spritzer
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Posts posted by spritzer
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The bias in the E90 is run off the HV+ line so 600V. That is fine for Stax but the issue is that the ballast resistor is not the right value and there is a cap after it. Now you could just place a 4M7 resistor on the adapter but I prefer to go into the amp and modify it with a voltage divider and moving the cap. The issue there is opening up the damn thing...
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Speed holes...
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Those parts from Nikko were probably here as I returned them a decade ago as fakes. They did find real ones to replace them back then but yeah... took back the fake ones and are probably selling those.
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Also cheaper not to buy the fuse insert. Clearly saving the big bucks here...
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...wait, there is more!!
I woke up early so what better than strip this shit down. First off was to remove the transformer and I found this:
Notice the wire coming off the IEC and into the end of the fuse holder...and another wire connected to that pad? Yeah...
I don't see any evidence that there had ever been any solder on that end of the fuse holder and the insert which holds the fuse is indeed missing. That would explain why, when the PSU blew it left this mark on the chassis
At least the IEC input is nice...
Gotta have that gold plating. I also don't understand how anybody could put "copyright" on this PCB with a straight face:
It's two traces between two terminal blocks... ok.
Now the real price, lifting the amplifier boards:
Notice the nice line of standoffs...yeah not connected to anything:
The heatsinks just sat on them, not connected in any way. So this thing has been shipped and the only thing securing the sinks are the transistor legs!! Spoiler alert but what could possibly happen...
So 3 screws hold the amplifier boards to the chassis but no lock washers anywhere and everything was loose. What a great way to support some of the heaviest objects in the amp.
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As many of you know, I for one have stopped releasing all new designs for a few years now after I got fed up with people building crap and claiming it was somehow connected to Kevin or I. Now this also means I don't release the PCB's for many of the older projects as I want to change something and often... make them smaller. So this hasn't stopped people selling crap with our circuits but at least they don't get any of the updates.
Now here is an amp I saw come up for sale in Japan a while ago. The new owner contacted Kevin to try and trouble shoot it but yeah, we don't offer any real help with these things. Something about the PSU did peak my interest so when it popped up again for sale for not a whole lot of money, I snapped it up. So here it is:
Standard KGSSHV here with some version of the offboard PCB's but the build... it is just so bad. All the wires are the same color which is just nuts. Also just cheap PVC China wire and I'll check if it is actually real copper in there. Here are some of my favorites:
Support the sinks properly... that is for suckers. Also I don't know why the volume extender is wrapped in Kapton tape...
The amp shipped like this, the sinks are just attached by the components. It takes no for to bend them like that.
I think this is some form of the GRLV but shit is is cheaply made.
Transformer wires thinner than 24AWG... yeah pure quality there.
Terminal blocks clearly cost too much but stuff like this at +580V can arc over.
Last but not least, no repairs are possible....
What I find truly fascinating about this thing is the PSU board as... well... they cloned my smaller KGSSHV design. That one was never released into the wild but I have posted plenty of high res pics of both sides and they seem to have made a new board from those. See this:
Now all the written markings or most of them, look real. What is not real are all the part numbers as Rxx or Cxx is not a system we use. The packages are all also a bit wrong so the board is clearly a clone. I'll dig it out and post some pics next to the real thing.
More coming as I strip it down.
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I do always remove the damping inside the earpads so that's well worth it. The older ESP950's (remember they have been in production for 30 years) also had damping on the back of the drivers which has to be removed.
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That really applies more to the older ESP950's as Koss have removed most of the damping by now.
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Why are you changing those caps? Any of the claims out there that this cap sound like this and this one is good for this spot... it is all bullshit. This is a niche circuit so special care has to be taken when picking caps for that.
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I agree, with the Massdrop Koss at 450$ it makes little sense.
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Bloody death rays!!!
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SR-30 and SR-30 Pro
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Stax have clearly been moving towards lessening the impact of the port for years now and they might just have plugged it. Still there is an opening on both sides which might need to be closed. Looks like I'll need to get a new set to test once all this pandemic stuff blows over.
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I've had my set for over a month now and I would take them over the SR-009's but then again... never liked the 009's. I've been meaning to write up some impressions for the last couple of weeks so now might just be the time.
