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I applaud this thread!!! On point 1 that James made, I am very guilty of helping cause this issue. I have mixed comments on the GRHV across threads for Blue Hawaii BJT, Carbon, and a few others as well. Just to make sure that it is almost impossible for anyone to learn from what I did. 😁 On point 2, I have tested 2 alternatives to the C2M1000170D, and both appear to work fine. One of them is pretty new and usually in stock: https://www.mouser.com/ProductDetail/?qs=vHuUswq2%2Bsy%2BS7yfkaWaCA%3D%3D Item on left is the one that is in stock. Item to the right is the alternative that I successfully used as well, but often not in stock. Middle is the standard part which appears to be quite elusive.

Scott Pilgrim vs. The World: The Soundtrack

Hi! i would like to share my work with you. I made an dynalo amp powered by grlv power supply and a pcm1794a/cm6631a dac. Everything is totaly made by me. I also designed the pcb nd ordered it from JLCPCB. Amp offset voltage stays at max +-1mV and it is totally silent. Case is DOUK AUDIO. pictures: https://drive.google.com/drive/folders/1a6cbGFpN6s5EadR8DA_lb21ZFwOwzK4R?usp=sharing

As a person I've always liked Jude. I know I'm in the house that "disagreeing with Jude" built, but as far as headphone villains go he's pretty low on my list. That said, this interview is a little weak in the way of journalism.

Nirvana - Bleach (obviously with a limited edition blue/black pressing until I get the crazy version) Denon DP-300F with Ortofon 2M-Red -> Headamp Gilmore Lite -> LCD-2

This topic has needed its own thread for quite some time (years), so starting one. I may see if I can get a mode to move some of the posts here (Carbon thread, not sure where else they are littered). 11 hours ago, Pars said: GRHV question: I'm building a pair of the singles intended for 400V output. On the BOM I have, there are 2 680uf caps for each board; 1 is a 550V caP, the other a 450V cap. I presume the 550V would go right after the rectifiers in the schematic, and the 450V on the output. The BOM that was posted by jamesmking uses 4 x 470uf 550V Kemets. Is there much difference between the 680uf and 470uf in terms of sound or anything? BTW, I think I had mentioned this before, but the GRHV really deserves its own thread. Confusing to have to weed through the Carbon thread, and I don't know how many other threads with GRHV posts in them.

I used to go to the one in Campbell all the time and the Sunnyvale one in a pinch. I knew a lot of folks in the Campbell area (used to live at the Upstart Crow coffeehouse there) and I'd run into some of them there sometimes. In fact, it was the last time I saw Lloyd (old member here) was there. I kinda dug the weird decor and the bargains on snacks and stuff that lined the checkout area. I really miss having a local electronics store (even Radio Shack was better than nothing) but there ya go.

There were so many computer superstores I can no longer remember names, but think of when driving by their old locations. Still a couple Computer Centrals, though one near me burnt down a couple years back and the rest are pretty dead. Micro Center shrunk and vacated the area. It still seems strange Silicon Valley can't support a large store for quick pickups, when there was once so many. Guess it's all Amazon and fast delivery now, same as everywhere else. Will be strange not to be able to pick up things on a lunch run. A ton of problems with Fry's over the years. I often wondered how Apple's big comeback affected them as they never really played in that space. And as Apple Stores popped up. Sold some Macs like Best Buy, but Fry's wasn't a general electronic store, though in the end tried to be. This is worth a read - https://mondaynote.com/the-frys-era-8709a7e602eb

OK, I need a groan emoji......

Is Jeff gonna get one of those 3d printers?

A link to a thread on the other site popped up in my Google News feed, where a certain Mr J had a conversation with the "Sennheiser Brothers" and felt much better for it. Other comments deconstruct the statements etc. Ad blockers advised.

This amazing 13 y.o. pianist playing Mendelssohn. Remember her name

Good luck T! Let us know when you get it.

