*high

Sorry, false alarm. Offset trimpot does respond, it took a while to realize which channel is and make a few rotations. So, Bias TP 488V (diff multimeter), bias 100V, balance and offset adjusted to zero. Thanks guys, very much appreciate your help! PS Bass has improved, mainly after voltage corrections, I guess. The hum is less audible, almost silent unless you touch stax cable. It is not a riddle, a girls has no name, just shitty electricity.

It's time for awesome / horrific stories Diodes are insulated, RCA single end is taken, the amp is star-grounded So the reading of my 450V: bias TP 575V, bias 397V, R+R- and L+ L- are balanced to 0V, and horror time: R+ GND 136V and L- GND 122V, offset pot doesn't seem to change that Huston, is it a big problem?

It's grounded all right, as far as three-phase power transmission goes, but it's pretty common ungrounded / unearhed system standard. It sucks, I agree, but not that bad =) So 15V GND and 450V GND and volume pot GND all connected together?

I'll show you all the grounding again when I remove balanced pcb. I guess just one thing is missing here https://docs.google.com/file/d/0B4NVeoQi85GgOTdvOGpxc1hyRFU/edit and therefore this build: 15V GND on the safety earth. On the other hand, that again may cause a ground loop. So, transformer shield is hidden. 220V and 2-pin power socket, no ground plug. Then there is and So I guess my mistake is that volume pot GND is not on the star ground, as a theory says it should be on the spot with the weakest current, which is a volume pot gnd.

Well, my universe is upside down now and I'm in Borat mode so to say So, no balanced, I remove that thing. Still using quad volume pot? A bit unsure how to +, - and gnd all that stuff.

isn't it correct grounding? so there are I+ I- inputs of the amp and gnd thanks for your help could you pls name the parts which should be insulated? upd I guess I see them poor little diodes, jammed lucky me 20 hours 'n no blow up? I keep on digging... all parts are the same as marked on the psu board 1.0 http://imgur.com/9wennYm - may have a look

The hum disappears when I ground the case or rca banana, i.e. touch it. The hum increases when I touch the headphone cable. PCB underneath the volume pot is rca unbalanced to balanced converter. My dac is has rca outputs only, unfortunately.

First of all, many thanks to Dr Kevin Gilmore and all contributors! I’m the lucky one to get KGSSHV… almost =) Well, here is the build, not my though. Long story short I bought the kit with all parts populated from someone I trust (and maybe he will help me, I’ll have to ship 30 pound unit a few thousand miles lol), PSU board was tested and amp boards weren’t. Then after dozen of refusals I finally found someone (highly qualified and reputable diyer) who agreed to do the casing and wiring, with no responsibility of how THAT may sound. Funny thing to say, I’m the first one to listen to this unit. And it DOES sound tremendously resolution-and-soundstage-wise, needless to say. Except one thing. It’s not just me crazy, two more experienced listeners heard the same spot on. Compared to 007t amp (as well as some other small diy amp) the bass is lacking big time. You can hear all the sub down to 20 Hz but dynamics and amplitude is missing. Barrel drums which are quiet on the recording are barely discernable (Shake off the Dust by Herlin Riley, to name just one) big drums sound much smaller and drier with more kinda mid-bass impact. No hint of that manner not in a single owner impression! The headphones are dyi, 3 models with different sensitivity and membrane thickness, no problem with them (they may hit hard like devil dare I say, close to HE-6 & beta22 rig). All parts populated are those recommended, though I can go into the details if needed. 20 hours warm-up. I’ll have it measured and will get the readings is two days… But what may be the problem? Voltage swing? Volume pot (rk27 btw, original)? Almost forgot to say, got the ground loop hum sound, pretty audible on sensitive headphone pair. The wiring is done strictly to that scheme https://docs.google.com/file/d/0B4NVeoQi85GgOTdvOGpxc1hyRFU/edit