Contrasting and Comparing 6DJ8 / ECC88 / E88CC Tubes

Note: This has been re-posted with comments removed.  An anonymous poster was using this thread to flame another tube seller--and we do not allow that type of comment on Old Stock Audio.

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We listened to only one piece of music - James Galway playing "The Flight of the Bumblebee" - to contrast NOS tubes.  The FotB is the ideal piece of music for comparing tubes. It's short enough to listen to all the way through with each individual configuration, and a good recording has enough detail that you can easily evaluate the accuracy and color of the different options.

Because it's the holidays and we're all strapped for time, I'm going to use my notes to give a short overview.  Since tube prices do fluctuate (and many people will base their interest in a tube partially on how affordable it is), I'll list each tube in one of four different price categories, from $ to $$$$.
These are (for the most part) 6DJ8-type tubes. I will say that I was very surprised at how well a few of the budget tubes stood up to some of the more expensive collector items.

It's good to know that a person just entering the world of audiophilia has some really strong options regarding where to start and how much money to spend. This is a fun hobby/obsession, but not everybody can immediately drop a huge chunk of cash on a rare pair of tubes, especially considering the rest of equipment needed to get started. Based on what we heard at our last listening party, I'd recommend that the beginning (or even intermediate) audiophile start out with a few sets of good, mid-level tubes and focus on upgrading his/her amps, speakers, and turntable (and collecting high-quality LPs) until their system is good enough to clearly hear the difference in the feel and color of the specific tube types. That's the time to start playing around with tube collecting.

That said, here are my thoughts about some of the NOS tubes we recently listened to:

Range $5-75 USD:
Mitsubishi 6DJ8 (made for Mullard in the 1960s)
This is the first tube we listened to. The sound was breathy and I couldn’t hear the bass much, plus there was almost no detail. Almost everything after this sounded great in comparison.
Toshiba 6DJ8
This is the only tube that possibly sounded worse than the Mitsubishi. (We didn't listen to them in sequence) I couldn’t hardly hear what was happening at all, and my notes say "audio systems like this are why people think classical music is boring."
RCA 6BQ7A
A very decent entry level tube! The bass had nearly the same quality as the middle-range, which seems to be rare in the budget options. I heard multiple attacks and dynamics in the orchestra at the same time, and a few details within the layers that I missed with some of the more expensive pairs. This was one of the last sets we listened to, and I was pleasantly surprised.
Westinghouse 6922
These have some detail and range. It’s not a particularly exciting tube but it does compare well against many of the other budget options.
GE 6DJ8
These were fuzzy - the instruments lacked identity, the sound was muddy in the middle, the bass was almost lost, and the top was fair. Not my favorite.

Sylvania 6DJ8
High level of mid-range detail, individual parts really stand out, full range of dynamics. Very musical for the money. Entry-level tubes that will take you far.

Range $$150-250 USD:

Amperex 6DJ8
Amperex as a brand has a very clear, light, detailed sound. I prefer a warmer, less crystalline feel to my audio, but I can understand why these have a following. Music has a nuanced and thrilling quality when listening with these tubes.
Mullard ECC88
These have an acoustic quality with a fuller, richer sound, strong bass, and greater dynamic range. Less detail but I didn't miss it much as there was so much more happening in the over-all blend. A terrific choice for every-day listening pleasure.

$$$300-400 USD:

Amperex PQE88CC
Very clear and detailed (I could hear pretty much everything on the recording) but not as much of a quality increase as the price hike implies. Still, these are exciting and playful and a quality choice for the discerning audiophile and/or Amperex fan.
Siemens. ECC88
Fantastic level of detail in lower register and lovely dynamics all the way through. The strings and triangle sound very shimmery and sparkly indeed. These are lively and musical tubes – no surprise that they are hard to find. I want these for my next birthday/Christmas/whatever present.

$$$$1750+ :
Amperex 6DJ8 pinched waist
Best choice for clarity and smoothness; high level of pristine detail; extremely crisp. A bit colder than most live sound, but definitely worth it if you have the money.

12AU7 / 12BH7 / 6CG7: What's best?

The 12AU7, 12BH7, and 6CG7 have very similar electrical characteristics and can usually be substituted for each other. When deciding what's best for you, the following notes may be helpful:

(1) A 12AU7 is identical to a 6CG7 electrically and in the circuit it will function identically. However, there is a different heater pin out. So if you are substituting you need to make a change. In addition, the 6CG7 draws twice as much heater current so be sure that this will work in your circuit. (This may be one reason it is not as popular as it should be.) If you need help write me via http://www.oldstockaudio.com/More/contact_me.htm.

(2) The 12BH7 requires no circuit modification to substitute for a 12AU7, but the plate resistance is a little lower (5300 vs 7700). Thus, even though it has a lower u (or amplification factor), the gain may be slightly higher depending on the circuit design. [This is mainly true for circuits that use an anode resistor load.] It will also draw a little more current, but the 12BH7 is a beefier tube and can handle it. For most circuits this should be well within the tolerances of the design, but you can ask the manufacturer to be sure.

With respect to audio reproduction there is a fairly large difference between these three tubes. The 6CG7 (or 6FQ7 which is the same exact tube) is identical in internal construction to the 6SN7. The 6SN7 has the reputation of being the most linear of the medium mu triodes and the 6CG7 follows suit. Also, the 6CG7 line is remarkably similar in audio performance across various manufacturers of the same vintage or age.  It is a good tube for early or middle stage amplification and has the added bonus of a grounded shield between sections, which reduces hum and increases channel separation.

The 12BH7 can lend a wonderful life to the tone that sounds great for jazz or vocals. For audio listening,  this tube can temper the harshness of CD's. There is, however, a wider variation in the sound of 12BH7s than 6CG7s, so some tube selection or rolling is in order. You can find very neutral 12BH7s (watch for a coming blog comparing them) . If you don't want to modify the circuit and are unhappy with your 12AU7--this is a good choice. 

The 12AU7 family has the widest variety of tonal characteristics which is probably why this tube is rolled so often by audiophiles. I personally find most 12AU7s a little tinny in comparison with the 12BH7 and 6CG7, but there are exceptions. The RCA clear plates from the 60s are more like 6CG7s in their sound, for example. There are lots of blogs and posts about the difference between 12AU7's so I won't waste your time repeating everything. My favorites are Mullard and Siemens, with RCA clear tops and Tung Sol a close second. A lot of people like Amperex, but they work best in a system that is not forward or bright as they add life to the midrange. My Lowthers are already bright in the mid-range, so I stay away from Amperex 12AU7s.

Part of the fun and magic of tubes is rolling them when listening to different types of music.  When you do, we hope you will consider our vintage tube offerings at http://www.oldstockaudio.com/ .