Review: A few previously unknown MG Head Tubes
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eric343

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Just some impressions I've typed up while listening to some tubes, more to come...

Recordings used: Pink Floyd and More Pink Floyd. And some Dvorak, and some bits of classic rock..

Headphones used: HD600 w/ Clou Blue

Source: Arcam CD72T with OPA2132 opamp in the analog stage. (upgraded from the TL072)

Format: [brand] [type]: [plate] [mica count] ([avg price], [where I got mine]) [review]

<DISCLAIMER>
A) I'm going by the box labels[unless mentioned otherwise], as most of the tubes have their labels rubbed off. So some tubes may be misboxed...

B)There's a definite conflict of interest; all of these tubes are for sale in the FS/T forum. I did write the Mystery TungSol 12AX7, Rayethon 12ax7, and Amperex review before deciding to sell the tubes, however.
</DISCLAIMER>


Mystery tube in a Tung Sol 12Ax7 box[I just noticed that THIS IS NOT A TUNG-SOL! The other TS{with Tung-Sol label on it} 12AX7 I have has totally different internal structure...]: Greyplate, 2-mica. ($100/quad on eBay) As much as I'd like to report that this one has the lush, liquid sound of its 5751 brethren, I can't. It's pretty much just a run-of-the-mill 12ax7, with not much in the bass and mids department and a very laid-back, almost distant quality. Stock tube grade.

Rayethon 12ax7: Greyplate, 2-mica. Funny "arm getter", similar to "the" Sylvania we all know and love. ($unknown, eBay) Nicely forward sound, bass has SLAM! SLAM! SLAM! although it doesn't go as deep as, say, the META42. Another Brick in the Wall (pt2) sounds great with this tube. Far superior to the TungSol. Very very noisy until it's warmed up a bit, and warmup also improves the bass. However, the tube is pretty sensitive to tape hiss in general. The treble is kind of harsh and distorts a bit at the very top end, but definitely tolerable. Mids are nice, the guitar work on ABITW2 sounds very good. Not a terribly "warm" sounding tube, but a very solid performer and one to get if you find it cheap. A "sleeper" tube? Heck yeah. Great for rockers...

Amperex 12Ax7:{$unknown, eBay} Bass is not very well controlled, bleeds into the rest of the sound, very obtrusive, almost boomy. My dad a/b-ed it with the Sylvie and said it sounded like the sound was horrible, like it was "bouncing off a wooden board."

Amperex 7025: {$50-$80/two, eBay} Much better bass. Nicely well rounded tube, definitely close to the Sylvie. In fact, listening to it and the Sylvie, apart from a (possible, slight) difference in gain, I don't hear much of a difference! Although it does warm up faster...

ITT 12ax7 (in a Curtis Mathes box): Greyplate, 2mica. "Halo" getter. {$unknown, eBay} Big, fat bass, although without the slam of the Rayethon. Sounds nice and cozy warm on "Echoes". The mids and highs are fairly smooth and guitar work sounds nicely clear but not overly so; overall a very non-fatiguing TUBEY sound. I think I detect a note of distortion in vocals, or maybe it's just that the tube isn't terribly clear overall. VERY good soundstage. The poster child for a tubey sound... Definitely goes well with Pink Floyd. Something odd, though - I popped in Dvorak's New World Symphony (last movement) and it made it sound rather far away, with not too much bass punch but air and "space" out the wazoo. Like listening in a concert hall from the back. Odd. *note: Just realized I was using the "headphone" jack with NF ON. That could do it


Sovtek ECC83 (In Ei Yugo box): Greyplate, 3mica, funny stainless steel supports. {$unknown, eBay} Now THAT's more like it! Dvorak sounds more lifelike now! There is still a slightly flat quality to the sound, this is a Sovtek after all
There could definitely be more bass, although there's mids and treble aplenty... What bass there is surprisingly detailed, definitely more detailed than the ITT. This tube is the first time I've really noticed the bow-work of the cello player... Switching to Pink Floyd, ABITp2, the "HEY! TEACHER!" has a sharp edge to it that seems new. Overall the sound is quite involving, it pulls you in...

