The Stax Thread III

[Kabeer]

... and users have reported that the X9000 is even more detailed than the ES-2a.

where? I saw the recent description where someone claimed they were even for detail.
I haven't A/B'd but id be surprised tbh. Other than the X9000 potentially sounding a bit lighter/maybe more treble which may come across as more detailed purely from more energy there rather than actually more detail.

 

[LarsHP]

where? I saw the recent description where someone claimed they were even for detail.
I haven't A/B'd but id be surprised tbh. Other than the X9000 potentially sounding a bit lighter/maybe more treble which may come across as more detailed purely from more energy there rather than actually more detail.

In the ES-2a thread.

 

[timb5881]

t1s with ccs costs money
better to buy carbon

??? I agree the carbon is top notch and top price.

 

[LarsHP]

Today, I plugged my SR-X9000 into Stax SRM-T1S energizer with either the Moon 430HA or Topping D90LE as DAC. Wow! What a drop in clarity!

Before I got the X9000, I heard a slight, but audible, drop in transparency and resolution when using Lambda Signature, coming from the Gustard R26 + Carbon in the living room. Man, the SR-X9000 doesn't cover anything up! The drop from the living room setup to the desktop setup was almost depressing. From now on, I think I will reserve the SR-X9000 for the living room only, and the Lambda Signature for the office.

This makes me think that, while it's true that the chain is only as good as it's weakest link, the transducer should definitely be the first priority in terms of sound quality (and typically also price). Changing the DAC or amp will make subtle or minor differences when using headphones or speakers of the same popular price classes, but going from, say, budget high end to top high end, makes a marked difference in resolution, details, transparency etc., truely showing what the upstream components are capable of.

EDIT: Regarding the X9000 having more details than ES-2a, user oneguy said:

"Comparisons between the X9000 and ES-2a. Are about what I expected going into this consider the 2a is in the same family of sound as the Omega. The 2a brings a more natural tone and instrument placement as compared to the X9K’s holographic placement/seperation. The X9K is a brighter headphone and, whether due to this brightness or not, offers more detail. If I had to pick between the two I’d opt for the X9K due to its uniqueness amongst estats with that high level of holographic placement. It’s a very “wow” thing that I think is cool but it’s not the best for all types of music."
https://www.head-fi.org/threads/es2a-discussions.976239/page-11#post-1864558

That said, I just now saw another post in that thread saying the two are roughly on the same level.

 

[aokman]

Is something going on in STAX land at the moment because a local retailer is selling everything at pretty insane prices

 

[newbluesuit]

Is something going on in STAX land at the moment because a local retailer is selling everything at pretty insane prices

It looks like this reseller has an ‘Easter sale’ going on, with very aggressive discounts indeed. It's not just for Stax: many other brands are included in the sale, with models such as the LCD-5 and HD 800 S at unusually low prices. Some PMC speakers are listed at half price!

I can't see any discounts on Stax products from other sellers in your area, so I guess it's something to do with this reseller rather than with Stax.

 

[ludoo]

Yesterday I refurbished the n-th SR-X mk3 to pass through my hands, and thought it might be a good time to jot down a couple quick pointers for whoever will have to do it in the future. And this will maybe also spur some of you into getting a cheap pair and trying them.

A couple disclaimers first

• out of the 15 or so SR-X models I bought, about 30% had driver issues so factor this in when buying (and don't toss away the non-working ones, parts are super useful)
• the SR-X have a very different form factor and presentation from Lambdas, so if you can't stand supra-aurals, or if you live and die by soundstage these are probably not for you

And let's also dispel the myth that SR-X mk3 are bright with no bass: they have more than enough, and at least as much or more than most of the Lambda models I had or tried. Part of the problem with this perception might stem from people replacing the old cruddy pads with totally unsuitable ones, which are either circumaural, too thick, or too rigid to suit their design. So if you are interested, read on past the spoiler.

Spoiler: Refurbishing tips and measurements

Refurbishing a pair SR-X is pretty easy:
- remove the old pads and scrape away the old adhesive
- replace pads with suitable new ones
- optionally open the cups and remove the internal resistors

Pads

Replacing the old pads is not really a matter of sound, as even when reduced to cloth they still measure very similar to original intact pads (which I have on one pair), with very minor differences in bass and upper mids/treble response. You typicall want to replace them as they have become uncomfortable, and are either dirty or flaking bits of old vinyl everywhere. This measurement shows some of my SR-Xmk3 with a variety of pads: original ones reduced to cloth, original ones in mint condition, and the replacement ones I describe below. As you can see the FR changes very little, especially accounting for model variations and discounting treble variations which are not really representative in amateur rigs.

The choice of new pads is pretty simple: you want flat, soft, supra-aural pads that when measured maintain the original tuning as much as possible. After trying a few I eventually settled on Aliexpress replacement pads for Sony headphones: 70mm pads for the MDR-ZX100, and later 75mm pads for the MDR-V55 that match the SR-X size slightly better. They both sound basically the same, with the larger pads being a tiny bit more comfortable, but also warmer on the ears. This is what they look like on the SR-X: smaller pads on the left, larger on the right.

