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Review: Lehmannaudio Black Cube Linear - Page 3
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Originally Posted by Sugano-san
Headphone Amplifier Review: Lehmannaudio Black Cube Linear
Silver face plate
The initial reaction I had when I first listened to music with this amp using my HD-650s was “Wow!” I was – and continue to be – quite impressed with this solid state amp. I will attempt to describe below why this is so.
Lehmannaudio, a German manufacturer that has built up a solid reputation with products like its phono stages Black Cube, Black Cube SE and Silver Cube, is a new sponsor of our forum, and I feel honored that I was given the opportunity to pen a brief review of this elegant little amp for head-fi.
Norbert Lehmann (the gentleman on the left, with his son David) together with “co-engineer” Klaus Böhm (according to Norbert a “superb project supervisor, pcb-wizard and - last but not least - down to earth audiophile”) are the designers of this very attractive 2004 addition to Lehmannaudio's product line.
Norbert and David Lehmann (linked from the Soundstage HighEnd 2004 report)
The Black Cube Linear measures only 280mm x 110mm x 44mm and weighs around 1.5kg. It looks very nice, and with these measurements anyone should be able to place it conveniently in the vicinity of the source of choice for headphone listening. Have a look at this picture for a better idea of the Black Cube Linear’s dimensions:
Two Black Cube Linears (linked from the Soundstage HighEnd 2004 report)
Its finish oozes class, what with the nice front plate (also available in black with a black volume knob and white lettering), the tight fit of the hex screws (flush with the surface) that hold it in place (see picture above for a shot of the amp without the front plate), the way in which the Neutrik headphone jacks are installed flush with the surface, the massive knob (no pun intended), the input and switches on the back, the DIP switches (more on those later) and explanatory legends on the amp’s underside (no picture available), the elegant and understated lettering and the smooth feel of the Alps blue pot.
The gold-plated and Teflon-isolated pair of RCAs on the left is the amp's signal input (input impedance is 47 kOhms), but the second pair is not a "loop through" or second input, it’s a veritable pre-out. And the coolest thing about it is that it is switchable, too. The line out is switched off when the left headphone out is used, but the right headphone out has no influence on the line out!
All this and more is explained in detail in the excellent user manual that comes with the amp and in shorthand on a sticker on the underside of the amp’s chassis. Of course both headphone output jacks may be used together, and naturally this works best with two headphones with identical or at least similar electrical characteristics (Norbert provided the example of HD-650 and DT-880).
I did not audition the Black Cube Linear in its capacity as a preamp, as I only use integrated amps at home, but from what I read in the available reviews it must be more than capable of serving as the centerpiece of a purist single-source hifi system.
Norbert told me that two more versions of the Black Cube Linear shall soon be released, one with a USB input, and another one with XLR inputs capable of accepting balanced signals (the amplification and headphone outputs, however, will remain unbalanced). The latter version will not have a line out, though.
The Black Cube Linear uses an opamp-based first amplification stage (I was told by the manufacturer that the chip is the OPA2134), followed by a discrete zero global feedback Class A output stage to amplify the incoming signals. Its shielded mains transformer sits in a compartment at the back of the chassis; the neatly-designed PCB sits in front.
I did not open the unit I reviewed, as it was a loaner and not my personal property, so I copied the picture below and some others from Lehmannaudio’s website, which is available in English and in German.
The Black Cube Linear has a switchable gain of 0, 10 and 20 dB. The DIP switches are located on the underside of the amp, accompanied by stickers that clearly explain the meaning of the different switch positions. This allows the user to adjust the amp to the sensitivity of the headphones used, the strength of the incoming signals and to any preferences as to the usable range of the volume pot. A gain of 0 dB is more than enough to drive my HD-650s without the need to turn up the volume to max, and with a gain of 20 dB, I am not likely to increase the volume beyond 11 o’clock or so. These gain switches represent just another of the practical and intelligent features of this amp.
The Black Cube Linear has an output power of 200mW into 300 Ohms (e.g., Sennheiser) and of 400mW into 60 Ohms (e.g., Koss). That should be more than sufficient for anyone. Norbert told me that the Black Cube Linear is also capable of driving the extremely power-hungry AKG K-1000s (within reason). I would conclude that AKG K-501s, K-240 DFs or any other not-so-easy-to-drive headphones should present no problem whatsoever for this amp’s power reserves, either. For the record, the amp’s output impedance is a low 5 Ohms.
