jose Posted July 13, 2016 Report Share Posted July 13, 2016 Today I could dedicate time to amp.It took me very little time regulate. The balance was 0~1 volt (derived a little between both values) and offset was 0~0,5volt (derived a little too). 1 Quote Link to comment Share on other sites More sharing options...
chinsettawong Posted July 15, 2016 Report Share Posted July 15, 2016 (edited) Fired up my Carbon last night. Adjusted the current to 20mA but back down to 16mA at the moment as I'm afraid that my transformer can't stand it. Being lazy, I utilize the power supply and chassis from my KGSSHV. So I should consider it as an upgrade. I'll buy a new transformer and adjust the current to 20mA later. The amp is running at 450V. Even at 16mA I can feel that it's running a lot hotter than my previous KGSSHV. The amp sounds wonderful. Thanks Kevin for sharing this wonderful amp design. Edited July 23, 2016 by chinsettawong 7 Quote Link to comment Share on other sites More sharing options...
purk Posted July 15, 2016 Report Share Posted July 15, 2016 Congrats....Yay!!! 1 Quote Link to comment Share on other sites More sharing options...
Kerry Posted July 15, 2016 Report Share Posted July 15, 2016 Congrats! You have so many beautiful headphones to use with this amp 1 Quote Link to comment Share on other sites More sharing options...
JoaMat Posted July 15, 2016 Report Share Posted July 15, 2016 Indeed, a really nice upgrade! I use old chassis for new boards. I even desolder components and move them to the new version/board. That way I keep number of amplifiers constant, an agreement with my partner. 2 Quote Link to comment Share on other sites More sharing options...
chinsettawong Posted July 15, 2016 Report Share Posted July 15, 2016 My servo doesn't seem to be working. Do I put a jumper on both the opto and the opamp or do I put it on either one? Quote Link to comment Share on other sites More sharing options...
congo5 Posted July 15, 2016 Report Share Posted July 15, 2016 only one jumper... both op-amp and opto installed 1 Quote Link to comment Share on other sites More sharing options...
Skooby Posted July 15, 2016 Report Share Posted July 15, 2016 I put DIP switches on the jumpers. Try one at a time to see what works best. I used 'switch 2' now. Pretty stable offset and balance voltages. 1 Quote Link to comment Share on other sites More sharing options...
chinsettawong Posted July 16, 2016 Report Share Posted July 16, 2016 (edited) Thanks! I'll try and report back tonight. Edited July 16, 2016 by chinsettawong Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted July 16, 2016 Report Share Posted July 16, 2016 Very nice! Quote Link to comment Share on other sites More sharing options...
chinsettawong Posted July 16, 2016 Report Share Posted July 16, 2016 The servo works very well now. I adjusted the output to around +13V from cold start, turned off, and put the jumper of the opto on. Turned the amp on, and the servo started to work immediately. It's very nice and stable. Thank you everyone for your help. 1 Quote Link to comment Share on other sites More sharing options...
JoaMat Posted July 17, 2016 Report Share Posted July 17, 2016 Great you found the opto servo working well. In my Grounded Grid I’ve omitted offset trimmer and its associated resistor and that works great. For time being I consider the opto servo as the preferred one. 2 Quote Link to comment Share on other sites More sharing options...
eggil Posted July 21, 2016 Report Share Posted July 21, 2016 (edited) Very nice amp! Need to get off my butt and starting building mine Edited July 21, 2016 by eggil Quote Link to comment Share on other sites More sharing options...
astrostar59 Posted July 23, 2016 Report Share Posted July 23, 2016 (edited) On 9 May 2016 at 11:15 PM, spritzer said: Where did you read such bullshit? I read here and at the other place from owners, but here is an excerpt from KGs post today from HF: Quote A couple of people think that the carbon is a bit bright at 20ma, and have turned their units down to 18ma. This is one way that the amplifier can be tuned. I will be able to stop reading and try myself in testing as my Carbon is coming in 2 weeks. It could be a positive IMO. I can tune to an extent with my tubed DAC, so if the bias does affect the HF sound balance, it may help some with solid state DACs. At this level of SQ the tiny tweaks can be the icing on the cake. Getting excited now. Edited July 23, 2016 by astrostar59 Quote Link to comment Share on other sites More sharing options...