First of the build quality is outstanding which means they are pretty heavy but yeah... very well made. The only issue I've run into is that there is a tiny bit of play where the forks attach to the cups but after a month of daily use they seem to be no worse for wear so probably not a long term issue either. I would also like some strain relief on the cables as they leave the cups (the 007Mk1 issues spring to mind) and on the plug but these are not easy to do on small scale build. They ideally have to be injection molded and well... that isn't cheap. Still this is me and I'm picky... 😉 The packaging is also superb and small touches like the markings on the cable splitter are appreciated. The fit is very much SR-Omega so a bit loose on the head and they have almost slid off a couple of times, usually when I'm lost in assembling some PCB boards or something like that and forgot they are there. Not really and issue under normal use.
Now for the sound, same system as usual, Denafrips Terminator dac feeding a Carbon CC. I've yet to try the other set of earpads so they have the stock set attached... I think. Anyway... the set they shipped with. TL:DR, I like them a lot though I wouldn't call them an SR-Omega clone...they very much their own thing. Balanced sound signature over all but not quite as warm and relaxed as the Omega. There is a small bite to the mid-range that bothers me a bit on some recordings but far away from the SR-009 level of aggression. So not as smooth as I'd like it but that smoothness was also the Omega's downfall in some areas. Bass is not up to the SR-007 levels of depth, control and quality but perfectly fine and superior to any of the 009's. It's linear and extended but not the best there is. Still this is a more relaxed sounding set compared to the 007's so that is to be expected. Sound stage is controlled, yet expansive but can't quite pull off the layering trick the 007's can do so well but again... not really a complaint.
Overall I don't think it is fair to compare them to the SR-Omega due to their status and the sad fact that so many Omegas out there sound far from stock. Bad earpads, badly treated drivers etc. all change how the old ones sound like while this one is nice and fresh... also not silly money. So very much recommended and it's always welcome when I have no complaints when testing something new. Small bite to the midrange that bothers me from time to time, not quite as engrossing as the SR-007's but yeah... just a different type of sound and nothing wrong with that.
Finally, this set has been running for well over a month now and the amp used is being subject to a lot of power cycles (i.e. I'm using the time at home to do some stress tests) and they have had no complaints. No imbalance issues, charge up instantly and dead silent drivers.
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I've posted the schematic for the amp so on there you can see that one side of the input fet has the gate tied to ground via a resistor. Remove that one and copy the other side of the fet (two resistors and a cap) and it is now ready to take a balanced input.
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Yes but I've never seen them do that. They usually take it down to 500V or so.
That 300V value does smell a lot of somebody measuring the bias at the output socket...
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The specs from Koss are clear plus the bias is directly off the B+ so 600V. There is a spot there for a voltage divider with infinite value resistor (i.e. open) from the factory which they can then engage if the squeal becomes an issue.
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The Quick is great and Weller is trash now. See the EEVBlog review of one which had no fuse for some reason...
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Here are some pics of the amplifier modules:
...and the back:
The model1 by comparison:
Same shit slightly beefed up.
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I want to try one but the amps in these are pure garbage. I found some nice
Also funny...this was supposed to be "cheap" tech.
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I haven't seen it yet but it is on the list. The rest is indeed apartments and the bakery is just on the ground floor.
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8 hours ago, Seed Lady said:
Hi. We just started The Valhalla Murders, a detective show on Netflix. Thinking its somewhat like The Killing but from Iceland.... in S1 E1 there is an aerial tracking shot midway, the police woman drives back to the station, and I say....hey....isn't that @spritzer 's bakery we just saw?
In a really distinctive all white 6-tower complex, waterfront?
Below is a stock photo....
Yup, it is there in the on right side of the white buildings in the center.
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I just put a new cable on my second set (beause reasons) and I do like them a lot. I also ripped apart one set to examine the drivers and a lot of effort went into these. Bunch of custom molded parts though the stators themselves are PCB.
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Yeah, word on the street is that people are not happy with this pile of fail. Color me surprised...
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Koss ESP/950 electrostat thread
in Headphones
Posted
Yes.