Still a work a in progress, and a sharp eye will see quite a few mistakes and errors.
Really impressed with this amp, opening my ears to music. At first it sounded great, but lacked bass. Swapped out the 0.22 uF caps for 0.33uF and it sounds much better.
Currently running without shade feedback. Will be trying that soon. The bypass caps on the carhode resistor is also wrong. I must have not ordered those, so I swapped in 100uF caps I did not use in the power supply.
Rather than use the third stage of filtering, I decided to use some 390uF caps for the second stage that I had extra for my power supply prototype test bed. Voltages are running the tubes at 96%. So need to watch it when installing the shade feedback.
Future fixes
Shade feedback
Correcting the 12ax7 socket to something that looks better.
Audio note cathode bypass capacitors on order
0.47 if coupling caps to try
Possibly rebuilding with a larger power transformer. This does get hot.
Selection switch needs to be improved. I used coax interconnect cable inside and it brings unloaded digital noise in when network streamer is not the selected source.
Clean up wiring, install bottom cover and feet.
Should keep me busy for a couple of months.
Oh the layout…I think you had your tube sockets oriented differently. I decided to just push through and do a bit of an alternative layout. Wanted to get to the working state.
Thanks again for making my first tube amp build a success…even if it is in process.
I have followed along on the R8 modes, swan DIY 2.1A speakers, ear preamp, and now this litttle amp.
Looking forward to the KT-88 amp build this summer, another load line refresher, and the output transformer impedance selection.
It sounds so good. I hear stuff in the music I have never heard before. Imaging seems better too.
Drives my Polk R700 speakers very well. Ear ringing 90 db range. Maybe a little less with feedback?
Ps the neutral and line wires are swapped in this photo on the ice connector. Fixed during the initial power on tests.
Awesome..Gonna build this using these tranny
https://www.antekinc.com/ms-30w25-30w-single-ended-output-transformer/
Without the schade feedback, it's gonna lack bass, sound shrill and so raising the coupling cap size might help cover that up. It's never going to sound right without it. Also cutting the cathode bypass in half hurts the bass response. Glad you had fun and looks good so far