SoupRKnowva
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Posts posted by SoupRKnowva
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Ok International webstore is selling reconditioned PS-800E soldering station with PS-CA2 coil compatible with SxV series tips for 79 USD: https://www.okinternational.com/us-web-store/english/globalnavigation/us-webstore-product-detail?productId=97366838-478c-439c-aa28-9cfaa96c172e
Anybody in US willing to help me buying this (+ an extra coil and some tips) and shipping to me by USPS?
So this is gonna be a really dumb question, but that seems like a really good deal, and I want to buy my first soldering iron. They don't have the PS-CA2 coils on the site anymore, would the PS-CA3 coil work as a replacement? and then, which tips would you recommend buying for DIY amp building? theres so many to choose from on the site.
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It's not that you can't get it to zero out, it's just how different the voltages are at power on.
Solution: leave it on all the time
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So I replaced my output bias resistors today. Im using the IXYS parts at 500 volts, so I was kind of worried, since you guys were saying they drift alot more than the sanyo parts do, and not to raise it too much. But i replaced the 180 resistors with 100 ohm ones. to raise the current to 10mAs, and I rebiased after about 2-3 hours of leaving it on and got all my biases down under .2 volts so I was pretty pleased
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Wanted to thank all of you for the advice, but it turned out to not have anything to do with the grounding at all, which I think is why it took so long to discover what happened. I was undoing the left channel from the pot, first from the input side, and nothing changed. Then from the output side, and it went away, but if I moved the wire sometimes the hum would come back sometimes not, so I looked at what was changing as I moved the wire. It turned out that during shipping I guess, from GeorgeP to me, the positive wire connection came out of the terminal block from the pot. So I unscrewed it, put the wire back in, screwed it back down. And now no buzz, and also, the channel imbalance I had, is also gone...
anyways, now I'm getting beautiful music from my KGSSHV and Sr-307s
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Well... at last I wasn't the only guy with the problem.... Mine only shorted once tho, and it was more like BOOM than popping, but it didn't look that bad.
I followed Birgir's advice to star ground everything on the PSU board. (IEC ground to PSU; AMP to PSU; Case to PSU, Input and pot to PSU) It doesn't have any noise whatsoever. The problem tho is finding enough place to ground on the PSU.
I was thinking the same thing, how would I fit all those ground wires into that one little ground spot on the terminal block on the Power Supply...I was thinking I would star ground everything to the bolt attached to the bottom of the chassis
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SoupRKnowva, did you ground pin 1 to chassis at entry point?
Uh...to quote GeorgeP, who I bought the amp from "The input grounds are grounded in accordance with the Rane standard which is the proper way to ground xlr - ie through the shield", pin 1 from the XLRs goes the the ground pad on the pcb for the pot, which is grounded to the chassis through contact.
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This happens during shipping so it's not a Stax QC issue. Just an annoying quirk of electrostatics.
Is like the normal periodic channel imbalance issues that crop up? Do you think it will go away after playing music for 2 weeks? Or is it something that we need to send them back to get fixed?
I feel like it was packaged pretty well though
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Now, if it makes you feel better, my 307s also had a significant channel imbalance. What's up with Stax quality control?
heh, now I have to deal with shipping them back to Price Japan and then waiting for warranty repair and then to ship them back. I guess even though they arrived essentially dead on arrival, they don't do exchanges of any kind...I'm starting to think the buzzing in the left channel might be related to the imbalance as well, since the amp was silent before it got shipped to me.
Palchiu, thanks for the advice, but something I left out is that the pot is grounded to the chassis already, and adding those two wires seems like it would make a literal ground "loop" of wire, which doesn't seem like a good idea?
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So I'm trying to track down some buzz/hum I'm getting in just the left channel of my recently acquired HV. The level of the buzz doesn't change with volume level at all. Here is a diagram of the grounds in the amp
The wire connecting the power supply to the star ground goes around behind the transformer, and when I move that wire around the buzzing changes, but it is weird that its only buzzing in the left channel during all of this.
