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Old 08-31-2022, 04:07 AM
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Listener in Training

Join Date: Apr 2009
Location: Old City
Posts: 2,528
Default McIntosh KT88 and 12AT7 tube impressions/experience

We've owned a pair of McIntosh MC2301 mono block power amps now for 4 1/2 years now. I bought a set of new Genalex Gold Lion tubes (16 KT88s and 4 12AT7s) back then, but waited until now to roll the Gold Lions in and replace the stock McIntosh branded tubes (my understanding is they are made by JJ for McIntosh). There was no special reason to roll now, except that our son is in town, and was willing to help wrestle these heavy amps and do the rolling with me. After the Gold Lions burn in a bit, I may compare, but this post is about the stock tubes and hopefully may help someone thinking about buying tubed gear.

The amps have been in service for about 44 of the 54 months we've owned them (put in storage for 10 months while we lived in an apartment while building our current home). I'd guess that we've averaged between 2.5-3 hours playing per day, which may seem a bit high, but they are used in the home theater setup as well as stereo from the C1100 preamp. That puts our usage on the tubes at ~3,700 hours, likely a bit higher.

I have an Orange VT1000 tube tester, which does a number of tests, but only shows an output of Good/Worn/Fail vs. detailed readouts of the individual tests. All the tubes showed Good and a numeric ranking of 7-11, with over half of them rating an 8. The upshot of all this is that the stock McIntosh power tubes were still going strong, and I plan to keep them since they test well and sound fine, and can function as backups.

These amps were our first major foray into tubes, and I had a lot of questions about going over from solid state amps, not least of which were regarding tube life and the possibility of degradation in sound over time. The bottom line is that my experience with the McIntosh stock tubes is that they have performed well for something approaching 4,000 hours and still have plenty of life in them. This isn't exactly a revelation or unexpected, but may help someone considering a tube amp for the first time get an idea of what ownership entails.
Sources: Vinyl: Clearaudio Innovation Wood turntable with 9" Universal tonearm, Da Vinci V2 cartridge, Stillpoints SS & Stillpoints clamp, McIntosh MVP 901, Apple Mac mini via Benchmark DAC 1, Aurender N100C via Schiit Yggdrasil
Control: McIntosh C1100, Mcintosh MX151
Power: Mcintosh MC2301s (front), McIntosh MC501 (center), Mcintosh MC402 (rear)
Speakers: Sonus Faber Amati Futura (front and back), SF Vox center
Power/connections: PS Audio Power Port receptacles, RGPC 400 pro (2) WireWorld interconnects and speaker cable
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