KGSSHV Carbon Build Thread

[audiostar]

Finally got some C2M1000170D and can finish my Carbon. Difficult times for DIYers... and availability is getting even worse. 

On 6/1/2022 at 10:09 PM, Reima said:

Anyone tried these connectors (the black one): https://www.mouser.com/ProductDetail/571-7969495

Why would you use the black ones?
Despite 300V rating they are much more expensive than Phoenix Connectors.

[Reima]

4 hours ago, audiostar said:

Finally got some C2M1000170D and can finish my Carbon. Difficult times for DIYers... and availability is getting even worse. 

Why would you use the black ones?
Despite 300V rating they are much more expensive than Phoenix Connectors.

If you look carefully you will see that the horizontal part of the metal connector is recessed deeper into the housing. Plus I have them in my parts bin.

[David Kim]

i want to assemble KGSSHV-CARBON, what pcb do i need i need ? and where can i buy it?

[Lord_Rexter]

53 minutes ago, David Kim said:

i want to assemble KGSSHV-CARBON, what pcb do i need i need ? and where can i buy it?

Maybe get in touch with @spritzer  he might be able to help you 👍

https://mjolnir-audio.com/diy-supplies/

[David Kim]

10 hours ago, Lord_Rexter said:

Maybe get in touch with @spritzer  he might be able to help you 👍

https://mjolnir-audio.com/diy-supplies/

i see thanks for the info, i want to confirm to make kgsshv carbon, it takes 2 pcb psu and 2 pcb amp? do we need pcb grlv ?

[BadgerMcBadger]

1 hour ago, David Kim said:

i see thanks for the info, i want to confirm to make kgsshv carbon, it takes 2 pcb psu and 2 pcb amp? do we need pcb grlv ?

im a beginner here too and from what i understand you can either split the psu into 2 boards or use 1. the amp needs 1 pcbs per channel so 2 pcbs in total. i would like if someone could confirm this though

[johnwmclean]

You can either use split or a single GRHV psu board, your choice there is no difference, just layout choices.

The amp pcbs are 1 channel per board, you’ll need 2.

You don't have to use a GRLV, you can use the onboard 15V circuit that is included as part GRHV psu.

[David Kim]

4 hours ago, johnwmclean said:

You can either use split or a single GRHV psu board, your choice there is no difference, just layout choices.

The amp pcbs are 1 channel per board, you’ll need 2.

You don't have to use a GRLV, you can use the onboard 15V circuit that is included as part GRHV psu.

 

i found pcb from ebay, for kgsshv version .6 and GRHV version 1.8 do i need to use GRLV ?

[simmconn]

You’ll need some kind of +/-15V power supply, GRLV being an option.
There are left and right versions of the GRHV board, one with the bias supply and the other with the 7815/7915 LV supply. The sellers from China cut the corner and only produce the GRHV board with the bias supply. You’ll end up receiving two of those, and still need the LV supply.

[BadgerMcBadger]

hey, which stepped attenuators / potentiometers are a good option for the carbon? most people use rk50 but thats too expensive for me

[Aspirant Audiophile]

1 hour ago, BadgerMcBadger said:

which stepped attenuators / potentiometers

I opted out of both, i.e. no volume control on the amp, to use the volume control on my DAC instead and therefore have a cleaner signal path on my amp. I'm very curious about whether this is (as) smart (as I like to think it is). 

I almost went for a RK50, but I haven't read much that indicates the difference between an rk27 and RK50 is so vast. Happy to be corrected if correction is due:)

1 hour ago, BadgerMcBadger said:

 

 

Edited August 19, 2022 by Aspirant Audiophile
Massive typo

[BadgerMcBadger]

well my dac is 16bit so using a digital volume control means losing information unless the volume is at max

(to my knowledge digital volume control works by reducing the bit depth, and anything below 16 bit means losing information)

[audiostar]

29 minutes ago, BadgerMcBadger said:

well my dac is 16bit so using a digital volume control means losing information unless the volume is at max

(to my knowledge digital volume control works by reducing the bit depth, and anything below 16 bit means losing information)

Yes, thats the simplest implementation. However one could also use a real preamp to drive the Carbon. On the other side a build in pot makes the headamp more of a  standalone device. 

Best would be a 10k pot, 4-gang for balanced. The RK27 is certainly not on par with the RK50 (which got even more expensive today).

Next would be the DACT or the Goldmund stepped attenuators (for around $450). And if you like a pot, then TKD 4CP-2511 for instance is a pretty darn good one for around $150.

