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My own Carbon, not going anywhere... IMG_6585 IMG_6590 IMG_6592 IMG_6593 IMG_6595 IMG_6596 IMG_6597

So I finished my my KGSSHV Carbon a few weeks ago. Been too busy listening to it, but I thought I would share my effort and measurements. I am lucky enough to have access to some test gear that allowe

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Depending on how much listening time I get during the week, I could give some impressions on the weekend.

@ johnwmclean: I know..  But there was no other option. I don't even know if I can keep the position of the powerswitch or if I need to move a bit more to the center. I'see when I design the front panel, which will probably be similar to the others, as I don't have any other ideas.

 

I have a question to those who have experience in building amps with offboard heatsinks. So far I only used thermal paste between the transistors, ceramic pads and angle brackets. I haven't put any between the angle brackets and the heatsinks. Would you recommend it, or is it rather unnecessary?

Edited by insanity
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I just wanted to give a bit more insight into my running carbon. 

I am running at 400V and 20mA per line. Total consumption of the amp in my configuration is 93W during normal operation. In the first few seconds it is up to 190W and then drops. The transformer is almost dead silent during normal operation. If I go really close with one ear, I can hear a very slight hum, but nothing to care about. During turn on there is a short hum which fades as the current draw drops. I use a custom transformer from toroidy with has the following specs:

TS200VA PRI: 2x 117V SEC:

 

> 2x 330V @ 250mA

 

> 2x 18V @500mA

 

> [email protected]

 

- flexible leads - 40 cm long

 

 

The reason for the 2 LV secondaries was stated before. 

As discussed previously I added thermal paste to all interfaces, now including the angle bracket to heatsink interface. I think to longest continues run time was 2-3h and the heatsinks were still touchable by hand. The amp boards clearly produce more heat than the PSU boards (heat gradient from front to back of the heatsinks). I use a 3U case from modushop. 

I listened with the 007 and 009. After a week I still think that it suits both headphones very well, which is a surprise considering that the headphones are quite different. IMHO the 007 was better on the conventional KGSSHV while the 009 was better on the KGST. I think the conventional KGSSHV (450V, 4686) provided quite a large soundstage which is almost too large in combination with the 009 (which provides a huge soundstage by nature) while the treble is a bit too harsh as well. On the other hand, the KGST provides a smaller soundstage, a bit less detail and a bit a softer sound, which suit the 009 much better. With the 007 it was just the other way around as the phones are more mid pronounced and have a smaller soundstage by nature (btw I love their sound too). 

Therefore I think it is surprising to find that the Carbon fits both phones well, although I cannot give a direct comparison between all amps yet. 

Just to mention: I use the ressonessence invicta as a DAC which provides the possibility to switch between various filters. I did not change them for the two headphones. I just used my favorite one, I have also been using with the other 2 amps. 

 

I would love to hear what others think. Also if you agree with my impressions on the KGST/conv. KGSSHV/007/009 opinion. 

Edited by insanity
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12 minutes ago, insanity said:

...

I would love to hear what others think. Also if you agree with my impressions on the KGST/conv. KGSSHV/007/009 opinion. 

Nice write up.

But isn't it like comparing oranges to apples? having three different amps powered from three different PSU's? To my ears the PSU has quite an impact to the final sound from the amp.

 

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  • 2 weeks later...

Finally got off my back side and populated some pcb's. Waiting for a transformer from Toroidy.pl so to test the GB HV i hooked it up to one that is powering another amp, it outputs 2 x 330v @150ma. The one i have on order is 2 x 330v @250ma  2 x 18vac I guess that should give me some headroom with regards to adjusting the output current. I had it running for a few minutes and had some digital thermometers attached to the angle brackets just so i could keep an eye on the temps. I am very happy to report i have working HV and LV psu's and the voltages between +/- are pretty close. Many thanks once more KG for giving us these amazing things to build and of course mwl168 and sorenb for taking the time and effort organising the GB's.

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Edited by kingofsnake
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Right at the heel of kingofsnake, I got my GoldenReference HV Dual up and running an hour or so ago. I don't remember if anyone else has reported successful build of the GR HV Dual board from the GB. I have not hooked up the PSU with load but the initial testing looks good. This particular board is configured for +/- 400VDC output. I hand-measured and picked the resistors and I ended up getting +405.9VDC/-405.6VDC. Close enough.

It's been a long time coming and many thanks to sorenb and Jay for the caps GB to make this possible. 

A word of safety caution; I am using 680uf pre and post regulation filter caps. Without load, 60 seconds after shutting down AC supply to the PSU, the positive rail still measured 262VDC. It took 163 seconds for it to go below 100VDC and 357 seconds to go below 1VDC. At that point, the bias still measured over 300VDC.

 

GR HV VDC Positive.JPG

GR HV VDC Negative.JPG

GR HV Bias.JPG

GR HV Dual.JPG

Edited by mwl168
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9 hours ago, mwl168 said:

Right at the heel of kingofsnake, I got my GoldenReference HV Dual up and running an hour or so ago. I don't remember if anyone else has reported successful build of the GR HV Dual board from the GB. I have not hooked up the PSU with load but the initial testing looks good. This particular board is configured for +/- 400VDC output. I hand-measured and picked the resistors and I ended up getting +405.9VDC/-405.6VDC. Close enough.

It's been a long time coming and many thanks to sorenb and Jay for the caps GB to make this possible. 

A word of safety caution; I am using 680uf pre and post regulation filter caps. Without load, 60 seconds after shutting down AC supply to the PSU, the positive rail still measured 262VDC. It took 163 seconds for it to go below 100VDC and 357 seconds to go below 1VDC. At that point, the bias still measured over 300VDC.

 

GR HV VDC Positive.JPG

Like your Fluke "eunuch"-edition ... 
 

 

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4 hours ago, johnwmclean said:

The storage capacity is quite remarkable and deadly without some load. I've been zapped by a KGSSHV PSU after a week being left off.

probably the BIAS ... the HV has balast resistors that will burn the energy 

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More progress today testing my HV Carbon build (V5 board from the GB). I am running 20mA (1.00VDC measured at test point) and have substituted the 182R tail resistor of the offset VR with a 100R one. No problem zero-out the offset and balance.

A few observations at start up (I have all VRs adjusted to mid point of its value before soldering on the board, I also hand measured and picked all passive parts including the LEDs except a few tiny capacitors):

1. the test points measured between 0.71V to 0.76V

2. the balance is around 3.8V

3. the offset is around 38V

I also found the following sequence of procedures worked well for me for adjustment:

1. Adjust the two 100R VR next to the test point to read 1VDC - my desired 20mA output current

2. Adjust the 2K balance VR to as close to 0V as possible (it'll drift a bit)

3. adjust 100R offset VR to as close as 0v as possible (it'll drift a bit and also interact with balance adjustment)

Next will be to wire up the input and output connectors and see if I'll get music. By the way, this thing runs HOT, much hotter than my KGSSHV. My test heatsink got very warm to the touch. 

Here are some photos: 

 

 

 

Carbon V5.JPG

Carbon V5 .JPG

Carbon V5 Test 2.JPG

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