I sold my SAE 5000A for $250 and in turn bought this dbx 500 for $169. This is the ultimate doo-dad for turning ordinary music into a Bass Pig smorgasbord. It works mostly on frequencies between 60 and 80Hz, rapidly becoming less apparent outside that range. What it does is it creates a sub-harmonic of those frequencies and fattens out the bottom end.

It works nicely for some types of "fat" bass guitar sounds, where the fundamental is missing and mostly overtones are recorded. The dbx 500 reconstructs the missing bass in the 30-40Hz range and "rounds out" the bottom end.

For other types of music, it adds an extra octave of bottom below the "boom bass" range (60-80Hz), creating 30-40Hz bass, or one octave below the original. It certainly turns any ordinary rock tune into an earthquake.

It has three controls: a bypass switch, a Low Frequency Boost and a Subharmonic Level control. The Low Frequency Boost also cross-feeds frequencies below about 100Hz to both channels with a maximum of 6dB cross-feed at the very low frequencies when this control is fully clockwise. The Subharmonic Level adds an equal amount of sub-bass to both channels in equal amounts. So the knob on the left acts more like a tone control, while the knob on the right actually adds newly-synthesized sound to the mix.

How does it sound? Amazingly-smooth, depending on the music. Because it works over a limited (filtered) range of bass frequencies, it's action can be a bit counter-musical on program material having extremely low frequency bass, because it will half the mid bass notes and do nothing on the low bass notes, by design. This can be confusing on a progression of notes going up or down the scale. However, since the dbx 500 was designed in the late 1970s, it's range of action fits just right into the music of that era.

Here's a rack shot of it: