KGSSHV Carbon Build Thread

[Skooby]

Agree, Birgir 100%.  This phase splitter measured like shit on the scope.  But there are situations that I need SE.  Like for testing, it's a pita to haul my Yggy out , so a SE CD player would have to do.  Will switch the power to the splitter off when using XLR when all tests are done.

[spritzer]

But you just install a switch which grounds the - input for SE.  Hell, just make two XLR plugs with pins 1 and 3 tied internally. 

Edited June 29, 2016 by spritzer

[chiguy]

I use two of these: http://www.neutrik.com/en/accessories/circular-adapters/na2mpmf

[gepardcv]

Can confirm. The Neutrik RCA to XLR plugs work really well. 

[wink]

That phase splitter sounds like an over-engineered underachiever......  

Needs a judicious application of Occam's razor......   

[jose]

I changed the LT1021-5 for LT1021-10. Now, psu it´s fine. 

HV: 402,5 volt. / -401,5 volt

Bias, 578 volt.

LV: 15,4 volt/ -15,1 volt.

Thanks

 

 

 

[mwl168]

On 6/28/2016 at 1:15 PM, mwl168 said:

I am fairly certain I've measured similar effect of my Carbon which I have been listening to on and off for months without issue.

I do disconnect my headphone before power on and off.

Was listening to my Carbon/009 tonight and before I shut it down I measured the offset. I have the opto servo engaged and the offset was hovering under 1 VDC while the amp is on. Upon shutting down the power, within a second or two, the offset shot up to just under 200 VDC and gradually declined from there. 

I plan to disable the opto servo and when I do that I will measure the offset again and report back.

[insanity]

I though Birgir said it doesn't matter as long as it is positive and the stax amps do it too? But certainly interesting to hear if the servo has an influence. 

[sorenb]

Nothing to do with the servo being enabled or not.
They all swing towards B+ at power up/down.

[JoaMat]

5 hours ago, mwl168 said:

I plan to disable the opto servo and when I do that I will measure the offset again and report back.

While experimenting - shut down HV with LV remaining and see what happens.

[mwl168]

6 hours ago, JoaMat said:

While experimenting - shut down HV with LV remaining and see what happens.

Will do. 

It may be a while before I get around to it - have been working on resolving a noisy I2S connection problem for the past month.

[jose]

Ok, I´m ready to check it.

 

[jose]

First start. I'm not lucky

I have all VRs adjusted to mid point

I turn on R channel; both leds shine. A second later, led arround PZTA56, don´t shine (+rail). Turn off the amp and the this led shine again!!! (until the capacitor discharges). The Led arround PZTA06 shine all time. Check Volt on + rail: 1,5 volt. Volt on - rail: -15 volt. No smoke or blown.

L channel, it´s similar to R; the same led is shining and then stop.

 

 

[sorenb]

56 minutes ago, jose said:

First start. I'm not lucky

I have all VRs adjusted to mid point

I turn on R channel; both leds shine. A second later, led arround PZTA56, don´t shine (+rail). Turn off the amp and the this led shine again!!! (until the capacitor discharges). The Led arround PZTA06 shine all time. Check Volt on + rail: 1,5 volt. Volt on - rail: -15 volt. No smoke or blown.

L channel, it´s similar to R; the same led is shining and then stop.

 

 

you might check your low voltage ... have the CT been connected correctly?

[congo5]

the 7815 Fairchild that I use have thermal overload protection, so if anything is shorted (or massively wrong) that would explain the voltage drop.

Does it get HOT?

Edited July 8, 2016 by congo5

[jose]

Thanks guys. Yesterday I was until 2 AM checked the amps. All components is OK, correct solders, all conections OK. Finally, I moved the trafo wires and I saw something, when I moved it the led shine sometimes. I saw that the PSU socket was rare: I desoldered this piece and a pin on the socket base was broken.

I don´t remember too tightly. I had had chinese sockets with this problem but not a Phoenix.

So I turned on and all was OK. Leds shine, volt ok. I adjusted the current to 1 volt (20 mA) and then I went to sleep.

Tonight I´m working with the balance and off set.

Thanks for your patience.

Edited July 8, 2016 by jose

[sorenb]

8 minutes ago, jose said:

Thanks guys. Yesterday I was until 2 AM checked the amps. All components is OK, correct solders, all conections OK. Finally, I moved the trafo wires and I saw something, when I moved it the led shine sometimes. I saw that the PSU socket was rare: I desoldered this piece and a pin on the socket base was broken.

I don´t remember too tightly. I had had chinese sockets with this problem but not an IC&C.

So I turned on and all was OK. Leds shine, volt ok. I adjusted the current to 1 volt (20 mA) and then I went to sleep.

Tonight I´m working with the balance and off set.

Thanks for your patience.

which pin?

[jose]

1 minute ago, sorenb said:

which pin?

CT pin.

I feel like a stupid . Spend two hours to review all and spend your time too

 

 

[sorenb]

Just now, jose said:

CT pin.

I feel like a stupid . Spend two hours to review all and spend your time too

 

 

Nothing stupid about that at all and you didn't spend my time.
I saw something similar a while ago, and spend some time tracking that down as well.
Components "allmost working" can be rather time consuming and cause chasing a lot of red herrings

[kevin gilmore]

always check the power supply first. Into a set of resistors if possible.

[jose]

Thanks all

Dr. Gilmore, What value recommended for HV?

[kevin gilmore]

for the high voltage 16 kohm 20 watt, you need a pair of them.

for the low voltage 500 ohm  2 watt

 

[mwl168]

On 7/3/2016 at 0:35 AM, mwl168 said:

Was listening to my Carbon/009 tonight and before I shut it down I measured the offset. I have the opto servo engaged and the offset was hovering under 1 VDC while the amp is on. Upon shutting down the power, within a second or two, the offset shot up to just under 200 VDC and gradually declined from there. 

I plan to disable the opto servo and when I do that I will measure the offset again and report back.

Tried again tonight without the servo engaged. Similar result - offset shot up to about 170 VDC a couple of seconds after power off. 

Will try leaving the LV supply on and see what happens as JoaMat suggested next - need to rig something up to separate the HV and LV power switches.

Edited July 9, 2016 by mwl168

[shogo]

On 09.09.2015 at 8:46 PM, mwl168 said:

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) 

Why links are inactive? Should buy it? Where then and how much?

[gepardcv]

You should read some threads on the DIY forum here, starting with this one: http://www.head-case.org/forums/topic/11779-stax-mafia-circuit-boards/

You will only be able to buy these boards if someone makes them available for sale, or if you order a manufacturing run for yourself. Some posts here contain discussions about where and how to do this.