Wednesday 11 April 2012

ECL82 / 6BM8 Tube Amp


Since I have a few bits and pieces and thanks to a few friends I have enough parts to build a we ECL82 amp, hope to get a couple watts out of it. The chassis is a cake tin, the transformers boxes are decorative tins from the 100 yen shop. Still at the start, but taking shape slowly.

Thanks to for helping.
Many thanks to Ken, please visit one of my favorite stores for all your tube needs.
Thanks to TC, Geoff aka tubehead and dangerous Dave for helping me out, you all know who you are :)

13/4/12 - Fitted speaker connector today
15/4/12 - Wired up the AC, switch, B+ transformer and fuse today :)
16/4/12 - Bridge rectifier and filtering 50uf 120ohm 50uf with a 270k resistor across the caps.
26/4/12 - Volume, all resistors, B+ all wired up to amp.
02/5/12 - Fitted coupling caps today.
18/5/12 - I have some audio transformers.
19/5/15 - Fitted audio transformers.
29/5/12 - Made we base for the amp to sit on.
30/5/12 - Second coat applied to the base
01/6/12 - I can confirm the amplifer works, has some AC hum issues to be resolved.

I hope you have all enjoyed my amp build and followed it along the way, not a fast build but just when I had the time. When I have some speakers I will let you know how it performs.

Top view, tube sockets, power switch, fuse and volume all mounted

Going to run a SS recitifer, you can see the we 200mA 200vac trasnformer to the left.

Diode bridge and filtering 260vdc unloaded

Cathode resistors in, volume wired up, may change volume is a bit messy

Top view audio transformers

Drilled holes in the bottom to let air in

Back view just speakers and power cord

Top view, amp sitting there quite nicely.

This photo and ones below of finished amp with 2 coats of stain on the base.


  1. do you change the design or you still use the original design.from
    how about the sound image out of music? .... how many watts 1 channel of this amplifiers?
    I also intend to assemble it.
    thanks .....

    1. Hello, no I didn't change the design, I have never tested it, I have no speakers to test it on. I was going to buy some fostex single driver but just haven't had the time. Thanks Bruce

  2. Can you specify the transformers I have to buy?

    1. Sorry for the very late reply, any single ended audio transformer 5k to 8ohms should do the trick. I got mine from here

    2. This address doesn't work.
      Somedody knows the new one for buying the transformers????

  3. if you've ever listened to the music of this amplifier?
    But did not you buy a speaker from fostex,
    and is functioning correctly?

  4. Hi,

    did you listened music using this amp?

    can you post a picture with the final connections, please

    I'm trying to build one like this, but I'm a kind of newbie with the tube amps.


  5. Hi, Maybe the HUM issue is becaus one side of the Tube heaters is grounded? Try Txmr filament 6.3VAC to tube sockets direct, no grounding?
    Another tip is rectify the 6.3V AC smooth it with a large 16V 10000uf electrolytic capacitor check you have 6.3V DC on load and use the smoothed DC for the heaters.

  6. better to create an artificial ground by wirin 2x47 ohm or 2x100ohm 5W resistors in series and to connect the center point to ground and the 6.3 leads to the other sides like the old guys did

  7. Best regards from Spain.
    I am traying to build this amplifier, and before starting I have two questions.
    1) Anybody has built it and check the quality of the sound?
    2) What is the power transformer? Model and trademark, if tou want, please.

    1. Hola. Construí ese amplificador y suena muy bien y no zumba nada. La fuente tambien la hice exactamente igual al schematic original de Nitin William, El trafo de poder lo hice bobinar. Los transformadores de salida son de TV antiguos 5K 8 ohms. No esperes un derroche de graves, Muy buen amp para un par de parlantes bass reflex frente al PC. Saludos desde Argentina. Italo

    2. Saludos y gracias por la respuesta.
      Me gustaría saber que potencia tiene el trasformador de entrada que has usuado. ¿50w?
      No es fácil de encontrar un trafo de 200-0-200
      ¿puede valer una salida de 170v reduciendo la resistencia de 100 ohm?

  8. I built it and wow using my turn table into it. Sound is awesome.

  9. I have also built it, after giving the cables a bit more room than initially, the sound was great. In transformer melted after 30 minutes (seems like a bad trafo).

  10. le rapport qualité prix compte tenu du son remarquable est imbattable, cependant, j'ai un HUM élevé et je n'ai pas trouvé la solution au problème . Félicitations pour votre article !

  11. Anybody have pcb? +91 9349991011