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Positive Feedback ISSUE 45
september/october 2009


mhdt labs

Havana USB DAC

as reviewed by Jeff Day








Harbeth Monitor 40.1 loudspeakers, Skylan M40.1 speaker stands.

Leben CS660P KT66 power amplifier, Leben RS28CX preamplifier, Leben RS-30EQ phono equalizer.

KAB Broadcast Standard Technics SL-1200MK5 turntable, Yamamoto HS-1A ebony head shell, Clearaudio Virtuoso Wood moving-magnet phono cartridge, Denon 103 moving-coil phono cartridge, Auditorium 23 step-up transformer for Denon 103, Apple iMac, Mhdt Labs Paradisea+ USB DAC.

Audio Tekne ARC-500 interconnects (DAC to pre), Audio Tekne ARSP-500 speaker cables, Acoustic Revive PCOCC-A oval single core interconnects (amp to pre), Locus Design Group Polestar USB cable from iMac to USB DAC.

Acoustic Revive RCI-3 Cable Insulators (under speaker cables), Acoustic Revive RGC-24 Ground Conditioner (preamp), Acoustic Revive Shorting Plugs SIP-8F (preamp), Acoustic Revive Pure Smokey Quartz Insulator RIQ-5010 (under equipment footers), Acoustic Revive Pure Quartz Insulator RIQ-5010W (under equipment footers), Acoustic Revive REM-8 EMF Canceller (on DAC), Acoustic Revive RPT-2 Ultimate Power Supply Box (digital components), Acoustic Revive RPT-4 Ultimate Power Supply Box (analog components), Acoustic Revive Power Reference power cables (all electronics), Acoustic Revive CS-2F Outlet Stabilizer (wall outlet), Acoustic Revive CB-1DB Receptacle Base Plate (wall outlet), Acoustic Revive CFRP-1F Carbon Fiber Receptacle Plate (wall outlet), Acoustic Revive Ultra Low-Frequency Pulse Generator R-77 (room), Acoustic Revive Acoustic Conditioner RWL-3 (3 used in room), McKinnon Furniture Bellevue Symphony media cabinet (walnut). 


Harbeth Super HL5 loudspeakers, Skylan SHL5 speaker stands.

Leben CS600 vacuum tube integrated amplifier.

OPPO BDP-83 Blu-ray Player, 42-inch Philips 1080P LCD television.

White Lightning Moonshine DIY speaker cables, White Lightning Moonshine DIY interconnects.


Omega Super 3 loudspeakers, Skylan Super 3 speaker stands.

Leben CS300X Limited Edition integrated amplifier.

Sony PlayStation SCPH-1001 as Redbook source.

Auditorium 23 speaker cables, White Lightning Moonshine DIY interconnects.

Almarro A205A EL84 integrated amplifier, Fi 2A3 mono amplifiers, Fi Y phono amplifier, Leben RS-100 line preamplifier (in for review), Leben RS-100U line preamplifier (in for review), Amarra Computer Player (in for review).


In Issue 38 I wrote about the $599 Mhdt Labs Paradisea + USB DAC (which has now morphed into an updated Paradisea 3 version which I haven't heard). I praised the Paradisea + as a $599 bargain in the realm of USB DACs for its sonic and musical attributes, and at least until I compared it one-on-one with my oddio pal Stephaen's Wavelength Cosecant USB DAC, it remained my favorite USB DAC.

Then along from ye olde PFO Editor Dave Clark came the $899 Mhdt Labs Havana USB DAC for a little follow-on reportage to his Audio Ramblings article in Issue 41, where he surveys a number of USB devices as part of his ongoing investigative journey through the computer audio landscape—which you ought to read if you haven't already.

Back in Issue 38 I introduced the Fab Four behind Mhdt Labs: Jiun-Hsien, Lin-Li, Ting-Ann, and Gia-Ann. Mhdt is a clever and fun-loving acronym created by using the first letter of the Zodiac name of each of the four friends: "M" is for mouse (Jiun-Hsien), "h" is for horse (Lin-Li), "d" is for dog (Ting-Ann), and "t" is for tiger (Gia-Ann). They later decided that Mhdt also stands for "Music Heaven Development Team" because they were getting so much musical pleasure in their lives from their pursuits at Mhdt Labs. I'll add one more acronym based on my own listening experiences with the Havana USB DAC: Many happy DAC times, as I have enjoyed listening to the Havana a lot during the review process.