The simplest way to go about replacing pads is to separate the external metal part of the baffle from the rest of headphone: just remove the headband, and unscrew the small posts where the headband forks slot in the cups. Then rotate/pull gently until the metal baffle comes away. At this point, tear off the old pads and remove the adhesive. If it's stuck and coming away in pieces, heat the adhesive with a hair dryer before peeling to soften the glue. Once done, give the baffles a nice clean.

Once you get new pads, use a pair of sharp scissors to cut away the bottom lip and the protective mesh. Then cut rings of thin double-sided adhesive film using the metal baffles as a guide, I use 3M 486MP which is readily available, and very strong. Put the rings on the baffles and fix the new pads.

Internal resistors

The SR-X mk3 have internal resistors across the signal contacts to protect against overdriving the diaphragm. Those are usually not needed, so I remove them. My unscientific measurements show a slight change in FR without them, and while I am probably deluding myself they are very easy to remove, so I do it on all mines.
Unscrew the tiny screws that keep the plastic baffle joined with the cups (use a good screwdriver as they are easy to strip), then gently separate the baffles and cups. The resistors are clearly visible and can be desoldered in seconds without messing with the driver wires, or the driver itself.

This is the same pair before (red) and after (greem) replacing pads and removing resistors, with one of my other good refurbished pairs in gray in the background for reference.

If you got to here, I hope you eventually buy a pair and enjoy them too.

 

[icnaiwhimor1975]

it's more detailed than even the 009S and hearing the X9000 several times, I can believe that.

this is good news

 

[ericj]

Yesterday I refurbished the n-th SR-X mk3 to pass through my hands, and thought it might be a good time to jot down a couple quick pointers for whoever will have to do it in the future. And this will maybe also spur some of you into getting a cheap pair and trying them.

A couple disclaimers first

• out of the 15 or so SR-X models I bought, about 30% had driver issues so factor this in when buying (and don't toss away the non-working ones, parts are super useful)
• the SR-X have a very different form factor and presentation from Lambdas, so if you can't stand supra-aurals, or if you live and die by soundstage these are probably not for you

And let's also dispel the myth that SR-X mk3 are bright with no bass: they have more than enough, and at least as much or more than most of the Lambda models I had or tried. Part of the problem with this perception might stem from people replacing the old cruddy pads with totally unsuitable ones, which are either circumaural, too thick, or too rigid to suit their design. So if you are interested, read on past the spoiler.

Those are probably varistors rather than straight-up resistors. Some energizers have them attached to the socket internally, spritzer said that sometimes they used some high voltage zener for that job. A while back i determined the modern equivalent of the MOVs in the srd-7 mk2 schematic, probably mentioned it in this thread or a previous one.

I would posit that given how popular the SR-X was and how many of them have driver issues, the MOVs and the PTCs in the energizers failed to provide meaningful protection in the first place.

In other news, a cheap SRD-7/SB arrived from ebay. The poor thing smells of mildew and has some rust on the frame, wax melted out onto wires from the transformers, plenty of small dings on the face. Cover was re-sprayed without first removing a rust blister up top. I may take it apart just so i can wire brush the chassis, scrub it down, and give it another layer of black paint. Or at least some dabs of rust converter.

One output lead from one transformer is tapped, from there into a 100k resistor just like the others.

The zener appears to be unidirectional. My guess is that "1Z100" is equivalent to the current ZL100 which would produce a maximum of about 83 volts. So the three stages of voltage doubling would be required to get into the 230v neighborhood.

I think a lot of the normal-bias-only energizers are only really producing around 200 at most, fwiw.

Then a 1uf reserve *before the ballast resistor (the 0.01uf cap often found in the 6 and 7 is *after it) and it's a 4.7M resistor rather than the 2.2M seen in the official schematics for the wall-powered energizers.

To me it's interesting anyway.

 

[aokman]

Finally clearing out of my projects and can come back to doing work on the bias and new Lundahl transformers. Unfortunately the early ones they sent to me a while ago never worked out and had the same frequency response issues.

Going to see about getting some custom wound ones based on the LL1630 but with a bigger core. I really wanted these ones to work as the core saturation performance was dam impressive.

 

[oneguy]

Yesterday I refurbished the n-th SR-X mk3 to pass through my hands, and thought it might be a good time to jot down a couple quick pointers for whoever will have to do it in the future. And this will maybe also spur some of you into getting a cheap pair and trying them.

A couple disclaimers first

• out of the 15 or so SR-X models I bought, about 30% had driver issues so factor this in when buying (and don't toss away the non-working ones, parts are super useful)
• the SR-X have a very different form factor and presentation from Lambdas, so if you can't stand supra-aurals, or if you live and die by soundstage these are probably not for you

And let's also dispel the myth that SR-X mk3 are bright with no bass: they have more than enough, and at least as much or more than most of the Lambda models I had or tried. Part of the problem with this perception might stem from people replacing the old cruddy pads with totally unsuitable ones, which are either circumaural, too thick, or too rigid to suit their design. So if you are interested, read on past the spoiler.

