My favorite power tube for my vintage McIntosh MC30 monaural amplifiers have been the gray plate GE 6L6GC's.

The GE's provided a warm, rich, and naturally musical presentation that even the highly esteemed black plate RCA 6L6GC's had to bow down to.

For my hot-rodded MC30's the GE's take musicality to another level, but they are getting expensive at around $90 USD each!

When my GE 6L6GC's finally died a week or so ago, I put in some HARMA 5881 cryo'd valves from Watford Valves in the UK that I bought to try in my Leben CS-600 integrated amplifier way back when.

I don't recommend you substitute 5881’s into an amp designed for 6L6GC’s unless you are sure the amps don’t exceed the ratings of the 5881, as a lot of modern amps calling for a 6L6GC tube will exceed 5881 ratings, which can cause them overheat or arc over.

Given I didn't have any other 6L6GC's to try at the time, I went with the 5881's until some new tubes arrived.

The HARMA cryo'd 5881's actually sounded quite a lot like the GE 6L6GC's in the mid-range to me on first listen, but after a couple of albums I became aware that they lacked the beautiful smoothness in the high-frequencies that the GE's have in spades.

I decided to look over the less expensive new production 6L6GC's out there to see if there was anything having a reputation of a smooth & warm tonal balance similar to the GE's.

As I was reading up on the current crop of 6L6GC's, the Tung-Sol 6L6GC-STR kept popping up as being a smooth & warm sounding tube with a similar tonal balance to the GE's.

Tung-Sol says their 6L6GC-STR's "... are clones of the legendary Philips 6L6GC STR ..." which I haven't had any experience with.

The 6L6GC-STR has a black anode coating which is supposed to give it "a nice smooth, warm sound".

I ordered two matched pairs ($44.50 per matched pair) of the Tung-Sol 6L6GC-STR's from Jim McShane, who is one of my favorite tube suppliers on Planet Earth.

To put a little perspective on price, the quad of Tung-Sol 6L6GC-STR's sell for less than the price of a single NOS GE 6L6GC, so from a cost perspective they're a bargain if they perform similarly to the GE's.

I didn't waste any time pulling out the 5881's and putting the Tung-Sol 6L6GC-STR's in their place.

I proceeded to warm up the MC30's while listening to a little NPR on the MX110Z's FM tuner for a little bit.

It takes about an hour for MC30's to warm up to the point where they're at their musical & sonic best, but I couldn't stand waiting that long, so after about 10 minutes I put Gillian Welch's & David Rawling's The Harrow & The Harvest on the Garrard and let 'er spin!

I was immediately impressed with the Tung-Sol 6L6GC-STR's in my MC30s, and the little buggers gave me goosebumps right off the bat with the way they portrayed Gillian's & David's vocals, with a sense of  immediacy & intimacy that I found very alluring.

It's always a little dangerous to make statements based on first impressions, especially when the Mac's aren't even fully warmed up yet as I'm listening, and the tubes have zero hours on them, but I'm really liking what I'm hearing from these Tung-Sol 6L6GC-STR's in my MC30s.

When I was up visiting my buddy Chad at Lake Chelan in Washington State, he played Fleetwood Mac's Black Magic Woman for me.

I was immediately smitten and ordered a copy of Black Magic Woman of my own from Discogs as soon as I got home!

As luck would have it, my order of Black Magic Woman from Discogs arrived at the same time as the Tung-Sol 6L6GC-STR's, so I got to give it a listen today.

Black Magic Woman was recorded back when Fleetwood Mac was a blues-rock band, before they morphed into the rock & roll band of later times with the addition of Lindsey Buckingham and Stevie Nicks. This might very well be my favorite Fleetwood Mac album.

My buddy Chad has superb taste in rock & roll music, and Fleetwood Mac's Black Magic Woman is a must have if you love blues and rock & roll!

But I digress, as this post is supposed to be about the Tung-Sol 6L6GC-STR's!

I really like the Tung-Sol's. They come across as naturally musical, warm and smooth, transparent and nuanced, with a nice sense of the musicians' touch on the instruments. and as I mentioned earlier, they have a really nice way with vocals.

I don't think these Tung-Sol 6L6GC-STR's sound like the GE 6L6GC's exactly, but they're pretty much in the same league, and in some ways are better, based on my very preliminary listening impressions.

The Tung-Sol's have more clarity & nuance than the GE's, and are to the warmer & smoother side of life, like the GE's. The Tung-Sol's have an electrifying sense of presence about them that makes music sound exciting, which I like a lot.

The high-frequencies are smoother than the 5881's, perhaps not as smooth as the GE's, but more nuanced.

Time will tell, as they're still brand new out of their boxes, but I like them a lot, and if they smooth out a bit in the upper mid-range & highs, they may very well turn out to be a desirable alternative to expensive NOS GE 6L6GC's.

I'll report back as the Tung-Sol 6L6GC-STR tubes get some more run-in time on them.

Day 2 Update

It's Day 2 with the Tung-Sol 6L6GC-STR tubes in my vintage MC30 monaural amplifiers. I didn't have time to get a lot more hours in on them, probably only about 7 hours more as I'm writing this.

I put back on the The Harrow & The Harvest for some listening as a baseline, and I continue to be impressed by the mid-range performance of the Tung-Sol 6L6GC-STR's. They have really nice mid-range tone, with instrumental timbre that sounds very lifelike, and a very interesting acoustic space that wraps around voices and instruments to give them a sort of spooky & spacious presentation.

One thing that has improved noticeably even in this short amount of time is the Tung-Sol's ability to convey tempos (and changes in tempos), and an increasingly dynamic prowess that makes melody lines become more exciting and engaging.

The Tung-Sol's upper mid-range sounds a little peaky & edgy in places on a number of albums I've listened to that sounded natural with the GE's (some vocals and muted trumpets, for example).

I'd like to hear a little more smoothness in the upper mid-range out of the Tung-Sol's, so hopefully they'll smooth out with more run-in time, as that's the only significant criticism I have of them at this point.

With that little bit of edginess as an exception, the Tung-Sol's are right in there in overall performance with the black plate RCA 6L6GC'S and the gray plate GE 6L6GC's, which are arguably the cream of the NOS crop of 6L6GC's.

I should say that I've made enough changes to the Westminster system lately that it's possible that the slight upper mid-range edginess/dryness I'm hearing could be due to one of those changes rather than the Tung-Sol's, so a little investigation is in order to check out that possibility.

More to come ...

As always, thanks for stopping by, and may the tone be with you!