I bought my first EL34-based integrated amplifier more than 20 years ago.
That amp was the Golden Tube Audio SI-50 MK2, a wonderfully lush if loose sounding specimen. For the past 6 or so years I’ve owned and listened through the original Leben CS-600 and then the CS-600x—both EL34- or 6L6GC-based. These days I run with the Aurorasound HFSA-02 that also relies on the same power pentode first developed by Philips’ subsidiary Mullard in 1955.
To stretch my tube-amp owning history back to its beginnings, I switched to a Sun Audio SV-300BE in the early 2000s, my first SET, after years of flirting with the idea which wasn’t foreign at all seeing as my father was building tube amps well before I was born.
In between the Golden Tube/Sun Audio years and now, you could say I went tube amp crazy and have owned a bunch of amps and preamps from the late Don Garber’s Fi, Shindo, Audio Note, Deja Vu Audio, a Melos SHA Gold, SAC Thailand Minute single-ended EL-84 integrated amp that I still have, and a few others including the tubed CAL Audio Labs Alpha DAC (re-review) and AH! Njoe Tjoeb CD player.
As you can imagine, I’ve rolled my fair share of tubes in and out and wrote about this adventure in fun and fine tuning most recently last August, comparing 4 NOS 12AU7s in the Leben CS-600x. As I said in that review:
Imagine you’re trying different frostings on your home made carrot cake.
Four different cream cheese frosting recipes to see which you like best and after tasting and re-tasting you find a favorite. If you approached this process the way some people approach tube rolling, you might be tempted to declare your favorite The Best! even though your spouse preferred a different one and both would be truly awful on crème brûlée.
The point being different tubes can impart different sonic flavors and just like things we eat, the point is to find the one we like best. To taste.
Of course I’ve also reviewed a bunch of tube gear in the 20+ years I’ve been writing about hifi and in some cases have rolled as part of the review.
For my Lebens, I replaced the stock Sovtek 6L6GC with current production Russian made Genalex Gold Lion KT77s, a drop-in replacement for EL34/6CA7 tubes and with the flip of an internal switch the 6L6 in the Leben. I buy mine from Upscale Audio because Kevin Deal knows his way around tubes and Upscale tests and where applicable grades the tubes they sell. If you’re wondering why I don’t go for some exotic NOS beauties, the short answer is I don’t have that kind of cash—original UK-made Genalex (Marconi-Osram Valve Co.) Gold Lion KT77s can go for $750/pair while early production Mullards fetch $650/pair or thereabouts. Well over a grand for the 4 needed in the Aurorasound. Besides, my amps get a lot of regular use so I need to be able to have a spare set of tubes, or be able to buy ‘em, without selling an organ. Or a piano.
For my money, the current production Gold Lion KT77s are perfect—they made both Lebens sound infinitely better compared to the stock tubes and they’ve worked without a hitch for many years of very regular use. The main improvements included much better bass weight, increased resolution, a richer midrange, more sparkle up top and an overall more energetic and expansive presentation. Just better.
As I noted in the In Barn post for the recently arrived Phasemation SA-1500 Integrated Amplifier (more info), “I adhere to the SwS principle when it comes to tube rolling—Start with Stock.” Which is how I’ve been using the Aurorasound integrated since it arrived back in July—stock Electro-Harmonix EL34s.
As timing would have it, I had a few days in between the Accuphase stack’s departure and the Phasemation’s arrival to let the Aurorasound play with the Ø Audio Ymir (more info). An admittedly odd couple price-wise using a $10k integrated with $65k pair of speakers especially coming off the Accuphase stack’s high, $65k-worth of high, but what the heck. At least they’re similar in that the Accuphase A-300 mono blocks offer 125 Watts of Class A solid state power compared to the Aurorasound’s 31 Watts of push/pull EL34 muscle (wink). Variety is the spice of hifi.
The rest of the system included the in for review Audio Note Izvor DAC (more info) fed by the Barn resident Gimm MU1 (review) with all cabling from AudioQuest (see full Barn and system details).
Hmm. My initial Aurorasound/Ymir impression was more lackluster than I hoped and frankly expected. Did you hear it? That ding signifying a thought? Now was the perfect time to roll and seeing as I had a spare set of Gold Lion KT77s in my trusty tube caddy, I was ready in minutes. But…We all know things like tubes, amplifiers, and speakers need time to break-in. Right? Right, so I let the newly fitted Aurorasound play for some time before I sat to listen but I can tell you they improved the sound of music right out of the gate and only got better with time.
The same improvements I’ve experienced with the Lebens sang out loud and clear through the Ymir with the more powerful and rich-sounding Gold Lion KT77-endowed Aurorasound. No ifs, ands, or buts—this change was obvious and obviously better. I offer my smile as proof. Music sounded more lit up, more alive, and the Ymir’s bass response got scary (in a good way) while the sound image grew in every dimension by…a lot. Bigger, better, badder (in a good way).
A matched quad of the current production Russian made Genalex Gold Lion KT77 cost $307.80 from Upscale for the non-cryo version, cryogenic treatment adds $32 for the set, and I’ll leave it up to you to decide if that’s a worthwhile investment. But in round numbers, a $300 upgrade in the case of the Leben CS-600s and now the Aurorasound HFSA-02 is a grand HiFi Bargain as far as I’m concerned as the Gold Lion KT77 lifted their level of performance well beyond the spend.