[TypodCrowd]

Latest News: It seem Stax got the same idea, just a few months late. L700mk2 has been anounced with Aluminium baffles and, you guessed it, detachable cables!

Stax Facebook Page

Pictures: (I love y'all but don't trust you just yet with my face )

Imgur Album: https://imgur.com/a/xLYjjjq

Why? Because I travel for work and school every few months. Also, because I can.

Inspired by the infamous video, I decided to mod my L700 with a detachable cable.

Spoiler: Youtube Vid

Conector Choice: 4-pin Hirose (MrSpeakers connectors)
- I like that they're orientable; forces the cable to stay in a certain position without risk of twisting
- They have a high DC voltage raing, as required for electrostaic headphone operation

Mod Notes:
- Space inside the baffle is very tight; the jacks cannot be placed flush against the bottom of the cups without needing to move the driver position upwards (which i was not willing to do)
- Since the jacks need to jut out of the cup, i'm currently using blue tack to stabalize them. The edges of the threads ARE clamped inside the cup, but not enough to be a solid hold on it's own.
- I plan to 3D print black plastic supports in the same style as the cups and epoxy them to the jacks and the cup extreior for a more professional long term solution.
- Made sure to protect the drivers during themoddind process. They are extremely sensitive to oils, dust, and ESD.

SQ Changes:
- Resolution, imaging and soundstage all remain unchanged
- Highs mainain Stax feel; mids have not changed at all and remain as per the L700 classic sound
- Bass depth and volume has increased ever so slightly; this was expected and desired so add a little warmth to the sound (the connections and the connector add just a tad bit of capacitance to the cable giving this minutely audible but oh so welcome change)

** SQ changes were tested by modding one side first and demoing left channel against right channel. I know my test tracks very *very* well, and also know my left/right ear imperfection imbalance very well. I've been coming to terms with it for a few years now. **

Amp Used:
I'm driving these with a modded SRM252s; I've upgraded most of the passive components in the power stage and it is audibly almost (so so closely) equivalent to an SRM323s. This statement comes from blind testing in an audio store with the store owner hot swapping between the 2 amps with my eyes closed.

Cheers folks! Feel free to comment, ask, request anything (related) you'd like!
I love modding shizzle; I'm down to take sane, well founded, productive requests!

 

[HiGHFLYiN9]

You need at least 600V wire for Stax, correct? At least that's what I've read on the subject.

 

[TypodCrowd]

Yes you do! My mod ultimately keeps the original Stax cable but makes it detachable for easier transportation. The Hirose connectors are rated for 400V for safe operation. Assuming that that spec is multiplied by a safety factor of 0.8, I should be okay up until 500V.

I know from my price range and spatial constraints, I won't be running an amp that passes voltages past 450V. Tense my choosing these connectors.

I meant to post pictures this weekend but haven't been able to find the time to sit on a laptop. Perhaps tomorrow.

 

[HiGHFLYiN9]

Great! Very excited to see your work. Very few people build custom cables for Stax. I did note that there are some older vintage Stax cable parts on Etsy if you need any.

 

[TypodCrowd]

Thanks for the heads up!

I plan to experiment over the next few months hopefully. Want to do it while I'm in the states though since most sellers are either there or are cheaper to have shipped there.

 

[TypodCrowd]

Bumping with updated OP! Enjoy folks!

 

[TypodCrowd]

Old thread, but just got some 3D printed supports made. Thought I'd give everyone a looky before I install them later this week.

They still need to be polished:https://imgur.com/YtlnNxh

 

[TypodCrowd]

Another update; v2 of the connector support. Now complete with cutouts for the orientation nubs and a back support so no side of the connector is left exposed.

https://imgur.com/lskfqcT

 

[georgep]

Yes you do! My mod ultimately keeps the original Stax cable but makes it detachable for easier transportation. The Hirose connectors are rated for 400V for safe operation. Assuming that that spec is multiplied by a safety factor of 0.8, I should be okay up until 500V.

I know from my price range and spatial constraints, I won't be running an amp that passes voltages past 450V. Tense my choosing these connectors.

I meant to post pictures this weekend but haven't been able to find the time to sit on a laptop. Perhaps tomorrow.

