Audible Illusions Modulus 2 Preamplifier
In the early ‘80s a new audio company named Audible Illusions burst on the scene with a single product, a dual mono preamplifier for about $300. It got a little bit of press and no one paid a huge amount of attention to AI until 1985 when their Modulus preamplifier debuted. It had dual volume controls on the front and took care to minimize the use of switching in the signal path along with careful circuit design to present a $595 preamplifier that posed some competition for the big bucks gear of the day.
The Modulus 2D, pictured here was the ultimate realization of this circuit and was made between 1988 and 1991 before AI moved on to their model 3 preamplifier which achieved international acclaim. Using just four 6DJ8/6922 tubes, two for the linestage and two for the built in phono section, the Modulus 2D was one of the best values in high end audio for quite some time. I owned one from 1989 until 2003 where it was still chugging along in my second system quite nicely.
Though it had no fancy stepped attenuator, remote control or outboard power supply, (it had a fixed AC cord as well) the 2D sounded fantastic and in the day was the closest thing to a giant killer I had ever heard at that point. The dual volume controls were a bit of a pain and the high level inputs were limited, but it really sounded great!
This preamp had fantastic imaging and if you sprung for a fairly expensive set of 6922s it would really sing. They still do – if you happen to be an Audible Illusions user, call Kevin Deal at Upscale Audio and he’ll take good care of you.
With the top cover removed, you can see that the 2D features a simple circuit using some of the best parts of the day. Though AI had a few service issues, these preamplifiers were workhorses; many of them are still in service today. To make sure I was not just waxing poetic, I managed to pick one up on EBay for $450, which seems to be the going rate and give it a good listen to refresh my memory.
Even in context of todays components, the 2D still delivers an impressive performance. I would still suggest a Modulus 2D today; dig out your soldering iron, upgrade a few caps, install some premium NOS tubes and you’re on the way. This is a premier preamplifier on a tight budget and remains a budget legend. -Jeff Dorgay