spritzer Posted July 24, 2014 Report Posted July 24, 2014 All of the film caps with a 15mm lead spacing have a 0.8 lead diameter, at least the ones I've searched for, which is too big for the onboard pcb holes. Nothing that a file can't fix, just thought I'd mention. I'm not sure how that happened as the previous version was just fine. I blame the software...
kh90123 Posted July 24, 2014 Report Posted July 24, 2014 How come I can't use all BJTs for the onboard amp on Production Rev 0.61 ? The pin outs of the MPSW mosfet goes from EBC, while the pin out of the Toshiba BJTs goes from ECB. That means I can't use the 2sc2705, 2sc2240, 2sa970 and 2sc1815.
kevin gilmore Posted July 24, 2014 Author Report Posted July 24, 2014 a lot of people were having trouble getting the original parts. you can still use the other parts in that board, just have to bend the transistors a bit.
kh90123 Posted July 24, 2014 Report Posted July 24, 2014 a lot of people were having trouble getting the original parts. you can still use the other parts in that board, just have to bend the transistors a bit. What about the fuse, is 3.15A ok for 230-240V, and is 4A ok for 115V? It's OK I can get the Motorola chips, just about 10 bucks more. I am just concerned if the performance isn't as good as the Toshiba chips. The board says EBC for the Motorola chips, while the Toshiba's datasheet says ECB, so I will have to twist the base and the collector around. I am afraid if B and C shorts out, something bad might happen. I guess if I really want it, I can prevent the twisted pins from touching using a hot glue gun. Or some epoxy. I read before that you guys mentioned that it's the output stage that will affect the sound more. Subjectively and objectively, how much worse will the amp be if I use the MPSW chips, with 2sa1486 BJT in 3rd n 4th stage, with IXYS CCS, compared to one using all Toshiba chips with IXYS CCS?
jgazal Posted July 24, 2014 Report Posted July 24, 2014 If I am not mistaken: Vishay Metallized Polyester Film Capacitor BFC237321105. Mouser 594-2222-373-21105. Capacitance 1µF (+/-10%). URdc = 100 V, URac = 63 V (standard size). Dimensions 6.0w × 12.0h × 17.5l (mm). Pitch = 15.0 ± 0.4 mm; dt = 0.60 ± 0.06 mm. http://www.mouser.com/ds/2/427/mkt373-201177.pdf
kevin gilmore Posted July 24, 2014 Author Report Posted July 24, 2014 (edited) yes I think that is the right part. too busy making these http://gilmore.chem.northwestern.edu/dsc_0783.jpg birgir had found another part that definitely works too Edited July 24, 2014 by kevin gilmore 1
spritzer Posted July 25, 2014 Report Posted July 25, 2014 The servo cap issue was just with the latest KGSSHV board so I'm not sure what is going on. Might have updated the component which set the CAD into some fury, who knows. I just drilled them out with a 1mm drill as all the traces are on the bottom so the connection in the hole isn't needed.
kh90123 Posted July 26, 2014 Report Posted July 26, 2014 Why almost all of my 680uF Nippon Chemi-con caps measured to be about 600 uF. I have been short changed 80 uF.
UFN Posted July 26, 2014 Report Posted July 26, 2014 Typical tolerance for large electrolytics is +/-20%, so 600uF is well within spec. //UFN
kevin gilmore Posted July 26, 2014 Author Report Posted July 26, 2014 charge them up for a week discharge them discharge them again measure
kh90123 Posted July 27, 2014 Report Posted July 27, 2014 (edited) Hi I need some advice. I know how to wire up the XLR inputs, as someone has posted a .pdf sometime ago here. I'd like to have another RCA input, but only have 2 cables from the XLR to the pot. How do I wire up the RCA input? The +ve of RCA should be connected to pin 2 of XLR right? What about the -ve, do I connect it to pin 1 (ground) of the XLR? Then if I am using the RCA input, wouldn't the quad pot be kind of floating? Please advise I think I might be wrong. Also I wonder if anyone here has made this DAC before: http://www.twistedpearaudio.com/digital/buffalose.aspx Edited July 27, 2014 by kh90123
kevin gilmore Posted July 28, 2014 Author Report Posted July 28, 2014 when using the rca inputs you have to have a switch that shorts xlr input minus to ground.
kh90123 Posted July 28, 2014 Report Posted July 28, 2014 Ok another thing to confirm. If I am using the ksa1156 for the PSU, I put in the 270V zener, and if I am using the 2sa1486, then I don't put in the 270V zener right? Which is more preferable? Seems like the older 2sa1486 can push more current on its collector.
DefQon Posted July 28, 2014 Report Posted July 28, 2014 (edited) Can any of the different hfe ratings/classifications for 2SC2240/970 and 1815 be used? I've got a massive order of 2240/970 GR's coming and don't want to run into troubles if BL is the preferred one due to its higher hfe base to collector ratings. Edited July 28, 2014 by DefQon
kevin gilmore Posted July 28, 2014 Author Report Posted July 28, 2014 won't matter as long as you use all the same of each part in an amp
DefQon Posted July 29, 2014 Report Posted July 29, 2014 Cheers Kev, this will help me avoid any headfuck troubleshooting that might come my way.
johnwmclean Posted July 30, 2014 Report Posted July 30, 2014 In the next week or so I’m getting a few quotes on panels for a KGSSHV build. Is any one in out there in Australia interested/ready at this point to go in with a combined shipment?
UFN Posted July 31, 2014 Report Posted July 31, 2014 Simple question really: I am gathring parts for a KGSSHV and would I be able to use 2SA1831 I already have instead of the 2SA1968 for the current sources - or would I be better off just buying the IXYS FETs from mouser instead? //UFN
kevin gilmore Posted July 31, 2014 Author Report Posted July 31, 2014 2sa1831 is only an 800V part. So you would have to cut the power supply voltages down to +/-400
kh90123 Posted July 31, 2014 Report Posted July 31, 2014 Got all my parts in today, I saw the biggest through hole 3W resistors I have ever seen. There are regen resistors much bigger out there, but those aren't as fascinating as the big round thru hole resistors. Quick question, is it possible for me to test a depletion mode MOSFET just using a DMM? I have to apply a negative bias to test it isn't it. Maybe I should get the Peak Atlas DCA 55...the DCA Pro is just a bit too expensive. I'm outta money after buying so many chips. Another one, I know how to match hfe on BJTs using the DY 294, but how do I test the LSK 389 JFETs using it?
UFN Posted July 31, 2014 Report Posted July 31, 2014 2sa1831 is only an 800V part. So you would have to cut the power supply voltages down to +/-400 Ahh, yes of course. I'll just stick with the FETs then. Cheers Kevin! //UFN
kh90123 Posted July 31, 2014 Report Posted July 31, 2014 Hmm I just plugged in the JFETs into the DY 294 like how I do with BJTs, I bought 6 LSK 389, luckily I got a pair that's well matched.
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