GrindingThud Posted November 2, 2013 Report Share Posted November 2, 2013 Thanks! I see I have choice of board thickness. I assume .062 is adequate for this build? Also see that there are two power supplies and some are using Sigma22. Is there an opinion on what supply is best? Www.pcbnet.com amp board is 10 x 7.5 inches 609 holes 10 boards from pcbnet.com would be $425 3 oz copper Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted November 2, 2013 Author Report Share Posted November 2, 2013 .062 is fine, that's what the current ones are. Quote Link to comment Share on other sites More sharing options...
trident900fi Posted November 2, 2013 Report Share Posted November 2, 2013 Www.pcbnet.com amp board is 10 x 7.5 inches 609 holes 10 boards from pcbnet.com would be $425 3 oz copper I order mine on www.safe-pcb.com, and there are a little cheaper... Very good quality for the price Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 4, 2013 Report Share Posted November 4, 2013 Ok, so I'm building this out in Mouser and notice the Vishay resistors are 1/4 watt (except the 2ohm at 3W) vs the Xicons at 1/2 watt. Is 1/4w ok? Lol....the parts are adding up quickly. Also looking at the LSK389...do we want A, B, or C version (different Idss ranges) Here is the Google doc. Quote Link to comment Share on other sites More sharing options...
spritzer Posted November 4, 2013 Report Share Posted November 4, 2013 They are RN60D which is a military spec so what is usually a 1/2W resistor is rated at 1/4W. Any of the LSK389's will work. Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 4, 2013 Report Share Posted November 4, 2013 Thanks!They are RN60D which is a military spec so what is usually a 1/2W resistor is rated at 1/4W. Any of the LSK389's will work. Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 4, 2013 Report Share Posted November 4, 2013 (edited) Read the thread again....these appear to be ok. Never mind...... The 4 extra 4.7uf Wimas are specd at 63v/5%....see any issue downsizing to 50v/10%? The main caps are 35v and these are in parallel with those. Saves $13 and they are in stock.... Has anyone settled on a nice transformer? I'm looking at this one, 50VA at 120V:http://www.mouser.com/ds/2/410/VPT48-1040-224303.pdf Thanks, got all of them. Not sure yet about q27 collector cap.The 4.7uf caps are at birgir's idea. (also kind of expensive)evidently no amp is complete without some wima's.will post again when i get home. Edited March 15, 2014 by GrindingThud Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 6, 2013 Report Share Posted November 6, 2013 Ok, I think the last thing on my order list is the pot.... Any suggestions in this area? I was thinking an alps 50K...what was in the Original Krell? Quote Link to comment Share on other sites More sharing options...
fordgtlover Posted November 6, 2013 Report Share Posted November 6, 2013 Read the thread again....these appear to be ok. Never mind...... The 4 extra 4.7uf Wimas are specd at 63v/5%....see any issue downsizing to 50v/10%? The main caps are 35v and these are in parallel with those. Saves $13 and they are in stock.... Has anyone settled on a nice transformer? I'm looking at this one, 50V at 120V:http://www.mouser.com/ds/2/410/VPT48-1040-224303.pdf The response a page back indicates that the 50V 4.7uf caps will be OK. Quote Link to comment Share on other sites More sharing options...
spritzer Posted November 6, 2013 Report Share Posted November 6, 2013 Ok, I think the last thing on my order list is the pot.... Any suggestions in this area? I was thinking an alps 50K...what was in the Original Krell? Some of them had the Alps RK27 while others used Noble AP25. I guess they just used what was at hand. Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 7, 2013 Report Share Posted November 7, 2013 I found a picture of one online that looks like it's got an ALPS 10K....I'll try that and see how it goes.http://www.avx.hu/forum/index.php?/topic/41329-krell-ksa-5v/?p=1313992 Looks like I'm going to try and squeeze it in here: Some of them had the Alps RK27 while others used Noble AP25. I guess they just used what was at hand. Quote Link to comment Share on other sites More sharing options...
wink Posted November 7, 2013 Report Share Posted November 7, 2013 Why nmot an Alpha pot? Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted November 7, 2013 Report Share Posted November 7, 2013 I found a picture of one online that looks like it's got an ALPS 10K....I'll try that and see how it goes.http://www.avx.hu/forum/index.php?/topic/41329-krell-ksa-5v/?p=1313992 Nice clear photography in that link. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted November 7, 2013 Author Report Share Posted November 7, 2013 what chassis is that, and what is the internal size especially height. Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 7, 2013 Report Share Posted November 7, 2013 eBay link here: http://www.ebay.com/itm/400523705862 Internal height is just under 2.5" Internal dimensions: Width 310mm Height 62mm Depth 240mm External dimensions: width 320mm Height 70mm Depth 248mm Front panel 8mm thickness. Back panel,Top and Base plate 3mm thickness. side panel:4mm thickness.what chassis is that, and what is the internal size especially height. Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 9, 2013 Report Share Posted November 9, 2013 I plan on using Neutrik connectors. Any opinions on if it would be worth also putting 4 pin XLR output? http://www.mouser.com/Search/ProductDetail.aspx?R=NJ3FP6C-Bvirtualkey56810000virtualkey568-NJ3FP6C-B http://www.mouser.com/Search/ProductDetail.aspx?R=NC4FD-LX-Bvirtualkey56810000virtualkey568-NC4FD-LX-B Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted November 9, 2013 Author Report Share Posted November 9, 2013 you do realize that there is no way you are going to get everything in one chassis... amp board is 254 x 191 mm original power supply board 150 x 98 mm Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 9, 2013 Report Share Posted November 9, 2013 Yes, PS will be in a remote chassis. . I may also use a sigma22 PS in one of these: http://www.ebay.com/itm/120945750823 Like this: http://cdn.head-fi.org/9/90/9037f0cb_b22_2ch_insides.jpeg you do realize that there is no way you are going to get everything in one chassis... amp board is 254 x 191 mm original power supply board 150 x 98 mm Quote Link to comment Share on other sites More sharing options...