The Havana USB DAC

I asked Jiun-Hsien what his design goals were for the Havana: “There are so many different kinds of music, such as classical, jazz, rock, pop, metal, folk, etc., and we found that some DACs worked very good with particular styles of music, but didn't work so well with other kinds of music. So, with the Havana our goal was to design a DAC that can handle all kinds of music equally well, and we think that the Havana will appeal to the audiophile or music lovers like ourselves. The name "Havana" tells it all, as we named the DAC after the music originating from Havana, Cuba, which is free of order, free of patterns, and never ceases to surprise and delight us.”

The Havana utilizes an aluminum chassis, except that is, for the acrylic faceplate that allows the Havana owner to glimpse the glowing NOS GE5670 vacuum tube from the front while listening to music, which is a nice touch.

On the back panel the Havana provides USB, Coaxial, and Toslink inputs, and utilizes a 96kHz Cirrus Logic CS8414 chip as the digital audio receiver. With the intent of doing the least damage to the signal stream as possible the Havana uses no digital filter and no op-amp for I/V conversion, uses a 16 bit R-2R Burr Brown PCM56P DAC, and uses a vacuum tube buffered output stage (a single NOS GE5670) in its circuit design.

Mhdt Labs doesn't like to use Delta-Sigma style of DACs, and instead prefers to use R-2R DACs, which Jiun-Hsien says, “produce the 'feel' of real music to us.” Mhdt labs says they believe a R-2R DAC provides a more musical and natural presentation, one that better keeps the 'feeling' of the music intact. Delta-Sigma DACs use oversampling and interpolation as a pulse density conversion technique which allows them to use a lower resolution (and less expensive) 1-bit DAC internally. Delta-Sigma DACs use a low pass filter, step nonlinearity, and a negative feedback loop to achieve Delta-Sigma modulation of the signal. An R-2R DAC, like the 16 bit R-2R Burr Brown PCM56P DAC used in the Havana, utilizes a simpler form of conversion using matched resistors in a ladder configuration that results in greater precision and less signal manipulation during the conversion process. Mhdt Labs feels this is a simpler and purer conversion process that does less damage to the signal and provides a more musically natural presentation. Jiun-Hsien told me, “So we chose the PCM56P DAC chip for the Havana, which outputs only current and voltage. This is very important to simplify the design. 'Less is more' is still the major rule we follow in our designs. By using the PCM56P, and due to its current output, we can omit the use of amplification (the OP amp), which provides a purer signal than can be achieved with a more complicated circuit.”

Not only that, but Mhdt designed the Havana so it would delight tweakers everywhere: Jiun-Hsien told me that “There is a secret that we only tell Havana users, that if they want to they can replace the stock PCM56P chips with AD1856 chips (which are pin to pin compatible), without changing any components in the Havana DAC.  We assembled the Havana with IC sockets for the two PCM56P chips. We purposely installed these two IC sockets so that Havana users could experiment with further possibilities if they wished, like the AD1856 chip, or others.”

That's pretty impressive if you ask me. I didn't experiment with swapping out DAC chips - perhaps that can be a follow up article to this one - but I did try swapping out the stock NOS GE5670 vacuum tube in the Havana's circuit with a variety of other NOS vacuum tubes to see what the results would be sonically and musically. The Havana can use a variety of tubes, including the aforementioned 5670, as well as the 2C51, 396A, 6385, 6CC42, 6854, 6N3, 6854, CV2575, CV4013, CV5894, CV8247, and CV2381. So between swapping out different tubes and DAC chips you ought to be able to entertain yourself forever. Not that you'll need to change things though, as a stock Havana is an impressive piece of kit.

Listening Impressions

For gathering listening impressions with the Mhdt Havana USB DAC, I used System 1 as described in the sidebar, with the exception of using the Leben RS100 and RS100U valve line stages that I have in for review in place of my usual Leben RS28CX full function preamp. I also used the Amarra Sonic Studio Engine during part of the review (which is also in for review, and which replaces the stock iTunes software sound engine with a higher performance 'studio quality' software sound engine designed by the studio people Sonic Solutions). Finally, I substituted NOS Russian 6Pc3-e tubes for the usual KT66 tubes in the Leben CS660P power amplifier (For Leben owners: I'm running them at a plate voltage of 450, and with a cathode resistor setting of 460 Ohms, which gives the most natural sound for the CS660P amp in my system). For a comparator I used the above-mentioned $3500 Wavelength Audio Cosecant V3 USB tube DAC with transformer-coupled output (starting at $3500).

