audionut

Uh, Yes, To clear up the "huge cap" comments, those are actually 100nF or .1uF, same spec as the ones in the BH and KGSS bias circuits. This circuit, which was drawn over a year ago, was just to verify with KG whether I had the components in the right places to try the extra filtering. Again, it hasn't been used in quite some time, but did work just fine for testing purposes back then. My damn ESP's were working fine again last night with bias set at 600V. So, I'm at a standstill and can't exacty experiment unless they start acting up again.

Yes, I may experiment, but I no longer have this exact same bias supply in my KGSS, as I went back with an adjustable one. Also, gonna have to see if my phones will act up again, and if and when they do, I'm gonna try the extra 5M resistor in series for a 10M total and see if that helps. To see which bias circuit I'm using, just look at the eXStata bias circuit, which is what I'm currently using im both my stat amps. Will report back if I find anything.

[ATTACH=CONFIG]2739[/ATTACH]

Manaox2, Yes, thanks, but I will have to do it this evening as my wife knows how to do this. Sorry, I'm not real good at posting diagrams, pics, online, but will hopefully have the circuit posted after I get home tonight, so Spritzer can see what KG reccomended. I have it drawn and saved using the Tina Software.

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Looks like my link above for the bias didn't work. Will try to figure it out and post later.

The final circuit ended up like this C:\Documents and Settings\Tommy\My Documents\Tina Bias 2.htm However, my KGSS no longer has this bias supply, as I recently went back to an adjustable one that's identical to the eXStata bias supply. Wouldn't you know it, my phones last night wouldn't act up (first time they've been good in over a week since getting them back from Koss) with my KGSS and bias adjusted to 500V. Didn'nt inrease it anymore as I wanted to listen noise free for once! Anyway, guess I'll increase to 600V tonight, and see if they'll act up. If they do, I'll add the 5M in to make it a total of 10M, and see if that helps.

Yes, let me clarify about the "noise". Mine actually makes 2 different kinds, one that I would describe as the squealing noise, and one that' more of a static noise (think TV snow noise, only not as loud). Since mine are fairly new, don't think it's a dust problem, because I've lightly blown them out on occasion, with no difference. Frustrating to say the least. Spritzer, you mentioned adding another 5M resistor. I can easily do this tonight, but exactly where are you talking about adding it? Were you saying to add it in line with the bias pin, which is very easy for me to do as both my KGSS and eXStata are not cased up? Let me know, as I can easily do some experimenting to see if this can be worked out.

QUOTE=HeadphoneAddict;331848]audionut, that's great information. I want to add that for the year that I owned ESP-950 with stax cable (bought from Spritzer) that I never had any squealing issues when used with SRM-1 Mk2 Pro, Woo GES, SRD-7 Pro, or E90 with adapter. It only seems to be some ESP-950 that do this, but not all of them. I really wonder why that is?

Gentlemen, This is going to be a somewhat long post regarding the infamous noise/squeal problems of the 950's. After reading Cetoole's posts on the E90 bias circuit, I feel I needed to add my experiences with the problem over the past year, so here goes. I bought my 950's new in December of '08. No problems with noise whatsoever with E90. After about 2 months, decided to build a KGSS P2P, which I did. The dreaded noise showed up in right channel only with KGSS bias set at 600V. Funny thing was, I could take the bias supply from my opened up E90, and use it for bias while using just the amp section of my KGSS, and all was well. I had many emails between KG and myself, trying to "fix" the bias problem with my KGSS, so I didn't have to use the E90 bias. He ended up telling me to try a using a zener string instead of the adjustable bias, with some extra filtering. The zener string worked, but I had to use 450V string to not have the noise issue. Anyway, after a few months, I decided to experiment by adding different zeners in to gradually get the bias up to 600V, and guess what, it worked, with no noise. This combo worked flawlessly for over 8 months, 600V bias with my KGSS. Fast forward to a couple of months ago, and my phones fell off my table and broke the headband where it attaches to earpiece. Sent them to Koss for the repair of headband assembly, and when they came back, the noise was back. I've sent them back to Koss 2 times in the last month, and both times, they still are making the noise in right side only. I got to thinking back to my original KGSS build and all the experimenting I did, and remembered after Cetoole's observations and posts, that my E90 read 597V before the resistor, but it read very low at the actual bias point. Yes, I know, my 10m Fluke 83 will load it down, but on my KGSS and eXStata, it loads it down way less. I never got around to measuring or looking at the actual values of the resistors used in the E90, but I, like Cetoole, think that the actual Koss bias is significantly lower than the 600V that are used in the KGSS and eXStata. I'm not really qualified enough to back this up, but I really feel there's something really different about how the E90 bias is developed, and that it isn't "a true" 600V bias supply as compared to the ones in the DIY amps like my KGSS. Tonight, I'm going to experiment yet again, and vary my bias down on my eXStata down to 350V or so. I do know for a fact, that when I hooked it up to the low bias circuit on the eXStata, and varied it up as hi as it would go (340V or so), no squeal or static. Really sounds like Cetoole maybe right, and the actual bias for the 950's should be closer to 300V. Again, hopefully someone (KG, Spritzer) can confirm this or finally figure this out.