MC2301 amplifiers - Tube rolling 12AT7's

[jdandy]

Originally Posted by MyPal

Dan... That's fantastic!! What a terrific opportunity. I bet you'll love the TFK ECC801S NOS. Look forward to your evaluation.

I just love the MC2301s with the grills off. My grills are in storage now, permanently!

Steve.......It was your suggestion that started me on this 12AT7 tube rolling adventure. I know you are thrilled with the Telefunken ECC801S tubes in your MC2301's. I was up until 2:30 AM last night. Just couldn't seem to turn the system off.

The MC2301's look interesting without the tube cages in place, but my preference is to leave them on. Once I have completed the auditioning of the various 12AT7's, I will be reinstalling my tube cages.

[Masterlu]

Originally Posted by jfray

Bob thanks!!! I am totally ignorant in the tube world and am curious about the sound (as you already know )

Josh... The sound is heavenly!

[jdandy]

Originally Posted by jfray

I know this is a dumb question but I will ask anyway..... How many tubes are there in a 2301 and how long does it take to change the out? This will be a great review for tube lovers. Thanks Dan for making AA a fun and interesting place.....

Josh.......Just so you know, I am not swapping the Gold Lion KT88 tubes. They are staying in the MC2301 ampifiers. I am only rolling the two 12AT7 driver tubes in each amplifier. That takes less than a minute to accomplish once the tubes have cooled slightly so they can be safely handled.

[jfray]

Originally Posted by jdandy

Josh.......Just so you know, I am not swapping the Gold Lion KT88 tubes. They are staying in the MC2301 ampifiers. I am only rolling the two 12AT7 driver tubes in each amplifier. That takes less than a minute to accomplish once the tubes have cooled slightly so they can be safely handled.

I am really curious to read your impressions..... That process is not too bad, I just envisioned you having to take the amps apart after each listen.

[MyPal]

Originally Posted by jfray

I am really curious to read your impressions..... That process is not too bad, I just envisioned you having to take the amps apart after each listen.

Josh...Tube rolling is easy on the MC2301s. If the MC2301s have shelves above them, it's much easier to have them racked without the tube grills/cages for easy access to the tubes, dusting etc. Yes, they have to be removed periodically for dusting & cleaning/polishing the inside chrome finish. I use isopropyl alcohol for this job. My open racks have vented & fluted shelves so heat is not an issue. When the MC2301s are racked in this manner, you can barely notice the missing grills. I actually prefer the look.

Each MC2301 has two grills which are fixed with six screws in total & are easy to remove. The grills lift upwards so approx 2x the amp height is required for clearance.

[jfray]

Originally Posted by MyPal

Josh...Tube rolling is easy on the MC2301s. If the MC2301s have shelves above them, it's much easier to have them racked without the tube grills/cages for easy access to the tubes, dusting etc. Yes, they have to be removed periodically for dusting & cleaning/polishing the inside chrome finish. I use isopropyl alcohol for this job. My open racks have vented & fluted shelves so heat is not an issue. When the MC2301s are racked in this manner, you can barely notice the missing grills. I actually prefer the look.

Each MC2301 has two grills which are fixed with six screws in total & are easy to remove. The grills lift upwards so approx 2x the amp height is required for clearance.

Thanks..... Learn something new everyday!

[vintage_tube]

Originally Posted by MyPal

Each MC2301 has two grills which are fixed with six screws in total & are easy to remove. The grills lift upwards so approx 2x the amp height is required for clearance.

My MC2301's are outfitted with one tube changer at the ready -- sort of like a F1 pit stop for tires. The grills aren't secured (screws are in the boxes), so when a tube needs changing -- the grill is lifted off in miliseconds and a tube replaced in 2.3 seconds.

Can u say Zoom?

Bob

P.S. I have to get back to work -- or else...............

[Still-One]

Originally Posted by vintage_tube

My MC2301's are outfitted with one tube changer at the ready -- sort of like a F1 pit stop for tires. The grills aren't secured (screws are in the boxes), so when a tube needs changing -- the grill is lifted off in miliseconds and a tube replaced in 2.3 seconds.

Can u say Zoom?

Bob

P.S. I have to get back to work -- or else...............

Bob
Hey, keep on track. You are letting your mind wander. Focus, focus. Today is is DCS day.

Jim

[vintage_tube]

Originally Posted by Still-One

Bob
Hey, keep on track. You are letting your mind wander. Focus, focus. Today is is DCS day.

Jim

As I slap myself across the face lightly --- oh yeah; dang. Bye.

