[mrinspire]

Tubeamp BL-2 has arrived in Earmass.com!

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Tubeamp from China had contacted me not too long ago after my Tubeamp TA-01 review for reviewing their current portable flagship, Tubeamp BL-2 (430USD), BL-2 is available in market for quite a long time already and I am sure some of you might heard of it before. Unlike TA-01, BL-2 is a true portable headphone amplifier (and older) that is using vacuum tube valve, which is one of the most seducing item in audio world.
Design/Build Quality/Pakaging/Finishing/Working

Packaging is very hefty

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Design is pretty simple and straight forward, I am familiar with the design, which look alike as the TA-01, good thing is, BL-2 is a solid brick as its brother and constructed nicely. Finishing is great, there is no rough end or edge, everything is nice and solidly built. I like the construction although there is nothing fancy, keep in mind that a good thing should keep you working, not just being beautiful, to be honest BL-2 is nice looking in my taste.

Packaging is really hefty although I have not see any necessity for Tubeamp to include this luxury packaging, while inside the luxury packaging box you will get a 3.5mm male to male interconnect, power adapter (Which you will be using this for charging as well) and the BL-2 itself.
Everyone knew that headphone amplifier that is using vacuum tube amplifier will exhibit a lot of heat, this is also true for BL-2, this is not a bad thing. From the picture we can easily see a ventilation/small hole on BL-2, that is not only use to show its beautiful tube, but also used to ventilate the heat inside BL-2. When BL-2 is working, you will be shocked how hot it is touching the ventilation hole, it is almost untouchable even in air conditioning room (Ventilation part itself is about 8x degree celcius while body is about 4x degree celcius), hot? It is quite hot honestly but this is not a problem. Ask yourself, why are you going to touch the amplifier when you are listenig to the music. Take me as an example, I don't want a cold tube amp if audio quality has to be compromised.
Audio Quality
Source : Dell Desktop, Soundaware D100 Pro Premium Edition
DAC : Firestone Audio CustomCute, Arce MDAC3 and M2Tech DAC
Headphone : Shure 940, Chord & Major 9'13 Classical, Shure SE425, Thinksound MS01
BL-2 has been burned in more than 200 hours before this review.
BL-2 is a true winner in anything related to audio quality. I have actually using it for more than 2 weeks not only for burning in purpose, but also for my personal listening pleasure. BL-2 is really this good as I decided to use it as my portable work-horse. It is not like tube amplifier that I knew, it is good with every music types that I threw at it.
Tube amplifier is often blessed/cursed by warm, forward and slow sound (Depend on your liking), but BL-2 is like nothing that I knew about as a tube amplifier.
First of all, coloration is really not that apparent for a tube amplifier, I doubted that I can tell you it is a tube headphone amplifier if I am in a blind test now. Sound is still forward rather than flat, soundstage performance is good. What I get here is a fairly balanced sound with good intimacy and engaging. It is not slow, this is what it as surprised me by degree. I especially like the bass quality of BL-2, drums kicked in nicely with grip on the texture, something that I have never expected for a portable headphone amplifier, I am not saying that BL-2 is superior than my desktop amplifier but for being such a small and portable device, sound quality is really good although there is still gap for portable amplifier to exceed performance of desktop amplifier, this is something very unrealistic. However, for portable headphone amplifier along, BL-2 deserved my recommendation.
Transient is very good, I used Chord & Major 9'13 Classical (Which is also an iem that have transient respond in mind), and gladly noticed that BL-2 has really bring out the transient respond of Major 9'13. I thought that it is because of how good the Major 9'13 Classical is, but when I switched to my Shure 940, the transient response is still there will great timing and slam. Vocal is not lush or smooth, but it come with some warmth and quite nice.
Downside?
BL-2 is powerful and it can powered up my 300 ohm German Maestro GMP400 and 62Ohm (But hard to drive) AKG Q701, 42 Ohm Shure 940 and various IEM from 16ohm to 32 ohm. However, for my AKG Q701 and GMP400, the soundstaging is not really there, so my guess is the best go is headphone that is like Shure 940 and Creative Aurvana Live!. IEM is very nice with BL-2 as well.
Final Verdict
I do think that Tubeamp BL-2 is a winner, in my opinion it is clearly a large step up for their own TA-1 and is one of the best portable amplifier that I have ever listened yet. I like how it perfomed and how it looks, price is not that expensive when you get into consideration. If you are worrying lifespan of the tube because it is hard to find, don't worry, I have a lot of friends using this type of tube and actually use for few years for no problem. I love BL-2 and really wish Tubeamp bring us a desktop amp/dac or anything intuitive again in near future.

 

[liamstrain]

Do we know roughly what the output impedance of this unit is? 
 
Looks great - I'd be curious to know how it drives 600 Ohm cans. 

 

[mrinspire]

  Do we know roughly what the output impedance of this unit is? 
 
Looks great - I'd be curious to know how it drives 600 Ohm cans. 

 
Hi Liamstrain,
 
Sadly to see BL-2 is meaned to drive headphones from 16-300 ohm, 600 ohm is definitely not a good try with BL-2.

 

[liamstrain]

I see that is their recommendation. Typically tube designs do not do well with 16-60 ohm headphones, so I'm curious about the actual output numbers on this (output impedence, and P-P voltage). Not their recommendation. 

 

[CJG888]

From another review, I remember reading that it is about 20 Ohms. I am still tempted to try it with my 25 Ohm DT48e, though.

 

[CJG888]

Remember also that this is a hybrid design with a tube buffer and a MOSFET output. The cans don't "see" the tube.

It does, however, have a high output impedance for a solid-state output stage. This can cause problems with low-impedance cans, but not necessarily. It just means that it is important to test that the combination of amp and cans works.

 

[liamstrain]

Thanks CJG888 - didn't realize it was a hybrid, though that makes the most sense given the power source and form factor. 20 is high for a MOSFET output... 

 

[CJG888]

How did it sound with the SE425s?

 

[CJG888]

Thanks CJG888 - didn't realize it was a hybrid, though that makes the most sense given the power source and form factor. 20 is high for a MOSFET output... 

AFAIK, the ASP TU-05 is the only "pure" tube portable amp. It costs much, much more than the BL-2 and, frankly, stretches the definition of "portable" (it's big).

 

[CJG888]

Has anyone had any problems getting through airport security with one of these?

 

[mrinspire]

Sounded marvellous