This is my first post on this forum but I read it for a long time ; english is not my first language (I am french) so I hope you will forgive some bad writing...
I like Stax headphones a lot (I can tell I am an addict...), I own one Lambda normal bias, one Lambda pro bias, one SR-X . My amps are : Stax SRM1 MK2 pro, SRD7 SB MK2, SRD7, and SRD6 SB
Source is a Sony CD player and writer RCDW100 (I have a Teac VRDS too, but the tray mechanism is broken and I did not had the time to fix it yet...and I found the Sony sound good enough for the price)
I use SRD7 SB MK2 energizer with a Dual CV 1460 amp (a gem) , the sound is stunning, even better than with SRM1 MK2 pro (yes! no wonder for those who know the cv1460, very well known among vintage amps in Europe for its great sound). The SRD6 SB recently came with an Ebay purchase of an SR Gamma that I don't like (defective headphone, unfortunately...), but itself works fine so I keep the small box. The SRD7 (normal bias) came too from another Ebay purchase with the Sr Lambda, but I prefer the sound I get form the MK2 version...
However I just discovered a little problem : despite the SRD7SBMK2 is the only one I purchased new in a store (all others are Ebay or second hand purchases) in 1995, I discovered today that it lacks a bit of treble compared to SRM1 and the old (!) SRD6 SB. I can hear it, and check it , since I have an Audio Source EQ-One/spectrum analyzer+its own calibrated microphone : for instance measuring Lambda frequency response using the pink noise generator (I use a carboard box with a hole for the mic : simple and effective tool), 16KHz is always 2dB lower on SRD7 SB MK2 than on SRD6 SB and SRM1 MK2 pro (these two having the exact same frequency response on my Lambdas. 8kHz and lower frequencies are all OK on SRD7SBMK2, only above 8kHZ does this problem appear )
Since, despite this issue, my SRD7 SB MK2 has definitely the better sound of the 4 amps (I wonder why, but this is very obvious on midrange, even a bit more "textured" than on SRM1 MK2 pro ! the soudnstage is also a bit better, more "3D", if possible), I still want to listen my Staxes with it first, and think about a worn component that could explain this little trebble issue ??
I did not open it yet, I think since it is self biased there are not many components inside, so anyone has some idea about what I should replace to get a flat frequency treble response ? Some capacitor(s) ? I know nothing about electronics...I just know how to use a solder iron, but nothing more...should I send it to Stax ?
Of course :
-I made all possible combinations between the gears listed (and between "A" and "B" speakers outputs of the Dual CV1460, the result was not changed at all)
-Irepeated several times the measurements
and finally always found the same result : my SRD7SBMK2 has a 2dB audible high frequencies loss :-(
Thank you for your help
Edited by Benoit62 - 10/14/13 at 10:58am