Lehmannaudio provide a calculator on their website, which allows calculating the maximum available SPL based on the individual headphones’ specifications and the voltage of the input signal. The amp’s manual contains a table with the recommendations of maximum exposure to different levels of SPL, which are based on German workplace regulations. Neat!
The first thing you notice when putting on your headphones is nothing. No hiss, no hum, no other noise, just nothing at all. Quite impressive. The manufacturer quotes a signal to noise ratio of >95 dB at 0 dB gain.
The first thing you notice when playing some music, and also the characteristic that caused my “Wow!” reaction mentioned above, is the amp’s treble energy. There’s just so much of it, but in an entirely benevolent way. This is not like an EQ’ed sound where the treble is obviously boosted, and there is no sibilance either. There is just an abundance of treble that results in a very transparent and highly resolved and dynamic sound.
I contacted the manufacturer right away and asked about his views on “burn-in” and the like. Norbert recommended leaving the amp on for some days, with a signal (I set the input selector on my amp to “tuner”) and the volume turned up, but with the headphones disconnected, and that is what I did. Sure enough, the treble became better and better integrated into the amp’s sound as a whole, and it ceased to stand out in the way described above. However, both the amp’s transparency and its resolution remained in place, and if someone asked me to describe the Black Cube Linear’s characteristics very briefly, these two words would be on my short list.
The third word would be “control”, since that is another thing that strikes you immediately when listening to this amp. Due to its power reserves, as described above, it firmly controls the headphones’ diaphragms, which does not only result in a very open, informative, detailed and expressive midrange but in particular in a bass that is ultra-tight, very variable, really deep, but at the same time never, ever overblown or boomy. This amp is definitely not for those bassheads who have no appreciation for the finer things in head-fi. There is no lack of bass, but more than anything else it is of a "gentlemanlike" quality.
I could imagine that the Black Cube Linear goes together very well with the Grado PS-1s. These headphones, which have a rather pronounced bass, should be combined with an amplifier which does not have a pronounced or boomy, but instead a very controlled bass, and which supports these headphones’ clarity and treble reproduction. It would appear that the Black Cube Linear belongs to this sort of amp, and the reviewer of the German magazine image hifi had nothing but praise for the Linear/PS-1 combination.
My fourth and fifth words to describe the Black Cube Linear would be “balance” and “civility”. There is nothing that really sticks out in this amp’s performance; it does everything with a stoic approach that makes long-term listening (if desired) a non-fatiguing experience. It is refined, not rowdy. From deepest bass to highest treble, you always perceive a balanced and civilized way of dealing with things, effortless and liquid.
If there is one noticeable characteristic then it is the treble energy. Even after the “burn-in” the amp retains a slightly bright timbre, an excellent veil-removing trait for headphones like the HD-650s, which it really wakes up and brings to life. This characteristic has pros and cons. On the con side, I noticed that the Linear has a slight tendency to draw attention to flaws in the recording (e.g., the tape hiss on the “Dark Side of the Moon” CD) or to vinyl surface noise. On the pro side, this thing has a way of revealing the finest details and of creating "images" by precisely and accurately positioning voices and instruments within the soundstage that I have rarely experienced before. This is very impressive indeed, and I would say that this quality easily outweighs the other effects described above.
I received the Black Cube Linear shortly after I sold my Grado PS-1s. In order to provide impressions with Grado-style headphones, I had to resort to the next best thing in my possession, i.e. a pair of Koss KSC-35s hooked up to the amp by means of a Grado extension cord. I can confirm that the sound was surprisingly good for these cheapo earclips, and I conclude that Grado owners should be very happy with this amp, too. In fact, due to the Linear’s dynamic, yet balanced and civilized character and the absence of any sibilance in the treble, it is hard for me to imagine a pair of headphones that would not sound good when driven by this amp.
The manufacturer claims “now you can hear the ultra transparent sound and the explosive dynamics formerly known only from electrostatic headphones”, and so I compared the Linear/HD-650/Mobius combo to my Stax Omega II set (with the tube energizer 007t). Unsurprisingly, the Stax is the clear winner, with an overall fuller sound, a sweeter and more charming midrange, and even more fine detail combined with less tendency to expose hiss or surface noise. But then, the Linear driving the HD-650s is no slouch either.