The Music Lovers

Given that Dave had already put the Havana through its paces, I didn't need to allow for break-in of the unit, as it arrived pre-conditioned (thanks Dave!), allowing me to kick off my listening immediately. To get my music Jones going I set my iMac's iTunes to iTunes DJ, and just let it play randomly through my music collection, which was an easy way to hear how even-handed the Havana would be at presenting a broad spectrum of musical styles of varying recording quality (i.e. the music lovers test).

Considering that Mouse, horse, dog, and tiger's design goal with the Havana was a DAC that would play all kinds of music equally well, I'd say they succeeded admirably. Whether my iTunes DJ was shuffling through Louis Armstrong's Skid-Dat-De-Dat from Portrait of the Artist as a Young Man, or Paul McCartney's Every Night from McCartney, or Joni Mitchell's Loveless Love from Court and Spark, or Arleigh from the Gibson Brother's Bona Fide album, or Murmullo from the Buena Vista Social Club album, or Escales from Paul Paray's Detroit Symphony Orchestra album, or whatever, and whether done with state-of-art quality like the JVC XRCD reissues, or in abysmal quality like some of the recordings from the Anthology of American Folk Music, the result was always compellingly musical and enjoyable. So for that reason alone, I would say that music lovers with broad tastes have reason to be enthralled by the Havana, as they can sit back, relax, and listen to anything their heart desires and have a compellingly musical experience flowing out of their loudspeakers.

My first impressions of the Mhdt Havana USB DAC were that it was somewhat warm sounding, and perhaps just a little bit dark like a late night jazz club is. It created a huge sense of recorded space when it was on the recording, and sounded very even and smooth top-to-bottom across the frequency range. It also recovered quite a lot of recorded detail, but always in a way that was consonant with the music, and never in a way that was excessive or exaggerated in such a way as to draw my attention away from the music. Soundstaging was quite good left-to-right, and with a lot of layering evident front-to-back. Imaging was quite good, but perhaps a touch 'soft' in density, a little diffuse around image edges, and with transparency that is good but not outstanding. The first attack on notes is a little soft as well, but with a beautifully articulate harmonic decay—cymbals are rendered in a positively hypnotic fashion. Time elements were presented in fine form, with melody, tempo, dynamic, and rhythmic elements infusing the music with the sort of aliveness and emotive impact that I crave. Perhaps most importantly, the Havana makes music really fun to listen to!

Now let's dig into the details of the Havana's performance a bit and see how it does compared to the Wavelength Cosecant.

Vintage Licks & Kicks

Take Louis Armstrong's Skid-Dat-De-Dat from Portrait of the Artist as a Young Man, which is kind of noisy and 'vintage' sounding from a recording perspective, yet it is terrific music to listen to for enjoyment. Some DACs render an old scratchy sounding vintage recording like this almost unlistenable, but not the Havana, which brings the music to life in an enjoyable way. The Havana does an almost analog-like feat where the noise of snaps, crackles, and pops in vintage recordings exist in a different plane altogether, one that doesn't interfere with the music, which is a trait I think LP devotes will be familiar with and appreciate. So while I can hear all the noise and such in Skid-Dat-De-Dat, the noise doesn't draw attention to itself in any detrimental way, which allowed me to get deep into a state of musical enjoyment. That's cool, and cause for music lovers who like to listen to music of varying recording quality to rejoice!

In this 'Vintage Licks & Kicks' test for lower-fidelity recordings the Havana bested the Wavelength Cosecant somewhat by being easier on the ears: the Havana was smoother and more forgiving, and less brash and bright sounding. For example, the Wavelength Cosecant could get a little too piercing, bright, and hard sounding on the brass in Skid-Dat-De-Dat, while the Havana presented a smoother, more natural and more musically accessible brass tone. With the Havana I enjoyed listening to Skid-Dat-De-Dat, but with the Cosecant I did less so. So for those of you who enjoy listening to a fair amount of lower-fidelity recordings for their musical content, and consider vintage lower-fidelity recordings an important and indispensable part of your music listening sessions, you should take note that the Cosecant isn't quite as forgiving as the Havana in that regard.

What kind of guitar is that brother?

Let's talk about the Havana's sound in the context of timbre. Timbre is those aspects of the sound of individual instruments that distinguish them from each other at a given pitch: the sound of strings versus woodwinds versus brass versus percussion versus keyboards, or more narrowly, the sound of a Gibson Advanced Jumbo guitar versus a Martin D-28 guitar. A reasonable sense of timbral accuracy of instruments is important to music coming across the way it sounded when the artists played it. One of my favorite timbre comparisons is from Jorma Kaukonen's Blue Country Heart album, not only because it is a great album of well-recorded music, but also because Jorma plays a Gibson Advanced Jumbo guitar made of Adirondack & Brazilian tonewoods on the album that is just like the A&B Gibson AJ I have at home, which makes for a convenient quick check of timbral believability.

