All about electronic valves and hi-fi
A great russian pentode valve similar to 4P1L, but with indirectly heated cathode. You can check the valve specifications here. I tested transconductance in left-handed triode mode: Gm=9.6mA/V @ Va=150V, Ia=50mA , Vg=-5.6V. Here are the curves for this valve: For the ones who want to test the SPICE model here is my take on … Continue reading “12P17L curves and Spice model”
CX301a DHT preamp Here is my latest incarnation of the DHT pre-amplifier: Many claim that the 26 is the best sounding DHT valve for a pre-amp. I will agree to a certain extent, however I personally found the thoriated-tungsten filament sound a bit more rewarding to my ears. A more clear and defined treble in my … Continue reading “CX301a DHT pre-amplifier”
Measuring triode linearity Today decided to do a quick distortion test of on a sample of a variety of different valves. All either triodes or triode-strapped pentodes/tetrodes. As per my previous tests, distortion was measured at +22.22dBu (10 Vrms) at the output of the valve in common-cathode mode. Valves were loaded with the CCS I … Continue reading “Valve THD analysis”
Finishing the curve tracer Today I did a bit of extra work on the curve tracer with a view of finishing it. It has been a long and painful journey, but I’m reaching the end of it. The transconductance tester is working perfect. I need to use the following ranges in my true RMS … Continue reading “”
After playing with DHT preamps (26, 71a, 4P1L, 46), I ended up staying with a CX301a version of it. I liked its warm sound and tone so I decided to stay with it. It’s been over 2 months so far that I haven’t returned to my precious 26 preamp (I will probably revisit my 26 … Continue reading “Improving the 01a DHT preamplifier stage”