I installed this opamp into a mil-max socket and then installed sockets in my latest version of my Pocket amp. I had all IC's soldered directly into the Board in keeping with High-Speed lay out Practace and used the layout around the opamp based upon the Evaluation board for the TI # THS-4022. so this Required me to Install Matching sockets on the Board to allow future IC Changes if Needed. The Addition of sockets did not seem to degrade the sound.
My pocket Amp is similar to tangents META42 but done My way using Walt's multil-Loop Feedback topology. IMHO this results in the best sound i have heared from Audio Amps in Monolithic Form. The Ability to controll the amount of Open-loop Gain is quite nice in an Opamp based design. I have tried other attemps to control the opamps open-Loop gain or shall i say reduce it by using matching resistors from the DC offset pins and One to ground and the other to the opamps output. this works with some but not all opamps it depends at what internal node the offset pins are on and is not an option with Dual opamps since Offset control pins are not available. This is the Beauty of Walt's multi-Loop topology. The resistor values around the feedback are also different than tangents. in addition the Power supply is more complex by virtue of Floating the Op-Amp Supply rails on JFET constant curent sources/sinks via 2N5911 dual JFET. with one half as the sink on the positive rail and the other half on the Neg. rail as the curent source. This is followed by a TLE-2426 virtual ground Driver Dedicated to just the opamp. This is bypassed with 1,000uF/10V Low Esr 105 deg Electrolytic and 0.1uF Wima Box Film caps. The Output stage consists of a paralel set of two EL-2001 Buffers. My MDR-V6's just don't sound dynamic enough with just one EL-2001 per Channel. The output stage uses two 2,200uF/10 volt low Esr 105 deg Electrolytics Per rail. Local bypasses for the buffers are 0.68uF/160 Volt wima box film capacitors. The virtual ground driver for the Output stage is from an EL-201 driven from another TLE-2426 Virtual ground driver as Tangent did in the Meta42. this is built upon a teflon Board Rodgers ultralam-2000. The board uses a full non broken ground plane with the Plane not around the opamp's inverting input so as to not induce any unwanted capacitence at this Critical node.
Ill get to the sound in awhile since i have to do somthing at the moment and The Microsoft network will disconnect me if left unattended and ill lose all i have typed so far.
OK I AM BACK> THE SOUND In Direct comparrison to the AD-823 the AD-8512 sounds Dark without the Splendid soundstage of the 823. the width is almost as good but the depth is flat, on track 10 of (Stereophile Test CD2)
http://www.me-au.com/stphile.html the person walking around the Church is a full 360 deg soundfield on the 823 with the 8512 this circle takes on an oval Presentation. The Clarity of the 8512 is Good and is slightly cleener than the 823 but this my be an ilusion due to 8512's lack of upper otave extention. On Flute Music this upper otave is Mised on the 8512. on(R. Carlos Nakai's Ancestral Voices Canyon#CR-7010)
http://www.canyonrecords.com/cr7010.htm the natural ambience of the Flute and guitar turn from a nice 3D pannarama soundfield with Lots of natuaral echo on the AD-823 to a Rolled off 2D Presentation with the 8512. The low Frequency extention on the 8512 is better than the 823 on (BachBustersTrack 15, Time warp track1, and california Project track 6 & track 15. All on Telarc. at
www.telarc.com/ the bass flat Kicks But on the 8512 vs the 823. this the 8512 is deffintly a rock and roll Opamp, with softened Highs. The Midbass on the 8512 is also more natural sounding than on the 823. on the R. carlos Nakai recording the acoustic guitar takes on a slight tubby sound with the 823 where as this is not Present with the 8512. The mids are about the same with the exception that the 8512 seems to lack some of the inner detail of the 823. The Blessing with the 8512 comes from Very low power consumption drawing about 2 ma Less than the 823 with +/- 7.4 Volt supply rails. The DC ofset vs supply voltage is also more stable with the 8512 than it is with the 823.
In Conclusion The AD-8512 is a Mixed bag it by no means close to My Beloved AD-8610 in any measure of musicality with the Exception of bass extention and Midbass Accuracy, However still lacking detail in these ranges vs the AD8610. For High End Audio use i think ill wait untill the dual 8610 comes out (AD-8620).
in comparrison To other dual Opamps i listened to at the time of this evaulation The AD-8512 is clearly Better than the OPA-2132,OPA-2134,OPA-2604,AD-712 it is clearly Better in all catigories Sound stage, Punch and Clarity. This makes an OPA-2134 sound vailed and Dark, with a soundstage aproaching Mono. The Oldie But IMHO a Goodie OPA-2107 is better sounding than the AD-8512. However the 2107 is a
Di-Fet Opamp like the OPA-627, However the performance of the 2107 is alot less than the 627 But still if a dual OPA-627 is what your after check out the OPA-2107. it sounds Musical and cleen with the Inner detail aproaching that of the 627. In comparrison the the AD-746 it is no contest the 746 wins hands down. This is a dual AD-744 and a wounderfull warm lush musical opamp capable if reavealing sutch subtilies as the decay of echo's and up to the Time the AD-746 is my favorite for Acoustic music.