RCA 12AX7: Blackplate, 2mica, odd Sylvania-style getter; except this one is tilted to the side. {$unknown, eBay} My first impression with ABITWp2 was that the drum hits were softer, and the vocals sounded isolated. I didn't listen much longer because I wanted to try the...

Real Tung Sol 12AX7: <review to come when Tung Sol 5751s arrive>

Truetone 12AX7 (marked "Major Electronics, Japan): Greyplate 2-mica, "halo" getter. {$unknown, eBay} Not a slacker, this tube. Although it does have some distortion in the top end and add a bit of grain to Elton John's voice in Saturday Night's Alright for Fighting, it did pretty well. Not a lot of air though.

"Old box" RCA 12AX7: Greyplate, 2mica, "d-halo" getter. {$unknown, eBay} I didn't give this tube as much of a warm-up as the others, only about 30sec-1min. More air and ambience than the Truetone. In exchange the midrange is a bit more recessed. The grain that I noticed with the Truetone is smoother, sounds more like the throat warble that it is.

Tubius Anonymous 12AX7(Unknown Brand): Greyplate, 2mica, "halo" getter. {$unknown, eBay} Listening to it after listening to the Sylvie (my reference standard, as you can tell), my first observation was that it is noisier. The blacks aren't as blacks, et al. That's pretty much to be expected, after all the 5751 is a lower-noise specification than the 12AX7 and one reason I don't think we'll find a 12AX7 to trump the Sylvie any time soon. Listening to some Mahler, the violin and cello strokes aren't as exuberant and open, the whole sound is compressed. Don't get me wrong - the crash of the symbols and the sounding of the trumpet is still impressive, it just feels as if there's something ...lacking... It reminds me kind of like my old CD player (before I got the Arcam). Also, the violas lack a certain creaminess to the sound...
Switching to Pink Floyd, I find this tube is pretty good at reproducing the subtle piano cord at the very beginning of "Echoes" and doesn't do too badly with everything else. It could have something to do with the fact that "Echoes: The Best of Pink Floyd" is mastered pretty hot, whereas the Mahler disc is pretty "cold" as things go... But anyhow, the vocalist's voice (in the "strangers passing in the street...and do I take you by the hand, and lead you through the land?" part of Echoes) comes out pretty well, distinquished from the surrounding guitar and drum work. In "Sorrow", the drum hits and the vocals with lots of ambience come out very well - giving the impression of both the ambience and a close-in drum kit. Quite frankly, it sounds like I'm in front-row seats at a concert with a really good sound system, a great engineer, and no fans cheering/yelling/screaming/doing things not mentionable in a family forum in the backround.
 
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Nick Dangerous

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Great writeup! I'm amazed that the Sovtek did as well as it did. You seem to hear what I hear: "detailed but sterile". I've heard a lot of Sovtek tubes and they all sound like that.

I'm not surprised the Amperex 7025 performed so well. The ITT 7025 is a great no-name tube in the THSP that I got for cheap. I haven't heard any other 7025's, but from the circumstantial evidence I suspect it is equivalent in performance to the 5751.
 
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sneared

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Eric343,

Great writeup!

I've been trying to test current manufacture tubes because of the unavailability of some of preferred NOS and used tubes. I'm trying to limit the tubes to those that nearly everybody sells.

Three that I have been playing with recently are (with very subjective comments):

Sovtek 12ax7lps

Currently my favorite. Really quiet with great bass extension

Sovtek 5751

Nice tube but slightly thin on the bass

and

Phillips JAN 12ax7wa nos

This would've been my favorite except that it has a large amount of hum that doen't vary with the position of the volume control. I assume that this is AC on the heaters.

I'm trying to make some quantitative measurements to see if what I hear correlates with what I measure. I posted the results with the stock tubes in another thread.

Someone also posted that they listened to the Electroharmonix 12ax7 and found them to be shrill....?

I probably need to listen to more Pink Floyd.

BTW I'm doing all my testing with HD600s with the switch on the "high" position.
 
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eric343

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Reposted to HeadWize...
 
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