07-03-2024, 01:49 AM
(07-02-2024, 01:04 PM)hifinet Wrote: @thomaschan are you using the Lampizator with the 5670 and the AN DAC3 tube output with 6922/6DJ8? Both circuits are SRPP. Transconductance of the 6DJ8 is much higher. Also, the cathode resistor is bypassed with an electrolytic cap (220uF) in the AN SRPP. This will add gain. The Lampizator circuit has some local degenerative feedback without the bypass cap. I am not a fan of the 6DJ8. Too cold and analytical sounding.
Yes, I am using 5670 in the Lampizator circuit and 6DJ8 in the AN circuit. You are spot on about the characteristic of the tubes. 5670 is definitely more musical. I had previously built a McIntosh C2200 preamp with 4 pieces of 5670 and it was very very musical.
For the AN circuit, I started with 75 ohm resistor in the I/V conversion but the gain was just way too high. I eventually tuned it down with a 180 ohm parallel to 75 ohm and this is the value I use in recording the Youtube video.
As for 6DJ8, it has low output impedance and quite many brands use it in preamp. I have a vintage Sonic Frontier Line 3 which use 10 pieces of 6DJ8. Convergent Audio Technology CAT SL1 use one piece of 6DJ8 in the output stage and this preamp is extremely good.
