Thoughts on Threshold Forte Model 3 Nelson Pass

Unsound,

The Model 3 did NOT use IGBT's like the later Forte models (after Nelson left). The Model 3 was the 200wpc AB amp of the exact same components as the 1a. The 1a was a 50wpc class A amp. And yes, Nelson had a hand in designing the early Forte models along with Rene Besne. Rene Besne was the designer of the IGBT Forte's.

You are correct Nelson didn't think IGBT's had any place being used in audio and he wrote a large paper about it which can be found on the 'net.

To correct my above post (can't seem to figure how to edit. Michael Bladelius-a Swedish designer was primarily responsible for the Forte Model 4 and 5 which used IGBT's at the outputs. Nelson's designs were still used on the front end of the amplifiers

Heiney, thank you! You are correct, my bad. Though I think it was the model 4's, 5's, 6's and 7's that used the IGBT's, and I believe that Rene Besne's input was mostly limited to the cosmetics. It is interesting that the early Pass designed Forte amps were not at all well recieved in their day, and the latter Bladelius Forte amps were huge hits, especially the smaller higher class A biased amps.

I just happened to have this info straight because I have been recently doing some research on Forte amps because some have come up FS recently. The facts are easy to confuse and I even found myself re-checking what I posted. The line certainly blurs easily when it comes to Mr. Pass and his amplifier exploits :-).

I have been recently interested in the earlier Forte's because the Alpeh's are in such short supply and I thought Forte might be the next best thing.

Didn't Nelson Pass design the ORIGINAL GFA-555?