But what am I doing here? Am I criticising the Linear for not being a Stax? Surely not, this is most probably an expression of my personal bias in favor of tube amps, as I also preferred the HD-650s out of the RKV, which has clearly less of the qualities that make the Linear such a transparent and resolving amp, but simply sounds a little more believable to my ears. But then, the RKV is a completely different design, and a much more expensive one, too.
So, what about the Linear's competitors in the same price bracket? The Linear's recommended retail price is EUR700 (US-$780 in the States), and as it happens that's just about the same as that of a Grado RA-1 (in Germany anyway, where its r.r.p. amounts to EUR 670 [approx. US-$880 at today's exchange rate!]). How does the Grado RA-1 compare to the Lehmann, then? The answer is: it doesn't! There is no aspect of the Grado amp that could in any way compete with the Lehmann's respective characteristics. In particular the Lehmann's sound, but also its appearance, its functionality, its materials and parts, its built-in PSU, etc., make it the clear and unambiguous winner of such a comparison.
Amendment, December 3: I just noticed that the Grado RA-1's price was lowered to approx. EUR500, which equals approx. US-$665 at today's exchange rate.
The Lehmannaudio Black Cube Linear is an extremely well-built and thought-out headphone amp with an elegant design that distinguishes it clearly from the many DIY attempts so often (and rightfully) discussed on head-fi. Its sound is dynamic, balanced and very transparent with very well-controlled bass, detailed midrange and an ever so slight emphasis on the treble, which is never obtrusive due to the overall balanced and civilized nature of the sound. It is clearly a solid state amp, and does not attempt to imitate a “tubey” sound in any way. To me that’s a good thing, because the amp does not only have a recognizable character, but it also plays all the best cards that a solid state approach has to offer.
If your budget is EUR700 or above, you must absolutely listen to this amp, even if you are prepared to spend more than that. If your budget is a little below that threshold, you should consider the Black Cube Linear anyway; you may well find that it could be worth the extra mile. Any road, the Black Cube Linear represents an important addition to the market for headphone amps, and I am grateful that I could try it out and summarize my findings for you.
UPDATE AUGUST 2005
After some more months with the Lehmannaudio Black Cube Linear I would like to report the following: Its sound has developed further over time and become even more pleasant. My overwhelming listening impression nowadays is that of an integrated sonic spectrum where nothing really sticks out.
This applies in particular to the ever so slight, but formerly noticeable emphasis on the treble, which has all but disappeared to be succeeded by a general feeling of linearity, transparency and balance. What has remained are the Black Cube Linear’s previously mentioned qualities, i.e., its powerful and dynamic sound, its excellent bass control, detailed midrange and its civilized, non-obtrusive way of going about things.
In addition, I understand that the above-mentioned USB version of this amp is well underway, which – in its own right – should make another interesting addition to the headphone amp market. An XLR input version has been announced as well. There are some posts by Norbert (norbert:lehmann) in this forum providing more details.
Moreover, mounting brackets with which the Linear may be fastened to the underside of a desktop or the like will become available soon. Computer-as-source users will be able to enjoy excellent headphone sound by mounting the USB verison of the amp underneath their desks and in the immediate vicinity of their computers, for shortest possible cable runs.
Finally, Norbert told me that a small power amp with 20wpc housed in an enclosure the same size as that of the Black Cube Linear is also supposed to be released later this year. You can position it next to the Black Cube Linear under your desktop and drive conventional room speakers with it, e.g. your desktop speakers (or K-1000's for that matter). That equals DAC, headphone amp, preamp and power amp plus excellent sound in two elegant boxes.
Lehmannaudio continues to be a manufacturer to keep on the radar screen, and to me the Black Cube Linear is certainly one of the most attractive offerings in the solid state-segment of the headphone amp market.
I just agreed to sell my Lehmann, had two amps and wanted to sell one to buy a new multi-source preamp (my old preamp will be up for sell soon), and just as I did I suddenly got depressed.
I will likely one day return and buy another Lehmann, after some more experimentation with other stuff.
The search goes on for us equipment addicts.
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Originally Posted by akwok
How does this amp compare to the RKV modded (and unmodded) when using HD650s?
With regard to the unmodded RKV I already posted my impressions in the main review and also in one of my earlier replies to further inquiries (cf. first part of this thread). The impressions re modded RKV remain fundamentally identical, just even more of the same, so to speak. Hope that helps.