My guide to golden reference high voltage (grhv) variants Here is my attempt at documenting some of the different GRHV board variations. (this will be work in progress for sometime) feel free to private message me with any additions comments, corrections etc. please note the schematic for version 1.5 has been reverse engineered by me from the gerbers and may contain error(s). location of the gerbers: https://drive.google.com/drive/folders/0B_iJFfZStuVhSE5nOHBVdTByR1k golden reference filename naming guide fat - boards which are wider and have less height than the non fat variants L bracket mounting only same as the non fat variants. fat with S as the last character of the filename - boards which are wider and have less height than the non fat variants and the height is about 6.3mm less than the fat variant. these boards also feature more screw hole options for the mounting the pcb to the case including an option of not using an L shaped bracket and mounting the transistors directly to the vertical face of a heatsink/side of the case. a silkscreen cut line is included to guide removal of the L bracket mounting roles to facilitate direct transistor to heatsink mounting. dual - has both positive and negative hv supply with additional bias and both positive and negative low voltage supplies on a single pcb left - has a single negative hv rail and both positive and negative low voltage supplies right - has a single positive hv rail and bias no new in the filename version - 1.5 boards high voltage starts instantly board has high voltage VAC power. Topology is much simpler then version 1.7 and 1.8 and therefore not considered golden reference. new in the filename actual golden reference boards with extensive post pass transistor regulation. new without sw in the filename- version 1.7 high voltage starts instantly board has high voltage VAC power. new with sw in the filename - version 1.8 or later boards same topology as 1.7 but high voltage will not start until dc power supplied to the cpc1117n no dual and no fat in the filename - minimal width and quite high. NOTE placement of the screw terminals for input VAC can vary considerably depending on if the board is a fat, fat S or non fat. Overview of the versions It is the extensive post pass transistor regulation that marks the golden reference out from the other power supply designs as such version 1.5 and earlier not classify as a golden reference since they lack any post pass transistor regulation. No details of versions before 1.5 or version 1.6 could be found in the gerber archives. Apparently pre 1.5 versions had on board heatsinks and ground lanes but there gerbers and not available in the google drive archive. No schematic could be found for version 1.5 although after reverse engineering it was found that the circlotronps.pdf is similar in topology but modified to support 900V output. No bill of materials could be found for version 1.5 and it is not certain what is the power rating for the larger resistors. All versions have the pcb tracks on the underside with no tracks on the top. All versions have no ground plane ALL versions have bleed resistors to help discharge the high voltage caps although version 1.5 and a few variants of 1.7 use a single high power resistor and the rest two 1/2W resistors in series. All versions have the same basic voltage regulator based low voltage positive and negative supplies All versions have the same bias supply although v1.5 has different resistor values. ALL versions use a LT1021-10 voltage reference All the versions 1.5, 1.7 and 1.8 use a C2M1000170D pass transistor All the versions use a 10M90S pre regulator although version 1.5 controls it with a zener string and 1.7 and 1.8 control with a DN2540. 1.7 and 1.8 are almost identical in topology although 1.8 does not automatically start the high voltages. DC must be applied to the CPC1117N to start. note 1.8 does not have provision for screw terminals for the DC to switch on the cpc1117n. versions 1.7 and 1.8 have more post regulation using a second 10m90s (which is not present in version 1.5) after the 1N4007 protection diode. version 1.5 uses a 10ohm current sense resistor and versions 1.7 and 1.8 use 5.1ohm by default. version 1.5 uses a 10K resistor to ground in the 3 series resistor chain to decide the output voltage, 1.7 and 1.8 use 20K to get 400V output. The other 2 resistors in the chain are the same for version 1.5 and version 1.7/1.8 version 1.5 uses two stn0214 which are replaced by two KSC5026M in v1.7/1.8 version 1.5 uses two stn9360 which are replaced by two BC557B in v1.7/1.8 Known non golden reference boards which are variations or predecessors to version 1.5 and golden reference variants NOTE These have not been looked at in detail by me or fully reverse engineered. The cyclotron power supply series follows a similar evolution to the golden reference. earlier cyclotron psus (circlotronps.PDF) use a variation of version 1.5 topology with modifications to bring the output up to 900V. However since it lacks any post pass transistor regulation it can not be considered a golden reference these psus do not have new in their name. The later cyclotron power supplies have the words new or newver in their name on quick inspection of the gerbers appear to be modifications for 900V of the version 1.7 power supplies, have post pass transistor regulation and may be considered golden reference variants. The filename conventions follows the guide above with dual, single, S and SWS versions available. circlotronhvpowerdualnew.zip appears to be derived from the version 1.7 topology with a similar complement of transistors. On the underside of the pcb there are two additional stn0214 transistors compared to the version 1.7 plus 3 mount points for a total of 500V worth of smd zeners. circlotronhvpowerdualnewer2.zip ditches the zener string and introduces another stn3960 and includes sw and sws variations. The kgsshv8g.pdf power supply appears to be an predecessor version of version 1.5. There are very close similarities in topology including no post pass transistor regulation. Current sense is still controlled by a 2n3904. The pre-regulator is 10m90s controlled by a zener string and a quad of transistors like the version 1.5. However the pass transistor is two parallel fqpf8n80c. The control transistors are 2sa1486 instead of stn9360 and 2sc3840 instead of stn0214. Both types of control transistor