[Rinat]

I heard that goldpoint's attenuators are good enough. 

[BadgerMcBadger]

do you think the rk27 is good enough? im going to feed the carbon only 2vrms so the pot shouldnt be turned too low

[audiostar]

5 hours ago, BadgerMcBadger said:

do you think the rk27 is good enough? im going to feed the carbon only 2vrms so the pot shouldnt be turned too low

Its not about how low, but consistency within the channels, etc. @migo was testing lately the RK27 and wasn't fascinated. Don't think there is anything you should put into a Carbon below the TKD 4CP-2511 pot or the DACT/Goldpoint steppers. 

However, the RK27 is cheap enough, test it for yourself. Maybe it will be good enough for you.

Make sure it is 10k.

Edited August 21, 2022 by audiostar

[tonyxu]

Hi there, I'm completely new here, bought a second handed JR Audio built Carbon a few years ago and it had stopped working last week (would still turn on, but with no sound). Would someone be interested in helping me go through the steps here or maybe in person(I am not very handy)? I'm attaching some pictures of the build. Thanks!

[audiostar]

6 hours ago, tonyxu said:

Hi there, I'm completely new here, bought a second handed JR Audio built Carbon a few years ago and it had stopped working last week (would still turn on, but with no sound). Would someone be interested in helping me go through the steps here or maybe in person(I am not very handy)? I'm attaching some pictures of the build. Thanks!

As it turns on, it shouldn't be the fuse, right. It looks like there is some relay based protection on the inputs, can you hear both relays click after turning on? 

How much did you pay for this (messy) build? 

Are you comfortable with measuring high voltages and do you have a DMM?

Maybe it is better to send it to somebody knowledgable for repair, if anyone is willing that is. Where are you located?

Edited October 21, 2022 by audiostar

[kevin gilmore]

this is another of the JR audio builds where they took my gerber files and reloaded them and then proceeded to do a hack job on the boards changing all the part values to R# and C# without supplying schematics, moved around a bunch of lands so that they could replace the english connectors with metric connectors, then had boards made with 1 oz copper.  the +/-15 supply is of their own design with the ic's having their numbers sanded off etc.

since there is no sound from either channel its likely that one or more of the power supplies is not functioning.

after the felista megatron, i am DONE with trying to repair stuff that is built like this.

someone with the expertise as well as a stock of required parts will be needed to fix this. many of the parts are on infinite backorder.

[tonyxu]

7 hours ago, audiostar said:

As it turns on, it shouldn't be the fuse, right. It looks like there is some relay based protection on the inputs, can you hear both relays click after turning on? 

How much did you pay for this (messy) build? 

Are you comfortable with measuring high voltages and do you have a DMM?

Maybe it is better to send it to somebody knowledgable for repair, if anyone is willing that is. Where are you located?

Thanks for the reply! I payed $3,000 for this build back in 2018, without knowing their reputation. I don't have a DMM (or know what it is) but I'm happy to try some easy steps to debug if there's not high risk considering the voltage.

I'm located in Seattle and I wonder if there are any builders locally (or not super far away) that I can go to for help. After all I don't want this large box to end up in garbage.

[kevin gilmore]

if you do not have a digital voltmeter and do not know how to use it, then you need to stop now before you get hurt.

find someone that has experience with high voltage tube amplifiers.

[audiostar]

https://www.myheadfi.com/2020/11/17/kgsshv-carbon-and-other-updates/

[audiostar]

1 hour ago, tonyxu said:

I'm located in Seattle and I wonder if there are any builders locally (or not super far away) that I can go to for help. After all I don't want this large box to end up in garbage.

Reading the comments here how great everything is, just wondering why don't you send it back for service? It obviously would cost something but it's their product? 

680uF/550V Capacitors x4 upgrade for $999 and a TKD 4CP2508 upgrade for another $999... 

[tonyxu]

36 minutes ago, audiostar said:

Reading the comments here how great everything is, just wondering why don't you send it back for service? It obviously would cost something but it's their product? 

680uF/550V Capacitors x4 upgrade for $999 and a TKD 4CP2508 upgrade for another $999... 

I was able to contact the original builder himself and he suggested that I look for local professionals. He also stated that many components for repair would be hard to find at this point (which I read as an implication that he might not guarantee a fix). Combined with the fact that I'll have to go through the hassle of shipping this heavy box back to China, I'd prefer to find someone here to take a stab first before I try that route.

 

[kevin gilmore]

all the parts in that unit are current production parts. but if you don't have them in stock you might have to wait 6 to 8 months.