spritzer Posted June 24, 2014 Report Share Posted June 24, 2014 I had 20 minutes to kill... Haven't tested it yet so hopefully soon. 1 Quote Link to comment Share on other sites More sharing options...
Mangler Posted June 24, 2014 Report Share Posted June 24, 2014 Thanks Birgir. I was a little worried since I haven't been able to find any matched quads, (maybe I'm looking in the wrong places) so Its good to know I can get away with a set of matched pairs though, since those seem to be available on ebay. Too bad the amp being ccs doesn't obviate the need for matched sets. Don't know where I got that bit from... Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
wink Posted June 25, 2014 Report Share Posted June 25, 2014 Are there any substitutes for the 6s4a? I've been looking and asking around a bit, but I haven't found anything. Try the Tube Depot https://www.tubedepot.com/products?utf8=%E2%9C%93&keywords=6s4a Quote Link to comment Share on other sites More sharing options...
wink Posted June 25, 2014 Report Share Posted June 25, 2014 Tube matching differences of opinion http://www.diyaudio....tput-tubes.html http://www.diyaudio....atch-tubes.html http://sound.westhos...lves/myths.html http://www.audiokarm...ad.php?t=291854 Quote Link to comment Share on other sites More sharing options...
DefQon Posted June 25, 2014 Report Share Posted June 25, 2014 Sometimes one can get good deals on ebay too with tubes, just make sure the tube is tested by the seller. Quote Link to comment Share on other sites More sharing options...
Sherwood Posted June 25, 2014 Report Share Posted June 25, 2014 I never would have thought to check ebay. 1 Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 25, 2014 Report Share Posted June 25, 2014 I just bought a bunch of tubes off ebay and it was... interesting. I bought close to 100 units and many are great but some are just crap. Some are even original factory rejects... Quote Link to comment Share on other sites More sharing options...
Mangler Posted June 25, 2014 Report Share Posted June 25, 2014 I asked both tube depot and the tube store about getting matched quads, but they both told me they don't have a large enough stock to put together a matched quad. I asked tubemazestore this morning, but haven't heard back yet. However it turns out vacuumtubes.net does have a large stock. They said each tube is $4 and there is a $4 per tube charge to match them electronically, so $32 for a matched quad. I'm putting my order in now Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
Remolon Posted June 25, 2014 Report Share Posted June 25, 2014 Could be interesting to read what Langford-Smith said about matching and the effect of mismatching.http://paleoelectronics.com/RDH4/CHAPTR13.PDFPag. 580-2 Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 25, 2014 Report Share Posted June 25, 2014 That was too funny, 5% distortion is good enough... Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted June 25, 2014 Report Share Posted June 25, 2014 Well I think the idea was he was using two completely different tubes, a 2A3 and a 45, so absolute worst case scenario. I don't think anyone is gonna try two different output tubes in push pull in their KGST. Quote Link to comment Share on other sites More sharing options...
Remolon Posted June 25, 2014 Report Share Posted June 25, 2014 In three pages there are some more information, such as the correct matching procedure to obtain trusted results and the differences for triodes and pentodes. 1 Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 29, 2014 Report Share Posted June 29, 2014 Quick update, PSU has been tested and it works perfectly. We discovered a small issue with the amp boards but it's been fixed now. Kevin will fire up his ST soon and then we can move on with this. Quote Link to comment Share on other sites More sharing options...
headinclouds Posted June 29, 2014 Report Share Posted June 29, 2014 That's great, thanks Birgir. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 29, 2014 Author Report Share Posted June 29, 2014 final pic before I put the fets in. works just fine. http://gilmore.chem.northwestern.edu/dsc_0591.jpg Quote Link to comment Share on other sites More sharing options...
Laowei Posted June 29, 2014 Report Share Posted June 29, 2014 Thanks for all the hard work Kevin and Birgir. I am really looking forward to building this. Quote Link to comment Share on other sites More sharing options...
JoaMat Posted June 29, 2014 Report Share Posted June 29, 2014 (edited) / Edited November 11, 2015 by JoaMat Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 29, 2014 Author Report Share Posted June 29, 2014 birgir messed up the lsk389 footprint on the test boards. how, he does not know as this should have been a cut and paste. version .4 of the boards will be production. also the one cap was too close to the ic socket. Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 29, 2014 Report Share Posted June 29, 2014 The board was a cleanup of some old board design which had the error to begin with so it just continued onwards. I'm cleaning up my huge stock of K170's so I didn't try the LSK389 until yesterday and then it issue was clear. That plus one mislabeled transistor and some component fit issues is not bad at all. Quote Link to comment Share on other sites More sharing options...
JoaMat Posted June 29, 2014 Report Share Posted June 29, 2014 (edited) / Edited November 11, 2015 by JoaMat Quote Link to comment Share on other sites More sharing options...
UFN Posted June 29, 2014 Report Share Posted June 29, 2014 Looks good (minor issues or not ) //UFN Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 29, 2014 Author Report Share Posted June 29, 2014 final kgst board http://gilmore.chem.northwestern.edu/kgst-miniv03.zip Quote Link to comment Share on other sites More sharing options...
JoaMat Posted June 29, 2014 Report Share Posted June 29, 2014 (edited) Great! Thanks a lot – Kevin and Birgir - for all work you are doing. Edited July 4, 2014 by JoaMat 1 Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted June 30, 2014 Author Report Share Posted June 30, 2014 power supply board http://gilmore.chem.northwestern.edu/kgstpsu21.rar Quote Link to comment Share on other sites More sharing options...
spritzer Posted June 30, 2014 Report Share Posted June 30, 2014 Here is the second KGST up and running. I don't recommend trying to build it this small... This one was supposed to be silver but I ordered the wrong chassis though I think it looks kinda nice. The transformer is the BH unit I was having trouble with and here it doesn't complain at all. The amp is drawing about 65W which is a far cry from the 170W or so from the Blue Hawaii. The real problem with something this small is the height. The tubes are simply too tall to use an 80mm chassis but I got away with it by hand selecting the shortest tubes in stock and using 6mm standoffs. This one also uses the KGSSHV mini PSU which is considerably smaller than the KGST unit. Just noticed that there is a typo on the back panel. Bloddy "electostatic headphone amps"... 6 Quote Link to comment Share on other sites More sharing options...
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