[Kokomo O]

Satwilson, I was talking about upgrading from the standard 1A "wall-wart" (I kinda hate that term) to the 3A Mouser power supply that you suggested. I went looking for that and alternatives, and also found a 4A unit on Amazon, including this one, which looks pretty reasonable--delivers even more current, and is cheaper than the Mouser. Having got about three quarters of the way through this thread so far, I noted that there was some discussion earlier, somewhere around page 45 to 50, of using beefier power supplies to improve the E/90's sound, and someone mentioned using a variable bench supply, which looked like overkill to me, although potentially effective overkill.
 
The thing about power supplies, and here I'm speaking as someone who hasn't done circuit design or analysis in 30 years, never got very deep into it and was never all that knowledgeable about it or good at it, but did know something, is that it's never good to starve an amp of power, and you can almost always benefit by providing a little more juice to run on. I'd be curious to hear Kevin Gilmore's view directly, but I'll bet his electrostatic headphone amps don't use a 9v 1A supply, and that it would be a good thing if the E/90 could pull however much current the music tells it that it needs. Now, if Kevin says the E/90 absolutely never needs more that 0.25A, and 1A is plenty of cushion, then I'd say the stock supply is almost certainly adequate.
 
The other thing is that if I'm right, then the area that should benefit most would be the area that many people complain about with the 950s, the so called bass slam, or what I would describe as running out of steam, which is often as much an amp issue as a speaker issue when it happens with full size systems. Maybe that's what's happening here. (That said, to be honest, I find the 950 to be amazingly natural sounding, with slam being a high point, and very realistic, although I admittedly haven't heard the top dynamics or recent orthos.)
 
I think I'll spend the $15 on that 4A supply and report back, and do my very best not to be fooled by my desire both not to have spent the $15 in vain, and to be correct.

 

[kevin gilmore]

get a new set of standard "C" size batteries and use the battery adapter.
(1.5v batteries, not the 1.2 nimh or similar)  Should be good for
at least 3 amperes. If you hear a difference, then go and get a higher
power power supply.  Makes sure its regulated 9V. Unregulated supplies
at higher power may cause significant damage.

 

[satwilson]

  get a new set of standard "C" size batteries and use the battery adapter.
(1.5v batteries, not the 1.2 nimh or similar)  Should be good for
at least 3 amperes. If you hear a difference, then go and get a higher
power power supply.  Makes sure its regulated 9V. Unregulated supplies
at higher power may cause significant damage.

Thanks Kevin  for jumping in here. I found the battery adapter to be more " maintenance" than what I was willing to endure. However the improvement in the SQ with a regulated 3a supply was what I was seeking. Thanks again for your thoughts via  our PM's, satwilson

 

[DefQon]

  My comments are based on some PM's I exchanged with Kevin specifically regarding E90 upgrades. I am not trying to "expand" on his posts in this thread, just relaying the info he shared with me via  the PM's. If you look at some of my earlier posts you will see me giving credit to him for these ideas.

I meant referring to kokomo's post, he was talking about the wallwart, not what you discussed with Kevin.

 

[satwilson]

  Satwilson, I was talking about upgrading from the standard 1A "wall-wart" (I kinda hate that term) to the 3A Mouser power supply that you suggested. I went looking for that and alternatives, and also found a 4A unit on Amazon, including this one, which looks pretty reasonable--delivers even more current, and is cheaper than the Mouser. Having got about three quarters of the way through this thread so far, I noted that there was some discussion earlier, somewhere around page 45 to 50, of using beefier power supplies to improve the E/90's sound, and someone mentioned using a variable bench supply, which looked like overkill to me, although potentially effective overkill.
 
The thing about power supplies, and here I'm speaking as someone who hasn't done circuit design or analysis in 30 years, never got very deep into it and was never all that knowledgeable about it or good at it, but did know something, is that it's never good to starve an amp of power, and you can almost always benefit by providing a little more juice to run on. I'd be curious to hear Kevin Gilmore's view directly, but I'll bet his electrostatic headphone amps don't use a 9v 1A supply, and that it would be a good thing if the E/90 could pull however much current the music tells it that it needs. Now, if Kevin says the E/90 absolutely never needs more that 0.25A, and 1A is plenty of cushion, then I'd say the stock supply is almost certainly adequate.
 
