The Stax Thread III

[Philimon]

Because stupid double post feature I am posting here for more reach and feedback instead of editing my post in the slow moving poor man’s Stax thread.

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@ludoo @gammi

252s vs SRD-7

^ averaged frequency response measurements, modded SR-X1, graph to highlight the differences only

Did I notice a difference subjectively? No.
The measured difference in high frequencies appears to trend with others within this thread whove measured and compared SRD7mk2 vs Stax amps. I suppose this possible tonal difference may be a pro or con depending on user and system.

I did notice that the 252s (with uprated power supply) could seemingly get louder than my SRD7mk2 (modded and paired with Schitt Rekkr 2W @ 8ohm) based on how much pre-amp (Saga2) volume was needed to reach 90dB. I intend to sell SRD7mk2 and save on desk space, dm me if interested, Ill create a classified soon.

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I want to padroll SR-207 so started by creating a pad adapter for common 100mm round pads.

Having previously owned the SOCAS pad adapter for L500, I assumed that the procedure would be the same which involves unscrewing the stock pad mount. And so I removed stock pads and screws from 207 but I was unable to get the stock pad mount to come off. I figured maybe it was just stuck from overfill adhesive from the stock pads. But after some prying then quick investigating I saw SOCAS x07 series pad adapter instructions were different and doesnt call for unscrewing anything but just stickying the pad adapter on to the stock pad mount. Does this mean I cant easily remove stock pad mount and should just do as SOCAS recommends?

Not a big deal to just adhesive the new pad mount on except that it adds an extra few mm to pad depth. I just like the idea of having them screwed-in.

Test fitting:

^ Oval pads make more sense for the shape of Lambda enclosure so will try that next. I just have so many more spare round pads to choose from that I wanted to try those first.

 

[yaluen]

And so I removed stock pads and screws from 207 but I was unable to get the stock pad mount to come off. I figured maybe it was just stuck from overfill adhesive from the stock pads. But after some prying then quick investigating I saw SOCAS x07 series pad adapter instructions were different and doesnt call for unscrewing anything but just stickying the pad adapter on to the stock pad mount. Does this mean I cant easily remove stock pad mount and should just do as SOCAS recommends?

Most likely stuck due to adhesive yes. x07s have drivers screwed onto the mounting plates, probably why SOCAS opted for a stuck-on solution.

 

[ericj]

Layman's question: Why are there so many aftermarket amplifiers, but (almost) no aftermarket headphones? Because you can't get the components for headphones on the market, but you can for amplifiers? Or is the assembly that much more difficult? There are people in Europe who will repair our Stax headphones and even replace the membrane, so it can't be too difficult?

Building excellent headphones involves a large amount of secret sauce. Getting the frequency response exactly how you want it is not a straightforward process. There are reasons for the FR curves being shaped the way they are. Do you know how to get that notch at about 7khz to reduce ear-burn from canal resonances? I don't.

I am skeptical of repair houses just replacing membranes with just off-the-shelf film. You can do it and the tricks to match the tension across two drivers are simple but it's probably not going to sound exactly the same as the driver did when it was new from the factory.

 

[Rob80b]

Would you describe the 007 as a more resolving 660S2? I like the L300, but still keep the 660S2 because I love it's presentation. It's better than the 600/650/6XX in my books.

Sorry..I never did get to audition the SR007MKII, to purchase it would have been a leap of faith.

Between the L700 and the SR007, I know many who would go for the lambda because they find the 007 sounds too much like a "normal" headphone. Thoughts?

Again, cannot comment but I've read similar, was the one of the main reasons I got cold feet as I've gone through many "normal" headphones but the L300 is an eye opener... so I'm probably like yourself, looking for the same sound signature, but better.

In what ways, if I might ask?

Ditto.

 

[hutzelmeier]

Building excellent headphones involves a large amount of secret sauce. Getting the frequency response exactly how you want it is not a straightforward process. There are reasons for the FR curves being shaped the way they are. Do you know how to get that notch at about 7khz to reduce ear-burn from canal resonances? I don't.

Thanks – but doesn't all this apply to amplifiers in a similar way? Or is it just much easier to mess up with the transducers than with the amplifiers? I'm really speaking as a complete layperson here, I have no idea about the electronics and mechanics.

 

[mbrennwa]

Layman's question: Why are there so many aftermarket amplifiers, but (almost) no aftermarket headphones? Because you can't get the components for headphones on the market, but you can for amplifiers? Or is the assembly that much more difficult? There are people in Europe who will repair our Stax headphones and even replace the membrane, so it can't be too difficult?

