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  1. yeah, they installed the glass other way round and protective film went inside ?
  2. It is sounding very natural and pleasing to ears. I can listen to it for hours and hours. As mentioned before, the amp is bit less responsive to tube rolling compared to previous caps which is infact a good sign. I settled on stock KT88 tubes with Miflex caps which is giving me really good low and top end. Mids are not as good as EL34 series tubes but not at all bad in any respect. In the long weekend, I thought of adding a 4PDT toggle switch and install the old caps along with Miflex so that I can switch instantly between two caps but after opening up the amp, could not decide the location of switch hence put it back ?.
  3. No, I drew this schematic long back without removing and tracing the Bias board initially and took this information from the schematic provided by China Hi Fi (which is way different in values too). The one I posted above this morning is the latest and modified one after I traced the bias board as well. That 1.2K is in between transformer out and 22K pot.
  4. I don't think that 1.2K is working as Grid stopper in any sense. It is not at all in line with Plate output of phase splitter. The one I installed (390 Ohm) as you suggested is needed for the protection.
  5. Hi @muon*, I believe the schematic he used is the one I posted earlier here which I drew without removing the bias board. Here is the latest one (has correction what he pointed out about 6SN7 being upside down) but is accurate. The resistor is on Bias board for sure and not on the socket.
  6. Very useful and interesting information going on here. I feel worthy with starting this thread ? With KT88 and plate current, what I feel is that yes, it is neither optimum nor close to max capacity what KT88 can handle but it is in the ideal range. I have compared this amp with another KT88 with higher plate voltage still found R8 to be better in SQ. In my opinion, the biggest advantage of this amp is output transformers. They are really good quality which is suppressing all other parameters. My gut feeling is that increasing the plate voltage in R8 for KT88 won't change any SQ (at least audible) but will increase the power output. If you are not struggling with power output then best to leave as it is. I personally love the sound of stock KT88 on this amp (specifically after changing to Miflex caps).
  7. Hmm..... copper is a non-magnetic material and it won't shield any electromagnetic induction, you need a ferrous metal for that like iron sheet.
  8. May I know why would someone put copper plate around the transformer?
  9. Yeah, if you swap the tube and it follows then nothing to worry as the filament might be bit more exposed than other tubes hence it is brighter. But if does not and the location is making filament brighter then you have issue of heater voltage on that tube (which I can't imagine of as there is only one source for all 4 power tubes)
  10. I don't think there is an issue. Must be wrong interpretation of the manual. Note that those manuals are originally written in Chinese and then translated to English. As long as the load (speakers) is connected to amp, it is not different to the state when it is playing music.
  11. I too somewhat agree to @muon*. Also adding 0.01uf silver mica in parallel to PIO would end up like having a stock polypropylene caps. 0.01uf will block low frequencies but will pass mids and highs, 0.22uf PIO will pass on all frequencies and at output of both caps, it will end up with little bit boosted mids and highs.
  12. Need to try out. but is it 0.01uf or 0.1uf? the link you mentioned is for 0.1uf.
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