kevin gilmore Posted October 4, 2015 Report Share Posted October 4, 2015 you really want most of the power in the resistor and not the pot.that said, i don't think andy/steve have the servo turned on, but the thing is already so stable...i still have 2sa1968's and 2sc4686's available, i'm keeping the rest of the stuff. also have fqpf8n80cthe circlotron is a must build, but way more complicated. Quote Link to comment Share on other sites More sharing options...
spritzer Posted October 4, 2015 Report Share Posted October 4, 2015 I chew through the 8N80C's like there is no tomorrow... Quote Link to comment Share on other sites More sharing options...
mwl168 Posted October 6, 2015 Author Report Share Posted October 6, 2015 (edited) Updated BOM and Mouser projects:For GR HV Dual - replaced the Fairchild uninsulated 7815/7915 with CJR insulated ones per wokstarr26For HV Carbon V5 - replaced 182ohm offset pot tail resistor with 100ohm to get to 20mA current per Kevin Edited October 6, 2015 by mwl168 Quote Link to comment Share on other sites More sharing options...
blubliss Posted October 6, 2015 Report Share Posted October 6, 2015 Dropped the current back down to 15ma on mine (had to put the 182ohm resistor back). The highs seemed a bit too intense at 20ma, seems better now. The drop may have impacted the soundstage some, making it more compact. I am really interested to see what others think/discover. I may try going back up a little more. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted October 6, 2015 Report Share Posted October 6, 2015 there was some discussion over there and calculations of the current needed to drive the headphones at full power at 20khz. That number is something like 18ma or so, the T2 is 16ma, a lot of the other amps are much less. at 20ma, the carbon has both a faster rise time and wider frequency response than anything else out there. So for a while it seems bright, then it seems more natural. Definitely a difference. 1 Quote Link to comment Share on other sites More sharing options...
spritzer Posted October 6, 2015 Report Share Posted October 6, 2015 That has been my experience. The carbon shines in the top end the more power you feed. Quote Link to comment Share on other sites More sharing options...
blubliss Posted October 6, 2015 Report Share Posted October 6, 2015 Yes, I will say it wasn't an annoying brightness, just something I was not used to hearing. Maybe I will try again. Quote Link to comment Share on other sites More sharing options...
gepardcv Posted October 6, 2015 Report Share Posted October 6, 2015 Clarification request: to run the Carbon with that 20mA output, you recommend using the 400V PSU, rather than the 450V? Quote Link to comment Share on other sites More sharing options...
spritzer Posted October 6, 2015 Report Share Posted October 6, 2015 You can run either one assuming the PSU and transformer are up for it plus the heatsinks. Mine are all run at 400V because I don't see the point in going higher. Yes, I will say it wasn't an annoying brightness, just something I was not used to hearing. Maybe I will try again.With the 009 perhaps....?? Quote Link to comment Share on other sites More sharing options...
blubliss Posted October 6, 2015 Report Share Posted October 6, 2015 With the 009 perhaps....?? I was actually making that comment as relating to the 007 which I was using yesterday Quote Link to comment Share on other sites More sharing options...
mwl168 Posted October 8, 2015 Author Report Share Posted October 8, 2015 I updated the BOM and Mouser project for the Carbon V5 to use Vishay RN60D 174K resistors for the two 175K positions. The correct part to use is Mouser part # 71-RN60D1743F. It's a mil-spec resistor that is actually 1/2W even though it's listed as 1/4W. The previously listed Xicon 174K resistors are rated 1/4W and not sufficient for these positions. Sorry for the oversight. Quote Link to comment Share on other sites More sharing options...
insanity Posted October 10, 2015 Report Share Posted October 10, 2015 i just wanted to share 2 things i noticed during assembly of the GB amp boards.The Dn2540 and the 100ohms trimmer adjacent to it, are quite a tight fit. I used vishay trimmers and the dn2540 has to be soldered with a slight angle. Maybe the bourns trimmer have slightly different dimensions?Furthermore, I noticed that the holes of the 1uf 50v cap of the servo are quite tight. This probably doesnt affect caps with this rating. but i had 1uf 250v and the leads are a bit too thick for a nice fit. I also must mention that the boards are very good quality. I have never soldered on boards the seem to suck in the solder that good. Quote Link to comment Share on other sites More sharing options...
nopants Posted October 10, 2015 Report Share Posted October 10, 2015 can put the dtn/100r on the opposite side. also related, can you use the to92 to220 2540 parts interchangeably?pre cutting the leads usually makes the installation easier not that you needed help Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted October 10, 2015 Report Share Posted October 10, 2015 to92 and to220 do not have the same pinout Quote Link to comment Share on other sites More sharing options...
