Making Bass!

EX1200 UltaBass Pro
I occasionally use a Behringer EX1200 in the signal path between my active crossover and subwoofer amplifier. It synthesises low frequency sub harmonics which have been lost in the recording process. Not HiFi, but this unit is a whole lot of fun!



The BEHRINGER ULTRABASS PRO EX1200 is a professional, universal bass enhancer for all live and studio applications. This digital sub-harmonic synthesizer allows you to add unbelievable bass power to any sound system. Whether in your disco or club, your cinema, with your touring PA or your home stereo, you'll add an entirely new musical dimension to your sound. You can choose between "Full Range" for compact systems and "Split" for satellite systems with subwoofers. A wealth of additional useful features makes the ULTRABASS PRO an unbeatable "power station".

The BEHRINGER ULTRABASS PRO generates additional sub-harmonics musically important frequencies, which can be set to one or two octaves below the lowest frequencies present in the original signal. The generated tones are based on waveform analysis and harmonize perfectly with the original sound. The sub-harmonic synthesizer creates a new frequency spectrum, giving you a beefy low end that warms the heart of any bass freak.

Features:

A few changes to my EX1200

After using the EX1200 for some time, I found it was lacking in some areas. The high pass F3 as given in the spec sheet is 16Hz. I felt I was missing some of the first octave when I had the EX1200 inline, and this lead me to do some measurements of my unit. This revealed an F3 of 24Hz, quite a bit different from the 16Hz spec. Another problem I encountered was the adjustable threshold for the subharmonic synthesizer could not be set low enough to prevent the unit from breathing on some source material. A system with higher signal levels would not suffer from this problem.

Another thing I noticed (for those who want to use the crossover function in the EX1200) is that the subwoofer low pass frequency is varied by the frequency control on the front panel. This means to use the EX1200 as a subwoofer crossover, the frequency control must be set to it's lowest setting to match the high pass on the satellite output, otherwise there will be excessive overlap between speakers.

After drawing out large parts of the circuit, I made several changes to my EX1200.

  • R71 changed to 56K from 10K. This increases the gain in the bass processor circuit. 22K was also tried, but this did not increase the gain sufficiently. In the last few units I modified, I used a 100K 22 turn trimmer in place of R71. This can be set to make the EX1200 clip just as the sub power amp goes into clipping. Adjusting the EX1200 this way will maximize the dynamic range of the unit.


  • C15 and C18 changed to 4.7uF from 2.2uF and C10, C11, C13 and C14 changed to 2.2uF from 1.0uF. These changes moved the F3 down to 16Hz and the F6 down to 10Hz.


  • I am now very happy with the performance of my EX1200. It is particularly effective when watching movies which have all low frequency content below 40Hz filtered out. (Almost all movies) The waves of sub-bass pressure in the listening room must me felt to be believed!


    Disks That Don't Need Any Help In The Bottom Octave

    Title Artist Label Comments
    1812 Overture Tchaikovsky Telarc CD-80041 Digitaly Recorded Cannons
    Great Fantasy/Adventure Album Erich Kunzel Telarc CD-80342 T-Rex and lots of other fun stuff
    Fantastic Journey Erich Kunzel Telarc CD-80231 More Telarc fun
    Time Warp Erich Kunzel Telarc CD-80106 Track 1 has some super low Synth
    Chiller Erich Kunzel Telarc CD-80189 More Telarc fun
    The Big Picture Erich Kunzel Telarc CD- In a word, BIG. Apollo 13 launch is huge!
    By Way Of The World Spies Telarc CD- Low and punchy modern jazz
    Pictures At An Exhibition Jean Guileau Dorian Supurbely recorded 32' organ pedals
    Watermark Enya Low bass pops up several times during the album
    Surfacing Sarah Mclachlan Lots of low bass, especially track 2


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