Bob

[jdandy]

Tube rolling is quite an adventure. In the words of fictional character Forest Gump, “My mama always said, ‘Life is like a box of chocolates. You never know what you’re gonna get.” And so it is with vacuum tubes, as well. Tube rolling can also be challenging trying to hear subtle differences in voices, instruments, sound stage, dynamics, and noise floors. This exercise can test your ability to concentrate, and tax your memory as you move from one tube brand to the next with the inherent delays during tube changes and warm up. None the less, it is an exciting and fun journey as your sound system lays bare the audible differences each tube manufacturer brings to your sound system.

It should be made clear that my results and what I think I heard from tube to tube may or may not be the same results you will experience. Tubes not only have their own unique sonic signatures, but also work in conjunction with an amplifier’s circuit topology. The same tube in a McIntosh amplifier may present an entirely different sound in an Audio Research amplifier. A tube is merely one more piece of an amplifier’s complex parts configuration, and thus will always remain dependent on the particular circuit’s quality, electronic design, and the total sound system synergy in a given room.

This tube rolling evaluation was performed using a McIntosh C1000C/P preamplifier, MC2301 power amps, MCD1100 SACD/CD/DAC, and the Olive 04HD music server through the MCD1100 DAC’s. The speakers are Sonus Faber Amati Anniversario's. Cables are Wireworld balanced Silver Eclipse interconnects, Silver Eclipse speaker cables, Supernova glass fiber, and Silver Elecra power cords powering all components from a PurePower 2000 AC regenerator. The MC2301 power amps are outfitted with Gold Lion KT88 power tubes which remained in place throughout the 12AT7 tube rolling auditions. My Gold Lion 12AT7 tubes (two per amp) were compared to old stock Siemens ECC801S, Telefunken ECC801S, and GEC A2900 (original Genalex 12AT7). The volume level was set to 44% on the C1000P and never changed throughout the testing. At this setting the MC2301’s output meters were peaking at approximately 20 watts. From my seating position this volume setting produced a C weighted average sound pressure level of 94 dB with some peaks only slightly higher.

To begin, I energized the sound system and let it warm for 20 minutes before doing any listening. My first audition was with the Gold Lion 12AT7 tubes, so this provided a fresh base reference in my mind. The Gold Lion 12AT7’s have a very smooth sound without being too forward or edgy. Bass is well controlled, authentic, powerful, tuneful, and goes deep effortlessly. I listened to a number of familiar recordings. The list included Christy Baron – “Not While I’m Around”, Valerie Joyce – “It Never Entered My Mind”, Jeff Beck – Emotion & Commotion – “Serene”, Peter White – Collection – “Undercover”, Ernie Andrews – “Don’t Touch Me”, Claire Martin – Secret Love – “Don’t Misunderstand”, Luqman Hamza – When A Smile Overcomes A Frown – “Can’t See For Looking”, Sarah McLauchlan – Surfacing – “Angel”, and Johnny A. – Sometime Tuesday Morning – “Lullabye For Nicole”. These songs gave me a wide example of how female voices, male voices, guitar leads, and jazz arrangements sound through the various tubes. I auditioned all of these songs and more with all of the different 12AT7 tubes.

After auditioning the Gold Lions, I inserted the Siemens ECC801S tubes in both amps, allowing them a five minute warm up. I never had the amps turned off for more than a couple minutes between tube swaps so the 2301’s remained warm, but I wanted the extra five minutes warm up between tube swaps to allow the 12AT7’s time to warm completely. Beginning my audition, my immediate impression of the Siemens ECC801S tubes was a slightly brighter mid and upper midrange presentation. The voices of Christy Baron and Valerie Joyce took a full step closer to me. Jeff Beck’s guitar also took the same step forward. Cymbals, drum snaps, and piano all seemed to gain volume in the midrange compared to the Gold Lion’s presentation. The bass from the Siemens tubes was rock solid, tightly controlled with plenty of impact. The dynamic range offered by the Siemens ECC801S is very wide, the noise floor was inaudible, and the sound stage was broad and stable.

I turned off the 2301’s, let the tubes cool a bit, then installed the GEC A2900 tubes, energized the amps again and let them have five minutes to warm up the GEC’s. Playing Claire Martin – “Don’t Misunderstand” revealed a similar sound from the GEC’s as was offered up by the Siemens tubes. Again, in comparison to the Gold Lion 12AT7’s, the GEC A2900’s brought Clair’s voice forward of what was presented with the Gold Lions. I heard the same slightly brighter mid and upper midrange with the GEC’s. Listening to Luqman Hamza sing “Can’t See For Looking”, his voice seemed to have an increased volume, as did the lead guitar, plus the crispness of the cymbals and the piano were slightly brighter. The same was true when I played Jeff Beck – “Serene” and Johnny A.’s “Lullaby For Nicole”. Both Jeff and Johnny’s fantastic guitar playing were a touch more in your face than the Gold Lions. There is a certain upper midrange sparkle in both the Siemens and the GEC tubes.

