insanity
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Posts posted by insanity
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Yes everything adjusts fine.
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Today I tried to listen to some music for the first time. One channel is perfectly fine. The other one only transmits low frequencies with distortion and no high frequencies. Without a signal it is dead silent. I changed the tubes, no effect. Where would you start to look for the problem? I guess it must be some device in the 1st or 2nd stage maybe?
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Could you elaborate what you mean by cracking?
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My KGST is up and running. Got the transformer yesterday from toroidy. As expected it is dead silent. Everything seems to work fine, no explosions. Balance and offset can be zeroed. Haven't had a chance to connect a source and headphones yet. I'll probably do this on the weekend. Uncased pictures will follow on the weekend.
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As usual with these DIY electrostatic amp projects, soldering is one thing. But you have to be aware of the high voltages involved and it is also useful to have a bit of an understanding of electronics. I mean you don't have to fully understand how the amp works, but electronics basics are essential. Otherwise you will end up blowing the whole thing up or killing yourself. Furthermore if you commit on doing this project, I suggest carefully reading other threads in the forum, such as the KGSSHV thread.
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Has anyone already made up their mind on what case to use for a KGST? Total height of the board to the tubes end is 75mm. With 10mm studs we end up at 85mm which is too much for 2U.
Either I have to go for 3U or find a case which has around 90mm internal height.
I don't think that using studs shorter than 5mm is a good idea.
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That did the trick. Used a 1.1mm drill bits end.
The bit has broken two times during the process, but the tubes fit in well now.
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Hey guys, as you can see I ordered and soldered in the tube socket recommended in this thread. http://www.ebay.com/itm/10-9pin-Ceramic-Tube-Socket-PCB-B9A-6DJ8-12AX7-ECC83-ECC82-12AU7-6922-6N11-Valve-/140891822701?pt=Vintage_Electronics_R2&hash=item20cdce9a6d
Since I have no experience with tubes, I am unsure how hard I need the push to get the tubes into the sockets. To me it seems almost impossible to get one in. I'm scared of breaking it.
Help?
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I just finished assembling the boards. Have a look:
Still waiting for the toroid though. Anyone else notice that the mounting holes of the PSU board are huge?
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Wonderful work. Congratulations. Seems about half as big as my KGSSHV.
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Beautiful! Looking forward to seeing mine.
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I'm just checking my BOM. I noticed that 621-GBU610 is out of stock at mouser. I suppose we can substitute with 621-GBU810. Right?
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Hello Guys
I have noticed some changes, on the silkscreen of the v0.41 (boards from the current group buy) compared to earlier versions. The BOM in this thread seems to have missed some changes.
1. on the amp board, there is a 1k and a 2k trimpot. current BOM says 2x 2k
2. On the PSU board the zeners are now 24V, BOM says 12V.
3. Can someone confirm which leds to use? I suppose its the same ones as in the KGSSHV (i.e. 859-LTL-307ELC) 1.7V, 2mA
4. Of course if you want to run at the recommended 350V instead of 400V you need to adjust the zenerstring to 2x100V and 1x150V
Happy building
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Yes its from that ebay seller. At the moment I have no way of testing them. I just thought I'd buy some, if I ever wanted to build another KGSSHV.
Is it through that ebay seller something like 6gbp for like 12 pcs? Let me know if they are real as I purchased 4 lots same as you and would not be a happy Jan if they turn out to be fakes.
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Today I received my recently ordered 2sc4686. Looks like i got 50 instead of 48 in an original? bag.
I guess they should be real then?
Any one?
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If you want the servo to work, then you need it ;-)
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Yes this looks like 12 pieces. Thats why I ordered 48 pieces. Now let's just hope they are real.
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For that money, you can probably almost get a custom one from toroidy.pl with all secondaries you need.
We were talking about this one: http://www.antekinc.com/as-1t275-100va-275v-transformer/
http://www.ampdesign.eu/pi4/pd73.htm
This one? -
I just bought some 2sc4686a. I will post pictures when they arrive.
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Does this look genuine? http://www.ebay.com/itm/12pcs-Toshiba-New-Original-Genuine-2SC4686A-C4686A-transistor-TO220-/281367004966?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4182c7c726#ht_1352wt_918
lots of 2sc4686a on ebay still for cheap. suggest you buy a bunch.
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I saw that one, but it's not in stock at the moment.
Antek has a very nice transformer at 275V (i.e. close enough) and then you just need a 30VCT transformer for the +/-15V supply
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As far as I have seen, it looks like custom is the way to go for 280v.
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Thank you for your reply.
If I go for 350V rail voltage, what are the transformer specs I need?
0-6.3V 1.4A (2x)
-18-0-18V ??A
300v? ??A
I think the Zenerstring would need to be 150 100 100V, right?
Anything else that needs to be adapted? What about the bias voltage?
That socket should fit but these are the most common ones and what I used/designed for:
Available from pretty much everywhere. The board also takes the teflon sockets such as this one:
For tubes its the 6S4A that works and nothing else. There are really no tubes like it though some are similar but with incompatible pinouts. I got some 6973's on Friday which are a beam pentode and in current production which might work on a modified ST board triode strapped. As soon as I get my new board then I'll try it.
As for matching, you need matched pairs for each channel but a matched quad doesn't hurt. Matched build is also what I'd go for so all of them RCA or GE, the actual branding doesn't matter.
A note about the voltage though. After running my tiny 400V for some time now I would advice people stick to +/350V rail voltages as 400V runs too hot for comfort. It's the first amp I've ever had to use a fully vented cover for...
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Since this will me my first amp built with tubes, I have two questions.
1. Which tube sockets should I get? Are these the right ones and ok? http://www.ebay.com/itm/4pcs-GOLD-9pin-PCB-Ceramic-vacuum-tube-sockets-valve-base-12AX7-12AU7-ECC83-6N11-/231285734941?pt=Vintage_Electronics_R2&hash=item35d9b43e1d
2. Which 6s4a tubes should I get. Can I use other types of tubes? If I understand correctly I need at least matched pairs, better matched quads. Which tubes are a good choice for the KGST?
Help is really appreciated, thanks!
kgst
in Do It Yourself
Posted
Bias is set to 580V,