Tag: Cartoon

Thinking in a restful position…

thinking in a restful position copyBank holiday weekends give us time to think in a fast world. A time where analogue beauty is almost eclipsed by the digital norm. In fact I like both or at least the right blend of them. At the end of the day we can create (as our predecessors did before) with what we have. Some may do good things and some may still produce a pile of rubbish.

3A5 DHT

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The 3A5 DHT is another interesting valve to bear in mind.  Many have used them successfully even in a phono stage. Great examples are Dmitry Nizh’s DHT phono stage and Sheldon’s. I will probably use them as well at some point.

Can you hear the microphonics SMALLWell, many DHT have been dismissed over the years due to their microphonic sensitivity. True, they are more microphonic, but this is manageable. Look at the 4P1L for example. I built a great preamp a couple of years ago and played around with the mechanics of the preamp to quiet it down. And I managed to, succesfully (as many have as well). The 4P1L sounds fantastic, despite so many turning it down because of its natural singing skills 🙂 Now, 4P1L is looked after, many are building DHT preamps and even full DHT amplifiers.

Looking at the specifications of the 3A5, we can see that the heater is attractive to be used with rechargeable batteries. Well, at least 220mA @ 1.4V is manageable. Key specs are:

  • Mu of 15
  • Anode resistance (ra) is 8,300Ω.
  • Anode dissipation (Pa) is 500mW per valve.
  • Vf=1.4V / If =220mA (paralleled filaments)
  • Transconductance (gm):  1.8mA/V
  • Maximum anode voltage: 135V

How linear is this DHT? Let’s look at the curves first:

Continue reading “3A5 DHT”

Peter King: Flying High

Saw him playing recently with his quartet @ Bulls Head. Kindly bought his autobiography with no big expectations. It ended up being my holiday book:astonished. A great autobiography. Peter shows a sincere reflection of a chaotic life full of rich experiences. A great musician and looking forward to seeing him again playing at the 606 club now in November.

I may try to find his email address and send him this sketch:

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