KOSS ESP-950 Thread - Page 8

QUOTE: "I for one don't think we dismiss the E.90 because of the plastic box and cheap parts. In fact there are some very nice parts in there and I don't think the volume pot needs to be replaced, certainly better than what's in many other amps. The simple fact is that the Stax SRM-Xh and its descendants are just far better amps. Do some small mods to the SRM-Xh and it is a very, very good amp."

I agree.

Got both the E90 and the SRM-252.

As far as el cheapo ES amps go, E90 aint bad, the Stax is better.

Of course my KGSSHV is best!

2 people have asked how i would do a dc coupled amp that does the kind of voltage swings

that a E90 can do.  I've been working on this for quite a while, and i have a working prototype.

2950 volts peak to peak stator to stator.

http://gilmore.chem.northwestern.edu/togte.pdf

Not for the faint of heart.  And certainly will not fit in a box the size of an E90.

Quote:

Originally Posted by spritzer 

First things first, not all ESP950's are the same.  This model has been in production since the 80's so there are some major production variances.  Anybody following Koss knows they like nothing better to mess with the designs (I counted at least 7 different versions of the ESP9...) so there is no way to nail down how the damping is in a particular set.  A few I've had here were very lightly damped while others used much denser materials. 

 

When modding the final sound is always a personal preference but I do believe in light damping for electrostatics.  Glass wool is ideal for this since it can be very thin and last for decades.  Fiber paper also works well plus the standard open cell foam. 

 

 

fwiw hennyo is talking about my esp950, which you will recall has red grilles on the backs but went in for driver replacement in, what, 2010? I think the only amp he'd heard it out of at the time was the SS exstata prototype. I don't recall if he tried the e/90. 

Quote:

Originally Posted by ericj 

fwiw hennyo is talking about my esp950, which you will recall has red grilles on the backs but went in for driver replacement in, what, 2010? I think the only amp he'd heard it out of at the time was the SS exstata prototype. I don't recall if he tried the e/90. 

 

Yes, heard E-90 at multiple meets now, along with the ExTatA SS and the ExTatA Hybrid. Thanks for bringing it! It's nice to have there to see the entire 'kit' every time. =)

Seeing what can be made of the E-90 would be amusing. Eric, want to borrow Stax jacks for an E-90? I think it voids the warranty? An E-90 SE would be quite cool... Again, doubt the warranty's doable though?

So has anyone actually attempted any e/90 mods? I see from jcx' images that at least his e/90 contains mc33077 opamps, which if i recall correctly are a sort of basically not hugely offensive part, like a glorified ne5532. 

Nothing about that chip seems particularly special, which would seem to indicate that perhaps something like an lm4562 can be dropped into it's place, for perhaps a little more refined sound? 

I'm not sure if it is still available, but for something like about $10 you can get a koss extension cable with the

right plugs on it.  Then hack off the one end and put on a male stax jack. Now the warranty issue is no

longer a problem.

Quote:

Originally Posted by kevin gilmore 

I'm not sure if it is still available, but for something like about $10 you can get a koss extension cable with the

right plugs on it.  Then hack off the one end and put on a male stax jack. Now the warranty issue is no

longer a problem.

It is and that's what I use.

Quote:

Originally Posted by kevin gilmore 

I'm not sure if it is still available, but for something like about $10 you can get a koss extension cable with the

right plugs on it.  Then hack off the one end and put on a male stax jack. Now the warranty issue is no

longer a problem.

I used to sell koss-to-stax adapters made out of a koss extension cord, a Cooper/WPI 6 pin plug with the center pin yanked out, and some copper plumbing fittings.

Got sick of putting my hobby to work so i stopped. Can't stand being in business. Built an adapter for personal use just a few days ago. 

But the E/90 interests me anyway. 

"never fail to take us to another place"

I was just thinking that.  Only the ER4S and ESP950 have done that for me lately.  I will probably get an ESP again.

there is a split volume knob - you can adjust the balance, once you get it right (or left, maybe center..) the friction between the two is supposed let them track - I find it a bit of a pain to use

I've never gotten them to track smoothly together; it doesn't really bother me though. 

Quote:

Originally Posted by jcx 

there is a split volume knob - you can adjust the balance, once you get it right (or left, maybe center..) the friction between the two is supposed let them track - I find it a bit of a pain to use

To sinae:

What headphone are you coming from? 

Quote:

Originally Posted by sinae 

I just received the ESP-950 very smooth dark sound but still high resolution but man that soundstage is soo to much in my head... anybody can tell me if the soundstage depth will be a little better with Exstata or KSGG amp... it's a little too much on the side right now.. similar to my DT250 soundstage
Also wish for more textured bass, more bass-mid linear connection and more refined and clear high... anybody what amp should i buy/build to get me there from E/90 to..

The KGSSHV did a great job making the 950s sound more linear and coherent IME.  W/ the E90 its more of a 'oh I see what this is about, cool' moment.  The KGSSHV that Livewire put together really let just get into the music and enjoy myself without thinking about the phone.  

IME you are never going to get an HD800 type SS from the 950 but I didn't get the impression you were looking to that extreme.  I'll be curious to hear the 950 w/ the LL in a few days.  Might be an interesting pairing from what I hear of the Cavalli sound.