KGSSHV Carbon Build Thread

[mwl168]

2 hours ago, tomoki said:

 

For the variac, I still feel a little bit confusing about the connection method.

The typical use of variac is to gradually bring up and set the AC voltage supply to the rectifiers of your power supply so it does not get hit by 110vac the instant you turn it on. This allows you check and verify operation points on the circuit.

You plug the AC cord of your power supply to the variac and plug the variac to the wall outlet. Make sure the dial on the variac is turned down all the way before you turn on the power supply.   

[tomoki]

 

 

On 9/15/2017 at 10:29 PM, tomoki said:

Thanks for your comment and kindly remind. the mica that i use is the ceramic type one with nylon screw and nuts 

For the variac, I still feel a little bit confusing about the connection method. BTW, due to my job I can try my office AC power stabilizer, I think it can tune the voltage that required.

Thanks for your advise. I am wonder both 2 are broken. planning to replace it both.  

http://tinypic.com/r/2hznv2e/9http://tinypic.com/r/2hznv2e/9

 

Thanks sorenb. Just a little bit confusing the method and I would like to confirm it before test it. For the CCS, is that I should use a AC source with voltage in between 15-20VAC, then connect it between the middle leg of the 10m90s and solder pad in between R2 and R1 (also the pin 6, for the 2nd 10m90s). 

Office day is a debug day~~~

I just start measuring the current for 2 10M90S, result is quite..............strange.........I Just upload photos to show what I get.

For the +VE board

 

For the -VE baord

 

On 9/16/2017 at 1:03 AM, mwl168 said:

The typical use of variac is to gradually bring up and set the AC voltage supply to the rectifiers of your power supply so it does not get hit by 110vac the instant you turn it on. This allows you check and verify operation points on the circuit.

You plug the AC cord of your power supply to the variac and plug the variac to the wall outlet. Make sure the dial on the variac is turned down all the way before you turn on the power supply.   

I think I know what you guy talking about variac. Using variac means that when the first time start we should use the variac to power the board and setup the voltage slowly (per you guys suggestion, 40-50V first).  Am I right?

 

 

 

[congo5]

Variac's are nice for many reasons, and can prevent catastrophic failure,  many components at once

I slowly turn the voltage from 0 to 120v (USA) while looking for heat/smoke and watching voltage meters on power rails, bias test points

invaluable for bringing up these high voltage boards, much cheaper than having blown transistors and burnt traces.

although it is exciting to watch 800v flash and smoke a bunch of parts

mine was $50 and its 500va, You can place smaller fuses in the front panel holder so it blows early, think I put 2amp fuses in

they make bigger and better ones, get what you like.

[Pokemonn]

Hello, 

I have a newbie question.

Can I use traditional 7815/7915 3-pin regulator IC for Carbon's +15/-15 mainboards power supply to save money?

does 7815/7915 degrade SQ compare to KGGR boards?

Thanks.

[sorenb]

9 hours ago, Pokemonn said:

Can I use traditional 7815/7915 3-pin regulator IC for Carbon's +15/-15 mainboards power supply to save money?

Yes

9 hours ago, Pokemonn said:

does 7815/7915 degrade SQ compare to KGGR boards?

People have different opinion in this regard. No problem in replacing with a GR later. 

You might consider using the BH PSU rather - it's simpler and a lot cheaper in comparison to the GRHV.

[Whitigir]

1 hour ago, sorenb said:

Yes

People have different opinion in this regard. No problem in replacing with a GR later. 

You might consider using the BH PSU rather - it's simpler and a lot cheaper in comparison to the GRHV.

This is very true.  People who wants the best would do GRLV later

Is there advantage and disadvantages from using BH PSU ?

[sorenb]

you can probably always do better.
Building a Carbon using a KGBH PSU will still give you a good Carbon.

[jose]

BH Psu vs KGGR ?

This can be a good topic to discuss and learning.

