Well, I just got my Apache back with the new National Semi op-amp mod
and made some quick listening tests.
(I will try to do some more extensive evaluation later.)
In short, I unequivocally recommend the NSM mod.
It was a big improvement with all of my phones
(Senn 650s/Zu Mobius2, Grado GS1000s/Moon Black Dragon, and AKG 701s/Moon Black Dragon).
While the type of improvement varies with the phones,
with all there is much more of an overall sense of ease,
and better bass integration and solidity, and sweeter but still extended highs.
There is just a more relaxing sound, and individual musical components
blend together into a nice, silky sound field.
Somehow, the latest Apache manages to ameliorate (cure to a major degree)
the colorations or shortcomings of the phones.
The Senn 650s are less veiled with better image body.
The Grados sometimes high-pitched sound on lesser recordings is still sparkly but
is no longer very painful or abusive.
The AKG's sometimes lumpy bass that was really annoying in controlled,
and the occasional "GLUMP" sound in the upper bass that would drive me crazy is gone.
The Senns gained more roundness in vocals and instruments and
had better bass definition. The Grados still have tipped up
highs compared to the Senns, but somehow the highs are much sweeter
and far less searing and much more listenable,
even on a CD that itself was raw and screechy.
Overall, the Senns were the winner for a totally relaxing and warm but still
exciting sound with lots of fine detail, but with much less grain
or distortion than I use to get with my older Headroom Max. There
is less distortion also than with the original op-amps in the Apache,
and a more open sound, with more fleshed out images.
But the Grados hold there own with the Apache, while less relaxing,
there is much better defined, tight bass, and the extended highs
sound liquid and inviting, less dry and piercing than with the
original Apache or even the Max amp.
The AKG 701 with the Apache also has it's charms. It stands between the
Senns and Grados in terms of high-frequency emphasis, and in that sense
is better balanced than the others. And the bass is now real and
evident, with a quality I never heard with the Max amp--a nice fundamental
bass, but not as tight or satisfying as the Grado bass. It is also not
as warm or relaxing as the Sennheisers. But voices and instruments
are pure, palpable, and realistic, and I can see how many could really
enjoy the 701s (I enjoy them too, but I think I will gravitate the the other
2 phones long-term).
In summary, the Apache with the new op-amp really seems to elevate all
these phones to a new level, and I hope others get to hear it.
(And I would be interested to hear impressions of the newest version
vs. the B52.)
Thanks for reading.
