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About Laowei

  • Rank
    Limited Edition Bronze Participant
  • Birthday 06/07/1957

Profile Information

  • Gender
  • Location
    Vancouver, WA USA


  • Headphones
    Stax SR-009, SR-L700, SR-007mk2, SR-207, SR-003mk2
  • Headphone Amps
    KGST, KGSSHV Carbon -in process
  • Sources
    Mac mini > Airport Express> microRendu > Schiit Yggdrasil
  • Other Audio Gear
    DIY PP 6V6 amplifier. ALTEC Model 19 speakers. ALTEC 809C Bolero speakers modified with vintage Great Heil AMT

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  1. Good news that you got your amp debugged. The GG really is a great sounding amp. What EL34s are you running now?
  2. An everything in one PS PCB with a footprint not much different than my iPhone 6 Plus. Incredible design and work Kerry!
  3. Really clean build. Great job! Any details on the PS?
  4. Bench racing is for the fucktards on Head-Fi. DIY build a GG and pitch in your own opinion here.
  5. Beautiful work!
  6. You'll need to characterize just what "acting up" is. We'll continue later when you get back. Have an enjoyable vacation!
  7. Using 2000 year date code SED Winged C (with no wings on tube label). Bought them from Watford Valves about a month ago. Very impressed so far. Especially when listening to the lowly SR-207. Might try JJs later. Heard they had reliability issues in the past with their octal tubes. But so far no problem with the Svets and sparkle with my GG and 207s. Pretty spot on presentation for my tastes. Might be a little hot with my 009. Tubes need more time run in, though. Been awhile since I used and sampled EL34s. Never warmed to NOS Mullards. Preferred pre-JJ Tesla E34Ls back in the day. Or my absolute favorite beam power tube, NOS WE350Bs (which would self destruct in a GG).
  8. Fixed!
  9. Thanks! A work in progress. A few questions first to start the troubleshooting on your GG. I'm only an ape with a DVM so will outline a methodology. What are your basic power on measurements: HV+/HV-, LV+/LV-, heaters? All LEDs on? Have you set your adjustments? What do they measureme: CCS/balance/offset? Where in the circuit is your amp going crazy when signal is applied? Help us understand what is "crazy". On one amp board or both PCBs? If one channel is good, use that as a standard to look for differences in the other. On one half of one LSK389 or both transistors on package? Is the symptom only at the headphone output? What are the LSK389 b,c,e voltages? Your issue might not be with the NFB. My amp's balance was so skewed that I was burning the same 50k resistor as Whitigir. Needless to say the same symptom had a different cause in my amp. The above info will be a good start at opening communication for help with evaluating your GG problem. Should not be too hard to localize and correct. I bought all my case parts/metal work complete from Head-Case member joehpj. Really nice design and product, and a great guy to deal with. Here's a photo after first receiving and trial fitting the all case parts. Listened to YouTube videos (MP3 audio with digital volume control) over iPhone on the GG with SR-207 last night. That combo was ridiculously great sounding. More headspace, bass slam and pitch, treble, detail, ambience, and just sounding quite a bit more natural than my Yggy>KGST> SR-009. Probably, the SR-009 on the GG really needs the refinement of the Yggy as source to really shine.
  10. Never mind the wiring rats' nest for now, it's making music! The problem I was having with one channel, worked out to be a cold solder joint on the global NFB resistor network on one tube. Was distorting the voltage (off by 10V) on its pzta56/lsk389 half and throwing the balance and offset WAY off. Once found and corrected, both channels are stable as a rock (while running 30 minutes) without the servo engaged. Under 1 volt balance and offset both channels. First listened with my SR-207 then my SR-009 (with a lousy iPhone 6 Plus as source). Using 2000 vintage SED Winged C EL34s at 20mA. Damn, this amp kicks major ass! Now time to mount the transformers, clean up the wiring and build the umbilical, wire up the bi-color power switch, replace the 12V zeners with 18V ones, get the RK50 somehow mounted in to the case, and button it all up. Will post glamour shots when done. Thank you Kevin for such an incredible 'stat amp. I'm really going to love this over my KGST.
  11. Working with the 60mm counterbore in the back face of the front panel and the brackets for the top and bottom covers will be a challenge. I think a 50mm dia x 4mm thick spacer will do the trick, along with cutting those brackets for clearance and trimming the RK50 connector PCB by 1/4inch. At least it works on CAD, hopefully in real 3D too!
  12. Not so successful so far. One of the channels is on the fritz. Balance and offset now both skewed in opposite polarity extremes. More troubleshooting to get it working correctly, fitting a huge RK50 and cleanup my mess of wiring before I post more photos here.
  13. Just powered up my GG amp and was having issues with the offset. Going over this thread for possible clues, and just now saw this note by Kevin. I stuffed that spot with the 12V zener marked on the PCB. Should I replace with an 18V? BTW, found the source of my offset issues. Since the 10M90S are structural, I built them up with the angle brackets leaving them loose to align the tubes thru the tight clearance holes in top cover and forgot to solder them in. Doh! I earlier set the CCS at 20mA with the LV supply, without B+/B-, so I thought things were good. Fully powered up with tubes, set the balance and tried to set the offset and the best I could measure were left: -60VDC, right: -243VDC. Finally found the problem after some trouble shooting. Soldered them and everything is running measuring good ATM. Will try with music and my SR-009 soon.
  14. Hey Vince, mind if I tap into your build experience here? I'm working on a GG with joehpl cases. I believe you wrote your amp was without hum. For your umbilcal cord, did you do anything more than twist the heater AC wires together along with scramble bundling the others carrying DC supplies?
  15. Thanks for taking the time to look into that, Kevin. Will gladly work around the larger dimension on my end (new cases) when this new tube input GG happens. Got a gut feeling this will be a killer amp!