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KOSS ESP-950 Thread - Page 31

post #451 of 969
9/14/12 at 4:42am

What Stax system did you get Chodi?

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post #452 of 969
9/14/12 at 4:53am
Quote:
Originally Posted by grokit View Post

What Stax system did you get Chodi?

This deserves a very long answer that I will place in the Stax thread with a complete description of my visit, probably tomorrow. Since you asked, I bought the 4170 system. This includes the 407 and the 006tII. I spent four hours at the dealers doing a/b with 3 different Stax amps and the 407, 507 and the 007mk2. I will go into a long winded description of my experience today and my findings, but suffice it to say I bought the only one of two combinations that I felt had the least negatives and the most positive without regard to price. I did not listen to the 009 as I do not want to take out a mortgage on my house to buy one. You can read the lengthy details later in the Stax thread. I did not set out to buy a pairing (set) but it turned out the Stax people put them together for a reason. And yes, I know Spritzer hates the 006t. 


Edited by Chodi - 9/14/12 at 5:13am
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post #453 of 969
9/14/12 at 8:03am
Quote:
Originally Posted by Chodi View Post

I emailed Headphones.com two days ago to purchase the ESP 950 from them. Their price is the best I can find. They have not even responded to my email?

 

Google is finding an orphaned page.  headphones.com stopped carrying to ESP-950 a while ago but failed to remove the page.  If you go to their home page and select "Koss" speakers you will find that the ESP-950 isn't listed as a headphone they currently sell. Just speculating that you got no response because they don't have any to sell you. A company more dedicated to customer service would reach out and say "Sorry, we don't have any and we don't have plans to restock." because it's the right thing to do as well as makes it more likely that you will get them a try when they have something else to sell you.

 

I called them on the phone today and suggested since they aren't selling in (not even in their inventory system) that it would be a good idea to remove the page.

 

--Mark

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post #454 of 969
9/14/12 at 8:44am
Quote:
Originally Posted by verber View Post

 

Google is finding an orphaned page.  headphones.com stopped carrying to ESP-950 a while ago but failed to remove the page.  If you go to their home page and select "Koss" speakers you will find that the ESP-950 isn't listed as a headphone they currently sell. Just speculating that you got no response because they don't have any to sell you. A company more dedicated to customer service would reach out and say "Sorry, we don't have any and we don't have plans to restock." because it's the right thing to do as well as makes it more likely that you will get them a try when they have something else to sell you.

 

I called them on the phone today and suggested since they aren't selling in (not even in their inventory system) that it would be a good idea to remove the page.

 

--Mark

Thanks for the explanation. I was wondering what type if company would not respond to a buyer. I guess I will just keep looking until I find a set somewhere. After the Stax purchase today paying full list for the ESP950 is not in the cards. 

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post #455 of 969
9/14/12 at 10:34am

I don't hate the 006t but it just makes no sense with the 323S in the lineup.  Now if they would finally drop the 6CG7's for the ECC99's things would improve but who knows when that will happen.  

 

The E.90 is also fine for a starter amp but it does have some major limitations.  It was designed for one goal, massive voltage swing at a low cost so they made quite a few compromises to get to that point.  Mosfet output devices are also a poor choice but since the amp is essentially free it's hard to complain.  The SRM-252S is arguably a better amp though. 

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post #456 of 969
9/15/12 at 9:59am

But does the SRM252S sound better with the koss in your experience?

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post #457 of 969
9/15/12 at 10:32am
Quote:

Mosfet output devices are also a poor choice

any SS device will have larger parasitic C than tubes, but T2, BHSE, KGSS, KGHVSS all use solid state output Q  on one side at least - some are now using IXYS MOSFET ccs on ouput

 

the E/90 output Q are awkward in lower V rating, being packaged in T0-92 which can't handle much power so are series cascaded and paralleled - and still not Class A

 

but those are specific device limitations, design choice for lower cost

 

 

the best recent IXYS MOSFET for the application haven't yet been given a open trial in ES headphone amps that I have read - I don't think they will be a limitation - except in the minds of those unwilling to credit anything except vacuum tubes


Edited by jcx - 9/15/12 at 10:33am
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post #458 of 969
9/15/12 at 12:05pm

Compared to something like the 2SC4686A then the mosfets are a poor choice.  The C4686A is naturally dead now as something this good couldn't last...

 

It will be interesting to see what Stax does as their favorite BJT is end of life as well (C5466). 

 

Quote:
Originally Posted by wiinippongamer View Post

But does the SRM252S sound better with the koss in your experience?

 

I haven't tried the two together as I sold my last ESP950 some years back. 

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post #459 of 969
9/15/12 at 1:32pm

2sc4686 ft peaking at 5 MHz @ 3 mA - dropping to 500 kHz @10 mA , hfe min of 15 - no thanks

 

I'll happily "spend" 20-50 % more standing current to charge the "large" MOSFET parasitic C for more than an order of magnitude more speed, 5x SOA

 

the speed lets the feedback be similar orders larger at audio frequency so I'm not worried by the nonlinearity of the MOSFET parasitic C either


Edited by jcx - 9/15/12 at 1:46pm
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post #460 of 969
9/15/12 at 4:49pm
Quote:
Originally Posted by jcx View Post

 

the E/90 output Q are awkward in lower V rating, being packaged in T0-92 which can't handle much power so are series cascaded and paralleled - and still not Class A

 

 

series stacked for voltage handing

 

not paralleled, those are protection zener diodes.

definitely no more than a few milliwatts of class A.

 

many of the ixys fets rated for voltage are a direct drop in in the kgsshv amp board.

run them as is, or turn up the bias.  ixtp05n100p is one of the devices that works well.


Edited by kevin gilmore - 9/15/12 at 4:55pm
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post #461 of 969
9/15/12 at 9:50pm

OT: Kevin--congrats on the ES2. Wow!

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post #462 of 969
9/24/12 at 10:29pm

I've done some searching and can't find the ESP-950s for under ~$950 in the US (the cheapest Amazon price is $959, and Buy.com has the same price, both from WW Stereo).  There are some no-name outfits advertising them for less. but they don't seem legit.  Where are people finding these headphones for $600-700 from authorized sellers?

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post #463 of 969
9/24/12 at 11:16pm

They'd been 600-700 for the past several years at amazon but recently jumped to MSRP of 1k, most likely due to this thread, they were $549 at one point this month, but quickly went up again after a few hours. The hype will pass eventually.

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post #464 of 969
9/25/12 at 12:44am

I've had them on order with headphones.com but they have not come yet.  They say Koss is having a production problem.

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post #465 of 969
9/25/12 at 4:12am
Quote:
Originally Posted by sorabji View Post

I've had them on order with headphones.com but they have not come yet.  They say Koss is having a production problem.

I don't see them listed on their site? What price did you pay?

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