The Audio Innovations 500

The Audio Innovations 500 is a 25 watt Class A integrated tube amplifier. It is a low feedback (14db) design. When the Audio Innovations was sold on the market it quickly get the reputation of being one of the best on the market in that price segment. To my knowledge there are 3 versions of this amp. In the Netherlands where the former distributor made some changes there are a couple more versions known as the Mk I, II, III.

The standard version is probably the best. It can be recognized by the loudspeaker posts. If you have a 16 Ohm tap than you have a beauty. This is because of the output transformer. In the other later version which only has a 8 and 4 Ohm tap this output transformer is of less quality. An other difference is a schematic one. There are versions with a buffered fase inverter and some without this buffer.

The Audio Innovations sold in the Netherlands where all modificated by the former distributor Ed de Jong. The standard switches were replaced with silver switches from ELMA and the tubes are replaced with Golden Dragons. The modificated amp was sold as an Mk II version. There was also an MK III. An Mk III is a Mk II in triode mode capable of delivering 9 watt per channel. Ed the Jong still services the Audio Innovations products. So if your own AI 500 needs service it still can be serviced. In the United Kingdom the firm Border Patrol services Audio Innovations products.

Many people ask me what the different small tubes will do. If you're standing in front of the amplifier you noticed 5 tubes standing in a half circel. The 2 most left tubes are the fase inverters. The one in the middle is the line driver, the valve that drives the power valves. Changing this tube to an other type or brand will be noticeable. The 2 most right tubes are tubes used for the phono section of the amplifier. You can experiment with using other tubes using the schematic in the tubes and modifications section of this site.

Generaly all the Audio Innovations 500 amplifiers has the following specifications: (not that they are important)