fishski13 Posted November 10, 2013 Report Share Posted November 10, 2013 (edited) fired up the PS: http://i23.photobucket.com/albums/b353/fishski13/002_zps0d93dd0f.jpg SumR 27V x 27V/50VA = 21.1V output unloaded Secondaries = 32.3V Collector Q1,Q2 = 42.5V Collector Q3,Q4 = 27.5V can i assume that when loaded, the V across the BJTs will drop a bit? with the above numbers, assuming a total current draw of 400mA and power dissipation of 200mA on each rail, i'm looking at 3W on Q1,Q2 and 1.3W on Q3,Q4. should be fine with 2" heatsinks and a little thermal grease with adequate ventilation. Edited November 11, 2013 by fishski13 Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 10, 2013 Report Share Posted November 10, 2013 Very nice! What transformer is that?fired up the PS: http://i23.photobucket.com/albums/b353/fishski13/002_zps0d93dd0f.jpg SumR 27V x 27V/50VA = 21.1V output unloaded Secondaries = 32.3V Collector Q1,Q2 = 42.5V Collector Q3,Q4 = 27.5V can i assume that when loaded, the V across the BJTs will drop a bit? with the above numbers, assuming a total current draw of 400mA and power dissipation of 200mA on each MJF pairs/heatsink, i'm looking at 3W on Q1,Q2 and 1.3W on Q3,Q4. should be fine with 2" heatsinks and a little thermal grease with adequate ventilation. Quote Link to comment Share on other sites More sharing options...
fishski13 Posted November 11, 2013 Report Share Posted November 11, 2013 (edited) the TX is from SumR. above maths is just the quiescent current draw. anybody have an approx total current draw per channel? Edited November 11, 2013 by fishski13 Quote Link to comment Share on other sites More sharing options...
GrindingThud Posted November 11, 2013 Report Share Posted November 11, 2013 Thanks. I'm assuming if it stays in class A, the amp won't draw much more from where it is biased at.the TX is from SumR. above maths is just the quiescent current draw. anybody have an approx total current draw per channel? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted November 15, 2013 Author Report Share Posted November 15, 2013 (edited) WARNING to any one that would even think of buying a Revelation Audio Labs power supply to amplifier cable for a real krell ksa5. These fucking morons can't even wire a simple cable and get the pins in the right order. Tom found this out when his ksa5 blew up. So its sitting on my lab bench, and about 3 hours of repair time to repair the damage. And tom was very lucky, it could have been worse. Ended up with -21 on the +21 line and vice versa. Without the protection diodes, very bad things would have happened. Waiting for tom to give me permission to rip the cable apart and see how bad the assembly job is. Shades of coconut audio with blobs of modeling clay. Edited November 15, 2013 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
fishski13 Posted November 15, 2013 Report Share Posted November 15, 2013 (edited) planked the amp out with a Blue Velvet. sounds excellent even with a cheap pot. some noise beyond sane listening levels with the 102dB AD2000 and 103dB D2000, and basically dead silent until the last hour or so on the pot with the 93dB K701, but a rats nest of wiring right now. can't wait to get it in a chassis with a TKD or GP. if my maths are correct, the gain is 5x? Edited November 15, 2013 by fishski13 Quote Link to comment Share on other sites More sharing options...
Kerry Posted November 15, 2013 Report Share Posted November 15, 2013 (edited) WARNING to any one that would even think of buying a Revelation Audio Labs power supply to amplifier cable for a real krell ksa5. These fucking morons can't even wire a simple cable and get the pins in the right order. Tom found this out when his ksa5 blew up. So its sitting on my lab bench, and about 3 hours of repair time to repair the damage. And tom was very lucky, it could have been worse. Ended up with -21 on the +21 line and vice versa. Without the protection diodes, very bad things would have happened. Waiting for tom to give me permission to rip the cable apart and see how bad the assembly job is. Shades of coconut audio with blobs of modeling clay. yeah, I saw Tom at the NY meet after this happened. He wasn't happy. Glad you could fix it for him. He's a good guy. Edited November 15, 2013 by Kerry Quote Link to comment Share on other sites More sharing options...
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