The other thing is that if I'm right, then the area that should benefit most would be the area that many people complain about with the 950s, the so called bass slam, or what I would describe as running out of steam, which is often as much an amp issue as a speaker issue when it happens with full size systems. Maybe that's what's happening here. (That said, to be honest, I find the 950 to be amazingly natural sounding, with slam being a high point, and very realistic, although I admittedly haven't heard the top dynamics or recent orthos.)
 
I think I'll spend the $15 on that 4A supply and report back, and do my very best not to be fooled by my desire both not to have spent the $15 in vain, and to be correct.

Kevin has spoken in the post above you and PM's being just that, will remain PM's. I believe you will be very happy with the upgraded 4a supply you have chosen. Please let us know your thoughts. satwilson

 

[Kokomo O]

Well, I think Kevin is suggesting that adding a different power supply may not be all that effective, and that a proxy for doing so should be using the battery pack to see what a 3A power supply will do for me, or for any of us that use the E/90. I'll give that a try. It's been a long, long time since I've used the battery pack.
 
I do note that it appears that the 4A supply that I found on Amazon and linked to in my earlier post appears not to be regulated, and I'm having trouble finding a regulated 4A supply. That leaves that 3A Mouser supply that Satwilson found and posted about. So, we'll see if the 3A of C cells makes a difference to my ears--if so, I'll try the Mouser. If no, perhaps one of these days I'll get a Stax amp, or something else. Can't report about the battery pack now, because as usual I've got three C-cells in my new battery box upstairs.

 

[n3rdling]

Is there any way to power a mini KGSS board from a wall wart or does that require an extra stage?  I have a chunk of aluminum billet that I want to carve for something nice, but it's too small for a full on build.  I'm surprised nobody has the E90 schematic.

 

[HiFiGuy528]

I'm using this with wonderful results.  It's adjustable to 9vDC via switches on the bottom.
 
http://www.tekkeon.com/products-mypowerall.html
 

 

[DefQon]

HifiGuy I enjoyed watching your ESP950 review but you said very alike to the actor Ray Romano from Everybody loves Raymond. lol

 

[kevin gilmore]

I have the e90 schematic. have had it for 10 years.
Its been posted a few times.

 

[jcx]

E/90 internals: http://www.head-fi.org/t/262845/the-koss-esp950-thread-esp-owners-please-contribute/285#post_6208556
 

the E/90 is powered by a 9 Vdc 1 A wall wart, center positive, line rating 15 W
 
mine measures 14 Vdc open - clearly not regulated - must accept a range since it also uses 6 cell battery pack which could be as low as 7.2 V with rechargable 1.2 V cells
 
some have sugested using regulated DC supply - the E/90 spec sheet claims 320 mA typical current draw

 

[spritzer]

  Is there any way to power a mini KGSS board from a wall wart or does that require an extra stage?  I have a chunk of aluminum billet that I want to carve for something nice, but it's too small for a full on build.  I'm surprised nobody has the E90 schematic.

 
Sure, that wouldn't be a problem.  I even have the PSU's here that could give +/-320V or so at a cost of 20$... 
 
Two high voltage switchers run as bipolar off a 13V DC line.  Yup it's official, the mafia has started to use switchers. 

 

[Kokomo O]

I've spent some time with the battery pack attached, using regular C cells, not rechargeables. I don't hear any difference, comparing the same track heard with the battery pack and the OEM transformer. Granted, this is me making the change between tracks. I really should have my son or someone else change the tracks, and then switch places, so we at least have single blind trials, since I'm not sure double blind would be possible. But I don't hear a difference after about a half dozen comparisons.

 

[s1rrah]

I have a ES 950 system on the way and have been following this thread. One person discussed feeding the E/90 energizer from the "variable" output of his DAC/Headphone AMP.
 
I am curious if this could be harmful to the E/90 energizer? I intend to eventually get a decent Stax amp to use with the Koss cans (it's shipping with an extension cable modified with the Stax connector at one end).
 
But in the meantime, I'm going to try some of the hacks/mods I've found in this thread (the 3rd party power adapter, etc.) but also was wondering if it would be damaging to use my dynamic headphone amp (a Ray Sam Raptor as a sort of "pre amp") and possibly as a way to add a bit more "heft" to the sound.
 
So is this ill advised? I've read that it is possibly damaging to Stax amps to use "variable" outputs with their energizers and would just assume that the same principles would apply to the E/90??
 
Thanks for any information...
 
.joel

 

[spritzer]

You could get the input stage to clip with excessive input voltage but you should be fine in most cases.