Will take some pictures shortly and send them along. Warning: I must have taken everything apart 10 or more times and rearranged and resoldered. Not pretty… but works fine. Still on my first 9 volt battery. You don’t use much energy changing volumes levels once and a while. I put the LED on the volume knob to remind me to shut it off when I turn off the main power and tube heaters. So far so good. Thanks for your interest.

Thank you Charles. Latest update: Brought it Friday to have the preamp looked at and worked on by some one that was recommended on canuckaudiomart, an older gentleman who has been in tube radio repair since 1960. He redid all of the signal wiring with bigger shielded cable (nice looking job actually) went over grounding etc, and ‘tested’ before giving it back to me $300+ later… Got home. Plugged unit in. After 3-5 minutes low volume hum started. Same as before. Called, him and asked it he put it on a scope. Not not necessary he said. FYI: This most recent (third) SMPS was shipped from your store to me. I have decided to ‘Throw in the towel’ for now. Frustrating because it sounds just marvellous, except on near silent passages. Time for me to move on… for now anyway. Thanks again. Wish the best to you and your dad.

Thank you for your response. Setup: Larger sized Hammond steel enclosure with R-core x-fo, chokes, large caps installed on top. Power and preamp boards inside. All components from either Valvesnmore, PartsConnexion, or Digikey. Rubycons, and Solen caps, Vishay resistors. When preamp hooked up to Pre-In on R8, sound is just wonderful, with more separation and clarity…but annoying hum=buzz faintly in background. Grounding: #1: Ground pin from receptacle to chassis (1 1/2 in. away, paint scared off) #2: 2 from J1 on power boards #3: (all shielded) 1 each for pre-amp boards; 1 for 2 switched inputs; 1 for Alps volume pot; 1 from SMPS input (for tube heaters and feeding remote control board … only Chinese component, LED’s on knob (from remote control board and switch… would forget on otherwise…) 1 for 2 outputs, Of note: 6 volt difference side to side from B+, buzzing present when music paused and SMPS unplugged. 1 volt difference on pin #6 13-14 Volts. R8 is completely silent at speakers when used with other inputs, no preamp. I am considering bringing it to a tech who has a scope if I can find one… My wife of 50 years is fed up with me trying to find a fix since October. Thanks for you help. Can send pictures.

Hi Jim. Really do not want to be a bother but I am truly stumped. Still experiencing humming when Universal Pre-amp plugged into PRE-IN. However, when I plug my NODE into the pre-amp, and plug the pre-amp into an input RCA (CD input), it plays just fine, with totally silent background, no matter what volume level selected. The motorized volume pot (ALPS) is working just fine. Cannot get it to hum at allI tried different power supplies. A 12 VDC SMPS (measured 12.26 Volts.with the .5 ohm resistance gives 10.6 VDC at heater terminals when energized. Once I look up the heater resistances I will try and calculate the value of resistor needed to achieve the 6-7VDC at the terminals. I now have a power supply with variable outputs. With it set at 7.5 VDC I get 6.49 VDC at heater terminals when energized. I also changed the power bar plugged into Hubbel hospital grade receptacle and 2#12 back to panel. Ironically, I used to call on electrical engineering firms for a living. I have built numerous projects in the past (including 3 hybrid integrated amps using tube pre-amp and Class D amp combos) I buy all my parts from Parts Connexion (Hammond, Nichicon, Rubycon, Vishay resistors etc.) and Solen (Canadian sales/warehouse a few km’s from where I live). However, 2 pre-amps stacked like that surely cannot give optimum results. I just cannot believe I have been unable to get rid of the hum. So silent using line inputs… humming when connected through pre-in…The humming does attenuate at half volume with the music to noise ratio seemingly better. Why would it hum one way and not the other? Thank you for your patience. It is probably something silly and simple that I just cannot see. Getting old and tired. One of these days I will have to call it quits… but right now, it still gets may juices going. I like my Willsenton for tube sound and my Naim for SS.

To simplify my question. I have 4 x 6sn7’s (2 stock Willsenton And 2 Tung-Sol, which sound much better than stock ones) When my pre-amp project is done, where would I get best results 1) installing the Tung-Sols in the pre-amp, or 2) Keeping them in the R8 and installing the stock tubes in the pre-amp?