Tuesday, August 28, 2018

"Grace" - 6SN7-SE preamp








The tubes are limited edition Psvane Treasure 6SN7-SE  globes or bulb shaped. They are strikingly beautiful with their gold metal and ceramic bases, quaint shape and gold markings. This build will not only be about a great performing preamp but an extremely beautiful build. 

Keeping as much gold as possible in parts selection the knob attached to a 24 step stepper (with gold contacts and only two resistors in circuit at any time) attenuator is 4oz of solid brass and gold plated. The six RCAs (two selectable inputs) also gold and the standard "retro-thermionic" name plate polished brass. The white sprayed chassis and wooden cheeks complete the lush look. The cheeks are rubbed with a finishing oil to lift grain and protect. A XLR connection on the back will bring in power required.

The external PS has double Pi filtering with a 5H Hammond choke. A total of 480uf of filtering and DC on the filaments insures quiet and stable operation. Expensive Jensen Copper foil, paper and oil are used as output caps, the only caps in the signal path. These large caps have silver leads. Silver solder was used and along with 4uf Russian military caps to hold the HT at the plate. 1W carbon resistors were used throughout though there is only three resistors per channel. These ensure a warm and balanced sound. No cathode bypass (Ck) capacitors are used to allow a little local NFB with no GNFB.

The circuit is designed to work to 100K and provide low output impedance. From a limited amount of serious listening I am extremely impressed with the overall sound which allows low level detail with hear with ease. Bas us rich and deep and mids flat throughout the whole range. A very balanced sounding preamp. 




2 comments:

szametu said...

God I would love to buy it :)

retro-thermionic said...

This one got sold and I have another order for another one.