Depends on what you mean by "aftermarket". If you get a new Senn headphone and plug it to your old Sony amp, isn't that an aftermarket headphone?

But I guess your question is more about the amplifiers made and sold by "DIYers-gone-commercial" types. Designing and building an amplifier is not exactly a piece of cake, but it's easy enough for a DIYer to read up and learn the design principles, and to get the parts. These things are pretty much equivalent to non-headphone audio electronics, or electronics in general.

Not so with headphones / loudspeakers. While loudspeaker parts are abundant, they can't be used for headphones, and the acoustics of a headphone is very different to a loudspeaker in a room. The mechanical expertise required to make headphone parts will be quite a bit above the head of most DIYers. But... nothing is impossible. And this. And this.

 

[Philimon]

Most likely stuck due to adhesive yes. x07s have drivers screwed onto the mounting plates, probably why SOCAS opted for a stuck-on solution.

Thanks! Ill just do adhesive then.

The first couple padroll measurements look promising. Will listen and try more pads later.

Spoiler: mehsurements

Minidsp EARS, 252s:

^ genuine Harmonicdyne Athena pads and fake "Ether" pads

stock SR207:

Spoiler: mehsurements

^ demonstrating various levels of pad seal which none of these are a completely full seal.

 

[Lucikun]

In what ways, if I might ask?

Perhaps I should have referred to it as a “noticeable” upgrade.

I didn’t spend much time with the L500, as I preferred the HEKSE, so my impressions are limited. However, I instantly fell for the L700. As someone who craves detail and a clean sound, I find the L700 to be a good complement to the HEKSE.

That said, it’s really a number of small improvements in the L700 that add up to a big difference in quality *for me*. The L700 offers a superior soundstage, greater detail, smoother sound, and a more engaging listening experience than the L500. When I first heard the L500, I thought it was a more flawed version of the HE1000se, but the L700 goes toe-to-toe with it, even adding a touch of warmth to the midrange.

I turn to the L700 when I’m craving a more intense listening experience, and reach for the HEKSE when I’m in the mood for a more relaxed, laid-back session.

EDIT: this is coming from someone who is primarily a Jazz and electronic listener who uses EQ on all headphones.

 

[ericj]

Depends on what you mean by "aftermarket". If you get a new Senn headphone and plug it to your old Sony amp, isn't that an aftermarket headphone?

But I guess your question is more about the amplifiers made and sold by "DIYers-gone-commercial" types. Designing and building an amplifier is not exactly a piece of cake, but it's easy enough for a DIYer to read up and learn the design principles, and to get the parts. These things are pretty much equivalent to non-headphone audio electronics, or electronics in general.

Not so with headphones / loudspeakers. While loudspeaker parts are abundant, they can't be used for headphones, and the acoustics of a headphone is very different to a loudspeaker in a room. The mechanical expertise required to make headphone parts will be quite a bit above the head of most DIYers. But... nothing is impossible. And this. And this.

The total number of aftermarket stax amps in use is probably pretty tiny compared to the total number of stax brand amps in use.

In the loudspeaker world relatively small companies can and do get various loudspeaker driver manufacturers to produce custom drivers for them, even without the OEMs name on them.

You think Ohm is forming cones, stamping baskets, and building magnet structures in-house? Of course they aren't. They also aren't using completely off-the-shelf parts, though the folks at audiokarma get their knickers in a twist if you pull the protective can off of a modern Walsh speaker and take a picture of what looks deceptively like a completely normal woofer sitting on its face.

There's a fun thread on diyaudio or something where the guy who developed the walshy tweeter on some legendary Infinity speakers tells the tale of how he and another guy prototyped them by painstakingly cutting up an off-the-shelf cone tweeter and gluing on a whizzer on his kitchen table, and how dozens, maybe hundreds were destroyed because x-acto knife blades really like to stick to magnets. careful . . . careful . . . *tink* well there goes another one. Also that the white goop on them didn't just *seem like heatsink grease.

In electrostatic headphones, who would you farm that out to? And how big would the market be? What would they have to cost to turn a profit? Way back in the day there were the electrostatic headphones made by Stax for the likes of Magnavox, Radioshack, Superex, etc. And they were relatively cheap, like $100 MSRP as i recall. And maybe Stax was finding homes for a bunch of old SR-3 drivers.

Companies that make electret mics can probably do it. Companies that make ESLs can probably do it but are they interested?

