520B SE TUBE AMPLIFIER
by SAKUMA princple

Name:     George Manios
Date:     31.07.2010
Country:  Greece
Subject:  EML-520B

Dear Jac

The tubes arrived last monday.I did the final adjustments and here is a picture of the amp. The path goes as : EC806 LL1660 , 6A3 LL1671@50mA , 520B (Out transf. core 120 X 100 X 60 @ 1.7 tesla turn ratio 17.64/1 primary 2.5k sec 8 ohm primary is five sections and sec is four eight ohm sections in parallel )

I was really amazed by the built quality of the 520 tubes. The 520 tubes are set at 495V and 140mA (plate dissipation 69 Watt) I was wondering if that's to much for them.

All The Best
G.Manios

Night view picture of George Manios' second "no-compromise" amplifier. Driving Altec 604 Speakers.

Comment by Jac: Watch this! Here is a somebody doing such an excellent design job. This amplifier has a concept I once called "Sakumo" style, and this designation has been picked up by others now. It means you drive a DHT output tube with another, possibly similar curves DHT output tube. It is beyond the purpose of this page to explain the virtues of this. Reference literature I only found from Rainer zur Linde, a German tube book author who did this with the AD1 tube. It is mentioned in the original Barkhausen tube theory books, and of course Mr. Sakuma from Japan practises this with great results.

520B-V3 Amplifier Schematic. On par with some of the purest amplifier designers from Japan.

Power Supply sectionm, mechanical works of the 520B amplifier

Schematics of the George Manios 520B amplifier