All this hubbub about the Cryotone tubes, esp the EL84, got me thinking. My first thought is it is going to be a real struggle for my Scottish Heritage to shell out 400+ bucks for (new production) power tubes for my UFOs, regardless of how good the reviews are. And second, apparently you don't need the "Hazen Grid Mod" to get great sound from a power tube. I tried a couple Russian EL84 types when I first got my UFOs and was not impressed, and was not motivated to try any of the more expensive, "heritage" NOS types and it doesn't seem like anyone else is either. (Maybe they are and are just keeping quiet about it....).

But I wondered if there were other EL84ish tubes out there, from the golden age of tube tech, that didn't have a bunch of guitar players bidding up the price... And I think there is one (or maybe two). I present the EL821 aka 6CH6 aka CV2127 aka CV4055. They are upspec'd EL84s designed for high bandwidth video and radar use (sounds kinda like the 6P15P types...). I took advantage of the favorable exchange rate to get some here:

https://www.langrex.co.uk/?s=6ch6&post_type=product

I got the cheaper Brimars for testing, and 6CH6 -> EL84 adapters from ebay. After burning in for several hours I think they sound excellent. Very different from my favorite EL83s, but not in a bad way. The sound (in my system so FWIW/YMMV and all that) is big and bold with really excellent bass. The presentation is very much forward, and maybe not as liquid and detailed but very engaging. Zeppelin literally jumped out of the speakers and music of a more genteel nature, say a Schubert String Quartet filled the room with glorious sound. There is also the very similar, but somewhat more expensive EL822 for which I have high hopes and will be ordering some soonish.

So there you go. Again I have no idea how they compare the Cryo'd tubes, but the EL821 sounds very different from any other power tube I've had in my UFOs and may be worth investigating if you are #tubecurious.

I rarely if ever give strong endorsements for any tubes.  Usually I try only to give my findings as many things can influence what is heard and then there's our own tastes.

In this case I'll depart from my usual approach and say, do yourself a favor and try the Cryotone brand of EL84's!  In the long run you will likely save a lot of money.

I had a SE84UFO2 and now have the UFO25.  I have tried a number of different EL84 power tubes.  None, including the 6P15PEV have come remotely close to what the Cryotone EL84 do.  They are profoundly different.  Not at all edgy or hard.  These were the ones that I rolled first.

The Cryotone ECC88 and especially the 12AU7-WCL and the 12AX7-WCM long plate are very transparent and revealing, which for me is a big plus but for others may not be if the upstream components are not analogue or top shelf digital.  The Cryotone EL84's on the other hand while transparent are less critical of upstream components and get along well with other choices of input tubes.

I don't even want to think of all the money I've spent, $25.00 to $50.00 at time on the different EL84's that I have tried.  I could have bought several of the Cryotone EL84's.

The list of the input tubes that I have tried is quite long, here it is and not in order of preference:

Matsushida/National PCC88/7DJ8, Mullard ECC88/6DJ8, Mullard 7DJ8, Valvo PCC88/7DJ8, Valvo PCC88 D getter, Telefunken PCC289, Amperex BB ECC88/6DJ8 (from the Tube Museum perfectly balanced sections), Melz 6N8S/6SN7, Brimar CV1988 clear bottle and I could go on.

In my UFO25 when I had the 6P15PEV power tubes and a Philips Miniwatt GZ34 Metal Base the Telefunken was in for the longest time.  Keep in mind that I also had a tube set in my CSP3-A that would have an effect.  If it wasn't for that I may not have kept it in as long as I did.

When I rolled the CryoTone in the UFO25 I started with the EL84-WC, then the 5AR4-WC.  While waiting for the ECC88-WC I ended up with the Valvo PCC88 in the in put and it was very nice.  Swapped it out for the CryoTone ECC88-WC and no contest!  I now have the CryoTone 12AU7-WCL in that position.  If you're thinking of a CryoTone for the input I'd start with the ECC88-WC.

In my SE84UFO2, I tried the Valvo, Siemens (I didn't list those) Mullard and Amprex ECC88.  From memory I think that it was between the Amprex PCC88 and Valvo PCC88.

As far as cost goes The Amprex cost $125.00, The Mullards $70.00 ea., The Melz $50.00, the Brimar $140.00 and an Adzam/Philips E188CC SQ $120.00.  The only deal that I ever got that was worth it was a Tesla PCC88 37 Plant for  $8.00!!!  Nice tube, very polite without being overly rolled off, but not up to the others.  I still have some as back ups.  If you have to budget, we all do, you might consider one of these knowing that you will roll it sooner or later.  For $8.00 its hard to go wrong.

The reason that I listed the costs was to show that good NOS tubes are often more than the CryoTone especially now as the inventory has been depleted.

Yes indeed those days are gone, and I still have my hair and 3 Tesla PCC88-37.  With the exception of one or two Mullard tubes, Mullards have not been my preference, although they are nice sounding tubes.

You mentioned in a previous post in response to my recent Omega review that you upgraded your upstream components to a Denafrips Terminator 2 + Gaia DDC + Jay CDT MK3.  Actually that proved to be very helpful.  These are not inexpensive components by any stretch of the imagination.  I think that you're getting a UFO25.  If that is the case then please don't put a limit on your upstream components and the UFO25 with a $40.00 input tube.

I do get that raising the limit may be painful (did you make reference to a Scottish heritage in a post by chance???), but that pain will be very short-lived after the first few moments of listening

I relate to that as the pain of paying for a very nice bottle of Bruichladdich Octmore or Ardbeg Corrywrecken and the pain vanishing after the first sip or two.  HMMM... I think it's time for a wee dram of the Corry....

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Actually I'm getting 2 UFO25s, and that is one issue. I use my UFOs as balanced monoblocks so every tube I get I need two (or 4 power tubes). But really my hesitancy about the cryo'd tubes is because they are new production and cryo'd or not I don't have a lot of faith in them. After you and others on the board been running them for a few years I'll reevaluate, but at the going rate I'm in no hurry to be an early adopter.

I appreciate your concern (seriously). Thanks largely to your suggestion/prodding I stepped (well) outside my comfort zone to get Mullard GZ34 fat-base smooth-plate rectifiers, though I couldn't go all the way to the metal base. And they made a nice improvement until I found I liked the GZ33 even better and it costs less. In truth the $40 limit is more of a guideline than a rule, I've spent (much) more than that, although not necessarily to the best effect. And I have managed to acquire most of the tubes you list for less than 40 bucks.

Of course I also have other expensive hobbies that need to be funded, like buying music to listen to on my fabulous system. And Scotch (or Whisky as we call it in the old country). I just bought a bottle of Talisker 15 and will need to replace my bottle of Highland Park 18 very soon. So cheers!