If it's not clear from the photo then this is a massive slab, 16" x 12", so quite a bit bigger then the production version. It will be built like the BHSE with the board mounted to the top of the chassis, with the tubes sticking out of the top and the components on the bottom. Massive heatsinks are needed to keep this beast cool and a single angle bracket is used on each side of the board to connect all the parts together and make assembly just a bit easier.

To honor the Stax legacy the following will be printed on the board: "With the utmost respect and admiration for Dr. Takeshi Hayashi, a living legend". For those who don't know, Dr. Hayashi is the designer of the T2 and also the son of the Stax founder. Without his great vision and talents we wouldn't have the quality of phones/amps we have today.

We will keep you updated as the project moves forward.

For example: A new enovation I find very interesting, is a new blade stop safety system from The Felder Group. Like the system from SawStop, it's immediate, and it drops the blade out of the way before any damage to digits can be done. Unlike the SawStop system, it doesn't use a sacrificial cartridge to stop the blade. Don't get me wrong, the SawStop system was nothing short of a miracle in my mind. You sacrifice a $75ish cartridge and whatever the cost of the blade you're using. And a separate cartridge for stacked dato blades. But again, a couple of hundred dollars vs. a digit or more? It's a no brainer. 

But along comes The Felder Group (Felder, Hammer & Format 4) with new technology for sliding tablesaws. The PCS system simply drops the blade out of contact with your flesh. No damaged cartridges to replace, no damaged blade to replace, no over-inflated ego to repair (I'm an expert on that last one).

Thoughts?

So i started looking for slightly less silly alternatives.  I think the 211 tube fits the bill. running with +/-750v power supplies at 35ma. So a megatron with 211 output tubes, 300b drivers and a high gain input tube.

unless someone has a better idea.

hope that this one won't go obsolete before the boards are out. I don't think so

because Fairchild has said that the bc parts should be available for at least 5 years

but onsemi said the same thing.

This one is a diamond transistor input set, used as a voltage to current converter.

A pair of Wilson current mirrors with input and output cascade as the VAS

and a triple darlington output stage.

http://gilmore.chem.northwestern.edu/cfa2.pdf

if someone knows of better surface mount parts to replace the bc series, I might

as well do that from the start.  ft >150mhz, hfe >100 Vceo >50 etc

Here is a look at the new PCB design which is pretty much ready:

It is 138*86mm. 

Another thing from the same vein is a fully discrete unbalanced to balanced circuit that we have been working on so no DRV134 garbage.  I'll start with this one though and order some proto boards this week. 

For those with problematic DAC's that put out a bit of DC, and balanced headphone

amplifiers happy to amplify said DC and produce differential DC on the output...

http://gilmore.chem.northwestern.edu/protector.jpg

This is the one case where ti kan's protection board does not work, unless

you want to use 2 of them.

  Well over a decad

I bought a ratty old HD650 and completely stripped it apart.  Headpad, earpads and cable went into the trash while the rest went for a long bath.  First step is to make the baffle flat so a lot of cutting with nice, sharp, flush cutters.  I naturally forgot to take a picture of that step...  Next step was to fully measure what area I had to work with and design PCB's to match that, while maximizing the open area.  The end result is three different PCB's, as they are all setup to be dual sided.  One for the stators, one which holds the diaphragm and finally the simple outline which holds the dust covers and can act as a spacer.  Some pics of them assembled in the housing:

Four nylon screws hold the sandwich together, fixed with PEEK nuts to get extra gripping power as the assembly had to be as flat as is possible.  Dust covers placed away from the stators so they don't cause any issues.  Earpad side:

Due to the screws, some earpad mountings have to be cut up to get the pads to fit but yeah, they are just cheap crap from China so who cares.  I could cut a slot in them to try and make it fit but maintaining as much pressure on the drivers as I can is far more important. 