are no longer in production and hence the conclusion this is older than version 1.5. Apparently these boards are classified as KGSSHV ------------------------------------------------ Version 1.5 boards ------------------------------------------------- predecessor to the golden reference with no post pass transistor regulation the board uses a single high wattage bleed resistor for each cap uses multiple stn9360s, stn0214s uses a serial zener string for to control the 10m90s pre regulator. LT1021-10 voltage reference based single sided board kgsshvpssicfetdual2.zip this has both positive and negative rails, a simple voltage regulator based low voltage positive and negative supply and 580V for stax headphones bias board size approx. width 152.7mm height 165mm silkscreen revision 1.5 kgsshvpssicfetsingle2.zip this has a single rail identical to the kgsshvpssicfetdual2 in topology and 580V for stax headphones bias board size approx. width 76.5mm height 165mm silkscreen revision 1.5 ------------------------------------------------ Version 1.7 boards ------------------------------------------------- considered the first known golden reference board version (given the lack of information on version 1.6) has extensive post pass transistor regulation. the board uses two serial bleed resistors for each cap uses a single stn9360s and multiple BC557B and KSC5026M uses dn2540 and 10m90s for stage early voltage control for the input to the c2m1000170D LT1021-10 voltage reference based double sided board kgsshvpssicfetdual2new.zip this has both positive and negative rails, a simple voltage regulator based low voltage positive and negative supply and 580V for stax headphones bias board size approx. width 152.7mm height 165mm silkscreen revision 1.7 kgsshvpssicfetsingle2new.zip this has a single positive rail identical to the kgsshvpssicfetdual2new in topology and 580V for stax headphones bias board size approx. width 76.5mm height 165mm silkscreen revision 1.7 single bleed resistor for each cap kgsshvpssicfetsinglenewleft.zip this has a single negative rail identical to the kgsshvpssicfetdual2new in topology and has a simple low voltage positive and negative regulators based supply board size approx. width 76.4mm height 165.3mm silkscreen revision 1.7 kgsshvpssicfetsinglenewright.zip this has a single positive rail identical to the kgsshvpssicfetdual2new in topology and bias supply board size approx. width 76.4mm height 165.3mm silkscreen revision 1.7 kgsshvpssicfetsinglenewleftfat.zip this has a single negative rail identical to the kgsshvpssicfetdual2new in topology and has a simple low voltage positive and negative regulators based supply board size approx. width 138.7mm height 103.1mm silkscreen revision 1.71 kgsshvpssicfetsinglenewrightfat.zip this has a single positive rail identical to the kgsshvpssicfetdual2new in topology and has a 580v stax bias supply board size approx. width 138.6mm height 103.1mm silkscreen revision 1.71 kgsshvpssicfetsinglenewleftfatS.zip this has a single negative rail identical to the kgsshvpssicfetdual2new in topology and has a simple low voltage positive and negative regulators based supply has more mounting options for the pass transistor, 4 holes for mounting to a case and can be used with or without an L shaped bracket board size approx. width 138.7mm height 98.6mm (slightly less height than the fat non S version silkscreen revision 1.71s kgsshvpssicfetsinglenewrightfatS.zip this has a single positive rail identical to the kgsshvpssicfetdual2new in topology and has a bias supply has more mounting options for the pass transistor, 4 holes for mounting to a case and can be used with or without an L shaped bracket board size approx. width 138.7mm height 98.6mm (slightly less height than the fat non S version silkscreen revision 1.71s ------------------------------------------------ Version 1.8 boards ------------------------------------------------- same topology as version 1.7 making this a golden reference board adds a cpc1117n and 600ohm resistor to control high voltage startup the high voltage will not start-up automatically. This negates the need for a external relay for delayed start-up and just requires dc power to be supplied to the cpc1117n (not present in earlier versions) for the high voltage to start-up. if you want the board to power up instantly simply omit the 600ohm resistor and cpc1117n and it will act just like the version 1.7 instant start boards. boards same size as the equivalent version 1.7 pcbs silkscreen 1.8 there does not seem to be a dual version of this board kgsshvpssicfetsinglenewleftSWS.zip this has a single negative rail almost identical to the kgsshvpssicfetdual2new in topology and has a simple low voltage positive and negative regulators based supply board size approx. width 76.4mm height 165.3mm silkscreen revision 1.8 kgsshvpssicfetsinglenewrightSWS.zip this has a single positive rail almost identical to the kgsshvpssicfetdual2new in topology and has a bias supply board size approx. width 76.4mm height 165.3mm silkscreen revision 1.8 kgsshvpssicfetsinglenewleftfatSW.zip this has a single negative rail almost identical to the kgsshvpssicfetdual2new in topology and has a simple low voltage positive and negative regulators based supply board size approx. width 138.7mm height 103.7mm silkscreen revision 1.8 kgsshvpssicfetsinglenewrightfatSW.zip this has a single positive rail almost identical to the kgsshvpssicfetdual2new in topology and bias based supply board size approx. width 138.7mm height 103.7mm silkscreen revision 1.8 kgsshvpssicfetsinglenewleftfatSWS.zip this has a single negative rail almost identical to the kgsshvpssicfetdual2new in topology and has a simple low voltage positive and negative regulators based supply has more mounting options for the pass transistor, 4 holes for mounting to a case and can be used with or without an L shaped bracket board size approx. width 138.7mm height 98.6mm (slightly less height than the fat non S version silkscreen revision 1.8 kgsshvpssicfetsinglenewrightfatSWS.zip this has a single positive rail almost identical to the kgsshvpssicfetdual2new in topology and has a bias supply has more mounting options for the pass transistor, 4 holes for mounting to a case and can be used with or without an L shaped bracket board size approx. width 138.7mm height 98.6mm (slightly less height than the fat non S version silkscreen revision 1.8