To give you an idea of why a reasonable sense of timbral accuracy is important in a Hi-Fi rig let me relay a real-life example to you: Once upon a time I was visiting the home of a well know audio journalist and listening to music with him on his system, a very nice system by the way, and one which weighed in at around $100K USD, if memory serves me correctly. When making such visits I often bring Jorma Kaukonen's Blue Country Heart album with me to use as a reference point for timbral believability, and I happened to have it with me that day, so we listened to it on his big rig. The general system sound was quite beautiful, being sweet, romantic, lush, and techni-colorful… but completely out of whack from a timbral standpoint. Instead of presenting Jorma's Gibson AJ as punchy and powerful, with beautiful bell-like trebles, and with harmonically complex, deep, and rich tone in the lower-registers, it made the Gibson AJ sound like a rather bland and generic nylon-string guitar, which is about as far as you can get timbrally from an A&B Gibson AJ.

My point: Have you ever heard anyone play bluegrass music with a nylon string guitar? Me neither, and for good reason, as that timbral signature would screw up the feel of what bluegrass music is about. For that journalist it had other implications with respect to his readers: every review he wrote with that system gave readers an invalid impression of the equipment under review, making those reviews suspect from the practical standpoint of trying to understand what the gear under review sounded like and how well it played music. Oops.

So, a believable sense of timbral reality matters if you want to experience music in the way that it was intended to be played and heard, and the good news is that the Havana presents the punchy, brilliant, and bell-like string tones of the A&B Gibson AJ very believably. In fact when my good friend John April dropped by a few days ago for a visit (a superb guitar, mandolin, and banjo player for the Badger Mountain Dry Band), he commented about how convincingly life-like the music was sounding. So the Havana does a really nice job of presenting the timbre of instruments in a believable way, and that makes it more likely that you'll have an enjoyably authentic music listening experience.

The Wavelength Cosecant also presents timbre in a realistically believable way, although in my system it tends to be a bit more colorful, a bit more bass-heavy, a bit more dramatic, and a bit more electronic and audiophile-like than the Havana (and life itself). However, please note that both the Cosecant and Havana are very good, and I can't imagine anyone complaining about the way either of them presents timbre. Which one of the two that will sound the most convincing in your Hi-Fi rig will probably be determined by your overall system balance and which one of them that complements that balance the best. Regardless, both of these USB DACs are superb performers when it comes to timbral believability, but in my system it is the Havana that gets the nod.

Brother can you spare a little good bokeh?

When audiophiles talk about sound they usually aren't talking about timbre, but rather about those non-musical electronic artifacts produced during the recording process that are commonly referred to as soundstaging, imaging, space (the recreation of a room acoustic), perspective (how close or far from you the recorded musicians seem to be), transparency, and the like, or to coin a new term—audio bokeh.

In case you're not familiar with the term bokeh, it is a term used in photography to refer to the aesthetic quality of those parts of a photo that are not its primary subject matter. In particular, photographers refer to how pleasingly artistic the out-of-focus areas are rendered behind the primary subject of the photo. 'Good bokeh' doesn't draw attention to itself, but enhances the presentation of the subject of the photo, and 'bad bokeh' distracts from the subject of the photo by drawing to much attention to itself. That's an over simplification, but I think it gets the basic idea across. For a very skilled discussion of bokeh, with photos showing good and bad bokeh, check out Ken Rockwell's website here.

In a lot of ways a recording of music is a lot like a photograph, where both artistic and technical elements come into play to produce the final result, so it's not really as simple as reproducing the original music event accurately—there's a lot of artistic interpretation involved in recording, mastering, and playback to achieve the satisfying final result. If we use a recorded music analogy, the subject of the 'photo' is the music itself, and the 'bokeh' refers to how aesthetically pleasing the non-musical electronic artifacts of the recording process are in enhancing the music listening experience. As in photography, 'good bokeh' doesn't draw attention to itself, but enhances the presentation of the music, and 'bad bokeh' distracts from the musical content of a recording by drawing too much attention to itself. Again, that's an over simplification, but I think it gets the basic idea across that if any of those recording artifacts like imaging, soundstaging, detail recovery, etc., are so obvious that it draws your attention away from enjoying the actual musical content of a recording, it's a bad thing, or 'bad bokeh'.