Stax bias is 580v - which both cups carry. Probably not an issue, but that would exceed the rating of the connector by a bit. "Running the amp" at 450v I expect is in reference to the power supply, which does not mean that a 450v psu supplies 450v to the headphones...

And why was it expected that the connector would add "warmth"?

 

[TypodCrowd]

Stax bias is 580v - which both cups carry. Probably not an issue, but that would exceed the rating of the connector by a bit. "Running the amp" at 450v I expect is in reference to the power supply, which does not mean that a 450v psu supplies 450v to the headphones...

The SRM-252s runs around +/-230V to the headphones. That is fairly low on the range of amps available for these headphones. Even with the higher voltage amps (450V, like the KGSSHV), it would be over the limit of the connector by a 50V without that much current. I'm fairly sure this would be under the absolute ratings for the connector (the rated voltages on the connector are given with a factor of safety).

And why was it expected that the connector would add "warmth"?

This is expected because any capacitance of the connector would act like a very minor, passive low-pass filter. Capacitance can be expected because the pins of the connector are so close to one another (without any shielding). The sound of Stax can change simply by changing the cable material (which has marginally different capacitance and resistance), which is exactly what Stax has done in the past between "lower" and "higher" tier Lambda models. The small capacitance added because of the connector does affect the lower freq's just a smidge for this reason, giving the overall effect of a little bit of warmth, or a tiny bass boost.

 

[georgep]

The SRM-252s runs around +/-230V to the headphones. That is fairly low on the range of amps available for these headphones. Even with the higher voltage amps (450V, like the KGSSHV), it would be over the limit of the connector by a 50V without that much current. I'm fairly sure this would be under the absolute ratings for the connector (the rated voltages on the connector are given with a factor of safety).

That is not how stax works ( or any other electrostat for that matter). Even the lowly srm-252 provides 580v to the headphones (very low current). You are quoting the output voltage, which is different. You should probably read up a bit more on how these amplifiers and headphones work.

 

[TypodCrowd]

If I'm wrong below, please correct me:

The specifications of the 252s state the following:
●Maximum output voltage: 280 V r.m.s. / 1 kHz
●Standard bias voltage DC580 V (PRO bias)

This means that the 580V bias is held constant (with low current), and the differential signal lines (L/R +/- pairs, AC, since they're analog signal) have an RMS voltage of 280v?

From my understanding of ratings of connectors, I should be more concerned about the 280V, since that will be carrying most of the current.

Yes, the 580V is going to be there regardless of the amplifier, but that is less concerning than the output voltage, because of the current that accompanies each of those respective voltages.

Once again, please do correct me if I'm wrong. I mean no disrespect or show-boatiness.

Edit: I've been quoting 230V instead of 280V. That's on me; my apologies. Fixed in this post.

 

[fjf]

Electrostatic headphones are essentially capacitors. Once you charge them (in seconds after plug-in) the current they consume is negligible. I still do not understand the need for super-mega amplifiers with many amps of current available. All you need to change is the voltage of the stators. That's what the E90 from Koss does, and works well.

 

[TypodCrowd]

I may be speaking illinformedly here, but I believe the high voltage is used for better control since electrostatic force is so weak compared to magnetic force (for example, which is used in planar magnetic headphones).

By lowering the voltage, the stators would have to either move closer to the mobile membrane/film, or the membrane's thickness/weight would have to decrease (if we're looking for the same sound quality). Without a proportional change in either or both of these, the lowered voltage would not generate enough force to move the membrane as it currently (pun intended) does, and the "speed" and "treble resolution" we have come to love from high end electrostatic headphones would not be achievable.

Thinner membrane means more expensive manufacturing processes and/or more expensive materials. I haven't taken a Stax driver apart yet, so I can't speak to how much closer the stators could safely be to the membrane.

Also, estat amps (the best) are only providing a few mA of current. Not a few amps

Once again, if I'm wrong, someone jump in.

 

[fjf]

You are right: https://www.head-fi.org/threads/kgs...nd-with-the-009s.766237/page-11#post-12009168
They are milliamps to the output, and as much as 180 watts to the heatsinks. Seems very inefficient, but for some reason it works.