• Item: Single Ended Integrated  
  • Type: Direct Heated 6A3 Triode  
  • Posted: 1 May 2012  
  • Builder: komkris2000  
  • Country: Indonesia  
  • Comments: 1  


I build this amp for my eldest offspring in Brisbane. Evaluating several tube types and amp topologies, I could not deny that the direct heated triodes (DHT) of the 2A3 family are the winners in sound character.

My choice thus fell on the 6A3 of which I had ample stock, they are a derivative of the 2A3 but with 6.3 Volts heaters. This enable me to build a amp with flexibility of a 2.5V or 6.3V heaters accommodating either the 2A3 or 6A3 tube types. With a tube converter the 6B4G - a 6A3 with octal sockets can also be used.

The amp is a "semi monoblock in one chassis", sharing 1 big mains tranny, dedicated chokes for each channel, separated heater supply of 2.5, 6.3 for the end tubes, separated heater supply of 6.3 easily converted to 12.6 for the line & drivers of 6SN7.

With the "semi monoblock" concept, the amp easily drives the low sensitivity 87dB Proac bookshelfs - R1S/R1SC/Tablet series and the 82Db Rogers LS35A family.

The amp weight a whopping 24Kg and is extremely stable.

Chassis is made of: wood cabinet with polyutherane finish, aluminium 3mm topplate handbrushed hairline finish

Parts: Custom wound Mains Transformer, custom wound chokes 10H/100mA, Lundahl 1664/100mA Output transformers, MKP Solen, JJ Electrolytics, Russian Paper in Oil K75-10 and MBM 0.1uF/1000uF, Cardas posts, Yamamoto teflon wire, Alps Black Beauty volume pot, ARMG and Kiwame resistors. Military Russian current meters

Tubes used: NOS Tungsol 6A3 endtubes , Mullard GZ37 rectifier tubes , Sylvania 6SN7 line & drivers

Paul Yahya


  • Wardsweb
  • 3 May 2012 at 06:51AM
  • You do exceptional work. Your attention to detail superb. I visited your web site and it only confirms my original thoughts.

    Kudos to you sir for keeping tube audio alive and well.

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