Orthodynamics are a different game - there are numerous companies that make flexi-circuits to order. I can get 100um prototype polyester diaphragms from pcbway in a week. I can have magnet structures laser cut in a couple days and pick them up 20 minutes from home.

 

[mulveling]

Interesting! What kind of issues or failures did you experience?
I'd be surprised if high voltage or heat are the sources of those issues. Hot amplifiers have been around for years, and they work well and reliably if designed and built well. The same can be said for high-voltage tube amps, which tend to keep working for many decades.

The high-voltage transistors used in many of these amps generate a lot of heat, and they get really upset if that heat is not dissipated away fast enough. When they overheat you can notice (at first) scratchy and intermittent noises near the floor (somewhat like rustling leaves in wind), and later an increasingly audible amount of distortion during music playback. One KGSShv (my favorite sounding one) did this because the cover didn't have enough airflow for the onboard heat sinks. It worked fine all day with cover off - but cover on, you had 30 mins to an 1 hour depending on ambient temps. This is also a constant worry with some T2's - they generate a LOT of heat, even compared to their seemingly big sinks (the Kerry T2's run nice and cool by comparison!).

In theory most of these amps should be able to generate signal somewhat close to their rail limits (e.g. 400V, 500V) before clipping, but a couple amps I've had have clipped much before this in just one channel (for some reason) - the other channel was fine.

Inexperienced builders might not properly insolate and space high voltage lines which can (obviously) cause big problems, but fortunately that's not going to be a problem with any of the well-known builders with good rep.

The tubes in these amps are generally fine; they can take some blows and deal with heat fine unless you do something really stupid. It's more often the transistors that cause problems, due to heat and high voltages. I've had a lot of gear and direct drive e-stat amps are the only ones that give me pause due to history.

I've had this cute little custom hev90-balanced amp that came with an undersized fuse, but once that was resolved (and with some bias help from Dr. Gilmore) it's been quite reliable! It's an all-tube design.

 

[TheAbyss2022]

The high-voltage transistors used in many of these amps generate a lot of heat, and they get really upset if that heat is not dissipated away fast enough. When they overheat you can notice (at first) scratchy and intermittent noises near the floor (somewhat like rustling leaves in wind), and later an increasingly audible amount of distortion during music playback. One KGSShv (my favorite sounding one) did this because the cover didn't have enough airflow for the onboard heat sinks. It worked fine all day with cover off - but cover on, you had 30 mins to an 1 hour depending on ambient temps. This is also a constant worry with some T2's - they generate a LOT of heat, even compared to their seemingly big sinks (the Kerry T2's run nice and cool by comparison!).

In theory most of these amps should be able to generate signal somewhat close to their rail limits (e.g. 400V, 500V) before clipping, but a couple amps I've had have clipped much before this in just one channel (for some reason) - the other channel was fine.

Inexperienced builders might not properly insolate and space high voltage lines which can (obviously) cause big problems, but fortunately that's not going to be a problem with any of the well-known builders with good rep.

The tubes in these amps are generally fine; they can take some blows and deal with heat fine unless you do something really stupid. It's more often the transistors that cause problems, due to heat and high voltages. I've had a lot of gear and direct drive e-stat amps are the only ones that give me pause due to history.

I've had this cute little custom hev90-balanced amp that came with an undersized fuse, but once that was resolved (and with some bias help from Dr. Gilmore) it's been quite reliable! It's an all-tube design.

My Carbon CC is left on 24/7 and it gets a little hot when the heating is on at night but I haven't had any issues in the past few months with it being left on. I leave it on because there is around a 5 hour warm up lol.

 

[alota]

My Carbon CC is left on 24/7 and it gets a little hot when the heating is on at night but I haven't had any issues in the past few months with it being left on. I leave it on because there is around a 5 hour warm up lol.

5 hours?????

 

[TheAbyss2022]

5 hours?????

Yes it sounds a little flat and dull for the first couple of hours. People think its only the tube amps that require warm up but actually the SS amps take even longer to properly warm up and the upside is the ability to just leave them on 24/7 to rectify this issue.

 

[arielext]

Opened up my SRM-600 limited today; here is a nude for you to enjoy

 

[alota]

Yes it sounds a little flat and dull for the first couple of hours. People think its only the tube amps that require warm up but actually the SS amps take even longer to properly warm up and the upside is the ability to just leave them on 24/7 to rectify this issue.

My ss amp needs warm-up too but around 45 min.