Also of note is that this is my first/only stat amp, and I only have one brand new pair of Stax, 307s, that got to me from Price Japan with a channel imbalance issue. So I can't test other amps/cans.
Any advice is appreciated guys
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Payment sent, thanks again!
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I am in for one.
14 to go?I was gonna ask if there was a rough estimate on how much all that would cost. Would it also involve a new run of boards for the T2 as well?
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Back when I was first thinking about building a KGSSHV, I remember reading you guys warning about taking the output bias too high, that the transformer/powersupply would run out of steam. Using the stock, non mini power supply, and a 135VA transformer at 500v rails, how high would you guys guess it would be safe to turn up the output stage biasing current without hurting anything? Would something like 15mAs be possible, or would i want to stay below 10mAs? I know that John only took it up a few to 8mAs?
Second question, would it be possible to make it so I could socket resistors to test different biases without having to solder all the resistors in each time?
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I don't remember about the current limit at the moment, will have to look
that up later.
Did we figure out if the new mini PSU was gonna work?
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Is the new dynalo board gonna make it into this group buy?
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Id be interested in a set of the new smaller KGSSHV boards, now that I'm getting back in headphones after a brief exit to speakers. I would also be interested in a set of boards for that new SuSy Dynalo, and I would buy a set of Megatron boards if they were offered just in case
at some point in the future I felt like putting it togetherI ever got the balls to build one. -
In case anyone was wanting to build one of these bad boys, i have since moved and now have room for speakers so i dont have any reason to build it anymore. I have the majority of the parts needed, no case or transformer, and i didnt get some of the power supply caps yet. But i did get all of the hard to find sand ahead of time. Just trying to get some of my money back on the purchases
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Thanks livewire
I was using the Lil Knight BOM and the 4.7M listed is the 293-4.7M-RC (xicon) which is rated only 350v...
The KOA Speer, although listed as 700v voltage rating at mouser, if you look at the data sheet, the absolute maximum working voltage is only 350v too.
The best I could get was the CMF-60 from Vishay/Dale, absolute maximum working voltage of 500v. Do you have any model that is rated at 600v spritzer? Looked at mouser and couldn't find any that kept the 50ppm/C and 1/2watt power rating
Thanks
why not use something like this http://www.mouser.com/ProductDetail/Vishay/VR37000004704JR500/?qs=%2fha2pyFaduiU7nw9S7xDMMvHHBNPX2%252b3%2fjJQVocKE2r89FMTyeG1R5W5Hn7RFMSD thats what i ordered. Though i guess it doesnt have the tolerance of the units you're looking at, but its not like you're matching it to anything, so thats not really of the utmost importance
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The wheels had already been turning in my head on this one after you said that about the power supply Spritzer, and i think you could pretty easily fit two power supplies and transformers into the 2U pessante case to stack nicely underneath the 3U Pessante Dissipante case the amp would be in. But an offboard version would be pretty cool as well...
This was also super convenient because now I'll have room for the AMB Delta 1 attenuator(since i missed out on the KG one) inside the amp case, i was wanting to use a couple of them, but couldn't find the room.
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WRT upping the HV bias keep in mind just how far the transistors can be pushed. 20mA at 500V is a lot of power and the PSU needs to be oversized as well. My plan is to lower the rails to 400-450V and increase the current that much more.
Wouldn't team overkill just use two power supplies rather than compromise like that?
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2.1v - vbe junction (.7) /180 ohms == 7ma.
But the led's actually are more like 1.7 volts due to
the drive current.
So its about 5.5ma.
You can change to a higher voltage led, but the red led's thermally
match the output transistors.
So you want to cut the 180 ohm resistors to something like 150 or 120 ohms.
So could you replace the emitter resistor with a like 200 ohm trimmer resistor so you don't have to solder and re solder to test different biases?
14 to go?
Megatron Electrostatic Headphone Amplifier
in Do It Yourself
Posted
What makes using 12 or 25 volts better than the current 6? And would it be possible to use the current boards at those filament supply voltages?