Take Gillian Welch's April the 14th (Part 1) from the Time (The Revelator) album: The Havana renders the imaging in a palpable wood and strings and flesh and blood fashion that emphasizes the tangibility of the guitars and Gillian's vocals commensurate with what you would experience at a live concert, but are not overblown and artificially etched sounding in the way that some audiophiles crave. The Havana presents images in a very musically natural and 'live' way, but live in the way you might hear at a concert, as opposed to the artificial and electronic 'aliveness' that overtly etched imaging causes. Through the Wavelength Cosecant April the 14th (Part 1) is remarkable in its musicality as well, although Gillian's voice takes on a little sibilance, hardness, and edge not evident with the Havana. The guitars have more timbral texture through the Cosecant, which I find attractive, but there is also a little unwelcome additional bass that combined with the Harbeth Monitor 40.1's already prodigious bass makes things sound a little overblown down under. The Cosecant is also more dynamic, with more vivid and solid imaging, and greater transparency. That all sounds desirable, but the actual effect in my system was to make the music sound a little more electronic and audiophile-ish rather than naturally musical, so the end result is that it made it a little more tiring for me to listen to at normal listening levels and enjoy, although at first blush it can be quite impressive.

A caveat: I suspect if you have a particularly laid back system or like to listen primarily at very low volume levels you might find the Wavelength's overall presentation quite enchanting, as it provides a sort of built in 'loudness contour' in the way it's voiced, and the more obvious Technicolor aspects of its presentation will be balanced out a lower volumes. However, in terms of imaging bokeh the Havana bests the Cosecant in my system, as its softer and more natural imaging enhances the music listening experience in such a way as to highlight the music, whereas the Cosecant's imaging draws a little too much attention to itself, diminishing the core musical experience in comparison.

On Crosby, Stills, and Nash's Our House the Havana's soundstaging is wide left-to-right, and has multiple layers going from the front-to-back of the soundstage. The distribution of the instruments and vocals in the soundstage's width, depth, and height evokes a sense of what you might hear at a concert with musicians on a stage. That combined with the smooth and natural musicality of the Havana provides a result that is quite beguiling. So the soundstaging bokeh of the Havana excels at highlighting the beauty and expressiveness of the music without drawing attention to itself, even though by any measure I consider it to be very good in the way it presents instruments and musicians in the height, width, and depth dimensions.

The Cosecant's presentation of soundstage is similar in width, depth, and height compared to the Havana, however, I would say that the Cosecant gives a more distinct sense of layering as you go back in the soundstage depth dimension, primarily due to it's more obvious imaging that has greater solidity and presence. The Cosecant might also present images to be ever so slightly more widely spaced than the Havana as well. The Cosecant is also more dynamic—a little too dynamic in fact - on Our House than the Havana, which seems to upset the intended mellow musical flow of the song. The Cosecant is more vivid, more Technicolor, than the Havana. In my system that makes the Cosecant a little tiring to listen to for extended periods, and makes the music sound a little more electronic and audiophile-ish rather than naturally musical. The bokeh qualities of soundstaging, imaging, transparency, and the like were just too much for me with the Cosecant, it was like it was constantly vying for my attention in 'Hear me! Hear me!' fashion that I found to get tiring compared with the Havana.

Summary and Conclusions

The Havana is a very musical USB DAC that always delivers a pleasurable listening session across a broad range of musical styles and variable recording quality. The way the Havana presents the musical content or recordings is simply beautiful, with timbre and time elements (melody, tempo, dynamics, rhythm, etc.) portrayed in outstanding and musically natural fashion. Of equal importance is the superb presentation of the audio bokeh of the non-musical elements of recordings like imaging, soundstaging, detail recovery, and the like, that always complemented, but never detracted, from the core musical performance—an outstanding combination of traits that the design team at Mhdt Labs deserves kudos for getting it so right.

The Havana is Mhdt Lab's statement USB DAC, and frankly speaking, at $899 it bests the superb Wavelength Cosecant V3 ($3500) in my Hi-Fi rig, making it some kind of miraculous bargain, and one which will surely delight music lovers on a budget. Without reservation I recommend the Havana to music lovers everywhere as a high performance USB DAC, and also as a remarkable bargain.

In closing, I should also mention that Mhdt has also recently released a custom USB and power cable, so at some point I'll follow up with a discussion on swapping out DAC chips and tubes in the Havana, and tell you about the performance of the Havana with Mhdt Lab's new cables to give you an idea of what to expect should you decide you want to do a little experimenting. Jeff Day

Havana USB vacuum tube DAC
Retail: $899 USD

Mhdt Laboratory
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