Sunday, August 25, 2013

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.


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."
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.
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.

Saturday, December 3, 2011

Questions about 6W6 parameters

I have been looking at 6W6 design and this tube has some amazing qualities.  For one, you can actually pull more power out of it than a 6V6 with the right tweaking, even though it is rated lower.  However, YMMV.  It might burn out the tubes a little more quickly as I am definitely pushing the envelope.

Thursday, August 11, 2011

12AX7 Black Plate Review, USA tubes as good as Mullard & Telefunken

"The earlier a signal is in the audio chain, the more important it's amplification is."  This truism places the 12AX7/ECC83 class at the top of a list for the most important tubes in your amplifier.  If you have done any tube rolling, you know from experience that the 12AX7 has more effect on amplifier sound than the following 12AU7 or any other low/medium gain stage.   The reason has to do with the high gain characteristic of the 12AX7 (or other high gain tubes like 12AT7, 12AZ7, 12AY7, etc.)  High gain is used successfully only on very small signals--hence high gain tubes are the first in line for phonograph or microphones or tape heads.  If you have never used a high quality vintage old stock 12AX7/ECC83, you will be stunned at the difference.  We are documenting our listening tests to help you select the proper vintage tube.

A little bit should be said about the equipment used.  The soon-to-be-released custom phono/line stage amplifier from Old Stock Audio has phenomenal articulation and uniquely reveals the subtleties of the tubes.  One of the features of that amplifier is that many of the audio path internal components are also old stock and hand selected including OIP (oil-in-paper) capacitors, military quality hardened switches, and hand built transformers.  This pre-amp feeds an E80L amplifier driving a pair of Teresonic Lowther-based speakers.  This setup truly reveals even the minutest details.

The oldest USA tubes are black plates and all of them are superb, but some really sing.  We tested after separating both by manufacturer, and construction/date.

            1.         Long 'D' Getter, early 50s, White Lettering:  The tone was excellent and even with very good articulation.  The timpani attacks in a large symphony recording came through sharp and musical.  The ambience was engaging.  One listener commented "There is so much room in the sound".  Highly Recommended
            2.         Large Horseshoe Getter with double crossbar mount, '50's, ULTRA-RARE!: If you took the tubes from #1 and sprinkled magic fairy dust on them, you might come close to the sound of this tube.  Far superior IMHO to a smooth plate Telefunken--I did NOT want to stop listening.  Utterly Sublime, and very rare.
            3.         7025 Bent 'D" getter, Orange Lettering and reinforced top mica: The 7025 label is often a military version, or ruggedized version of the standard 12AX7 or ECC83.  This tube was very similar to #1, but we felt that solo instruments came forward in the sound stage just a little more.  A classical guitar solo entranced us, as did the french horn.  Highly recommended.
            4.         JRC (Military) Long 'D' Getter, White Lettering, early '50s:  Again this military version of #1 was very similar to it, but with even greater resolution of the sound stage and articulate subtlety.  The bass was tight and wonderful.  Descriptive words: Subtle, Gentle, Strong, Fast.  Very Highly Recommended.
            5.         Early '60's Long D Getter, Orange Lettering: Not as articulate as #4 or #2, but still very musical and smooth.  Reminded me more of a Sylvania style sound than traditional RCA.  Recommended.
            6.         U-Getter with Foil Crossbar, White Lettering, early '50's, ULTRA-RARE:  Absolutely wonderful sound! Enormous sound stage.  Super articulation without any harshness.  Tight Bass.  Possibly my favorite Black Plate.

There are seven different styles of 1950's and early 1960's Raytheon 12AX7 & 7025 that we were able to categorize.  The sound was so similar in all varieties that it is not possible to break them out individually.  As a class of tubes, the black plate Raytheon are truly superb--equal to the best of the RCA.  The Raytheon sound has a hint of darkness added to the detail.  In passages like the middle of the first movement of the Dvorak 9th, this darkness exposes the melancholy of that passage and makes the listening experience almost transcendent.  I love the Raytheon black plates and highly recommend them without reservation.

Sylvania Black Plate
Sylvania is traditionally known for its smooth and musical sound.  It is close to Mullard in that sense.  The Sylvania vintage black plate adds articulation that is near to TungSol along with a large sound stage and very tight bass.  Another feature that is common to the Sylvania line is their ability to handle complexity.  Reproduction is faultless, and in the case of the Sylvania Gold Brand, absolutely unmatched.  The Sylvania Gold Brand/Gold Pin are not black plate, but they are my all time favorite 12AX7.  These are factory graded for low noise and have a very long break in period.  I only wish they were not so rare.  I highly recommend all Sylvania Black Plate and Gold Brand tubes.

