High end audio fans always talk about how Tube Amplifiers sound better than their semiconductor counterparts. Well I know the theory about electron tubes and I like listening to music.. hmm..
Since I never had built an electronic device with electron tubes I decided to build my own set of ‘high-end’ amplifiers.
There are many circuit diagrams for DIY tube amplifiers to be found but in a an old Radio Electronics magazine (from 1962!) I found an article stating: ‘an audio amplifier of exceptional quality’..
The specifications mentioned a frequency range from 20 to 100000 Hz (yes, 100 kHz). That is way beyond the audible range.
The circuit was not very difficult, two EL84’s and a ECF86 tube. The latter is not very common in audio equipment but I gave it a go.
First I had to find the components. The necessary tubes were found on a website specialising in new tubes for Guitar Amplifiers and such. For the capacitors and resistors I used high quaility modern day equivalents.
The original transformers are no longer in production so I replaced them by high-quality Amplimo toroid transformers. The output transformer was designed by Menno van der Veen and even though the frequency range is according to specifications ‘only’ up to 50 kHz, it would be more than adequate.
By building two seperate mono amplifiers (aka monoblocks) I have no problem with crosstalk between the channels.