Final assembly with a King Sound cable as I have a couple of those sitting around.  For the diaphragm I used my usual stock of 1.4um film and the earpads are just the cheapest leather pads I found on ebay.  I have a couple of nicer ones but these are the thickest and that helps make them more balanced sounding.  The diaphragms were stretched by hand on a mirror (which is my preferred way) and glued with wood glue (thanks for the tip Aumkar!) which is just perfect for this.  Coating is anti-static spray which means they energize in five seconds or so which I can live with. 

Now for the sound... pretty damn good for something so simple and literally being the second set I assemble.  Well that and zero effort has been put into sealing the baffle or just any sealing at all.  I just stuck the PCB's onto the baffle and built up the stack.    Overall sound signature is similar to the HE60 but not as diffused and with far more bass output.  Maybe a tad too much at times as there are some oscillations that I can pickup at very high volume levels and under high excursion.  I tend to go with slightly less tension on the diaphragm so that might be it.  Treble is very pronounced with the thinner pads but with the ones pictured, it is just perfect.  These are not forward at all and the soundstage is excellent for this size of a driver and non-angled earpads.  Sensitivity is slightly lower than the regular Stax sets but still only marginally so.  All in I'm very happy with the roughly 150$ outlay for these. 

Now this is version 2.0 but the first version used a HD58X from Drop, brand new in the box that I cut up.  Same driver profile but thicker stators so the efficiency was really bad plus the stators had full solder mask on them.  Now I'm out of the spacer PCB's for the dust covers so next time I order PCB's, I'll make another set.  I also have some diaphragm spacers which would work well for normal bias as I've always wanted to mess more with that. 

class B output stage. and they seem to be proud of this crap.

discuss

dx5ii.PDF

use either the tube unbal/bal to bal board, or the solid state version

result is about 125 watts rms into 8 ohms at thd of .005% 

will definitely drive 4 ohms with suitably large power supplies.

transistors are standard pinout, so pick your favorite output transistors.

the to220 transistors are mje15034/mje15035

perfect for so many things, including esl boost transformers.

pioneera09.pdf

similar to srmxh,srm252,srm270  etc.   3 times the power, +/-400v power supplys, no obsolete components etc.  designed to be mounted to the bottom as a heatsink with silicone thermal sheet in between.  should be about $250 in parts unless you go nuts with the volume pot. not sure of casing yet.

I recently got a ripping great deal on an SRA-3S in unknown condition. And since all of these are at least 50 years old, there is much to go through. 

There are some existing resources to link, and I will come back and add more as i scrape 'em together: 

It's a shame there are no component designations on the boards or schematic, so we'll go ahead and muddle through without them. Maybe I'll annotate some images. 

The area in the red box is the phono preamp. It's not much of a preamp. I hear you can pull the board and leave it out. An enterprising nerd could build a better phono preamp to plug into the same slot. 

The modern replacement for all transistors in this box is the KSC1845. These are available from Mouser and other 1st tier vendors so there is no reason to look for them from secondary sources. The pinout is reversed. If one of the four on the driver board is bad you should probably replace all of them. I suppose i should put together a complete BOM at some point. 

You will need to remove the bottom of the case and desolder the RCA connectors on the back in order to angle the main board out to work on it. 

Starting with the power supply in the area in the blue box. The vintage diodes should be replaced with 1n4007, uf4007, or similar. I used BYV95C fast soft recovery rectifiers because i have some. Probably doesn't make a difference what you use here as long as it's a high voltage rectifier. 

My unit actually had 22uf 350v caps in the power supply. I installed 39uf 350v. They are comically small compared to the original caps and it may be wise to anchor them with some hot glue. I used Nichcon UCY2V390MHD, qty2. I am not sure if it is wise or useful to go big here. 

Axial caps are getting harder to find and there are few choices. It might be totally reasonable to get radial caps and attach wire to the positive lead, maybe wrap it in heatshrink or plastic tubing of some kind. 

