mwl168

Checked the board today. 80-C320C104J5R (two needed) is for the servo position. 667-ECQ-E2105FK (one needed) on the BOM is for the 1uF/50V position on the board. It's 1.5mm lead spacing and rated 250V.

I purposely picked the 1.7V LED because that's what I built the KGSSHV with. If you read the original KGSS article Kevin published in HeadWize, the first and second stage LEDs will even each out regardless of 1.7V or 2.1V LED used. However, higher voltage LED on the output stage will bias the amp to run at higher current I believe. Hope Kevin, Burger or others can chime in.

I like to keep it simple. You cannot "flip the wrong switch" so to speak since the secondaries are not energize unless the main switch is on. The worst thing can happen is no delay to the B+ supply - everything is energized all at the same time. I've grown very used to this power on sequence - it's employed on the OTL speaker amps I've used for almost 10 years.

I am looking for on/off switch for 325vac secondaries on power transformer for KGST, SRX etc.. Anyone knows where I can source them? The highest voltage rating switches I can find on Mouser seems to be 250v. I think I need 350vac rating or higher. 1A or 0.5A should be sufficient for current rating. My plan is to have two power switches on my power supply. The main switch controls the primary windings of the transformer(s) and energizes the low voltage power supply/regulator and the tube heater supply. I then flip on the second switch after 30 seconds or so which connects the secondary windings for the HV supply/regulator. A simple, poor-man's delayed B+ control if you will.

Out of town at the moment so cannot check the board. But I believe these caps (80-C320C104J5R) are for the servo. There is another 1uf cap (ECQ-E2105KF) listed in the BOM for the 1uF position. Will double check when I return home.

Would it be better to keep the XLR and the signal wires as far away from the toroid as possible?

Does it matter what forward voltage LED to use so long as D2/D8 and D1/D9 match?

Thanks Birgir. I measured the footprint of the 100uf/25V caps on the GR HV Dual board and it can accomodate up to about 7.5mm diameter caps. So either should work. The one I included in my Mouser project and BOM is 6.3mm.

Thanks Insanity, Birgir and Pars for your help. I took a close measure and I believe Birgir is correct that the lead spacing for the 100uf/25V caps is indeed 2.5 mm. I changed the Mouser project and BOM to use Panasonic Low ESR caps with 2.5mm lead spacing and 5000 hours rating. hope this is the last time I am making correction to this part If anyone has stuffed the board please chime in and verify.

According to Vishay data sheet, RN60D and RN60C are the same power rating and same physical size. C is 50ppm and D is 100ppm. Both are rated at 1/4W @ 70C and 1/8W @ 125C. Not sure why Mouser lists RN60D as 1/4W and RN60C as 1/8W. 3N254 is listed in both the Mouser project and BOM for GR HV Dual. Will confirm the lead spacing of the 100uf caps in the morning and correct if necessary. EDIT: Thanks to jdineshk for catching this error. The 100uf/25V caps on GR HV Dual need to be 3.5mm lead spacing. I've corrected both the Mouser project and the BOM. I picked a different cap, 647-UTT1E101MPD for its low ESR rating. It's not listed as an Audio grade capacitor like 647-UFG1E101MPM which is a Nichicon's Muse series. Both caps will work. Also, 10M90S is back in stock at Mouser.

Thanks JimL for your detailed and thorough insight. This is really great information to have.

No particular reason from my own perspective. I've always used Vishay RN60D in the past and started using KOA Speer for the first time when I built my KGSSHV. From everything I read both should work fine. I do go for the better 50ppm spec whenever I can but I don't get hang over it. I do like the KOA Speer's blue color better although RN60D is much easier to use for me - I don't have the color coding scheme memorized. Just my 2 cents worth. I am also very interested in hearing others' thoughts of this matter.

Hi JimL: I came across this discussion at diyAudio while searching for information on tube heater power supply wiring. http://www.diyaudio.com/forums/tubes-valves/211731-heater-wiring-good-bad-ugly.html. It offers some observations about AC vs DC heater supply among other things. It also discussed the effect of reducing heater voltage and quoted a study done by RCA in post #27. I am very interested in hearing your thoughts and comments.

Thanks Kerry! For 400v secondary, the pre-regulator filter capacitors will need to be rated for at least 600VDC. I would also pay attention to the heat generated by the pass transistors.

I am looking for the drop-out voltage - the smallest possible difference between the input voltage and output voltage to remain inside the GR HV regulator's intended operating range. 360vac for 450VDC works out to be 50V difference. That seems very high to me.

What is the drop-out voltage of the GoldenReference HV PS? I remember one of the advantages of the GR HV PS over the KGSSHV PS is the lower drop-out voltage. This information will help to spec the proper transformer for the HV Carbon build.

