Difference between Forte 4 and 4A amp ?

I had a model 4 and it was my first step into the high end world. I didnt even know it was made by Threshhold and I have no idea of the difference between models. I can tell you that its a pretty sweet amp and regardless of the difference between models you will be very pleased with it.

I owned a Model 4a - both face plate and back sticker were marked "4a".

I am not sure if this is correct, but I believe that it is close to correct. Forte originally offered a model 1A and a model three amplifier. The model 1A was a fifty watt per channel class A amplifier and the model 3 was a 150 watt per channel class AB amplifier.

Threshold and Forte began using IGBT, insulated gate biploar transistors, and the model 4, as well as the model 6 if I am not mistaken, were born. The Model 4 being the 50 watt per channel class A amplifier and the Model 6 being the 150 watt class AB amplifier. I am familiar because I owned a Forte Model 4 amplifier sometime around 1993.

I am not sure if there is a difference between the Model 4 and 4A. I believe that one model was preceded by the other and that one model, the latter model, offered balanced and rca inputs and the other model offered rca inputs only. I could very well be wrong. I know that the amplifier changed very little, if any, after its initial product run.

What I remember most is that the Forte Model 4 drove a pair of Celestion SL600's in a wonderful way. It was a great amplifier, a little dark and a pleasure to listen to.

Enjoy,
Drew