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Yes, get a good handle on what you're hearing.  What you like and what you don't like.  Then step back, so to speak, if there's something you don't like try to figure out if it's as a result of the tubes or possibly something else upstream that is now being revealed.

If you haven't tried the CryoTone 12AU7-WCL long plate, try it!  But not right away.  Listen to what you have for at least 40 hours and then try the CryoTone 12AU7-WCL in the UFO25 input position with a good adapter.

BTW, I isolated the hiss to one of the ECC88’s in my preamp. Since I just put these back in, I’ll see if I should try to let these cook for a bit more before anything else.

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These are the adapters that I got.  There may be better, with these I had no complaints.

I got 2 ceramic gold plated socket and 1 with the Korea tin plated Korea socket.  I think the Korea may be a Belton socket.  I decided to try each in turn to see if there would be a difference in the sound.  There was.  When I had my CSP3 I had the gold plated in it and the tin plated in the UFO25.

Right now my system isn't set up so I don't know which I will end up using in the UFO25.

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No you're not crazy... mind you, some think that audiophiles are crazy 🤷‍♂️.  
There could be a number of reasons to explain what happened.  In some areas incoming power is affected at different times of the day and that can have an affect.

Once I had a similar experience and couldn't figure out what was going on until I noticed that the rectifier that I thought I had rolled in fact I didn't roll.  The original was still in place! 🙄🤦‍♂️ felt like a 🦍.

James, you had me at “I’m home”.  What a beautiful way to describe it! I can relate to it considering I took a 2-month hiatus from listening and what I am experiencing now is “I’m home and it looks damn sexy after the remodel’ (I hope I can also say that about the actual house once the on-going remodel concludes).

Thx—for clarifying that your comment was based on the other 300b amp.  With Sarah, I think I’m getting both (beauty and truth).

Love that you’re already tube rolling—-fantastic discussion from other members—-lots to learn from this thread!  I have for now decided to take things slow (I’ll share more in my thread).

Oh, can we have a picture of your new setup please?

This has been a very interesting day....and it isn't over yet.

I started out by going back to the 53KU rectifiers, which sounded really good. More air and more space, but slightly less bass compared to the GZ33. Then I added one of my favorite input tubes from the UFOs, RCA black plate 6CG7. For those unfamiliar, the 6CG7/6FQ7 tubes are 9 pin tubes with the electrical properties of a 6SN7. You can use them in place of a 6DJ8/6922/ECC88 without an adapter. They made the sound even better, but I figured I should try a 0D3 instead of a 0C3 in front and wow. With the bias switch at high the sound was just amazing. Huge sound stage, tons of detail, all the bass I could want (or expect from my 6 1/2" single driver speakers) and just the most living, liquid sound I've ever heard.

I could have stopped there, but the 6CG7 was so good there was another tube I wanted to try. I picked up some ECC40 tubes to try in my (non-Decware) 300B amp. They are an early attempt to miniaturize (i.e. make cheaper) the 6SN7 and they have a funky 8 pin English base. But you can get adapters for either a 6SN7 or 6DJ8/6922/ECC88. They were too warm and rich for the 300B amp, but I thought they would play well with the '25s and I wasn't disappointed. They sound like the 6CG7, but are more dynamic and with more bass. The sound stage is still huge left/right and up/down but has kinda collapsed front to back (which was never great in my room) so that is a bit of a downside. I'm not sure how these are going to play for the long run, but right now the sound is amazing.

Re: break in. For the last few days the sound has been very consistent on my '25s and (knock on wood) I feel like I'm through the weirdness. I'm not a patient person so I like to run new gear overnight to get it broken in faster. And when I do that with amps I run them pretty hard, both by playing them louder than I would ever listen (I play them into a dummy load and set the volume right below clipping) and also going with more aggressive material. IMO what new caps really need are transients, and harmonic complexity. I play a lot of big, modern orchestral music and I have a "burn in" track from an old Stereophile test CD that is a bunch of people pounding on pots, pans, drums and other noise makers plus electronically generated low and high frequencies that I run for a couple hours each night. I also have some Tibetan singing bowls albums that I would listen to when I needed to chill out after a bad day at work, but after Steve said they were good for breakin I mix them in too. To me they sound like tuning forks (pure tones) rather than something harmonically complex, but whatever. So I play the amps for 10 or so hours over night then turn them off for 3 or 4 hours in morning to cool off. This worked really well for my UFOs and it seems like I worked equally well for the '25s, but JMO/FWIW/YMMV and all that.

What I learned over my Thanksgiving Vacation:

• The UFO25s have amazing powers of resolution.

