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livewire

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Posts posted by livewire

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

    in Do It Yourself

    Posted

    That's good to hear, so I guess the design of the battery circuit is a sound one.

    Please remember that I initiated the trouble both times. (blew it up)

    I suspect that rille's woes were from HV shorting to the heatsink, but i'm guessing here.

    This battery sub-circuit is shrouded in mystery to me.

    It seems that after things "went sideways" I could not get the battery circuits to function

    properly no matter what I did. I got tired of shooting in the dark. Then I saw the (zener) light.

    I know they are probably noisier and may not regulate down to the last nanoamp, but should be good enough.

    You have used them in most of your previous psu's.

    Without knowing the inner workings of the battery circuit I have a gut feeling concern about

    the 2SC3381 sand and the two 100 ohm resistors sitting right on the -450 volt rail.

    They do seem like a weak link and fried on me both times I shorted things out upstream.

    I'm just a tech, not a design engineer. I dont have an understanding of exotic circuits such as current tunnels.

    It would be nice to have a "blow by blow" on how this battery circuit functions.

    That is one of the things that I appreciated while reading about your stat amp designs in your HeadWize site.

    Though not detailed, the sub-circuits were explained in a way that a novice could grasp or at least research further.

    Anyhow, blah-blah-blah. Please excuse my moaning.

    I am really happy to have a functioning stat amp even if it was a little over my head to build.

    There will not be a T2 in my future.

    Next thing for me is to learn what I need to test the audio output on the KGSSHV for quality.

    I may take it to a lab, cause I have no idea what is needed to test audio that has a 900 volt swing.

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

    in Do It Yourself

    Posted

    No, nothing exists that shows test point voltages.

    If you read back about seven pages, you will see that I asked similar questions and had similar findings.

    When this happened to me, I also found the 100ohm resistors in the battery sub-circuit to be fried

    as well as the 2SC3381 sand. Since I wasnt having any luck with understanding how the battery outputs work,

    that coupled with the negative rail still bad and the positive rail working but not regulating under load,

    I gave up and went to a simpler iteration of the power supply circuit sans battery, using a zener string instead.

    FWIW, I started researching older psu designs on KG's HeadWize site, then tripped across his earlier psu design

    in this thread. It all made perfect sense to me now. This I could understand and implement. Worked fine for me.

    I would like to revert to the battery regulator design, but wont for now until those questions are answered

    regarding it's function and input/output voltage test points.

    So long story short, I left the crippled battery circuits in place and cut some traces

    to disable current flow through them and soldered in the zener strings(3ea@150V-5W) as shown in the schematics below.

    kgsshvps2.pdf

    post-2625-0-03359700-1303848974_thumb.jp

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

    in Do It Yourself

    Posted

    Thanks for the compliments guys.

    I just wanted a clean "econo-build", nothing fancy to help keep the price down.

    Kerry, you're right about the "start saving".

    I heard an O2 Mk1 (I believe n3rdling's) through the KGSSHV at the meet last weekend.

    All I can say is WOW!!!

    His Blue Hawaii with the original Omegas trumped that experience. I AM IN AWE!

    Now where am I gonna find $11K for a BHSE and a SR-009?

    Aint gonna happen soon unless I were to win the lottery.

    Think I'll stay content with what I got. It does sound nice. :D

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

    in Do It Yourself

    Posted · Edited by livewire

    Thanks, I'm a stat n00b so I dont have much in the way of comparisons to other stat amps.

    All I've heard is what I own. The Stax SR-202 & SRM-252II amp, also the Koss ESP-950 system.

    Compared to any dynamic headphone setup in general, stats rule. No real comparison IMHO.

    Here again, I'm a "mid-fi" guy so take what i say with a grain (or truckload) of salt,

    I have not heard any of the real high end dynamic stuff. (but want to, someday)

    Actually the KGSSHV's performance is a bit of a let down for me due to the fact it is

    a mismatch with the Stax SR-202s. It tends to overdrive them at higher volume levels.(@SPL>95dB)

    Distortion sets in and no decent improvement in bass response.

    The Stax Basic headset works great with the puny SRM-252II amp it came with, a match made in heaven.

    The sound is as good as it is with the KGSSHV but limited to a SPL of ~95dB.

    So I guess the Basic Stax setup is matched well, just not head shakers or bass thumpers.

    The Koss ESP-950 on the other hand.....

    Wow! These cans can handle all the power the KGSSHV throws at them.

    For a stat there is gobs of butt stompin bass and they can produce insane amounts of volume without distorting.

    They sound fine with the little plastic box amp they came with,

    but with these cans the KGSSHV makes a marked difference, although on the extreme end of things.

    I dont know if I can (or really want to) take those SPL levels for very long.

    The overall sound of the KGSSHV is very neutral, no coloration,

    no perceived noise at all at any volume setting.

    It suits me fine, just what I was looking for in a DIY stat amp project.

    I have found that with the quad DACT attenuator I just installed,

    the highs are sharper. There was a slight "upper veil" with the RK27 pot.

    The log taper is different to what I am used to, there is more finite adjustment to the middle range.

    Just as well, I dont need to have my head blasted off with the volume maxing at 12 o'clock

    therefore having the upper half of the range unusable.

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

    in Do It Yourself

    Posted

    Will be showing the KGSSHV at a local HF meet next Saturday.

    We have reserved a meeting room at a hotel in downtown San Diego with a private patio overlooking the beach.

    A sponsor will be picking up the hotel tab, forty or so expected to be in attendance.

    I'm wiring in a 50K DACT that I recently picked up from Justin.

    Curious to see the improvement over the existing quad RK27.

    Also gonna do some surgery on the bias circuits.

    Just picked up a Koss ESP-950 and want to do 610 volt bias

    instead of the existing low voltage Stax bias which I will prolly never use.

    Finished "big box" pics to follow.

    The theme will be "Back To The Future".

    Ha-ha, it kind of looks like a piece of lab equipment designed by a mad professor. :D

  25. The Headcase Stax thread

    in Headphones

    Posted

    I accept that these types of equipment need to warm up but I don't like the sound of the amp when it has been sitting on for a long time. The sound seems to get thin, lacking in bass and have some slight rise in background noise. I prefer to short period of sitting, say 30 minutes and then a minute or so of playing louder than I would be listening.

    I dont know about the ERS paper treatment but I do prefer the Hello Kitty drapes!

    At the risk of being heckled like poor Ed, I do notice the same thing with my Stax setup

    when left on for prolonged periods. (although never any background noise whatsoever)

    Good to know that I'm not the only "nutcase" around here. ;)

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