KOSS ESP-950 Thread

[Amish]

I haven't tried a Stax amp, so I can't comment on the sonic differences in this particular discussion, but I always find it interesting about people saying the stock amp doesn't go loud enough. Headroom is not an issue I have. I barely turn mine up a quarter turn (about 9 o'clock if it had an indicator) before it gets too loud for me. I guess I just listen quieter than most.

Yeah, as I have said in an earlier post, if you listen at low volume, then you may or may not hear a difference. I like my music loud. The stock system starts to break up at the volume I listen to but on a better amp, I can go louder than i can stand and the SQ is always clean and clear.

 

[charliex]

I recently purchased one of the cheaper Stax SRM-1 MK 2 units that were listed here - Birgir has a lot of junk laying around so don't be afraid to email him!
After finding a spare Koss cable and converting it to a Koss -> Stax adaptor, I had the unit + cable shipped to me for around $800 AUD. Not a bad price for a refurbished amp that honestly smokes the stock Koss energiser.

Received the ESP-95X back from Koss today; looks like they just replaced the entire unit so I'll be breaking the drivers in from scratch again.

That's what I love about the Koss ESP=950. They are the last and only headphone that they guarantee for life - no questions asked.
Instead of repairing the phones they always just exchange them for a brand new unit.
One of my favourite mid-priced amps is the Stax SRM -T1 (Vacuum Tube output).
However, the amp I'm currently using for all of my electrostatic phones is my coveted HeadAmp KGSS (built by Justin).
Enjoy your Koss!
Bryan

 

[adeadcrab]

Sounding so much better with the dekoni perforated leather earpads...
Also sounding better after burning in the drivers - Will try it for a full 300 hours and see if it really makes a difference.
Not as much low end as the HEDDphone + Eletech Inferno copper cable, and maybe just half a notch lower in detail (the HEDDPhone is the most resolving I've heard)
The ESP-95X has a more even treble, so it sounds a little bit brighter than the HEDDphone which can be welcome also.

 

[timb5881]

So has anyone been experimenting with their ESP950/9xx?

 

[Reticuli2]

Probably the phenomenon described above by milosz has something to do with why ESP-95X seems to sound better after about an hour of use and maybe also why they sounded awful when I first plugged them in. They need to charge. Amps I think also sound a little nicer after they warm up.

Are you guys sure it's the earphones that change their sound after an hour and not the E90? I remember actually preferring the sound for monitoring when it was first turned on, and then found them to sound more conventional after an hour or two of being left on. This seemed to occur independent of whether I was listening or not for that span. They'd go from being super tight, flat, transparent, great separation that could be easily heard even at low volumes, and with a high macro detail but limited punch, to instead being more flabby and less transparent like normal headphones, and trading macro detail for like micro detail. The punch was still not there, but that didn't bother me. The black background was suddenly populated with more stuff from the source, but the earphones also needed to be turned up more to get the original macro detail and sense of separation. Their flat response would slightly warm to become closer to the sound of the K701 & HD580 but just more extended, while still being delicate, and, again, still very detailed, just a different kind of detail compared to when it was first turned on. When first turned on, it was almost like a combination of interpolative upsampling harmonics were present that made sounds easier to latch onto and an extender processing the sound to hype the dynamics and macro detail in a very useful way.

 

[timb5881]

So today I am listening to my ESP950’s through a Stax SRD 7 Pro powered by a Carry Rocket 88 amplifier. Makes for a dreamy warm listening session.

 

[Svperstar]

So today I am listening to my ESP950’s through a Stax SRD 7 Pro powered by a Carry Rocket 88 amplifier. Makes for a dreamy warm listening session.

How does that compare to the Koss energizer? I keep almost buying a modded Stax amp and I keep not doing it, lol.

 

[timb5881]

How does that compare to the Koss energizer? I keep almost buying a modded Stax amp and I keep not doing it, lol.

Well I use the Stax SRD7 Pro, so I can use any number of amps that I have. Now I also have a Stax SRM 212 amp, and a a Stax SRM1/Mk2. I have ran the Koss on those 2 amps and they sound fine. The E/90 is a good amp, like the SRM 212 they are limited by their power supplies, I improved both of them with a regulated power supply with about 5 watts power.
A good Stax amp like the 006/7 tubes are good, the SRM 313/23 are not much of an upgrade from the E/90. The 717 and 727 will be a big improvement.

