milezone1

I noticed in this link regarding the standard KGSSHV (http://tee8tee4388.blogspot.com/2013/07/kgsshv-amplifier.html) it instructs not to populate certain components of the board if using a higher (500v) transformer instead of a 450v transformer. Is there a similar design on the Carbon boards? In addition, what purpose do the jumpers/pins serve? Is there a good resource for formal documentation about the amp as I still haven't found it? Any help is much appreciated.

Makes sense. Thank you.

Why is a 1/4 resistor not okay? I cannot find a scenario aside from the the 4.7m resistor, where the dissipated power would near/exceed 1/8w. In addition, aside from the resistor values above 200k or so, in my understanding, it's very unlikely that the voltage amounts would be anywhere near 300v regardless of the load. I've read the data sheets properly. I'm inquiring about max operating voltage, not dielectric strength, which according to the data sheets, is rated for 300v. At no point did I mention dielectric strength. Furthermore, I'm aware that the RN60D is a CMF60 rated for 1/4 watt so as to fall within military specification - no need to tell me what I already know. Here's a data sheet: http://www.mouser.com/ds/2/427/cmfmil-223788.pdf I respect some of your contributions in the realm of Stax knowledge. Suggesting that I read the data properly seems a bit unwarranted. I'm by no means an electronics expert and appreciate any clarification one can give.

Haha, alright thank you. I still don't have a complete schematic but was able to calculate some values using the BOM. Please share a link to the schematic if you have one. It seems using 1/4 watt resistors is just fine in most instances except for the 4.7M resistor on GRHV boards. It might make sense to use 1/2w resistors for the 1M resistors to be safe but I'm not certain it's necessary. If my calculation is correct, a 1/10w 1M would be just fine assuming it can handle ~450v(?) - however that seems unlikely. It seems the half watt resistors in the BOM were chosen for their high max operating voltage. I'm fairly certain 300v across a resistor is possible. Max operating voltage usually refers to the maximum voltage a resistor can withstand for a minute. I have no idea how much sustained voltage resistors in the circuit are receiving. Is a 350v max operating voltage necessary, I'm not sure. Are these resistors the operating at 85 degrees C* when the amp is playing music at listening volume for 15 minutes? A cheap laser thermometer is great way to determine this. And if not, it would seem that using a resistor with a max operating voltage of 300v might be okay.

Thank you Birgir. I see some builds incorporating RN60 resistors which have a 300v mwv - is this a problem in your eyes? And why? In addition, I presume it would be okay to use a 1/4w (250mw) resistor rated for 500v - despite the BOM calling for 1/2w resistors? Quoted from mwl's initial post: "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."

Hi, I'm also sourcing materials for Rev 6 and am curious what the proper maximum working voltage is for resistors is on the amplifier boards. I see the BOM at the beginning of this thread includes KOA Speer 1/2w resistors with a Max Working Voltage of 350v. I'm curious as I'd like to potentially use a resistor type with a MWV of 250v or 300v. Is this okay? In addition, are there any changes in values/parts between the rev5 and rev6 builds or is it just topology changes?