I just got my BCL (USB version). It's hooked up to the dedicated stereo outputs of my Oppo-83. Have been listening to my 650. Initially disappointed. Very smooth sound, but not much body. Also kind of slow. I can't believe I'm saying this, but the headphones sound more juiced up connected to my tiny little HeadRoom micro amp. I think the BCL has slightly widened and deepened the soundstage, but it is most noticeable playing rock rather than orchestral music. The Kinks' "Low Budget" sounded disjointed and analytical. "Monster Movie" and "Soon Over Babaluma" (Can) sounded better though. The bass doesn't seem tight or punchy at all. Maybe I'm just used to the Headroom sound and need to adjust? Maye the BCL needs to break in? Any thoughts? Maybe the Oppo and BCL aren't a good match? I think it will sound better as it breaks in, but out of the box it wasn't too impressive.
Edited by Heidegger - 2/2/11 at 4:00pm
I've logged in over ten hours with the BCL. I would describe the sound at this point as ethereal, soft, polite. It's so smooth that nothing pops out at me, no textures. I really wanted something much more aggressive with more drive and energy. Any owners out there have the same experience at first then waited and have the sound totally change on them? Or is this pretty much what I can expect with this amp? If so, it's going back to Needle Doctor.
Edited by Heidegger - 2/2/11 at 4:00pm
Nope, the Lehmann has found a home. I took the advice in the review and left it on for three days playing music with the volume all the way up (with no headphone plugged in). It worked like magic. This is one helluva an amp! What confused me is that the reviewer claimed that his amp sounded good right out of the box. Not mine. It sounded blurry, slow, with this ethereal, far-away sound. But that was then; this is now. Fantastic amp. Although I've owned them for years, I didn't know just what the 650s are capable of. It's like I bought brand new headphones.
Congrats on your new BCL - glad to hear that some burn in brought it around for you. Mind if I ask where you picked it up? I've been on the hunt for one for months and all I can find are "Out of Stock" notices. lol
Yeah, I got it online at Needle Doctor. Nice people. They were out of the non-USB version.
The amp has really opened my headphones up beautifully.
Edited by Heidegger - 2/21/11 at 4:00pm
EXACTLY! : it will improve almost ANY headphone. Specially inexpensive, middle of the line Headphones!
I have just bought a used example of the BCL (It was no less than a well used DEMO at the local Store called "Mundo Sennheiser in Mexico City. This small store sells only Sennheiser headphones and IEM's. but they also sell the three Lehmannaudio amplifiers (the basic Rhinnelander, the Black Cube Linear and the USB one)...
At a recent Professional Audio Expo in Mexico City, I briefly heard the HD-800/BCL combo playing a recording made by Sennheiser engineers. My impression was, "OK, this sounds very clear and defined" but, having no idea on how the recording should sound, or having never heard the HD-800 previously, I had no way to compare the resulting sound...
Last week I visited the mentioned store and asked for a demonstration, and took my inexpensive Shure SRH-940 headphones together with several of my CD's and even a couple of Direct-to-Disc LP's and my much modified Thorens turntable/Grace 747 arm/Grace F9E-F9E Ruby...
Because my funds are not unlimited, I have a Shure SRH-940 headphones as my main headphone for this moment (and maybe for the next couple of years at least). I was curious to know if the slight impression that the Shure 940's were just needing a little amplification in order to sound "correct", since they projected a slightly "constrained" sound with my Harman-Kardon CDR-30 headphone outlet, suggesting that the 940's are NOT as easy to drive from a Home CD player as my previous Sennheiser HD280 Pro were...
As soon as I listened to the Lehmannaudio Black Cube Linear dedicated headphone amplifier... MAN!!!, the Shures sound signature literaly exploded in a colorful, really detailed and beautifully integrated music projection! Previously I had a hint about the 940's requiring some amplification, since results when listening to portable devices without a headphone amplifier suggested something was not working fully well.
Next day, the lady at "Mundo-Sennheiser" store was kind enought to let me listen at lenght both my Shure 940's and their Sennheiser HD-800 demo unit, both with my newly bought Lehmannaudio. Results as follows:
1) The price gap between the SRH-940 and the HD-800 is $299.00 UDS to $1,570.00 USD at my local store, that is about 5 1/4 times!... but the actual sound is surprisingly close between them (a shocking, -nice for me- surprise, no doubt).
2) While the HD-800 undoubtely has a (slightly) more spacious sound stage, most other aspects are quite close between the two designs (the surprise is still there!).