Now it was time to roll in the Telefunken ECC801S tubes. Once they were installed I gave the MC2301’s another five minute warm up, and played Peter White, “Undercover”. The slightly forward nature of the Siemens and GEC tubes disappeared. The Telefunken ECC801S tubes offered a very smooth and neutral presentation. The opening acoustic percussion sounds and cymbals on “Undercover” rang beautifully. The deep driving bass line came through with solid control and plenty of rich bass texture and authority. Peter’s acoustic nylon string guitar hung perfectly in the center of the sound stage, and the drums were dynamic and energetic. The sound stage with the Telefunken ECC801S tubes seemed to have more depth than did the Siemens and GEC tubes. Playing Sarah McLachlan, “Angel”, the opening low octave piano notes treated me to the warm vibrating richness of hammered strings, harmonics, and overtones one hears when a real piano is played in the room. The clarity of Sarah’s sailing voice was joyfully realistic, while the blackness of the background reinforced the excellent dynamic range of her voice. The Telefunken tubes pulled me into the music in a way that the Siemens and GEC’s were unable to duplicate. There is a difference between being enveloped and caressed with musical pleasure versus having music pushed upon you. The Telefunken’s presented music in a manner that invited me to sit for hours wanting nothing more than one more song. To continue, I played 3rd Force – Gentle Force, “Journey To Now”. From the opening piano to the deep reoccurring bass that supports the foundation of the song, including the ringing chimes, tubular bells and the electronic keyboards, the total performance was spread before me like a fantastic feast. The separation of instruments was without flaw, each sound floating in its own space and time. This particular recording is a true test for a quality sound system, and the Telefunken’s did not let me down.

Finally, after removing the Telefunken ECC801S tubes from the MC2301's, I reinstalled the Gold Lion 12AT7 tubes and played 3rd Force, “Journey To Now” once again. I must admit, I am impressed with the Gold Lion 12AT7 gold pin tubes. When compared directly with the Telefunken ECC801S tubes, the Gold Lion’s hold their own admirably. There is plenty of air around all musicians and acoustic percussion instruments. The sound stage width, depth and dynamics do not leave you wanting, either. The Telefunken’s offer a slightly silkier performance that seems to capture your attention more intimately, but it is not a run away, hands down, slam dunk difference. I am pleased to make this discovery about the Gold Lion 12AT7 tubes. They are definitely in the ballpark of high-end vacuum tube performance to my ears, and stand up very well against the Telefunken ECC801S’s.

So, there it is. Almost 14 hours of listening to some of my favorite music through some excellent tubes. Ultimately I would pass on the Siemens and GEC (original Genalex) tubes, but only because of the present synergy my sound system delivers in the studio. The revealing nature of my studio system has no need for an additional bump in mid and upper midrange energy. Sometimes when audio performances become slightly brighter it is easy to initially think it sounds better, crisper, but upon extended listening it becomes apparent that listener fatigue will soon set in caused be the mild exaggeration of midrange frequencies. This may or may not prove to be the same with another system or another room’s particular acoustic properties, so your experience with the Siemens or GEC tubes may prove advantageous. Experimenting is the key. It is also the reason tube rolling can be a rabbit’s hole that only gets deeper as you travel its corridors. It’s all good, but be prepared to spend some cash for the hard to get old stock tubes if that's what you seek. At the current price of Gold Lion tubes in all their various offerings, they represent an excellent price to performance ratio, and deliver outstanding sound and value. Throughout this test of the 12AT7 tubes, the Gold Lion KT88’s also showed their stuff. The GL KT88’s will remain my choice for power tubes. They had no problem clearly reproducing the subtle and not so subtle differences in all the driver tubes operated with them. The Gold Lion KT88's are keepers for sure.

If I had to choose between the Gold Lion 12AT7, Siemens ECC801S, Telefunken ECC801S, or the GEC A2900, I would select the Telefunken ECC801S. They delivered the most involving musical performance. This opportunity to audition these fine tubes in my MC2301 power amplifiers has been enlightening. Most surprising, I am extremely pleased to discover just how close the Gold Lion 12AT7's performance is to that of the Telefunken ECC801S.

Happy tube rolling, gang. It’s exciting, educational, captivating, addictive, and great fun.