
DOD series II 1/3 octave realtime analyzer 31 20Hz - 20kHz 5 yes 4dB or 12dB window, filters have 18dB/octave slope $309
Gold Line LM27P5 1/3 octave realtime analyzer 27 40Hz - 16kHz 5 yes 12dB or 21dB window, fast and slow decay rates, checkout Gold Lines other analyzer offerings $499
HP 35665A FFT dynamic signal analyzer inf 244uHz - 102.4kHz ? yes dual channel, hold and store, averaging, storage to disc drive, waterfall display, selectable windowing, selectable linear/log/dB magnitudes, optional 1/3 and 1/12 octave realtime mode $13500
HP 3569A 1/3 octave realtime analyzer 36 1.6Hz - 20kHz ? yes portable, LCD, dual channel, A/C/flat weighting, hold and store, averaging, memory storage for 3000 spectra, 0.3dB accuracy, optional RT60 calc, FFT mode for finer frequency resolution $9000
Rane RA-27 1/3 octave realtime analyzer 27 40Hz - 16kHz 3 yes 1dB or 3dB window. product discontinued $361
SigBlips baudline FFT dynamic signal analyzer 65536 2mHz - 192kHz 2048 yes multi channel. capture, record, play. Zoomable Displays: color waterfall spectrogram, average, histogram, waveform. Adjustments: calibration, equalization, windowing. Distortion measurements: SNR, THD, SINAD, ENOB, SFDR. Only works on Linux. free

My comments, words of caution
In my opinion the purpose of graphic and parametric equalizers is for either correcting some of the bass room modes (standing waves) or for correcting a speakers F3 (-3dB) roll off point. Pink or warble noise, and a SPL meter or spectrum analyzer (RTA), plus the knowledge of how to use them is required for proper calibration of EQ's. Sub-harmonic sythesizers are just fun toys for frightening small animals.

Electronic bass augmentation devices are very dangerous to the safety of your audio system. Sub harmonic sythesizers and equalizers can create an undue burden on speakers, subwoofers, and tactile transducers. Remember that extremely low frequencies are harder (require more excursion) to reproduce than higher frequencies. Keeping the SPL the same but dropping down an octave requires +12dB more excusion. This hardship could destroy your speaker drivers or melt your amplifiers, so be careful. Also vented subwoofer enclosures are prone to speaker "flapping" below their vent tuning frequency.

Remember +12dB is equivalent to 4X'ing the number of drivers and amplifiers. So if you insist on cranking the 20Hz band up +12dB or you crank that sub-harmonic sythesizer up then you will have to quadruple the number of your bass drivers and amplifiers. It is either that or reducing the max volume you listen to by -12dB, or have a melt down. Your choice.

Sub-harmonic "rumble" filters (HPF's) are recommended not only for vented cabinets but for all low frequency drivers, but then you really won't be able to get that flat 10Hz - 80Hz frequency response curves! You have been warned.

Also, most pro gear only have 1/4" and XLR inputs and outputs. Some like the Rane ME60 and Alesis MEQ-230 also have RCA connectors, but this is rare with pro gear. So if you mix pro and consumer gear then special cables or converters, and caution is recommended. Know what you are doing.

Suggested "Augmented" Bass signal path (top to bottom)
  1. source: CD, LD, DVD, ...
  2. preamp/decoder: pro-logic, AC3, DTS, 80Hz crossover, line level sub output
  3. sub harmonic sythesizer: restore missing bass or create totally insane bass. Split signal into two paths after this point, the subwoofer and the transducer side.
  4. equalizer: graphic or parametric, smooth out room modes (standing waves) or correct for driver response roll offs.
  5. compresser/limiter: prevent overload and allow level matching between devices that have drastically different output levels.
  6. digital delay line: for the transducer path to correct for the difference of distances between the sub woofers and the tactile transducers. Could be placed before the equalizer. It is debatable which position makes better use of the DDL's dynamic range.
  7. amplifier: plenty of power is essential, class A's run very hot which I don't like, and most pro amplifiers have fans which are loud and annoying. Choose your amp carefully.
  8. subwoofers/transducers: the output devices.

Check out my quest for bass page.