For the 30uf 150v caps, my unit actually had 22uf. Which i foolishly ordered 22uf replacements for. They were expensive and about the same physical size. I'm thinking about ordering some 33uf long-life radials and adapting them however it will work. 

A retrofitted power supply for a JDM Esoteric SACD player

Amp design by me, power supply designs and circuit board layout by kerry, support by birgir

+/-300 volt power supplies.  complementary push pull all bipolar design with cmos style multiplying current mirror.

I would like to mod my SRM007Tii so that it can use 6S4A tubes. However I am almost new in messing around with electronics circuit. Need some guidance from you all.

Pictures below show my 007Tii board with re-routing & termination labels (Incomplete). I took quite sometimes to compare snapshots available online posted by Spritzer & Justin. All of them have slightly different wirings. The one I understand the most is the one Spritzer posted for the first time, so my preliminary outcome is similar to his one although it is still incomplete. Therefore I would like to clear my doubts before I start messing around with the PCB.

This is my guidance to get the idea where should I re-wiring to. I also have a fluke 175 to check the continuity between 2 points.

The Back part of the PCB

Q1: For the Yellow wiring, can I skip the plate 2 and connect directly on plate 1?

Q2 : According to the Basing Diagram Pin 3 & Pin 6 are linked. Can I wiring Pin 6 to Pin 3 or vice versa? (Example drawn on Left Bottom tube)

The Top part of the PCB

I cant find much info about the Mod on the top of the PCB. Logically some traces should be cut for termination. Please kindly advise if I labeled them correctly.

Hopefully my understanding (routing wise) is good enough so I can proceed further. I am really new in this therefore alot of questions popped on me. The safest way for me to have this successfully modded is to fully get to know how to convert 6CG7 routing to adapt 6S4A tubes plus some really careful soldering jobs. In terms of technical I have no idea at all..

As proposed, I started this thread for all to share your KGSSHV Carbon build experience and to exchange Q&A. This is a natural follow up thread to the Carbon Group Buy thread.

Here are the version of Gerber files used for the boards in the group buy:

kgsshvcarbonv5.zip (amp board)

kgsshvpssicfetdual2new.zip (GoldenReference HV power supply, all-in-one version)

kgsshvpssicfetsinglenewrightfat.zip (GoldenReference HV power supply, B+ and bias) 

kgsshvpssicfetsinglenewleftfat.zip ( GoldenReference HV power supply, B- and 7815/7915 based +/-15V regulator)

goldenreference4.zip (GoldenReference LV bipolar power supply)

goldenreference4plus.zip (GoldenReference LV V+ power supply   

goldenreference4minus.zip (GoldenReference LV V- power supply)

bias.zip (stand alone regulated Pro and Normal bias supply) 

I (or others) will follow up with BOM. 

EDIT 10/8: Updated the BOM and Mouser project for the Carbon V5 to use Vishay RN60D 174K resistors for the two 175K positions. The correct part to use is Mouser part # 71-RN60D1743F. It's a mil-spec resistor that is actually 1/2W even though it's listed as 1/4W. The previously listed Xicon is 1/4W rated and not sufficient for these positions. 

EDIT 10/13: Updated the BOM and Mouser project for Carbon V5 to use 3M 961102-6404-AR for the servo jumpers. 

Note that the BOM does not match the shared Mouser project due to parts availability at Mouser. I apologize for the errors in project/BOM.

EDIT 9/10: link to shared Mouser project for the GR HV Dual. Need to add 2 LT1021-10 and missing parts not available at Mouser. Please help check for errors.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=54687aa8fa

EDIT 9/12: link to shared Mouser project for the GR LV Dual. Need to add 2 LT1021-10 and your choice of insulation kits to mount uninsulated sands. Please help check for errors

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b6d687c7f7

EDIT 9/20: link to shared Mouser project for the Carbon V5  (1 channel only). Please help check for errors.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=7F837B24AA

EDIT 10/19: GR HV Dual BOM in spreadsheet. More complete than the shared Mouser project above.   GR HV BOM_Oct19.xls     

EDIT10/11: GR LV Dual BOM in spreadsheet. More complete than the shared Mouser project above.     GR LV BOM_Oct 11.xls 

EDIT 12/11: Carbon V5 BOM (1 channel) in spreadsheet, uses KOA Speer resistors.   HV Carbon V5 BOM_Dec11.xls

Example (and the reason I started this thread):

I'm looking for an IEC module that contains a voltage selector switch. So far I've found 4 that I like, which I've listed below.

