As spin-off of thread below I build a unbalanced tube input board for my purifi modules as mentioned in the thread below.
https://www.diyaudio.com/community/...urifi-1et400a-amps.379211/page-3#post-7027789
Picture from Jasper84
I made a PCB for the unbalanced version, a 6n6p tube with mu-follower topology.
The preamp has a gain of 9 times and no problems to drive the 2k2 input impedance of the 1et400a modules.
Timing circuit around Q1 has a 13 seconds delay. This gives the tubes time to heat up without getting a big thump and shutdown the amp modules without strange noises.
Led D2/3 is on the “amp on” signal and can be mounted in a B9A socket with a hole in the middle. Tube bottom will light up when amp is on.
Combined this input board with 2 x 1et400a Purifi amp and Hypex smps1200a400 and smps 265v/6.3V then you get amp in picture below.
This amp is a pleasure to listen to.
https://www.diyaudio.com/community/...urifi-1et400a-amps.379211/page-3#post-7027789
Picture from Jasper84
I made a PCB for the unbalanced version, a 6n6p tube with mu-follower topology.
The preamp has a gain of 9 times and no problems to drive the 2k2 input impedance of the 1et400a modules.
Timing circuit around Q1 has a 13 seconds delay. This gives the tubes time to heat up without getting a big thump and shutdown the amp modules without strange noises.
Led D2/3 is on the “amp on” signal and can be mounted in a B9A socket with a hole in the middle. Tube bottom will light up when amp is on.
Combined this input board with 2 x 1et400a Purifi amp and Hypex smps1200a400 and smps 265v/6.3V then you get amp in picture below.
This amp is a pleasure to listen to.
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