I just checked and looks like 3N254 which is marked on the silkscreen on the GR HV dual board is too large correct for the GR HV Dual board but too small for the GR LV board. I will check the actual boards when I get home tonight and make necessary corrections. Thanks for catching this. EDIT: Also see Kevin's post below. 3N254 is correct size for GR HV Dual board. For GR LV Dual board, RS402L is one of the bridge rectifiers with the correct physical size. It's rated 4A/100V, Mouser part #: 583-RS402L. These observations are made by fitting the actual parts onto the boards.

I am whining but I am in US and just placed a large order with Mouser ($300 +) and I have to pay shipping. I guess that beats having to worry about VAT Also, Mouser does not carry LT1021, the 10M90S and C2M1000170D are back-ordered, and the aluminum oxide insulator 4171G for TO220 is not in stock at the moment. These are all available at Digikey.

Many thanks Todd!

All boards have been shipped as of today. Please let me know when you receive them. Happy building! EDIT 9/12: It's ironic, the padded envelopes I ordered from USPS showed up yesterday, same day I finished shipping all packages

Another batch of packages posted today (Wednesday 9/9), all US destined packages have been sent. More packages will be posted tomorrow. On track to have all packages posted by end of this week.

As proposed, I started this thread for all to share your KGSSHV Carbon build experience and to exchange Q&A. This is a natural follow up thread to the Carbon Group Buy thread. Here are the version of Gerber files used for the boards in the group buy: kgsshvcarbonv5.zip (amp board) kgsshvpssicfetdual2new.zip (GoldenReference HV power supply, all-in-one version) kgsshvpssicfetsinglenewrightfat.zip (GoldenReference HV power supply, B+ and bias) kgsshvpssicfetsinglenewleftfat.zip ( GoldenReference HV power supply, B- and 7815/7915 based +/-15V regulator) goldenreference4.zip (GoldenReference LV bipolar power supply) goldenreference4plus.zip (GoldenReference LV V+ power supply goldenreference4minus.zip (GoldenReference LV V- power supply) bias.zip (stand alone regulated Pro and Normal bias supply) I (or others) will follow up with BOM. EDIT 10/8: 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 is 1/4W rated and not sufficient for these positions. EDIT 10/13: Updated the BOM and Mouser project for Carbon V5 to use 3M 961102-6404-AR for the servo jumpers. Note that the BOM does not match the shared Mouser project due to parts availability at Mouser. I apologize for the errors in project/BOM. EDIT 9/10: link to shared Mouser project for the GR HV Dual. Need to add 2 LT1021-10 and missing parts not available at Mouser. Please help check for errors. http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=54687aa8fa EDIT 9/12: link to shared Mouser project for the GR LV Dual. Need to add 2 LT1021-10 and your choice of insulation kits to mount uninsulated sands. Please help check for errors http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b6d687c7f7 EDIT 9/20: link to shared Mouser project for the Carbon V5 (1 channel only). Please help check for errors. http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=7F837B24AA EDIT 10/19: GR HV Dual BOM in spreadsheet. More complete than the shared Mouser project above. GR HV BOM_Oct19.xls EDIT10/11: GR LV Dual BOM in spreadsheet. More complete than the shared Mouser project above. GR LV BOM_Oct 11.xls EDIT 12/11: Carbon V5 BOM (1 channel) in spreadsheet, uses KOA Speer resistors. HV Carbon V5 BOM_Dec11.xls

Any chance that the attchment feature can be extended to support Excel spreadsheet file types?

Sent 12 packages out today. More will go out tomorrow. Still waiting for USPS to deliver the large padded envelopes I ordered so I can finish packing all the orders. The overseas shipping will be quite high due to the weight of the boards. Most will likely be around $26.50 US for USPS Priority Mail (up to 4 lb max weight). The only cheaper USPS fair is the First Class mail which only saves about $3 once the weight of the package goes above 24 oz. As a reference, 2 Carbon V5 plus 2 HV Single Fat boards weight in around 11oz.. It's a rotten deal for those outside of US - in some cases the shipping ends up costing almost as much as the boards. On to another matter - should we start a new dedicated thread for the KGSSHV Carbon build? If enough people think this is a good idea, I can start a new thread with some preliminary information including BOM for the V5 boards and GR HV PS. Speaking of which, I have not found a way to attach a spreadsheet - I know I was able to do that before the forum software was updated a few weeks ago. Thoughts?

A bit of good news following the disappointing news last; my wife was able to score a few of the USPS containers (large padded priority mail envelope) I have been expecting from a grocery store of all places today. The attached photo is some of the packages ready to be shipped. As you can see some of them are still awaiting their containers. The photo is out of focus on purpose to protect privacy