sorenb Posted July 23, 2016 Report Share Posted July 23, 2016 26 minutes ago, astrostar59 said: I read here and at the other place from owners, but here is an excerpt from KGs post today from HF: I will be able to stop reading and try myself in testing as my Carbon is coming in 2 weeks. It could be a positive IMO. I can tune to an extent with my tubed DAC, so if the bias does affect the HF sound balance, it may help some with solid state DACs. At this level of SQ the tiny tweaks can be the icing on the cake. Getting excited now. an isolation transformer might be your Sancho Panza, before you set out on this Odyssey. Chances are, you might move a fair bit closer to him upstairs, getting a bit too excited by accident ... 1 Quote Link to comment Share on other sites More sharing options...
astrostar59 Posted July 23, 2016 Report Share Posted July 23, 2016 (edited) 17 minutes ago, sorenb said: an isolation transformer might be your Sancho Panza, before you set out on this Odyssey. Chances are, you might move a fair bit closer to him upstairs, getting a bit too excited by accident ... Dunno. I use a PS Audio P10 for my system which regenerates the mains power and wave form. The mains in my house is quite dirty so it has a big effect. I was in the mains is mains camp before I heard the effect. I also use a linear PS for my music server which also helped things. I guess all these things may help as elements outside of the amp design itself. The P10 was not cheap, but the fact it also helps with my speaker system is a bonus. Edited July 23, 2016 by astrostar59 Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted July 23, 2016 Report Share Posted July 23, 2016 (edited) the psaudio is still referenced to safety ground. So its not going to protect you from line voltage induced death. A whack from 220V is still nasty. the capacitors in the power supply will still be able to kill you. No question about that. So if you don't understand how to set the currents and then adjust the offset voltages, some extra reading/looking at the board pictures might be a good idea. Edited July 23, 2016 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
sorenb Posted July 23, 2016 Report Share Posted July 23, 2016 you might ask the builder to check whether the tail trimmer and CCS trimmers will make you able to adjust to the currents you want ... Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted July 23, 2016 Report Share Posted July 23, 2016 and a pair of matched and isolated digital voltmeters, very hard to do with one Quote Link to comment Share on other sites More sharing options...
astrostar59 Posted July 24, 2016 Report Share Posted July 24, 2016 15 hours ago, kevin gilmore said: the psaudio is still referenced to safety ground. So its not going to protect you from line voltage induced death. A whack from 220V is still nasty. the capacitors in the power supply will still be able to kill you. No question about that. So if you don't understand how to set the currents and then adjust the offset voltages, some extra reading/looking at the board pictures might be a good idea. Crossed wires, I use the PS Audio for cleaning the mains only, not adjusting the voltage in any of my amps as such. I think my Carbon will have an mA adjuster. Thanks for the head up on the lethal aspects, I was aware and folk need to take care. Quote Link to comment Share on other sites More sharing options...
sorenb Posted July 24, 2016 Report Share Posted July 24, 2016 2 hours ago, astrostar59 said: Crossed wires, I use the PS Audio for cleaning the mains only, not adjusting the voltage in any of my amps as such. I think my Carbon will have an mA adjuster. Thanks for the head up on the lethal aspects, I was aware and folk need to take care. No, you are not aware - you probably be better off having someone with proper skills to do the adjustment. But you still need to make sure your builder choose resistor values that makes it possible to adjust for the range you want. Quote Link to comment Share on other sites More sharing options...
astrostar59 Posted July 24, 2016 Report Share Posted July 24, 2016 1 hour ago, sorenb said: No, you are not aware - you probably be better off having someone with proper skills to do the adjustment. But you still need to make sure your builder choose resistor values that makes it possible to adjust for the range you want. Thanks sorenb, I will talk to him. I can test at his house and may end up setting it there at maybe 17mA or 18mA and leave it at that. Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted July 24, 2016 Report Share Posted July 24, 2016 Just needs a good DAC for 20mA and it's perfect for SR-009s. 2 Quote Link to comment Share on other sites More sharing options...
s_r Posted July 25, 2016 Report Share Posted July 25, 2016 I've just recently gotten to where I can test the PSU boards, however there's something up with the +450V supply. I only get +14V out of it. I get 569V out of the bias line so I think I can rule out the bridge rectifiers not working. I suspect the steel screw for the cree fet may have shorted, so I've swapped it for a peek screw. No change in behavior though. Anything I should check out with a scope first before I try swapping out the cree? Excuse the blurry pic. Quote Link to comment Share on other sites More sharing options...
Skooby Posted July 25, 2016 Report Share Posted July 25, 2016 Check the LT1021? Not the 5V or 7V versions? Quote Link to comment Share on other sites More sharing options...
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