Van Alstine Amp: Mod/upgrade suggestions, anyone?

This is an Omega II 260 (130 W/ch) amp from 1996, and I'm asking for some suggestions in upgrading its SQ/performance. It has not been used that much so the electro caps should still have several 100 hours left in them.

Under the hood, this MOSFET amplifier features a circuit with "no overall feedback". Nevertheless, "feedback does exist," according to avahifi.com (Audio by Van Alstine), via a "unique active and buffered powered feedback loop that is electrically and thermally matched to the active input parameters". The result is "smoother, quicker, tighter and more detailed audio without the solid-state artifacts", avahifi.com claims.

Internal components include eight big die heavy-duty TO-3 Hitachi J50 power MOSFET devices, a Plitron toroidal-transformer-based power supply, and the input and output circuits. The power supply section is bottom-plate-mounted near the front and the input/output section is horizontally-mounted on the back wall.

The parts quality is generally good, but the soldering work is a bit sloppy.
The MOST PROBLEMATIC aspect, as visible in the pics, are the glued heatsinks for several solid-state devices (to-92 transistors and op-amps). Not sure why they are used ... to genuinely cool the devices (they run cool on finger-touch test), or as an anti-reverse-engineering tactic as they cover up part identification info.
AVA_Omega_260_1996_IMG_9066_061105_155130_small.jpg
AVA_Omega_260_1996_IMG_9067_061105_155500_small.jpg

AVA_Omega_260_1996_IMG_9069_061105_160000_small.jpg
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kevinkr

Administrator
Paid Member
Presumably the heat sinks are there to actually cool the parts, there are much cheaper and easier ways to obscure what the parts actually are if desired.

IIRC AVA was always pretty good at sharing schematics with people who owned their mods. (Usually came with the original kit.)

You might just contact them and ask for schematics and any recommended improvements.
 
Presumably the heat sinks are there to actually cool the parts, there are much cheaper and easier ways to obscure what the parts actually are if desired.
Maybe, but heat-sinks could simply be a slicker (= more "tactful") way to obscure. Untactful or , in layman's parlance, TACKY anti-RE methods include crude-n-cheap permanent marker or sand-/file/Dremel-off.

Dunno ... it may be just my (overly)suspicious nature ... but, like the "sales-talk" on the company's web site, the heat sinks might have been put there to look fancy and purposeful (and/or the infamous "security-via-complexity" trick).

IAC, I've never seen heat sinks on those ICs before ... not in the DIY community and not in high-end gear. In fact, very rarely (if ever) have I seen heat sinks on audio-gear ICs or non-power-transistors.

IIRC AVA was always pretty good at sharing schematics with people who owned their mods. (Usually came with the original kit.) You might just contact them and ask for schematics and any recommended improvements.
I think AVA has changed his "philosophies" since the 80's. Not really a kit supplier or DIY outfit or even a mod-house for your old Dyna/Heathkit/Hafler gear. His main biz is made-to-order stuff from the online catalog.

BTW: Yes, I and others have asked for schematics. AVA is, shall we say, hostily uncooperative in this matter. Maybe he has a reason to be: i.e., to protect his IP. That said, and IAC, the guy seems to be kind of a crook:
The Audio Critic (and other publications') revealatory articles about AVA gear are sprinkled throughout the Net.
More here.

Back to the orig. query ...
As noted above, this design is from 1996. FYI, AVA patented his design in 1986:
Forward transimpedance amplifier US 4,801,893
Modern versions of this amp are now called the "Insight" series -- although I haven’t kept up, I assume the design has been updated and "improved" several times since 1986, and my purchase in 1996, respectively.

So, beyond replacing stock with boutique parts, how can this design be improved ... even a little?

Thx!