mwl168 Posted October 11, 2015 Author Report Share Posted October 11, 2015 Any particular benefit to using the film QYX1H474KTP over a standard ceramic .47uf 50v cap? The film ones have some size to them as well. Hi George: I received my Mouser order today and you are right - the QYX1H474KTP is quite large in size. I am not sure if using film caps in these positions has any benefit over using the MLCC capacitors. I picked film caps because I generally prefer them over ceramic caps. For better fitment, I updated the BOM and Mouser project to use MLCC caps (Mouser part #594-K474K20X7RF5TH5). Hope others more knowledge about the circuit can chime in which caps are better for these positions and why. Quote Link to comment Share on other sites More sharing options...
congo5 Posted October 11, 2015 Report Share Posted October 11, 2015 Thanks to Kevin, Birgir, Kerry and James....and mwl168 for the GB!!Mine is running now...very yummy!I used a 32120 Full aluminum chassis Amplifier Case External Size:320×120×311mm boards mounted vertical with Antek transformers, Xicon 273 series resistorsI swing the heatsinks out to adjust pots and use a 16" non conductive toolit came up fine with no problems, adjusted current to 14ma for now, set balance and offset.not using the servo's yet, Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted October 11, 2015 Report Share Posted October 11, 2015 Mine is running now...very yummy!Pics or it didn’t happen, internal shots as well Quote Link to comment Share on other sites More sharing options...
congo5 Posted October 11, 2015 Report Share Posted October 11, 2015 (edited) one internal shot at other place in profile album... will update tomorrow... Edited July 2, 2016 by congo5 Quote Link to comment Share on other sites More sharing options...
insanity Posted October 11, 2015 Report Share Posted October 11, 2015 My progress so far. I still have to solder the LSK389, which I simply forgot to solder... . Besides that I am waiting for the transformer and the Caps from the GB to do a test. Quote Link to comment Share on other sites More sharing options...
Pars Posted October 11, 2015 Report Share Posted October 11, 2015 (edited) For the GR LV board (not sure if this applies to the HV as well), I'm not sure why "audio grade" electrolytics were chosen for the 220uf and 4700uf caps (Elna Silmic and Nichicon KS) with 85ºC rating instead of long life higher temp 105ºC caps?Measuring for the 220uf cap, the board allows up to 10mm diameter with 5mm LS. For the 4700uf cap, up to 25mm diameter with 10mm LS (snap-in, though leaded could probably be used). Edited October 11, 2015 by Pars Quote Link to comment Share on other sites More sharing options...
insanity Posted October 11, 2015 Report Share Posted October 11, 2015 (edited) I used the following caps on the LV board:http://www.mouser.ch/ProductDetail/Nichicon/UVZ1H472MRD/?qs=%2fha2pyFaduhJNBfNrn1z57sARJAwCa5EYPGgZi6O34PyKHzMMWJAtA%3d%3dhttp://www.mouser.ch/ProductDetail/Nichicon/UHE1V221MPD6/?qs=sGAEpiMZZMtZ1n0r9vR22VnKtxyD4xsRvYMdZpGna94%3dWhich are both rated to 105C, in case you were refering to my boards. I'm using rn60 1% resistors in almost every place. I am surprised how accurate the GR LV is. They read +15.005V and -15.006V. As you might have noticed I also had to cut a strip off the ceramic insulator pads on the GRHV PSU because the two adjacent 10m90s wouldn't fit as is. Edited October 11, 2015 by insanity Quote Link to comment Share on other sites More sharing options...
Pars Posted October 11, 2015 Report Share Posted October 11, 2015 No, I was referring to the published BOM. I figured leaded caps would work fine for the 4700uf. This is what I think I will use:LGU1H472MELZandEEU-FM1H221Silmics are good caps in my experience, so I may just use the Silmic that is spec'd in the BOM. Quote Link to comment Share on other sites More sharing options...
mwl168 Posted October 11, 2015 Author Report Share Posted October 11, 2015 (edited) Hi Pars and insanity:I chose the caps in the GR LV BOM for no particular reason other than personal preference. I always liked the Silmic caps. However, the longer life spec should be a major factor to consider as well. I have added the caps Pars listed in both the Mouser project and BOM as alternatives. Size wise, they all fit the board fine. The 220uf Silmic is a bit taller. Edited October 11, 2015 by mwl168 Quote Link to comment Share on other sites More sharing options...
mwl168 Posted October 11, 2015 Author Report Share Posted October 11, 2015 Double posting here but I had my GoldenReference LV Dual running which is built with board from the Carbon GB. The regulated output is rock steady and even though it shows +/-14.98VDC it's within the range of the LT1021-10 tolerance (0.5%). Quote Link to comment Share on other sites More sharing options...
wink Posted October 12, 2015 Report Share Posted October 12, 2015 A better meter with more digits in the display would give you greater accuracy not only in the number of digits but also in the accuracy of the meter. When I used to calibrate meters I found some multimeters such as "Parameters", whilst not as rugged as a Fluke and not specced a good as a Fluke were usually more accurate than a Fluke. i.e. they were very close to spot-on rather than just somewhere within the tolerance range. Quote Link to comment Share on other sites More sharing options...
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