McIntosh MC275 VI preamp tubes

From another forum...

Telefunken Elektroakustik is the company name, a partnership with JJ tubes. The Telefunken Elektroakustik Black Diamond tubes are essentially JJ tubes that have been cryogenically treated, silk screened in black with the Telefunken logo, tube designation, and sold in Telefunken packaging. They are definitely not Telefunken old stock tubes made in Germany. These tubes are being manufactured in Slovakia.

I should have known I couldn’t recall correctly. It was Ei in Yugoslavia that bought the Telefunken equipment according to this web page:
12AX7 Tube Gems - Tubes for Amps

Which is kind of odd, in a tube nerd kind of way, because Ei was owned by Phillips who owned many brands like Mullard, Amperex, Siemens, Valvo, etc. but not Telefunken. Maybe Phillips cut Ei loose when demand for tubes began to drop. Anyway here’s a quote from the link above:

"Ei was a tube factory that operated in Yugoslavia. Ei had close ties with Dutch Phillips. They even coded their tubes just like Phillips did.

Ei also supplied OEM tubes to companies such as Telefunken when they shifted their focus away from vacuum tubes. In fact, Ei built their small tubes on tooling supplied by Telefunken.

Now, although Ei got their tooling from Telefunken and tutelage from Phillips, their quality control tended to be minimal. So Ei screened their small signal tubes and labeled the good ones as Elites and sold at a higher price. They also offered gold plated pin version as Elite Gold."

Prices for 12AX7 RCA's have really increased. Take a look at Brent Jessee's stock of GE tubes, about $50 each.

+1 @tomcy6 .
I agree, don't expect these tubes to sound like NOS Tele's.
The risk in trying them is that JJ manufactures them, not known to be very durable tubes.

I tried the Gold Lions in my McIntosh C2500 preamp and didn’t care for them at all.  I went back to the McIntosh branded tubes which by the way cost me $15.00 each and they most certainly did not come in a wooden box with their name burned in on them. I wish they did though. 

The Black Diamond Telefunken tubes are are made by JJ in Slovakia:

"TELEFUNKEN vacuum tubes have been the benchmark of excellence in all audio applications, both production and reproduction, for many decades. This rich history continues with the introduction of new production tubes from TELEFUNKEN Elektroakustik, in partnership with JJ Tubes from the Carpathian Mountains of Cadca in Slovakia."

JJ tubes in general do not have a reputation for good sound, but the black diamonds may work for you, who knows? The one thing to be aware of is that new production tubes have nothing in common with the vintage tubes whose names they use. These new production tubes license the names from whoever owns the rights and that’s it.

Some of the classic tube makers sold their equipment to others when they shut down production. I think Telefunken sold some equipment to Tungsram and some Mullard equipment went to Japan, IIRC, but even then the tubes produced were not identical to the originals. They could be very good tubes though.

@ mrklas, I concur with @oldhvymec.  When I first got the MC-275 it sounded really good...much better than the parasound A23 I had.  However, it was a little bright and the bottom end sounded thin...again, still better than the Parasound.  I did seek out Brent Jessee, and bought a mix of Tung-Sol and Mullard's...I think (it's been 4 or 5 years), and it changed the sound, a little more well rounded overall, but still wasn't entirely happy.   I ended up settling on used RCA tubes that I got from an estate sale.  The best sounding so far.

@noromance , It could be the KT-88's, but the reason I'm leaning more toward the preamp tubes is because the Golden Lion KT-88 I purchased new.  I also have a Golden Lion new 12AX7 in the inverter spot.   As I mentioned, the 12AX/AT7 were used RCA's from an estate sale.  That's why I suspect those over the power tubes.  I will say the RCA tubes are just absolutely excellent with my system. 

