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Just like Carbon we built. Same box, same PS. Relay=120s. Separated filament transformer.      

Another Grounded Grid lives.  Have been listening to it for about a week. Powered by the same GRHV/GRLV PSU I use to power my KGSSHV, Carbon and Blue Hawaii. 400VDC rails and 20mA plate current.

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Thanks! And happily reporting that there is no "hum", not even a fainted bit :D.  Excellent transformers, thanks again Joe and Ang!

it had been running for 3 hours now, and temp is steady at 39 C on the chassis.

Edited by Whitigir
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On 4/23/2017 at 8:12 AM, joehpj said:

Push'em harder! 20mA at least :P

I just turned her to 20mA and using reissues mullar el34.  She dives deeper but and finer trebles but has more distortions on deep Sub bass and some trebles at complex passages.  No weird glowing plates or such...... Is GG ok with 20mA ? Gotta wait on 6ca7 and see if it helps anything...

well, after reading some more, it appears the Mullar just....sucks....lol

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Swapped in 6CA7 from Electro harmonic and the sub-bass is better :D ..... Tubes rolling is fun and GG is amazing ! Thank you Kevin !!!! Can't thanks Kevin enough

The LED switch is awesome from Joe and Ang, 2 tones, so white is my warmed up and warmed orange is operational 

 

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  • 3 weeks later...
2 hours ago, Laowei said:

Are you using the servos? 

Yes, opto Servo is engaged.  It settles much faster than Carbon does, and is more stable with offset and balances values as well.  The only thing is the current which may slowly drift upward from 20mA to 21mA, but then it stays stables over hours without problems and heat dissipation is not an issues 

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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? 

 

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I only tried to separate the AC heater as far as possible using the empty pins for spaces on the umbilical cord and as far away from other wires as well 

 

for the PSU cable wirings, I twisted the AC heater together with ground wire and the other wires twisted in pairs, and cover them in a braided shielding and a sleeve.  You can also overkill this by using a huge aquarium hoses and cover these 3 to create spacer away from the rest of the bunch.  I don't care for a flexible PsU cables, just as long as it work great.  I did not use the hose though

The main hum problems should be from the main AC that may get too close to other wires, especially input-output.  Just as long as you manage to keep them away from those, you should be safe.  That is just my experiences 

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On 1/2/2016 at 0:30 PM, kevin gilmore said:

zener needs to change to 18v

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. 

 

 

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 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. 

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