Most, if not all, public published GRHV boards are with c2m1000170d but if a bit creative you might use fqpf8n80c. If you do - please tell us how it turned out. We have to find ways to tackle unavailable parts.

1. part of the headcase experience is trawling a massive number of posts in one thread e.g. the carbon to find out about the grhv. Having a dedicated thread is seen as cheating. 🙂 2. to build a grhv you need C2M1000170D which are out of stock just about everywhere with little hope of being back in stock anytime soon... this is one of the issues delaying my megatron build. I can't comment on any sound quality differences, but there very few options if you want a 680uF cap that is 550V and will fit in a 2u case, i.e. be about 65mm in height or less. 450V or better 500V would be fine for the output cap with 400V output. The + lead of the input cap is connected to the centre pin of the large C2M1000170D. Output cap + lead is connected to the cathode of the IN4007 protection diode that is directly inline with the 5.1ohm 3W current sense resistor.

Sure they can be driven by most amps pretty easily. Typically I'd recommend something like an OTL tube amp for them.

It's probably not going anywhere. Various iterations were either unstable or too noisy. Circuit boards for the Raal experiment (code named "Bridgeport") have been ordered. I should know more about that in a few weeks. Also, there is some thought to doing a very small run of a 10 year anniversary version of the L2. The basic circuit would remain the same, but there are a few changes that should serve as an upgrade to the original.

RIP Fry's Electronics. https://www.theverge.com/circuitbreaker/2021/2/24/22298616/frys-electronics-going-out-of-business I haz a sad.