• The 53KU Rectifiers may not be right for the '25s after all.

• If the 7308 tubes don't sound good something else is wrong with my system.

• Even though the front VR tubes and bias switch have big impacts on the soundstage, you still need to move the speakers to get it right.

So, the long story short is I was a little frustrated that the 7308s didn't sound better than meh in the new amps. Maybe it isn't healthy to have an emotional attachment to vacuum tubes, but 7308s and I have been together for a long time, and they've sounded great wherever I used them. So I went through a ton of tubes, both in the '25s and my (non-Decware) preamp and ended up very close to where I started the whole journey:

Mullard GZ33 rectifiers.
Mullard EL822 power tubes, with adapters.
Amperex 7308 input tubes
Raytheon 0B3 in the back
Hytron JAN 0C3 in front.

The story has a happy ending because for the last couple days I've been listening to the biggest, most detailed, most dynamic, most intoxicatingly liquid sound I've ever heard. I need to get the preamp and the speaker placement just right for everything to finally lock in. Now all the other tubes are back in the caddy (for now) and I've stopped worrying about tweaking stuff. I'm just listening and it is a great place to be.

CAJames wrote on 11/28/23 at 00:26:53:


It's always great when the first dance ends and you can sit and talk. I've been in and out of that stage lately. These amps have so many potential worlds of sound within them.

CA,

I’m most interested in changes to your speaker placement.

What is your room size, and before the 25th’s speaker location, and after?

Toe in?

Love following the progress! Yours as well as Kamrans.

Best,

Geno

FWIW here is a picture of the room (and Nicholas) from another thread, when I still had my UFOs:



The open side is to my right, and to the left there is a fire place.

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Your room is also extensively treated, a situation in which I am unlikely to ever be.

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Yes, that is exactly what I'm doing. You don't need any changes to the stock amps to run balanced, you just need the custom XLR -> 2x RCA jumper. I had mine made by a seller on ebay.

As for a preamp, I'm using a Woo Audio WA22. It is also my headphone amp. For me personally I learned a long time ago I need a tube preamp in my system. It adds just a little bit of secret sauce to the sound, in addition to the convenience features.

If you pursue this I'm very interested in your experience.

So I've been re-listening to some of the recordings that sounded "beautiful, but maybe too beautiful" with my non-Decware 300B amp. And the differences between it and the UFO25s are both subtle and shocking. The overall "sound" is pretty similar, the big difference is the 300B had a little juicier low treble to high bass while the '25s have more high end sparkle. But the '25s are shockingly more dynamic.

I guess the word that I would use is sudden. Both loud and soft seem to jump out of the speakers. I knew the 300B transients were smoothed out a little, but I didn't expect anything like this. Its been almost a year since I was listening to my UFOs (with the anniversary mods, also balanced monos) but I'm pretty sure I never heard anything like this with them either. It is resolution like this that was the reason I wanted to upgrade to the UFO25s, and good on me because this is sound I've been looking for. Imaging in my room is never going to be great (although the '25s image better than anything else I've had) so the spatial illusion of "musicians in the room" is less than convincing. But the sound of musicians in the room is remarkably lifelike. Better than lifelike in a lot of cases because the recording was made in better acoustics than a lot of venues where I've addended concerts, or played or practiced myself back in the day.

Has it really been over a month since I posted in this thread? I've long ago stopped counting the hours but I'm sure I'm well over 500 hours on the amps. Before Christmas I did one more big tube tryout day, because there were tubes on my "list" that I still hadn't heard. What I settled on was a bit of a surprise.

Mullard PCC88 input
Mullard EL822s power
RCA 5R4GY, WWII, DD getters rectifier
Hytron 0C3 in front
Raytheon 0B3s in back

Neither the PCC88 or esp. the 5R4 was anything special on my UFOs, but on the '25s they have that goldilocks balance of speed, transparency and tube yumminess. Maybe just a little less speed and transparency compared to the 53KU, but the extra yumminess more than makes up for it. What they really do it highlight the tubes I have in my preamp, which I also feel like I have well sorted. So for the last several weeks I've been just listening everything sounds great. No promises, but I'm not planning on making any changes for a while.

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Yeah. The one thing I'm still temped to do is try more VR tubes, both front and back. But so far that just seems like "too much work."

Tony, that made me laugh!! Yeah, guilty... I just futzed. James got me curious again. I'd tried the 0B3's in the output VR position several months ago and determined it wasn't for me, but couldn't remember why. Sylvania 0B3's warming up in the amp as we speak.