Something new with the Koss ESP950

[spritzer]

The squealing is a known issue due to sub par dust covers on the drivers.  Koss even built in a fix on the amp which was just a voltage divider for the bias supply.  Pop in the right resistor to drop the voltage 10% and it should go away. 

 

[kwkarth]

Quote:

The squealing is a known issue due to sub par dust covers on the drivers.  Koss even built in a fix on the amp which was just a voltage divider for the bias supply.  Pop in the right resistor to drop the voltage 10% and it should go away. 

Thanks Spritzer!
 

 

[WilCox]

Back in the early 90's I bought an ESP 950 but returned it since I thought it was significatly outclassed by my Stax Lambda Pro/SRD-7 Pro.
 
Today I received a new ESP 950 from Amazon and I am amazed how great these sound!  My Stax O2 systems, HD 800 and LCD-2 certainly have given me an appreciation for state-of-the-art headphones, but I am amazed how good this Koss system is for a "mere" $600.  I need more listening time to sort through all of this, but I am most genuinely impressed with the ability of this system to deliver the goods.

 

[Reticuli2]

I thought they sounded bright, harsh, and thin at CES.  Junk.  Maybe Koss was using a defective pair?

 

[AudioCats]

more likely an amp problem.

 

[Anaxilus]

Quote:

I thought they sounded bright, harsh, and thin at CES.  Junk.  Maybe Koss was using a defective pair?

Bright and harsh is nothing like the 950.  Thin, that's the amp.  Well, 'energizer'.  I much preferred the ESP950 from the KGSSHV over most Stax amps.  But then you'd need to have a KGSSHV.
 

 

[WilCox]

I'm using the Koss with an SRM-717 and they sound better balanced that any Lambda I've owned -- no upper mid-range peak to make we want to yank then off after 20 minutes.

 

[Reticuli2]

It was their setup, though.  All stock stuff connected to a Koss portable.  Either the energizer must have been defective, the CD portable was defective (or junk), the energizer inputs didn't like whatever load the portable was feeding it (most headphone jacks even provide o.k. line out), or Koss was using some terrible MP3 CD in the portable.  It was brittle, thin, harsh, and tinny as all hell.  Very very bright and no lows at all.

 

[Anaxilus]

Quote:

It was their setup, though.  All stock stuff connected to a Koss portable.  Either the energizer must have been defective, the CD portable was defective (or junk), the energizer inputs didn't like whatever load the portable was feeding it (most headphone jacks even provide o.k. line out), or Koss was using some terrible MP3 CD in the portable.  It was brittle, thin, harsh, and tinny as all hell.  Very very bright and no lows at all.

Very odd.  The 950 is considered to be warm by electrostat standards.  Could have been the recording?  Did you notice if there was channel imbalance?  They have separate right and left gains that a prior listener could have messed with.  Here's a review for consideration.
 
"The greater warmth in the Kosses was never heavy or oppressive, always musically convincing. Their sound, on a wide range of good to excellent recordings, never failed to make a positive impression. It was never analytical or etched; the midrange was, as I've already stated, gorgeous; and the highs were simply there, neither obvious nor dulled."
 

 

[WilCox]

Quote:

It was their setup, though.  All stock stuff connected to a Koss portable.  Either the energizer must have been defective, the CD portable was defective (or junk), the energizer inputs didn't like whatever load the portable was feeding it (most headphone jacks even provide o.k. line out), or Koss was using some terrible MP3 CD in the portable.  It was brittle, thin, harsh, and tinny as all hell.  Very very bright and no lows at all.

When I first unboxed my new ESP-950s a few weeks ago, I was a bit disappointed when playing though the Koss energizer.  The bass was week and the sound diffuse.  When plugged into my Stax amps, however, the sound was exactly as Anaxilus describes -- warm and inviting -- better than most Lambdas I've owned.  Now I'm not a believer in burn-in or break-in making significant changes in electronic components, but after a week or two of being powered up, the Koss energizer started to sound much closer to the Stax.  One crazy theory I had was that Koss purchased a shipload of these things back in the early '90's and they've been sitting in a warehouse for almost two decades.  It's possible that it takes a bit of time for the capacitors to reform and the circuit to stabilize.  In any event, they now sound very different from what I heard right out of the box.  They are definitely keepers.

 

[Reticuli2]

Definitely noticed the separate volume knobs on top of each other at CES... and the cheapo plastic construction, but the life time warranty would make up for that.  Would any of you guys consider the quiet bass on the properly working ESP950 to be not much quieter than the ER4S unamped?  I tend to think people over obsess about bass quantity on headphones, since the lower registers can't be felt.  Compensating for slightly anemic lows with more volume down there can end up making you less sensitive to audible bass when you listen to properly setup speakers.

 

[livewire]

A match made in heaven...
 

 

[Anaxilus]

Quote:

A match made in heaven...

Jim, to this day the 950 still sounds best to me from your KGSSHV.  Superb.  Kudos to you. 
 
Bass on the ER4S?  Depends on how you hear the ER4S, especially unamped and from what source.  I would take the bass on the 950 over an unamped ER4S anyday.  I guarantee you if you plug in the 950 to the amp above you won't ever ask about that comparison in the low end again.

 

[livewire]

Thanks Mike.
FYI, a DIY T2 amp is now in the works. I want more of them Blue Hawaii style euphonics.

Gathering parts at the moment, prolly take a year to build it.
I'm taking my time this time.

 

[Lil' Knight]

Thanks Mike.
FYI, a DIY T2 amp is now in the works. I want more of them Blue Hawaii style euphonics.

Gathering parts at the moment, prolly take a year to build it.
I'm taking my time this time.

Sounds like you're gonna have fun (and hopefully productive) year ahead.