 

[ElectroCit]

Has anyone taken the ESP/950 or ESP/95X headband apart? Doesn't seem too complicated at a glance, but I don't want to break any plastic clips or other thingamajigs while going in blind.

 

[timb5881]

I just received a pair of Dekoni sheepskin ear pads for my ESP950s. A bit of a b***h to get on. My Hands are too small to do the job so I had my grandson get them on for me. They are very comfortable and the first sonic difference I noticed was a cleaner and more extended high frequency extension.

 

[timb5881]

Still trying the Dekoni ear pads, like them very much. Using the Stax SRD-7 Pro, I have tried a couple of amps, and in each case the ESP950’s came up a notch higher in performance.

 

[Svperstar]

So Ifi released the Phantom:
https://ifi-audio.com/products/ican-phantom/

I've been debating getting a modded Stax amp to run my 95X plus then I can jump into Stax which I currently don't own any.

However the iCan Phantom also runs electrostats. It appears to be the ultimate end game amp.

Rather then buy a modded Stax amp the Phantom seems to deliver more power then any Stax amp ever made.

I guess due to the cost reviews seem to be scant. Has anyone in this thread plugged their 950/95X into a Phantom?

 

[charliex]

Would be nice to read a side by side comparison to the penultimate Blue Hawaii.

 

[JimL11]

"Rather then buy a modded Stax amp the Phantom seems to deliver more power then any Stax amp ever made."

Well, it's not quite clear. The iCan website says the Phantom can deliver 640V, however it doesn't say whether that is RMS or peak voltage. The Stax SRM727 is speced at 450V RMS at 1 kHz, which works out to about 636V peak. And incidentally, 400V RMS should give 113 dB (116 dB peak), which is enough to give you a good case of permanent hearing loss in short order, so that is more than loud enough IMHO.

BTW, the original Stax T2 was speced at 630V RMS at 1 kHz.

Of course in either case you'll need an adapter cable for the Koss since its cable plug is not compatible with the Stax socket.

But there is more than voltage involved. You also need current to deliver power. Why do you need current? Because even though an electrostatic headphone resembles a capacitor, whenever the voltage driving the headphone changes, current needs to flow onto or off the headphone. It may be only fractions of a milliamp, but it needs to flow. The relevant equations are V=Q/C, where V=voltage, Q= charge, and C = capacitance . or change in voltage = current/C. And of course a stat headphone isn't exactly a capacitor, because it makes sound (duh!) which means it burns a little extra current which is converted into sound energy.

For example the Koss amp that comes with the 950 delivers more voltage than any Stax amp, but very little current (approximately 2 mA/channel). This low current is required because it has a plastic case. If it delivered a good amount of current it would probably melt as you need [metal] heat sinks to withstand the standing power involved. The result is at high voltage levels it goes into current-limiting and cannot deliver the needed current, especially at high frequencies. In order for an amp to deliver power, you need both voltage and current. The Stax amps all run at about 14-16 mA standing current/channel, the BHSE runs about 36 mA/channel with +/-450V power supplies and the T2 about 28 mA/ channel, with +/-500V power supplies. The BHSE or the T2 probably have more power output than the Phantom, at least that is my guess.

Personally, I'd rather have a Stax SRM-T1/T1S modded with constant current output loads (which to my ears sounds better than the Stax SS amps), and a separate amp for dynamic/planar headphones, but then that's me. YMMV.



.

 

[Svperstar]

Personally, I'd rather have a Stax SRM-T1/T1S modded with constant current output loads (which to my ears sounds better than the Stax SS amps), and a separate amp for dynamic/planar headphones, but then that's me. YMMV.

I've never jumped on the Stax train because I can never decide on what amp to get. I was close to dropping $4,000+ on a nice Stax set and a modded Stax amp but waited too long and they got sold to someone else. I had an Arya Organic coming in the mail and waited to play around with that first. Been on the fence with Stax for almost 20 years now lol