spritzer

A small comparison here... SR-X Mk1 and Mk3 PRO hidden in the back and SR-Sigma 303 sidelined while I repaint part of the chassis... I'm sure my set isn't a lemon since the brightness is tied to volume level same as with the SR-Omega. Many other owners have also reported the same. As for being a power hog, I've only done limited test but yeah, they do like plenty of power. I prefer to use the KGSS over the BHSE for some reason though...

OKI (Metcal) PS-900 soldering station plus spare parts for my broken PS-800.

Happy Birthday Amos!!

Nice work Tyll. I do think that some of the reservations about the 007 could be fixed by adjusting the fit since those arc's are just set to "some" setting. You have a ...ehhh... larger head like me so making the arc's wider would be a good move. It's not a make or break type of deal but it does improve the sound quite a bit. Same deal on earpad placement and indeed their condition. The Mk1 earpads are only good for a few years before foam inside becomes too soft to seal properly. We never said this was an easy headphone to measure... I have my own shootout going on but first impressions show that this one is going to be tricky. The SR-Omega/009 are so different in presentation to the 007's that this will have to be a long comparison. Quick changes will always be in favor of the more open sound similar to why the HE90 is so well liked in short burst. Hell, first time I plugged the 007 Mk1 in I thought it was broken and wondered why it sounded strange. Then I remembered what source I was using... It was interesting to plug in the SR-007A and listen to the utterly out of control bass. This is a stock unit save for fit adjustment and the port nonsense is showing it's ugly head. One thing I'm going to give the SR-009 and that it is the most comfortable headphone I've ever used. 6 hours straight aren't an issue and I hardly feel them sitting there.

The amp was utterly fubar when I got it so no measurements possible but the math places it around 13mA. This goes in hand with the schematic I found online. No metal around it except the metal steel brackets used to secure the HV boards in place. Here is a picture of the inside which shows how bloody small this thing is about 30cm long by 17cm wide... Now my bloody soldering station just died...

Now that's what I'd call mafia approved pics!! I've been holding off the comparisons while I finish my backlog of headphones I need to refurbish but it should be soon. Now if some idiot hadn't damaged the paint on this Sigma then I'd have a Sigma/303 to compare against...

AFAIK the SRA-10S is identical to the SRA-12S. The service manual shows no differences aside from what one sees over a long production cycle. This unit is relatively old which is why I'm going totally overboard in rebuilding it. The design is that far off from the old Stax tube amps, in this instance we have just a low voltage SS stages feeding the outputstage which runs off a 640V B+. Simple resistor loading of the output stage so not much anybody can do there and the PSU is a bit too small for my liking. Since I will be ordering a custom transformer for this one I'm contemplating PSU changes. Now the space available is pretty much zero but a simple regulation like the old KGSS PSU should work here and the voltage can be managed simply by regulating each of the two stacked supplies independently. In stock form it is just a 260-0-260VAC transformer feeding a bridge and two stacked 47uf/350V caps. I can easily fit much larger caps so that will be the first step but it is always better to add regulation... As for the SRA-3S, the basic building blocks of the amp maybe similar to the T1 but the circuit is quite different. The T1 is fully DC coupled but the SRA-3S has both input and output capacitors . Now on the amp I have here now I changed all of these (plus all other caps just to be safe) and it sounds just lovely driving this SR-Lambda I just made from Sigma parts.

Happy Birthday Jim!!!

No progress I'm afraid. The SZ2's just need to have the arc's bent for a proper fit but the SZ3's are tricky...

I don't listen at insane levels either but I do think the SR-007 needs to be pushed a bit to truly excel. Not to insane levels mind you but this "MOAR POWAH!!!" crap has some truth to it. When the SR-Omega (and to a lesser degree the SR-009) start to misbehave the SR-007 still just takes it all and asks for more. If any of you are brave enough, listen to the intro of Megadeth - Trust at silly levels and report back. The SR-009 doesn't like it one bit but the SR-007 is just fine with the BHSE maxed out... Still, I only try this for academic reasons.

Glad you like it. Here are some more: The RCA sockets all soldered and hopefully all the correct wires went to the right spots... The PowerKon is a tight squeeze and required some cutting of the support bar next to it but it went better than expected. I still need to install two 392K resistors on the PRE OUT1 sockets as that's how this unit was configured. 100nf/1000V caps added to the B+ line right on the sockets. This is what we do on the most current Stax amps and given the rather basic PSU design at hand here it makes sense. I also used the empty tabs on the sockets to install a voltage divider for the Pro bias. The B+ is around 640-650VDC so a 10% decrease is needed to get 580V and 22K/220K does that perfectly. I also tweaked the normal bias voltage divider so that it now outputs 230V instead of the stock 200V. Both outputs have a 100nf cap between the divider and 5M ballast resistor.

Yeah, doesn't sound like a SR-007 to me. Same is true about statements that the SR-007 is less smooth than the SR-009, not true to these ears unless you are listening at whisper quiet levels. The SR-007's crowning achievement is to remain smooth even at silly levels. Push the SR-009 just a little bit and they bite, hard.

To my ears they always sounded pretty much the same. I've spent a lot of time with the HD800 and I think I'll keep my Stax... I do think it is time I tried my new M3 amp with the HD800 so a trip to the Sennheiser dealer is in order. The SR-007Mk1 also uses that frame but those drivers are from a early Mk1 and the SZ3 Mk2.