TungSol Black Plate:
I almost decided not to include the TungSol Black plate because they are so rare and generally unavailable, but there is an excitement to TungSol Black Plate that is unique.  Whereas the Sylvania Gold Brand are unmatched in their neutrality, the TungSol black plate are unmatched in their articulation and attacks, without losing the tonal beauty.  It is a matter of personal choice and amplifier type as to which 12AX7 is right for your system.  My system is one that reveals details so I tend to use the Sylvania Gold Brand for symphonies, the Raytheon Black Plate for solo and ensemble, and the TungSol Black plate for Jazz and Rock.  Highly Recommended.

GE Black Plate:
Finally we come to the GE Black plate in the USA line-up.  Most of these are labeled Kenrad, but they were made by GE.  GE gets a bad rap a lot of the time, but it is not deserved.  Their quality control was excellent and tube to tube similarity is much better in the GE and Raytheon lines than in the RCA lines.  The GE Black plate 12AX7 (and 5751) have an enchanting and beautiful sound.  Articulation is excellent, though not as detailed as the TungSol.  Sound stage is expansive and inclusive.  As an all around tube you cannot go wrong with the GE Black Plates.  They are great performers and very durable.  Microphonics is rare in the GE line—again due to the excellent quality control.  I use GE tubes as my everyday and background listening tubes.  Highly Recommended.

Monday, May 31, 2010

12BH7 Listening Test!

The 12BH7 shares many similarities to the 6SN7 (also a favorite tube around these parts), but is characterized by a darker sound.  In the past, this tube was known simply as a favorite driver for the old Macintosh amps, or as an inexpensive alternative to the 5687 and the 12AU7.   Lately, however, the 12BH7 has experienced a resurgence in popularity as audiophiles have been discovering its remarkable musicality.

Although they are no longer manufactured, there are still significant numbers to be found due to their original use in audio amplification for television as well as in stereo systems.But some of the brands in this category are becoming very collectable… and, as a result, much more difficult to acquire.

Our 12BH7 stock comes from old tube collectors and aficionados who stocked up decades ago. We tested several nearly identical types of Sylvania and RCAs as the metal used in the plates, the type and position of the getter, and the manufacturing process itself can vary and significantly affect the sound.The differences in quality and texture are often more than variances in the individual tubes and so we tried to create a helpful purchasing guide for our customer’s use.

Here are my notes (in listening order) from a recent 12BH7 tube comparison binge.  We listened to Hilary Hahn’s “Barber and Meyer Violin Concertos”.  The asterisks indicate the tubes deemed (with pretty much unanimous agreement) to be the best of the night.  Enjoy!

Amperex 12BH7A (Orange World): Still, unadorned quality. Seems to be a good level of detail throughout the low, mid, and high ranges. Appealing sound, immediate and bright, but slightly thin. 

Sylvania 12BH7 pinched plate from the 60s: Sound is a little richer than the Amperex. A more musical tube as well –rounder and more full. Both hushed and urgent moments are fleshed out and equally affecting.

Sylvania 12BH7 black oval plate from the 50s with U-getter: Lovely. Very musical. More detailed than the Amperex. Very rare. Soft, lush sensuality to the sound. Velvety.

Sylvania 12BH7 black oval plate from the 50s with D-getter:  Slightly bolder, slightly less lush sound but with even higher level of detail. Maybe a little more musical than the previous – first of this selection I would describe as having a “live” sound.

Sylvania 12BH7 grey oval plate with D-getter from 60s: Tested three, all with yellow lettering.  Two were slightly muted. Still detailed in the low and high ranges but the sound didn’t blossom as fully as the previous tube. (Suffering a little, I think, in comparison.) The third had a nice sound but more noise in the high range and still a loss of detail in the big moments through the mid range. Absolutely a nice tube, but doesn’t stand out against the other Sylvanias. 

Sylvania 12BH7 dark grey oval plate with O-getter from 60s and no copper grid posts (red lettering):  Much clearer and more musical. Pleasant, well-modulated detail. Possibly a little noisy in the mid-range, but still one of my favorites so far.

