This amp uses the UX-171-A 1920s tube (matched pairs) which are rare and produce only 1/2W. There are no resistors or capacitors in the audio cct. a Hammond 124B nickel core inter-stage trannie couples to the power tube. Edcor 10W OPTs in the metal case. Bias is provided by 3 X 9V batteries and 230VHT by two step-down trannies on in reverse. The rec tube is a very old "80". PS filtering under the top plate (ply timber). The base will house the power trannies and is a 1940s wooden pot stand. The amp sounds excellent but I have other tubes (Silver Dragon) which sound better with more power.

I have named the amp "Intermezzo". You build an amp like this because you want to use very old and excellent sounding tubes. This detracts in no way from the overall sound which is transparent, soft sounding and musical. Easy to listen to and when matched to a pair if speakers like the Fostex FE206 based dual chambered boxes you have more than enough volume and a unique setup.

Comments

• Stixx
• 3 April 2013 at 04:56AM
• Just love those old DHT's though I haven't built with them anything...yet :)
  
  I also like the style of your box... it matches the idea of a classic amplifier well.
  
  Do you really use only one stage in this amplifier... no driver tube?
  
  Oliver

• Retro
• 1 June 2013 at 09:03PM
• Yes only one tube in the amp. I was hoping the the input tranni would offer some passive gain with a 9:1 turns ratio from input to output. But under test this did not happen. What I have is a single stage tube preamp with a BoZ backend. The input impedance to the amp is 400ohms. BoZ will drive this OK. With my Fostex FE206 speakers there is plenty of volume.

• pb
• 17 June 2013 at 11:42AM
• Great job.I like the idea of pairing the vintage tubes with an equally vintage looking case.
  Keep it retro,Retro!
  And keep up the good work.
  

• Retro
• 10 August 2013 at 08:01PM
• pb: Sorry I missed this comment. Thanks I currently making another 6EM7 amp (3rd) on a heavy Acacia chopping board. I like timber. I'll post it here. Not really super retro like Intermezzo but an old world feel.