Been working on this for a while, have got most of it done. I still need a bottom plate (for safety) and a bulkhead/shield between the PSU and main board (getting a tiny bit of hum when ear up against speaker....). I'll probably also tidy up some solder joints (taking pictures lets you see what can be improved....). I also need to shorten my standoffs for the main board so the tubes stand a little higher (so I can change them). Also need a knob for the pot (I'm using a relatively high output cartridge, so added the 50K pot so I can adjust output as needed).
I did some changes based on a thread on the lencoheaven forum (https://www.lencoheaven.net/forum/index.php?topic=26658.0)
I'm using JJ E83CC/12AX7 Frame Grid tubes - planning to try a SPAX7A for V1.
I was using a Schiit Mani for my phono stage (which I liked). This sounds more open, and the bass is tighter. Hopefully it will get even better as it gets some use. (The turntable is a refurbished Rotel RP850)
For those looking closely - the piggy backed (parallel) resistors on the PSU board in the 0.22R spots was my "fine tuning" to get 6.3V on the tube heaters. With 0.22R alone I was only getting 6.1V.
Need to shorten the standoffs to get the tubes a bit higher.
Hi very nice build! I'm a big fan of your youtube channel. Just wondering are we able to mount the tube socket on the back side of the board without any wiring changes?
Nice clean job on your build. Your sure to get some great sound from your Rotel turntable. Thanks for sharing your project.
I wouldn't worry about any hum if you have to put your ear to the loudspeaker. Nobody listens that close. If you can't hear it from your listening chair it doesn't matter. There is a tremendous amount of gain from that tiny diamond in the record grove until it gets to your ears.
They are called a thumb nut and just a screw and a nut to ground it. Hope that helps.
@SimonP Im having trouble finding the ground post for the phono amp. Did you assemble it for different parts? Any help would be appreciated
@SimonP Thanks for letting us no about your Phono Stage. I’m in the process of building one myself. I noticed the power cable inlet with the on/off switch built in. I have one ordered an waiting of it to come in. (Thanks for that) I have the fab work done an the board completed. Thanks for your input on the volume knob, I’m going to leave it out for now. As for speakers I’m no expert but I did have a speaker business for meany years. It was mainly fiberglass for boats an off-road vehicles. It’s been my experience with tube amps you need very efficient speakers. Most of these very expensive high end speaker cabinets are not worth the money to put it politely. I’m experimenting with mounting some old 1950 something speakers on a board, Open Baffle, I’m still tweaking with the measurements but I’m on to something very good
Looks very good. Let us know how it sounds after you get it burnt in. I was thinking of putting a volume knob on the one I’m building, but I’m not sure what pot to get or how to wire it up
That looks great, really nice work!
Looks super nice!