Spoiler: Refurbishing tips and measurements

Refurbishing a pair SR-X is pretty easy:
- remove the old pads and scrape away the old adhesive
- replace pads with suitable new ones
- optionally open the cups and remove the internal resistors

Pads

Replacing the old pads is not really a matter of sound, as even when reduced to cloth they still measure very similar to original intact pads (which I have on one pair), with very minor differences in bass and upper mids/treble response. You typicall want to replace them as they have become uncomfortable, and are either dirty or flaking bits of old vinyl everywhere. This measurement shows some of my SR-Xmk3 with a variety of pads: original ones reduced to cloth, original ones in mint condition, and the replacement ones I describe below. As you can see the FR changes very little, especially accounting for model variations and discounting treble variations which are not really representative in amateur rigs.



The choice of new pads is pretty simple: you want flat, soft, supra-aural pads that when measured maintain the original tuning as much as possible. After trying a few I eventually settled on Aliexpress replacement pads for Sony headphones: 70mm pads for the MDR-ZX100, and later 75mm pads for the MDR-V55 that match the SR-X size slightly better. They both sound basically the same, with the larger pads being a tiny bit more comfortable, but also warmer on the ears. This is what they look like on the SR-X: smaller pads on the left, larger on the right.



The simplest way to go about replacing pads is to separate the external metal part of the baffle from the rest of headphone: just remove the headband, and unscrew the small posts where the headband forks slot in the cups. Then rotate/pull gently until the metal baffle comes away. At this point, tear off the old pads and remove the adhesive. If it's stuck and coming away in pieces, heat the adhesive with a hair dryer before peeling to soften the glue. Once done, give the baffles a nice clean.

Once you get new pads, use a pair of sharp scissors to cut away the bottom lip and the protective mesh. Then cut rings of thin double-sided adhesive film using the metal baffles as a guide, I use 3M 486MP which is readily available, and very strong. Put the rings on the baffles and fix the new pads.

Internal resistors

The SR-X mk3 have internal resistors across the signal contacts to protect against overdriving the diaphragm. Those are usually not needed, so I remove them. My unscientific measurements show a slight change in FR without them, and while I am probably deluding myself they are very easy to remove, so I do it on all mines.
Unscrew the tiny screws that keep the plastic baffle joined with the cups (use a good screwdriver as they are easy to strip), then gently separate the baffles and cups. The resistors are clearly visible and can be desoldered in seconds without messing with the driver wires, or the driver itself.

This is the same pair before (red) and after (greem) replacing pads and removing resistors, with one of my other good refurbished pairs in gray in the background for reference.



If you got to here, I hope you eventually buy a pair and enjoy them too.

Driver failure indeed is highest in the SR-X compared to any other line. It’s taken a while for me to assemble viable examples of some of those older stax.

 

[icnaiwhimor1975]

Finally clearing out of my projects and can come back to doing work on the bias and new Lundahl transformers. Unfortunately the early ones they sent to me a while ago never worked out and had the same frequency response issues.

Going to see about getting some custom wound ones based on the LL1630 but with a bigger core. I really wanted these ones to work as the core saturation performance was dam impressive.

boards are always great)))

 

[ludoo]

Asking for advice on something that has been bugging me for some time: my ESP/950 have a background hum, and this happens regardless of amp/dac/power strip. All my other stats are dead quiet with the same setups.

The hum almost (but not completely) disappears if I touch the amp case, which makes me think it's a grounding issue. But why would it only be a problem with the ESP/950? I did a second Koss/Stax adapter to exclude it from the equation, and of course it wasn't the culprit (unless the Koss adapter which I reterminated is indeed the problem).

Any ideas, or even better advice?

 

[ericj]

Asking for advice on something that has been bugging me for some time: my ESP/950 have a background hum, and this happens regardless of amp/dac/power strip. All my other stats are dead quiet with the same setups.

The hum almost (but not completely) disappears if I touch the amp case, which makes me think it's a grounding issue. But why would it only be a problem with the ESP/950? I did a second Koss/Stax adapter to exclude it from the equation, and of course it wasn't the culprit (unless the Koss adapter which I reterminated is indeed the problem).

Any ideas, or even better advice?

I recall that we discovered that the ballast resistor in the E/90 is 10Mohm, so i wonder if putting a 4.7M resistor in the adapter may help

 

[ludoo]

I recall that we discovered that the ballast resistor in the E/90 is 10Mohm, so i wonder if putting a 4.7M resistor in the adapter may help

Thanks Eric, mystery solved.

I tried the ESP/950 on my desk where I have a Modi Multibit and 313 and they were dead silent. But I recalled switching DAC in my main setup with the T1s and that had made no difference, so I was a bit puzzled.

Changed DAC again on the T1s, and sure enough hum was back and touching the back of the amp made it go away.

Then I disconnected the USB-C DAC cable from the laptop to move something, and hum disappeared. Tried reconnecting USB-C to laptop, hum back. Unplugged laptop from power supply, hum disappeared again. Aha! Ground loop, laptop is on a different socket.

Tried a different charger, and there's absolutely no hum. So a) it's a ground loop, but b) it only happens with my portable Pine64 GAN charger. I can live with that.