3) Tonal balance is quite similar, so that just concentrating on the music itself, the differences tend to vanish after a few seconds of listening. One has to really try to focus on a very specific aspect, like the impact of a certain piano chord attack decaying into the recording room acoustics (repeatedly listening to the same exact passage), in order to be able to recognize the small differences.
4) Nobody would ignore the obvious construction materials quality differences, since the Sennheiser HD-800 is a true example in a no-cost cutting materials selection engineering exercise; but the thing still is: How did Shure to get such a good result by using more conventional materials? Undeniably, Shure engineers extracted much more performance from their materials selection, or, to say it in other words, the results obtained by Sennheiser with the very best materials at their disposal were, hmmm... very good, but not as magical as the results obtained by the Shure team, at least when comparing them in a cost-to-benefit analysis.
5) While nobody could validly claim that the Shure 940's are exactly in the same league as the Sennheiser HD-800's, the thing is that the 940's still performs surprinsingly close to them in most respects. The Shures simply DON'T sound like $300... more like at least two to three times more!
6) Does it make sense to spend as much as $720 USD for a Lehmannaudio BCL amp to be used with a less than $300 USD phones? the answer is a resounding YES!, since this high quality amplifier could be kept to be used later on, as newer and (hopefully better) headphones arrive. In the meantime, I'm quite happy (to put it mildly) as how my set-up sounds. The performance of the Shure SRH-940 with the Lehmannaudio BCL amp is so synergistic, that even the owner of the store that sold me the amp was literally shocked when he listened to the combo against its Sennheiser reference HD-800, as he was uncappable of understanding how the hell an american product (made in China), could sound so good and so close to his reference! He repeated the comparison and listened and re-listaned several times, and even went to use his own recordings in order to realize that he wasn't having a bad dream (He only sells Sennheiser products). BTW, He tried other mid-price Sennheisers, and quickly found they were no match for the Shure...
Conclusion: My previous assumption that a dynamic Headphone should not represent a "difficult" load to the typical headphone jack in the typical CD player, or common integrated amplifier was plainly wrong. Even at the low milliwatt power levels required for the Headphones, the several dozen ohm impedance of the headphone still demands quite a lot of finnesse together with the delicacy that a transducer placed at less than two inches from the ear needs.
If someone believes an inexpensive headphone such as the used Shure 940's does not benefit from a dedicated amplifier like the Lehmann, I invite you to taste it.
Even at 2.6 times the price of the headphone alone, this amp deserves careful consideration, don't let the Shure's low price make you think this combination is not worth trying. While the HD-800 is in a class by itself, and uses the best materials and best manufacturing practices, the difference between the SRH940's and the HD-800 is not what everyone would expect, but smaller. Sincerely, Amclaussen.
Recordings used to compare both phones: a) Dave Grusin: Discovered Again Plus CD and Original Direct-to-Disc Sheffield Lab LP. b) Rosemary Clooney: Brazil, HDCD, c) Arne Domnerus: Jazz At The Pawnshop HDCD, d) Ryuichi Sakamoto: Discord HDCD, e) Getz/Gilberto Remastered CD, f) Several Chesky 128x CD's., g) some live recordings made with my EDIROL R09HR at 24 bit-96KHz, first generation takes, that I use to show people the slight differences in the sound that different makes of concert pianos have, comparing the same song played in a Steinway 9', agains a Yamaha Concert Grand 275 , to a Bösendorfer and finally a Baldwin.
In response to: HEIDEGGER... "Nope, the Lehmann has found a home"... "I didn't know just what the 650s are capable of. It's like I bought brand new headphones."
I hear exactly the same impression as you, but with my Shure SRH-940 phones... The Lehmannaudio Black Cube Linear make them sound notably better. Now I no longer enjoy them connected directly to the headphone output of the CD player... Now i need to use the BCL! And after a full year of use, I declare my unit a "keeper". Amclaussen.
Edited by amclaussen - 12/21/12 at 7:46am
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What we are talking here, is about control and not simply gain or amplification. Every time impedance varies at different frequencies, the driver-amplifier output stage interact... it is not as simple as "just augment the level of the signal and that's all". It is the reason why amplifier stages included in CD players, portables etc., seldom compete with dedicated Headphone amplifiers. At least this is what most experienced listeners are finding, and that explains why the nuimber of Headphone amplifiers is growing at such pace. Very few headphone jacks really provide firm and solid control at the deep bass, together with finnesse, clarity and without noticeable distortion and added noise. Amclaussen.