I got my ST-120 Kit yesterday and I'm really excited to commence with the fun!! Thank you for what should be a great project. My first question revolves around the feasibility of wiring the amp for a balanced input and output. My only experience with a balanced system is with my fantastic headphone set up : ALO's MK3-B balanced amp, Algo Rhythm Solo DAC, Audeze LCD-2 headphones(cabled for balanced input), and 160 gig iPod. The staging, imaging, and overall sound quality is simply amazing. I've read the JENSEN AN-003 paper discussing the "Interconnection of Balanced and Unbalanced Equipment", and also BLUE JEANS CABLE "A Question Of Balance". I am intrigued by the possibility of wiring the ST-120 to incorporate a balanced system. Is this feasible, or not worth the effort?
My second question is about the output circuit of the amp. I have two different speaker sets that I would like to be able use with the ST-120: my original 1972 AR-3a's (4ohm) and a pair of 1967 Altec Valencia 846A's (8/16 ohms). The AR-3a's are pretty straight forward as far as your instructions about how to wire. The Altec's confuse me as to the spec sheet stating that they are 8/16 ohms. Because I physically don't have the pair of Altec's yet, I can't see what the input connections look like. The high/mid freq. drivers are the 806A listed as 16 ohm. Does the crossover network take care of splitting the different impedances? How does the tube amp. handle this?
My third question: is it possible to wire the amp. output jacks to be able to switch between using the AR's and Valencia's different impedances?
Any and all comments and suggestions would be appreciated before I start to wire up Bob's great looking amp!!! I will post some photos during the build.
Thanks so much,
Gary M. Jensen