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Original Message
Wham! Bam! it's the Tram 2 - DHT OTL Linestage
Posted by bcherry on April 8, 2010 at 20:16:16:
It's done!
The guided tour:
Back: 2 tubes are the Direct Heated Triodes - 2A3 or 45 plug and playable without any circuit changes.
Middle: left tube is the Super Mu 6AS7 and right is the 5U4 rectifier
The tube sockets are mounted in a subplate which is compliantly mounted to the chassis. Rapping on the chassis produces no audible feedback.
Front: the power transformer. From our 98db speakers we can hear just a little tube rush from the 2A3. No hum.
Front panel: Remote controlled selector then power switch left, 120 step volume control on the right. Selector has 5 inputs (also additional inputs for REC on back panel)
Back panel: 6 prs RCA inputs and 3 prs outputs, +6, 0, -6db (this can be changed internally) for system matching which is absolutely necessary to marry DHT and high efficiency speakers.
Inside the chassis: Will post pics next report but power supply is FCUPS and all film cap (big L small c). Ultra Low noise Filament Supplies on the 2A3/45. Auto bias Supply controls the DHT. Etc Etc.
On the bench we get extremely linear and low distortion test results.
OK more later.