Sonic Frontiers Line 1 Preamp from scratch

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Algar_emi

Algar_emi

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Joined 2002
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#1
I got the main PCB from an other diyaudio member at a good price. It a fully balanced design with sophisticated regulated power supply, almost completely DC coupled signal path (just one very good quality, low value capacitor) using a DC servo, high grade power transformer, very high quality 2oz copper PCB, three tubes per channel, input tube polarized with CCS current source, etc. For the price, I can never build such a sophisticated preamp, very nice indeed. To complete it, was only missing a delay timing circuit for the HV relays and a mute circuit that close when the already built-in DC error protection was detecting a DC offset at the output. This PCB was extensively moded with the best available, Vishay Bulk Metal foil, Caddock and Holco resistors. Multicap Thin-Foil fim capacitors, soft recovery diodes and instead of using the IC volume control, I use two external Noble potentiometers (much better, and no need for computer control). Here a picture of an original Line 1.
 

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#4
bit late to the parade

Hi... nice job on that line 1.. I acquired one a few months ago totally stock. I am considering installing 2- 8 pin sockets so I can install upgraded digital volume chips. Do you know where I can access a service manual and schematic or even get info on how to remove circuit board to de- solder and replace the two sockets. Any information that would help would be greatly appreciated... Have a great New Year.... Bill
 
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