[gepardcv]

I have built a KGSSHV and a KGST using mini BH PSUs, and a Carbon with the GRHV. Though I have not used an oscilloscope to check the builds, I’m pretty sure the GRHV is quieter. Just my impression, anyway...

[mwl168]

Kevin has mentioned in one of his posts that the GRHV is much quieter than the mini BH PSU and also much more voltage stable. 

IIRC, he quoted on the noise level of the GRHV. I'll post it here if I can find it.

[Whitigir]

@tomoki have u ever found your problem? Checked 9360 ? Is the 390k burned ? Hope u found it 

Edited October 15, 2017 by Whitigir

[mainlythemusic]

PS current setting.

I might be terming this incorrectly, but I have a KGSShv Carbon with GRHV. The bias /current from the PS is set to 18mA. I have read here some have it as high as 20, but others a bit lower. Has anyone had any experience with lowering it to say 16mA and what effect that had to the sound. I am wondering if by lowering it a bit I might drop the treble energy a bit and warm it up. I am talking subtle, nothing drastic. I don't want to loose too much of the dynamics and soundstage of the amp. It is already fantastic. Just wondering if it is possible to tweak it a bit.

Any info on this would be great guys.

 

[kevin gilmore]

That is definitely one way to tune it

[mainlythemusic]

Thanks Kevin. What effect do you think I would hear by dropping down from 18 to 16?

[kevin gilmore]

At low volume levels it will be hard to notice. But as the volume increases the frequency response will change

[Whitigir]

1 hour ago, mainlythemusic said:

Thanks Kevin. What effect do you think I would hear by dropping down from 18 to 16?

I ran it from 18 and 16 before.  For the carbon, I prefer 16mA for Stax 009, but on Grounded Grid I stay at 20mA.  On 009 and 16mA, the bass has better warmth and the tonality has more realistic tone to it in comparison to 20mA, but other people may not agree

[Blueman2]

I am about to embark on building a pair of KGSSHV (edit: I meant GRHV) Fat PSU boards (off-board heat sinks, as referenced in first post).  I notice on the board silk screen it shows a 600R resistor, but none was listed in the BOM.  I assume to 600R does need to be populated?  

Edited November 17, 2017 by Blueman2

[mwl168]

The boards you have are the GRHV PSU, different from the KGSSHV PSU. The 600 R resistor and the CPC1117N are there for those that want to implement a timed delay for the HV (for the amps using tube output like Blue Hawaii) You can simply leave them out if you don't need the delay function.

[Blueman2]

Thanks once again, Michael.  My next question was going to be the CPC1117N so you answered my question before I asked it!

[chinsettawong]

13 hours ago, mwl168 said:

The boards you have are the GRHV PSU, different from the KGSSHV PSU. The 600 R resistor and the CPC1117N are there for those that want to implement a timed delay for the HV (for the amps using tube output like Blue Hawaii) You can simply leave them out if you don't need the delay function.

I'm making a GG and will be using this GRHV board as well.  How can I enable the time delay HV function?  How long does it delay the HV to come up?  Do I need other circuits to work together with this function?

Edited November 16, 2017 by chinsettawong
Edit questions.

[kevin gilmore]

the opto switch is on the grhv power supply boards. You need to drive it with something external. That can be as simple as a switch, or a time delay circuit of any kind, like the one stax uses, or the one on the diy t2 which is 555 timer based etc.  Never did a board for that

[chinsettawong]

Thank you Kevin.

[Blueman2]

Another follow up on the timer delay. Is there any issue with populating the board with the 600R resistor and the CPC1117N and just not using it?  Or do I need to jumper something to make HV come on in this case?  I figured while I am building it, I might as well future proof the PSU.    

[kevin gilmore]

if you populate the cpc1117n part, then you need to apply voltage to turn the power supply on, its normally closed.

[Blueman2]

Thanks, Dr. Gilmore.  So that is what the +/- points are on the board?  What voltage is required to trigger 'on' state?

In any case, I think I will leave unpopulated for now.

Edited November 16, 2017 by Blueman2