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livewire

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Posts posted by livewire

  1. i'm on a roll... the kgsshv

    in Do It Yourself

    Posted

    My power supply is still not working. Could any of the changes between Version 3 and 4 help? If I change to the simple version with zener diodes I would only need the diodes? Also the cap in parallel (C5, C6)?

    I get ~60V from the positive rail. I changed all semiconducters already :(

    Sounds just like what I went through...

    Maybe Kerry can help you solve it.

    Read back to my post #833 (@ page 42?) for info on the simple psu. Click on the attached schematics.

    KG did mention that something's not right with the 10 volt reference diode, but didnt explain what's up.

  4. i'm on a roll... the kgsshv

    in Do It Yourself

    Posted

    Thanks for your comments Frank. I do appreciate your input.

    I have not had a chance to open it up and poke around with my DMM yet.

    As far as the filter caps go, they are running right on the rated voltage.(450 VDC)

    I bought them from Digikey, I dont trust ebay imported crap. Yes, a lot of it is fake.

    When I previously shorted the psu output, I pulled the caps and tested them.

    They checked ok (static capacitance on a RCL meter & had stable DC output under load).

    The amp has been running fine since then for about the last month and a half.

    I have around 100 hours on it.

    2) Will do.

    3) Thanks for the tip!

    Antek it is, $54 for a beefy dual 475 volt secondary toroid. Excellent!

  7. i'm on a roll... the kgsshv

    in Do It Yourself

    Posted · Edited by livewire

    Sorry to hear about the transformer woes jim. :( I guess some sort of soft start circuit would help here?

    That and a bigger trafo? I dunno. :blink:

    The start-up surge on this thing is quite intense.

    A loud buzz/thump can be heard, while the livingroom lights go dim for a second.

    I mentioned this earlier during the build, another more experienced board member dismissed it

    saying that he wouldnt worry about it, or something to that effect.

    So I figured why bother and didnt implement a soft start. I will now.

    BTW, the trafo never ran really hot, it was just warm to the touch with the amp turned on for an extended period.

    I couldnt find any cheap Hammond trafos on ebay, usually they have them for about $50.

    New, they are $105 on up, so I'm not going that route for an older, noisier design.

    This fried SumR toroid only cost ~$100 with the core band insulation added.

    Craig Sawyers talked of some super-duper trafo that has every turn layer insulated

    which he sourced for his T2 build, I might look into that as well as a fully encapsulated unit.

    So it's back to SumR? Makes me cringe, although I will spec something a bit more substantial this time around.

    I have room for it in this chassis.

    EDIT: Another thing. I'm not actually blaming SumR here due to the fact that

    I had previously shorted the power supply twice in the past,

    possibly weakening the trafo insulation in the process.

    I am aware that they are getting a rep for "donut fail".

    Since I dont have a failure analysis lab at my disposal,

    nor want to pay to have that done, I can only guess.

  8. i'm on a roll... the kgsshv

    in Do It Yourself

    Posted

    Been kind of quiet around here. Anybody else finish their kgsshv yet?

    Welp, last night I was immersed in a four hour listening session with my kgsshv.

    Did I ever mention how good this thing sounds? Had the bass a-thumpin on the ESP-950's.

    Was listening to a lot of vintage Allen Parsons Project. Heavenly!

    This morning I turned on the kgsshv, and nothing. Blew a fuse.

    Put in another fuse and it fired right up.......with a faint buzzing coming from the transformer.

    Then the smell of magic smoke accompanied with substantial heat rising from the toroid.

    Seems like my SumR piece of shit has a short. :angry:

    Oh well, I have yet to tear into it and form a plan of action.

    I'll just fire up my itty-bitty Stax amp and experience bliss without the bass. :D

    FWIW, Previously I did order from SumR, the beefier (100ma?) trafo spec that Spritzer mentioned.

    I think that I may head to ebay and pick up a cheap Hammond dual 500 volt job and be done with it.

    I have a 15VDC Sola brick (ala the original kgss) that I will be using in addition for the low-v stuff.

  14. i'm on a roll... the kgsshv

    in Do It Yourself

    Posted

    I've never heard the KGSS, so Doctor G would have to answer that after listening to both.

    I've heard that the KGSS has plenty of power for driving electrostatic headphones, I would guess that

    the extra headroom afforded by the KGSSHV's higher voltage rating is a good thing to have for the harder to drive models.

    On paper, the KGSSHV is the higher power modernized version of the (12 year old?) KGSS design.

    450 volt vs 350 volt rails, it also has a newly designed very low noise, current limited power supply.

    The design of the KGSSHV amp boards is very similar to the KGSS. Compared to the original design

    the KGSSHV has higher voltage withstanding output transistors and the option to use high voltage mosfets

    for the current source. The dual input fet (lsk389) is also a newer, very low drift design.

  21. i'm on a roll... the kgsshv

    in Do It Yourself

    Posted · Edited by livewire

    Hi charlo89, nice to see you are taking on KG's build, love your case design.

    The connectors I used are a discontinued 6 pin female mil-spec microphone connector made by Amphenol.

    The part number is 91-PC6F. The number when encountered, may be prefixed with "WPI" or "CNA".

    These are available through some electrical surplus resellers.

    Kevin Gilmore used this connector in his first prototype KGSS amplifier.

    You can see it on his HeadWize website which also has much useful information about the KGSS amp.

    Allied Electronics also carries a plastic version of this connector without the chrome outer shell.

    It is a WPI design now distributed by Cooper Interconnect.

    EDIT:

    Hmmmm, just did a search. It seems that Cooper still makes them.

    Newark or Element 14 part number: 38F1544 ~$26 each

    Come and get em! Only 11 pieces in stock.

    Surplus houses sell them cheaper. Just sayin.

    +

    2 pieces on ebay @ $20 each plus shipping. Auction # 350113117987

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