It just finished the prototype and test run last night, may be not too many reel to reel owner will have interesting of this post because most of them only use as a play back machine, We do live recording, modify repro amp can catch up in any time later but miss a good preform in recording will no more chance to get it again, so I do this one first,the prototype with tubes has a switch option back to the original circuit, we used two A80 in tape to tape copy, only one try my partner and I got the answer no need to repeat again, he said the texture was completely different whit tubes although it has not break in yet,sound more closer to the original tape which he did in live recording, I only adjusted it to the same sensitive level to the original no measurement of distortion, noise level or frequency respond, because those numbers will not give me the idea of sound's texture, I am sure the tube one has higher distortion than the original A80's one, but it sound more live like less down grade from the original tape, two sets of silver transformers had been ordered for replacement of the cooper one in the prototype, expect more improvement in future and can make more good copies of good recordings
tony ma
tony ma