KGSSHV Carbon Build Thread

[joehpj]

Are 2SA1486 still substitute for STN9360 and 2SC3840 for KSC5026 for the usage in carbon/GRHV?

I happened to still had some 1486 and 3840 at hand.

If new ones are better, than I'd buy some new.

[astrostar59]

I am interested in the Carbon, and in particular how it compares sound wise to a typical Sanyo KGSShv 450V off-board. Right now my KGSShv sits well with the 009s and is probably warming up the sound a bit which I think may help those headphones in particular. Can I ask some opinions of guys here who own both these amps, or who have heard them side by side with the 009s. It would help me a lot to get a handle on the sound of a Carbon. I can't get to hear one yet.

Edited February 27, 2016 by astrostar59

[Laowei]

Build one and report back. 

[wink]

7 hours ago, astrostar59 said:

I am interested in the Carbon, and in particular how it compares sound wise to a typical Sanyo KGSShv 450V off-board. Right now my KGSShv sits well with the 009s and is probably warming up the sound a bit which I think may help those headphones in particular. Can I ask some opinions of guys here who own both these amps, or who have heard them side by side with the 009s. It would help me a lot to get a handle on the sound of a Carbon. I can't get to hear one yet.

Spritzer has 2 ready to ship

http://www.mjolnir-audio.com/products/

"I’m struggling to keep the Carbon in stock and the two I finished last week were gone in a matter of hours.  As of now there are two Carbons in stock ready to ship.

Price:  4600$ plus shipping "

Suck it up, big boy........  break the bank......   

[spritzer]

Actually just one but I'm too busy to update the website... 

[astrostar59]

Yes I know Birgir has that amplifier for sale. It is a bit over my budget though, and with VAT and import duty into the EU makes it even more so, closer to BHSE territory....

[sorenb]

25 minutes ago, astrostar59 said:

Yes I know Birgir has that amplifier for sale. It is a bit over my budget though, and with VAT and import duty into the EU makes it even more so, closer to BHSE territory....

why don't you build one yourself? 

[JoaMat]

Will the opto servo be able to control offset without the trimmer/tail resistor?

[joehpj]

I am sourcing parts now. Having a few questions. It's so hot in summer here so I am going to run carbon @400V to give more headroom for cranking up the current. So correct me if I am wrong.

trafo: sec:335V@250mA GRHV: pre reg cap:500V, post reg cap:450V both up to 680uf.

2SA1486 substitutes STN9360. Need to flip 1486 for the pin definition.

 questions here:

1.Is there any substitute for op27 for the servo? after searching op27 as keyword I didn't find a clear answer. Kevin said opa445. I wonder if TL-0x1 works.

2.Need a Led for power indicator. About how much mcd should I choose for soft light after reflecting from the desktop? I want to put it on the bottom of the chassis.

3.Is there easier way to match 1000170D? I don't have a curve tracer I could reach to. Or no matching required?

Thanks!

Edited March 3, 2016 by joehpj

[leonjo]

On 3/3/2016 at 2:01 PM, joehpj said:

I am sourcing parts now. Having a few questions. It's so hot in summer here so I am going to run carbon @400V to give more headroom for cranking up the current. So correct me if I am wrong.

trafo: sec:335V@250mA GRHV: pre reg cap:500V, post reg cap:450V both up to 680uf.

2SA1486 substitutes STN9360. Need to flip 1486 for the pin definition.

 questions here:

1.Is there any substitute for op27 for the servo? after searching op27 as keyword I didn't find a clear answer. Kevin said opa445. I wonder if TL-0x1 works.

2.Need a Led for power indicator. About how much mcd should I choose for soft light after reflecting from the desktop? I want to put it on the bottom of the chassis.

3.Is there easier way to match 1000170D? I don't have a curve tracer I could reach to. Or no matching required?

Thanks!

It is just for reference from my carbon Bom list. You could check these part No. from www.mouser.com

1.  584-OP27GPZ

2.  The normal 2.5mcd should be OK. (859-LTL-4221NLC)

3. 941-C2M1000170D

[milezone1]

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?

[spritzer]

350V is the absolute minimum. 

[milezone1]

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."

[luvdunhill]

It's quite simple. Look at all the values in the schematic and look at the wattage rating. Is 300v across a resistor even possible?

[milezone1]

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.

[spritzer]

1/4W resistors are not ok and the RN60D resistors are actually CMF60 units which are rated at 500V.  Read the datasheets properly. 

[milezone1]

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.

[JoaMat]

If builder decide to use only one series of resistors, then one should probably choose 1/2W. Othervise most of them could be 1/8W.

[milezone1]

Makes sense. Thank you.

[gepardcv]

On March 24, 2016 at 7:09 AM, milezone1 said:

Here's a data sheet: http://www.mouser.com/ds/2/427/cmfmil-223788.pdf 

On that link, click through to the CMF60 data sheet (http://www.vishay.com/doc?31018), which shows the maximum working voltage: 500V. I use RN60D for everything that calls for conventional resistors (i.e., not the high-power ones or for exotic builds like the T2).

[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.

[kevin gilmore]

there is no 500v version of the carbon, current sources limited to 900v

 

[mwl168]

 

2 hours ago, milezone1 said:

...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? ...

 

On the Carbon V5 board, the jumpers/pins are for engaging the two optional offset servos. you should be able to find some discussion on this thread.

[JimL]

8 hours ago, milezone1 said:

 Is there a good resource for formal documentation about the amp as I still haven't found it?

Nope, the thread is generally it.  Ask a specific question and you'll get a specific answer, otherwise the general philosophy of DIY on Head-Case is similar to Gobber the Belch in How to Train Your Dragon IME:

 

Snoutlout:  Wait, aren't you going to teach us first?

Gobber:    I believe in learning on the job. [releases the dragon]

[kevin gilmore]

not sure where to put this, this is Kerry's first take on a new bh power supply

http://gilmore.chem.northwestern.edu/boards/bh-ps-singlerail-v4.zip