Victor Chew Posted March 20, 2012 Report Posted March 20, 2012 Some infomation about my build. Powered up the psu just now. Voltages were sitting as per spec. both at the +ve and -ve 500vdc and 15vdc. Then power up the amps. Balancing was perfect. However, I was not able to get the dc offset down to 0v Max I got was about +60vdc and was out of turns. Kevin suggested to either decrease the value of R26 or increase the value of R12 and R19, citing that the IXYS part was pulling too much current and is out of spec. Can't understand why the IXYS which is from mouser would do that. Anyway, Kevin said to change R26 from 2k to 1.5k. Didn't have that in hand so used a 1.2k. Hurray! Was able to balance and get the DC offset to roughly zero. What fuse rating would be good for this amp? The KGSShv pulls 5.5ma x 4. http://www.head-fi.org/t/582518/electrostatic-amplifiers-voltage-ratings
Maxvla Posted March 20, 2012 Report Posted March 20, 2012 It looks like the same guy who started this train-wreck of a thead over there is actually going forward with his build. I'm not making it up.. http://www.head-fi.org/t/582131/is-anyone-building-the-kgsshv/75#post_8233782
Victor Chew Posted March 20, 2012 Report Posted March 20, 2012 I think the KGSShv deserves a lot better casing than that. What a shame. If the amp runs into problems, he will have a tough time getting the boards out. I am not talking about future problems but problems with the build at start up.
El_Doug Posted March 20, 2012 Report Posted March 20, 2012 I'm not entirely sure what that switching pc power supply is even doing in there - he can't be using it to power the fans, can he? that is beyond foolish
livewire Posted March 20, 2012 Report Posted March 20, 2012 Yup, prolly to supply 12vdc to the fans, cheap & dirty... That's rilly fucked up, prolly a noisy POS in more ways than one. Let's see, four motors spinning and a fuggin switcher in the back, gotta be good for the noise floor. Pffft! Aint nothing like the whir of an armada of fans in the background of your open headphone music pleasure. Turn up the volume and act like it aint there. Sheesh! What crap. FWIW, to those who may not know - the KGSSHV does not get that hot if one uses the correct heatsinks. It is a fairly cool running amp, fans are total overkill. (and not recommended in any headphone amp)
Victor Chew Posted March 20, 2012 Report Posted March 20, 2012 As far as I understand, he is using the pc psu contained in the silver box to power the 5 fans with the intention of cooling the psu and amp. 2 on top of each amp board and one, not shown, inside the slver box to cool the PC power supply. He doesnt realise the amp and the transformer readings will stabilise when a certain temperature is reached. Callibration of the DC offset and balance as we know is achieved more accurately when the amp has warmed up. Currently 80mm fans but he wants to use 120mm for more cooling. The whole thing looks like a big computer box. Further I dont know how he is going to adjust the pots with the fans running.
Maxvla Posted March 20, 2012 Report Posted March 20, 2012 Needs more LEDs, a plexi window and water cooling then.
ujamerstand Posted March 20, 2012 Report Posted March 20, 2012 I wanna know how he'll be dealing with DC offset with all those fans blowing.
n_maher Posted March 20, 2012 Report Posted March 20, 2012 Needs more LEDs, a plexi window and water cooling then. You should strongly consider revising your posting habits.
spritzer Posted March 20, 2012 Report Posted March 20, 2012 For the fuse I use 2A slow blow but I use that for pretty much anything smaller than a T2/BH/ESX. I think the KGSShv deserves a lot better casing than that. What a shame. If the amp runs into problems, he will have a tough time getting the boards out. I am not talking about future problems but problems with the build at start up. Hey... I'm using those cases too.... So exact same setup with an even smaller box (2U) and no heat issues, in fact it runs cooler than my old KGSS. Now take the normal thermal drift of the IXYS parts (the 2SA1968 are much better in this regard) add forced cooling and there will be some very interesting results.
ujamerstand Posted March 20, 2012 Report Posted March 20, 2012 ...(the 2SA1968 are much better in this regard)... I like what I'm hearing.
kevin gilmore Posted March 20, 2012 Author Report Posted March 20, 2012 (edited) You want +/-500 volt power supplys, you have to give a little. Both the 10m90s and the 2sa1968 are much more thermally stable with respect to current, but are only 900 volt parts. The 10m90s is designed to be a sharp cutoff device and 50ppm. The ixtp01n100d is not designed this way. Stacked current sources don't perform as well in a standard configuration and have to be bootstrapped to perform at low Thd levels. Edited March 20, 2012 by kevin gilmore
cobra_kai Posted March 21, 2012 Report Posted March 21, 2012 As far as I understand, he is using the pc psu contained in the silver box to power the 5 fans with the intention of cooling the psu and amp. 2 on top of each amp board and one, not shown, inside the slver box to cool the PC power supply. He doesnt realise the amp and the transformer readings will stabilise when a certain temperature is reached. Callibration of the DC offset and balance as we know is achieved more accurately when the amp has warmed up. Currently 80mm fans but he wants to use 120mm for more cooling. The whole thing looks like a big computer box. Further I dont know how he is going to adjust the pots with the fans running. I made these exact points to him on HF and he waved the suggestions off. I have decided to stop trying to help him and sit back and enjoy the show
Nebby Posted March 21, 2012 Report Posted March 21, 2012 (edited) I made these exact points to him on HF and he waved the suggestions off. I have decided to stop trying to help him and sit back and enjoy the show As we saw in his first thread he's not looking for suggestions, he's looking for confirmation. Edited March 21, 2012 by Nebby
vvs_75 Posted March 21, 2012 Report Posted March 21, 2012 (edited) Sooner or latter he will stop looking and start begging for HELP. Edited March 21, 2012 by vvs_75
livewire Posted March 21, 2012 Report Posted March 21, 2012 Sooner or latter he will stop looking and start begging for HELP. Then again, maybe not. I do wish him the best outcome for his quirky project.
wink Posted March 22, 2012 Report Posted March 22, 2012 (edited) I just hope he doesn't make this year's Darwin Awards..... Edited March 22, 2012 by wink
El_Doug Posted March 23, 2012 Report Posted March 23, 2012 So one of my 4700uF caps on the +/-15v PSU just exploded (I think C11, whichever is closer physically to the regulators on the board), and U3 (the 7815) got extraordinarily hot. Before the cap explosion, I was reading 14v across the output (instead of the expected 30v), which steadily decreased until the pop. Before I simply replace the cap (which was oriented properly), any suggestions on what may have caused this? Anything else potentially die?
cobra_kai Posted March 23, 2012 Report Posted March 23, 2012 What was the voltage rating on the caps?
kevin gilmore Posted March 23, 2012 Author Report Posted March 23, 2012 They should be 4700uf/25v caps, and the unregulated voltage should be 21 volts.
El_Doug Posted March 23, 2012 Report Posted March 23, 2012 Fun... I'm getting +/- 10.5v from my main output on the +/-500v rails. I am getting 506v AC from the transformer. Looks like I have an all-afternoon meeting with my multimeter
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