*Sylvania 12BH7 dark grey oval plate with thick O-getter from 60s and no copper grid posts (marked with red top - possibly a factory rating for audio): Very full, rich sound. Can really hear Hillary Hahn’s bowing technique instead of just the grating buzzing that one usually hears with recorded violin (an artifact, I think, of placing the microphones too close and not allowing the sound to expand before being captured). If life sounded this good more people would probably like classical music. Incredibly rich detail. Nicely developed mid range. High notes really sing. Very beautiful.   What stands out upon re-listening to this tube after the RCAs is the comparative delicacy of the sound. Sort of like fresh poached salmon as compared to a juicy steak. Both are good, and the difference in enjoyment is going to depend on personal taste.
RCA 12BH7A square black plate winged plates, U-getter, late 50s: very nice tube. Close second to the last one we listened to. Very melodic and detailed. Some buzz in the larger string sections. Can still hear bowing technique. Tube really does sing.

RCA 12BH7A square black plate with double wings , U-getter, late 50s (white lettering):  Back to the Amperex stillness, which doesn’t compare well with the previous 2 tubes. Still very a good level of detail, almost comparable to the sound of an old phonograph.

RCA 12BH7A oval black plate with double wings, bent D-getter, late 50s (red lettering, green paint?):  Very clear, rich sound. Sings. Something very honest and straightforward about the sound of this tube – you can hear everything that was heard in the better tubes, but the detail seems less modulated. I can see this tube being a lot of fun to listen to on a regular basis. Glorious in the larger sections.

*RCA 12BH7A long black plate with double wings, dimpled square-getter, late 50s (white lettering):  Similar to the last tube, but with many more dynamic levels. Softer details perhaps, but a very high level of detail all the same. Never thought I’d see the day that an RCA blew an Amperex out of the water.

*RCA 12BH7A square black plate with double wings, O-getter, late 50s (red lettering):  Crystal clear sound but still completely filled out. Solid dynamic range. High level of detail. Beguiling musicality.

RCA 12BH7A square grey plate with double wings, O-getter, 60s (red lettering):  Really not quite as detailed, a little noisy. Some real sweetness at the top. A warm tone. Balance is a little off, some parts pop too much and others are too muted.

RCA 12BH7A grey square plate w/ double wings, halo-getter, early 70s (red lettering):  Clear consistent forward sound, good detail, perfectly decent tube. Not at the very top of the list, but stands up well to some of my favorites tonight.

Sunday, February 7, 2010

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
(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 .

Sunday, January 31, 2010

Testing the New Phono Amp

Congratulations! Burning the midnight oil in preparation for T.H.E. Show (The Home Entertainment Show, Las Vegas 2010) has certainly paid off for you. I've never before heard recorded music sound better than it would in most seats of a concert hall.

 As both a classical musician and budding audiophile, I was very surprised. (The difference, of course, comes from how sound waves move in each individual acoustic space, and how close you are to the sweet spot. I recently missed a lot of the nuance of a Bartok piano concerto because I was sitting too close to the stage and at that proximity the grand piano overpowered everything but the violin section, which was right in front of me. It sounded like the pianist was banging away a' la Rachmaninoff at a college-level competition, which he wasn't.)

 I do wish we'd listened to more than high-quality classical recordings, as amazing as they were (thank you very much for introducing me to Gary Karr's Adagio d'Albinoni, a purely analog-to-vinyl recording using restored vintage equipment).

When we test the amp again I'd like to expand our listening selections - the purity of Kerr's base and the clarity of the strings on Guaneri del Jesu (with Paganini's original violin!) both argue for a high fidelity to any original live sound. (Was it the Albinoni that we could tell was recorded in a studio and not a concert hall? So much fun to be able to hear the actual acoustics of the original "performance" space!) I'm thinking I want to hear some middle eastern folk, Indian classical or a Piazzolla tango. This is, of course, pure personal greed - this is the most detailed and live sounding audio set-up I've encountered, and I want to hear some of MY favorite music played like that.

12AX7 Tube-Rolling Notes

Last night, while hosting a big blind listening test, we decided to compare a few 12AX7 tubes.

We'd started our evening with old-stock 60's black plate RCA and Raytheon pair. Just for fun I put in a pair of Sylvania Gold Label, Gold Pin tubes with low noise testing from the manufacturer. These tubes are really not available from any dealer, anywhere -they are ultra rare, I just happen to have a few quads. (The lettering is real gold leaf! I think they may have originally been made for Amperex.)  Anyway, we put in the pair and oh my, oh my!! I put on a record of J. Heiftz and Brooks Smith doing a recital at the Dorthy Chandler pavilion and you would swear that the Steinway Grand was sitting in your living room! Wow!

The Mullard 12AX7 long plates have long been my favorite for phono stage, but these Sylvania Gold were definitely their equal.

For phono stages, the GE 5751 receives high recommends as well. It is a sleeper tube equal to the Mullard, but often at a better price.