Lab12 Melto 2 - tube rolling

To add, I have borrowed NOS Siemens from my friend and a pair of NOS Russian 6H23P EB tubes I can test in place of the Electro Harmonics. 
I will report back after hearing these tubes. 
 

My thought process is because I bought this phono amp used I don’t know how many hours are on the tubes thar are currently installed. Seller said low hours. In several years even at 1hr per day average that would be 300+ hours per year. I will assume the tubes have between 2000 and 3000 hours. Not a lot of people buy this level of phono stage to have it sit around. 
The sound is absolutely spectacular. I am running it at 58db gain and 240ohm load which in my system is a good match. I will fit this unit with a fresh set of tubes just as a piece of mind. Which tubes…will see. 

“I have borrowed NOS Siemens from my friend and a pair of NOS Russian 6H23P EB tubes”
@audphile1 

Good call, that’s really the only way to find out how responsive the Melto2’s tube circuit is to tube rolling.

The tubes in output stage in theory has no voltage gain as @lewm pointed out but in real world, they behave quite differently.  A cathode follower has no voltage gain, it’s there to lower output impedance, provide current and buffer stages. So on paper, it shouldn’t influence the sound much, right…lol! 

But in real world, it still does. Tubes differ in transconductance and behavior under load, which affects microdynamics and low-level detail. They also shape the distortion profile, influencing tone, texture, and decay. Since a cathode follower is about current delivery not gain, how a tube handles dynamic current impacts attack, ease, and overall musical flow. 

If one is averse to tube rolling, you might as well buy a solid state component and call it a day. IMHO, you don’t tube roll or buy a tube component to change the sound or add coloration….you buy them to make the music bites feel more human. 

@lewm ​​​​@billstevenson 

There’s definitely a difference. And it isn’t small.

With the Siemens 6922 the sound is bigger and warmer without the sibilance (albeit very minor) I noticed on female vocals with the EH tubes. 
Dire Straits “Calling Elvis” from On Every Street album sounded bigger than ever with the drums and the bass laying a massive foundation. The drums hitting harder and weightier. 
Took several hours for the tubes to settle. At first they were a bit tipped up in treble. Once warmed up…Biggest delta in bass, overall warmth of the presentation and size and weight of instruments. Vocals are honey. No noise. Dead silent by the way, just like the EH. 

Next up is the NOS Russian 6H23P EB. 

 

Very interesting.  I am learning all the time and appreciate the update.  @lalitk thank you for your comments as well.  I almost makes me want to tube roll on my ART Phono...nah.

@audphile1 

Drop the stylus on “You and Your Friend” from the same album and get ready to be blown away by the inner detail. When the electronics are properly dialed in, you start uncovering just how much nuance musicians and recording engineers have packed into those familiar tracks.

@billstevenson 

Haha, the temptation to start tube rolling on the ART Phono is real but I completely understand…just enjoy the music. CJ does an exceptional job with carefully selecting and matching their tubes. I’ve always wanted to own CJ phono, just never got around to it. I got my eyes on Phasemation EA-1500…let’s see what audio gods have in store.