Phone stage build
Update!
Final version after painting. Holes were off for the tiubes, but I figured I could elongate the hole and use curtain rivets like Stephie suggested in one video to cover up my mistake and make it better looking at the same time.
Also used auto body filler to clean up corners and fill the one accidental hole on the top.
Hooked up one dc rail backwards and blew half my electrolytic capacitors. Luckily I bought 3 extra and had enough to replace. Also had bad hum on the channel that did not blow, but that was the input wire polarity swapped. Still have some hum at louder volume. Seems tp be 60hz and is real bad if phono preamp gnd is disconnected. Will try adding a bulkhead , once I get some aluminum sheet metal.
Also will try some of the notes at the Lenco heaven page..try changing the caps to 33uF and bypass them. I did buy the lowest esr caps I could find at mouser.
https://www.lencoheaven.net/forum/index.php?topic=20984.0
May end up putting it is a really big chassis and put it under my turntable, as I big, short copper strap between my turntable may kill the hum better. But it sounds good.
I scrambled to get the first sounds out of this last night. I still have chassis issues to fix as not happy with placement of holes I punched thru the chassis for the tubes. So I have not bothered installing shielded wire for the audio path yet. I still need to cut a bigger hole around the tubes and add a trim plate with holes for the tubes aligned better, paint, and add the ground screw. Oh and add some shielding for the 60hz hum, but a lot of that goes away with the ground wire pressed to the chassis. I may just make a whole new chassis for it some point. Enjoyable build and your videos helped a lot. Would have never tried this or even thought of making one of these if it was not for your videos. Building this brought a lot of happiness into my life. Thank you!
I am shocked, amazed, the bass is intense. My room is very hard to fill with bass, but this combined with the R8 is amazing. Some reviewers of my Polk R-700 speakers would complain that they can over pressurize the room. I had no idea what they were talking about till now. White Stripes, Ball and Biscuit sounds like the bass drum is in the room!
So much better than my built in pre-amps and Fozi audio tube preamp that previously impressed me with better sound.
I do need to figure out some ultrasonic filtering though.. I will post more photos as I clean it up and finsh the chassis and wiring.
Capacitors. I am having a hard time sourcing capacitors. There is a pair of Mundorf evo oil on the other side, these purple clarity caps were available, so I bought them.
I took the advice from your videos and bought the EH 7025 right off he bat.
After I painted the unit, I installed cheap coax style interconnect cable. Shielded, but not ideal. I will look for that cable you get from guitar stores. I have some but it is too big and hard to work with.
The caps on the amplifier board were blown on one channel, and I replaced all on that channel and the two low voltage caps just for good measure. I checked them with my capacitance meter, they were a few pf, instead of 22uf. Do you think I might need to replace any other caps?
Good to know about the 14 awg. I have 18 in there now. At normal listening levels there is no hum now.. I am thinking of printing up a insulator washer like the rca jacks use for the input gnd stud . Isolate that so it's single point gnd, without multiple paths through chassis. One day...no rush, as I am pleased.
The problems were good learning experience. Made me feel good to figure it out, even if it was to figure out my own mistakes like the reverse polarity on the audio signal. That made serious hum.
I have already moved on to the next project in my head. Trying to down select to what type of amplifier to build. Thinking El34 or KT88, like one of the designs from the GEC or Mullard application notes. But also thinking I should make a smaller less expensive one for my first amp.