#1: Digi-Key - 603-1149-ND (Manufacturer - 10SB3S)

Pros: simple all in one, filter could be a plus

Cons: voltage selection is not user friendly, don't need the built in power switch

#2: Digi-Key - 603-1144-ND (Manufacturer - 06AK5)

Pros: much better voltage selector

Cons: i hate snap in modules

#3: Digi-Key - CCM1375-ND (Manufacturer - PE0SSS000)

Pros: good mount, good voltage selector

Cons: don't need the switch

#4: Digi-Key - 486-1090-ND (Manufacturer - 4301.0001)

Potentially perfect, just not entirely sure how the voltage selector works. I read the data sheet and probably need to do so again.

Anyone have any bright ideas other than me sitting down with the Digikey catalog for a few hours?

I’ve used them in dc blocking and seem to have a neutral sound 

has anyone tried these in Amps and pre amps 

I’m curious to know what others think 

I’m not a fan of anything oil as I feel they color the sound. 
In addition in stat amp builds 400 vdc seems on the edge of max range 

why don’t builders use 1000 vdc rated caps ?

ABD0000C255.pdf

The most useful thing to start with would be plug specs. Pin diameter, length, pin circle diameter, and housing outer diameter, in case you want to make a recessed socket. Here's a drawing of a plug I got from Dan Clark (I can't guarantee that it's the same as his current production plugs) and a plug from the Hifiman Jade II. If it would be useful I could make a complete model of both plugs and share the STEP files. Next week I'll be able to add the dimensions for the Audeze CRBN2. Eventually I should be able to measure some Stax plugs.

Found partial catalogs for Cooper and Amphenol 78-S6S socket and 86-71-6S/91MPM-6S plugs, but neither specified pin diameter.

Standard pin diameter seems to be .093" or .094" (2.36-2.38mm), the same size as a 3-pin XLR contact or an octal tube socket pin, or a Size 12 circular connector contact. There is a standard housing layout for #12 contacts that matches the position of a 6-pin Stax plug, arrangement 16-6 or 17-6, but I haven't been able to find any documentation of the pin circle diameter. Neutrik also makes a crimp socket contact, HA-3FXX. 

The threaded socket most commonly used for electrostatic jacks and tube sockets (like this, or these) is good and conceptually simpler to design a housing for, but I would love to find a design guide or get some advice on the right way to make a hole for circular connector contacts or that Neutrik contact. They're probably not easy cavities to machine from a single piece of material, but 3D printing is useful, and I saw some mil-spec circular connectors that appeared to use stacked layers. 

Standard pin circle diameter is . . . something between the .406" (10.31mm) in the Cooper catalog and the .435" (11.05mm) of Kevin Gilmore's socket drawing. The Hifiman plug was closer to the Cooper at ~10.5mm. The Dan Clark plug seemed to match up perfectly with the KG drawing. My estimate of this Viborg socket from their drawing puts it closer to 11mm.

If anyone has any dimensions to share I'd be happy to add them to a single reference PDF. Any other useful application information about connectors would be good to include as well, if anyone has had experiences with pins being too long or too short, or pin-to-pin clearance standards, or other things. Cable-related information would also be valuable. 

EstatPlugDimensions.pdf

mc 7915ctg

mc 7815ctg 

mc 7915ctg

mc 7815ctg 

Bottom right is where the reg were 

Below the vishey 4700uf caps