The work continues to rebuild this beast from the ground up. The input sockets were way beyond salvage and so was the power cord so time to break out the drillpress: Now the PSU was utterly fubar with scorch marks next to the HV diodes so I'm doing a 100% rebuild. Same deal with the amp boards, they will be completely rebuilt except for the transistors which I hope are ok.

It's what I do...

No closeup that I could find and the drivers are packed away in storage. The stators resemble a chain link fence so the copper is woven together. There is the unofficial Stax site in Japan but they rarely pull anything apart for diagnoses. It takes somebody as insane as me to rip this stuff apart... Nothing wrong with linking to the nearest alternative but Stax has changed the internal design quite a bit. So the lineage is like this: SR-007 Mk1 early version (different driver frame plus some minor material changes, older style carbon fiber box), SR-007 Mk1 late version (the version tested here and the most common of the Mk1's, S/N either 7xxxx or SZ1-xxxx), SR-007A/SR-007Mk2 (S/N SZ2-xxxx, Stax change the earpads, how they sit and introduce a port to the earcups. Sound is a mixed bag depending on fit but can be fixed to sound pretty much like the Mk1) SR-007A/SR-007Mk2 (S/N SZ3-xxxx, often called the Mk2.5, Stax supposedly change the diaphragm which results in a much more forward sound signature) Now you should point out that these are indeed SR-007 Mk1's just for the sake of clarity. While we are on the subject, does anybody want to play "spot the difference" between the earliest and the latest SR-007 drivers?

Kiertijai has been posting all that info since he's bought one. He sent me info which was presumably parts of emails from Craig which stated 6SN7 or 6SL7 drivers with 300B output tubes. I even asked about 211/845's since 300B's make no sense for an output stage but there was just some info about the tubes in the PSU. The amp was also supposed to be ready quite a while ago so it seems he's changed the design to me...

The big question is, how does Tyll like the 'stats. It's a late model Mk1.

Just checked the first page and I really suck at posting stuff I meant to post... Anyway, I'm always fixing up some Stax amps so here is a SRA-3S I just gave some much needed TLC. It was just the usual stuff, replace all diodes, film and electrolytic caps with equal or uprated parts. Nice curve on the PCB and previous service attempts complicate matters but it all went well in the end. It's a bit startling just how much stuff was crammed into this tiny box as it it only a bit bigger then a SRD-7. I also added Pro bias to one of the sockets and it sounds pretty nice driving a SR-007Mk2....

It's here and the place is called Bessastaðir. It's basically our version of the White House and is located in one of the towns adjacent to Reykjavik. I think reason for all that smoke had something to do with the whole Icesave mess we have been dealing with since 2008...

The Micro Seiki were designed with input from Stax but weren't OEM units like the Marantz, Realistic, Magnavox etc. etc. AFAIK there were two versions of the M-S sets, the MX-1 set which was an electrostatic with a 9V battery to generate the bias and the MX-5 which was an electret setup. The diaphragm material in the MX-1 was indeed not mylar but the plastic material shopping bags are made out of which will break down with time. 50 year old mylar is just as tight as the day it was stretched and heat treated if it has never been exposed to direct sunlight.

22% import tax, that's nothing! Our VAT alone is 25.5% and it goes on top of the import tax, special electronics tax and the shipping... As for the cable, the change is minor and not worth messing with such a rare beast.

I'm bumping this since I have a SRA-10S here in for complete restoration. The unit is in rough shape with a note from the Japanese seller that it kept blowing fuses. No wonder when resistor are clearly failing all over the place, diodes look suspect and even the RCA's on the back are utterly fubar. Transformer is 100V only (even ripped it apart to look for hidden windings) so I need to have a custom unit made but the amp was cheap enough so why not have a little project. Now my issue is what exactly differentiates a SRA-10S from a SRA-12S? These look all but identical too me and the schematic I posted earlier in the thread is a perfect match for the SRA-10S. Sure some parts are missing and/or the wrong value but that is par for the course with Stax schematics. They draw the same power from the wall and all the SRA-12S amps seem to have the model number on a sticker on the back, not silk screened directly on the metal. Could be the same amp but different names for different markets?

Silver BHSE FTMFW!!!! I rearranged my system yesterday and moved in the KGSS and swapped out the APL for the RAKK dac Nate built. This setup doesn't have the resolution of the APL/BHSE but it does make the bright nature of the SR-009 less annoying to me. Only one version of the SR-009 we are aware of and given that there are less than 300 units out there a second version is highly unlikely. That would be a SR-007 Mk1 unit. Take extra care to get the fit of the earpads right since they rotate and so does the housing. Given that the artificial head might be a bit thinner then what the headphones are setup for, you might have to bend the two metal arcs to get a good fit. For my rather large head I normally open up the arcs, make them wider and also remove the "break" next to the earcups. As for run in, I've owned a lot of new Stax headphones and compared them to well used examples with no difference that I could discern.

The HP2 is indeed one of the few Grado's I can stand but the price and fragile nature of the drivers scares me. There is a set 5 minutes away from me that I can borrow at anytime so that is good enough for me. It is a real shame that the SR-X Mk3 Pro's are so rare since they largely deliver on the greatness the normal bias model hinted at. Besides the SR-2 then I guess this is the rares of all Stax headphones as they almost never show up on the used market. SR-X Mk1's are also silly rare, I first now have a set after all these years.