I was emailing back and forth with Ron Cornelius from Mcintosh in 2016 when I first got the MC-275.  He mentioned that the tubes should last on average 5000 - 10000 hours unless driven hard for long periods of time (something that can easily be accomplished by myself as a preferred metalhead, hard rock, blues, then jazz fiend in that order).  He also mentioned that the Mark VI version has the color changing LED's when a tube goes bad, but it's only for a catastrophic failure.  It does not alert you when a tube is getting weak.  

My friend and I went in on a tube tester years ago....but I ended up moving only 13 hours away...so checking the tubes is a bit of an endeavor.

Years ago I heard that the Telefunken tubes would be the best if I could find them and afford them (at the time they were running about $300 - 400/tube).  I see that they are making new black diamond Telefunken tubes...has anyone tried them before? 

If push comes to shove, I'll pick up a batch of RCA tubes.  I am just beginning to worry about how much life they have left in them.  I just wonder if the Golden Lion KT-88's have been as good as they are, then how about their 12AX7 and 12AT7's are.  

Why not buy exact replacements? I may be counterculture in an audio forum but what’s wrong with the date you brought?

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Because anything is better than the current stock Mcintosh super cheap Chinese valves they sell at 100 times the price THEY paid.. Talk about CHEAP valves.. Under 5.00 each in bulk. 3.00 usd, is more likely.

But there are people in some countries trying to sell them for 2-4k. because of the 10.00 wooded box they come in, and the word Mcintosh burnt in the wood.. 300.00 usd worth of CHEAP valves at best.. JUNK..
The shipping cost more than the actual valves..

Regards..

I bought 6sn7’s from Brent Jessee for my Cayin Integrated Amp. I always test new tubes when I receive them, they were good.

http://www.audiotubes.com/12ax7.htm

I did not like their sound.

He had me wait and listen after breaking them in (60 hrs), and if I still didn’t like them, return/exchange them. I paid shipping, bought less expensive tubes, they sound terrific, and got a full refund for the originals.

Make your best guess, buy from Brent, see if they sound good, Oh Happy Day, if not, try another.
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Do you have a tube tester?

they give you good clues, and confidence in existing and new ’matched’ tube sets. find problems, find non-problematic but weak(er) ones ..... I test all tubes annually prior to Thanksgiving, ready for the Holidays. They last a longgggggggg time.

My simple tester always agrees with my big one, I don’t bother with the big one any more. All 17 tubes of my McIntosh mx110z’s tuner/preamp tested good here. Audio Classics overhauled it, they didn’t replace any tubes, (surprising from past experience with others). That gives you more confidence in them as well as my tester.

you may want to test the input tube for performance. As others have noted, they usually last quite a while. If you do not have a MC tester, some places offer testing for a reasonable price 

Re-reading this. Small signal tubes last a long time. You sure your KT88s are not getting tired? I suspect they might need re-biasing, if not replacement. 

Why not buy exact replacements?  I may be counterculture in an audio forum but what’s wrong with the date you brought?

I can appreciate upgrading and I’m a history major. So I make engineers and scientists to achieve my goals. 
I have  MC 2600 preamp and I appreciate the impact of my preamp. I’d be more inclined to add a phono stage than change the phone tubes. After all that engineer is more trained than I. 
If I final a better preamp, I’d be happy to buy it and would rather upgrade than try to tweak myself to the same results 

# 1 Telefunken or RCA (I don't trust to many of them any more RCAs)
Valvo, Mullard, Mazda, Marconi (Expensive) or Tungrsram (Expensive). Then Tung sol, GE, GL (not a big fan of their little valves) Sylvania (always bright).. GL KT66,77,88s good stuff, great sound.. KT66 in particular..

Regards

+1 on the GE 3M/BP. They are a fine tube but not suited to all applications due to their lower gain.
At your price point, the Gold Lion are a good choice. 

Andy at Vintage Tube services in Michigan.  is my go to guy for great tubes

A vintage 12AX7 that's still a rock solid value is the GE black plate 3 mica 5751.  Good examples can still be had around $100/pair.