Kippei 0 Report post Posted January 11, 2006 (edited) The buzz goes away when i touch the input RCA. So whats the deal So whats the next big thing you gonna make? Edited January 11, 2006 by Kippei Share this post Link to post Share on other sites
squalle 0 Report post Posted January 11, 2006 I think you might have a ground loop problem there you touched the ground part ? try resolder that part or errm change the ground wire to the star ground I cant test it out myself as I'm not using any RCA sockets yet Share this post Link to post Share on other sites
huangyong 0 Report post Posted January 11, 2006 mind you diode will get hot!! Share this post Link to post Share on other sites
1bit 0 Report post Posted January 11, 2006 wow guys you really do talk a lot haha i mean it's page 11 already haha i feel like i'm far behind i just got the sijosae MHHA kit from neutralzz today there seems to be a lot of discussions about the power supply here how do you guys apply the power? can i use wallwart type of dc supply? or is a diy transformer and regulator a real necessity? Share this post Link to post Share on other sites
squalle 0 Report post Posted January 11, 2006 SOHA's supply and MHHA or millet are different MHHA and millet use relatively low voltage (24 volt only rite?) SOHA needs 60v then 40v at plate, so we're using 15-0-15 trafo, then by using voltage doubler we can get 60v or thereabout. then just use RC network to filter off the ripples. for ur MHHA, it's simple aint it? if u can, just get some trafo with 28volt secondary, either 14-0-14 or just 0-28 then use LM317 regulate it down to 24 volt. and u're done with PS of course PS layout and scheme is as usual, which if not sure, you can chk with tangent's TREAD. either follow that, or you can choose to omit some things from there oh, you need to recalculate small things like resistors' values.. Share this post Link to post Share on other sites
1bit 0 Report post Posted January 11, 2006 mm i guess so why SOHA needs more voltage? is it because of the selection of tubes? Share this post Link to post Share on other sites
squalle 0 Report post Posted January 11, 2006 errrmm not really I did try running the exact same tube at 20+ volt but as you might've known, tubes are not for low voltage run if u read the specs of tubes, all starting at 100v and above it will sound nicer at higher voltage as the designers believe Share this post Link to post Share on other sites
kross 0 Report post Posted January 11, 2006 I think you might have a ground loop problem there you touched the ground part ? try resolder that part or errm change the ground wire to the star ground I cant test it out myself as I'm not using any RCA sockets yet i seem to have to same problem. When i touch the psu ground the buzz is gone. how do you make a star ground? right now, all grounds share the same ground plane, including the input, output, volume pot ground. Share this post Link to post Share on other sites
squalle 0 Report post Posted January 11, 2006 for me, somehow erm, the ground is placed at a spot where from all "modules" are about of equidistant modules here are like, 12v PSU, then ground for tube,ground for signals nothing much special... gotta see ur amp man... hard to play guessing work Share this post Link to post Share on other sites
kross 0 Report post Posted January 11, 2006 so it is better to first separate the signal ground, (input socket and output socket) from the tube ground and then join both of these ground to the main filter cap ground? am i right to say that? Share this post Link to post Share on other sites
squalle 0 Report post Posted January 12, 2006 (edited) Is your ground a real ground or just a floating virtual ground? mine comes from the centre tap of the trafo and I dont do exactly a star ground I made 2 units, 1st one using a ground "lane" (not even a plane, LOL) 2nd one somehow a star ground, per module basis like I've elaborated above. both are OK maybe it's the AC signal that's interfering and also have you check for loose connection. the buzz comes from both sides? ADD: the buzz happens when the input is there, but of course no song's playing or with no input. if no input then it buzz, it's somehow normal especially when you dont put volume pot Edited January 12, 2006 by squalle Share this post Link to post Share on other sites
kross 0 Report post Posted January 12, 2006 ok, i get wat u mean by virtual ground. my ground is the ground from my psu, which is actually the ground from the output of a lm317, similar to that in the TREAD, not a real mains ground. i am currently redoing my connections to eliminate any lousy connections. the buzz is from both sides, even when there is input. and the peculiar thing is that there is no buzz when the vol pot is turned on to near max but the buzz gets louder when i start to turn the vol pot towards minimum. Share this post Link to post Share on other sites
squalle 0 Report post Posted January 12, 2006 then try checking ur ground on the volume pot yeah, go check all connections. use old toothbrush and brush over hard enuff to break a loose connection that's what I did and managed to get my protection diode loose then cause oscillation on my output op-amp Share this post Link to post Share on other sites
squalle 0 Report post Posted January 12, 2006 that blooze guy in this page having similar problem with you guys http://headwize.com/ubb/showpage.php?fnum=...5896&fpage=9999 wonder why... any of you have access to oscilloscope? Share this post Link to post Share on other sites
kross 0 Report post Posted January 12, 2006 i spent hours today redoing all the connections, and made two different grounds before connecting them together. well, the buzzing has reduced significantly, although at certain positions of the vol pot, the buzzing is still there, but much much softer and better. therefore, i think grounding is quite important here. i think i should have made a single pcb board in the beginning. and i think when i have the time again I'll change to a better pot. my current one has terrible imbalance on L and R when near min position. I have access to oscilloscope but how to check? Share this post Link to post Share on other sites