MHDT Labs: R-2R NOS Tube DACs

Discussion in 'Dedicated Source Components' started by luckbad, Feb 13, 2016.
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  1. Luckbad
    This thread is to discuss the exceptional non-oversampling (NOS) R-2R (resistor ladder network) digital-to-analog converters (DAC) created by MHDT Laboratory Audio Devices.

    There are a few threads dedicated to specific DACs from this company, but I feel we would benefit as a community if we combined our discussion of their various offerings into a single thread. The idea is to offload the general discussion that goes on in the Havana thread and keep things current with a regular Head-Fi member who can update the original post.
    I would like to keep this post up to date with information and guidelines on MHDT's current and past lineup.
    I will also attach current user manuals and drivers if the forum software lets me. Otherwise, I'll provide a link to them.

    Current DAC Family Comparison

    Mhdt Labs DAC Families ​
    Havana 2​
    Stockholm 2​
    Input Capacity USB (Max)​
    Input Capacity SPDIF (Max)​
    Output  Format​
    Digital Receiver Chip​
    USB Chip​
    DAC Chip​
    DAC Chip Construction​
    R/2R Multi Bits​
    R/2R Multi Bits​
    R/2R Multi Bits​
    R/2R Multi Bits​
    R/2R Multi Bits​
    Delta-Sigma 1 Bit​
    I/V Stage​
    Voltage out
     DAC's Internal OPAMP ​
    Current Out
    Discrete Transistors I/V,  No OPAMP, No feedback​
    Current Out
     AD847AQ as I/V​
    Tube Buffer​
    Tube Buffer with 5670/2C51 ​
    Output level​
    Output impedance​
    32 ohms​
    32 ohms​
    32 ohms​
    32 ohms​
    32 ohms​
    32 ohms​
    Inputs Available​
    3 Inputs -- USB/ RCA/Optic​
    4 Inputs -- USB/RCA/BNC/Optic​
    USB Input Topology​
    USB Driver for Win XP/W7/W8​
    No Needed​
    Yes, Needed​
    USB Driver for Linux/Mac​
    No Needed​
    Dimensions clear (WxDXH) ​
    276 x 150 x 60 mm​
    Dimensions w/ socket ​
    295 x 170 x 60 mm​
    Box Color Avialable​
    Black Only​
    Black/Silver Selectable​
    Silver Only


    Other MHDT Threads

    1. MHDT Labs Havana: Thread for the discussion of the current entry-level PCM56P-J variant
    2. MHDT Labs Pagoda: Thread for discussion of the PCM1704 variant
    3. MHDT Labs Stockholm: Thread for discussion of the PCM56P-J variant
    4. MHDT Labs Stockholm v2 Tour: A tour graciously initiated by @Soundsgoodtome, the godfather of MHDT on Head-Fi!
    5. MHDT Labs Stockholm v2 Review by @s1rrah, co-godfather of MHDT Labs on Head-Fi
    6. MHDT Labs Paradisea(+): Owners club for the Paradisea variants.

    MHDT Labs Drivers & Manuals

    My MHDT Labs Atlantis

    R-2R NOS AD1862N-J Tube DAC
  2. Luckbad

    Frequently Asked Questions (FAQ)

    How long should I leave my DAC powered on?
    30 minutes is enough to warm up the R-2R chips in MHDT DACs. You can leave the DAC powered on 24 hours a day if desired. However, the I/V stage is unique and should be shut down for ~10 minutes every 4-6 hours.
    Commercial tube life is about 5000-6000 hours, while military tube life is about 8000-10000 hours. Working in low voltage in the MHDT DACs may benefit tube life, but be aware that the tubes will last longer if the unit is powered down when not in use.
    [Source: Jiun]
    Would MHDT DACs benefit from a linear power supply?
    The power supply inside these DACs is already a good linear supply. It is unlikely to provide audible benefit to purchase an external linear psu.
    [Source: Jiun]
    Do they support 6SN7 tubes with the proper adapter (Garage1217)?
    Subjective/anecdotal impressions would suggest that 6SN7 tubes do indeed work (@Soundsgoodtome @Barra @ericr). More testing is needed.
    Do they support 6N2P tubes with the proper adapter?
    At first I thought he meant that tubes sound best when they are very old and about to give up, but I believe he means they generally work best when being pushed hard and that the MHDT dacs don't push much voltage into tubes.
    Editor's Note: I ordered two different adapters from Hong Kong to try out 6N2P-EV tubes and will report back in this thread after they arrive. They seem to be a good possibility for a cheap alternative tube type if Lampizator is to be believed about their prowess, as their specs align pretty closely with 5670 tubes.
    What's the best tube?
    Depends on your ears and your gear. The tube section below will eventually be updated with subjective thoughts. If you stick to 1st class and 2nd class tubes from the MHDT site, you'll be happy:
    Why don't I see the Atlantis/Pagoda/Havana 2 on the MHDT website?
    The website is terrible. MHDT makes incredible DACs and bad/outdated websites. Details on the current offerings can be found at Basshead.Club (grab the manuals).
    Which DAC do I want?
    The standard answer is that music is personal and we can't possibly know which DAC works best for your ears or your setup.
    That said, none of us at this time have heard all three of the top tier offerings (Stockholm, Atlantis, Pagoda) and can't accurately differentiate between all three. @s1rrah has talked about differences between the Stockholm and Pagoda (the former being more musical, the latter being more accurate and detailed).
    We hope to have at least a few of us in the know about all of the DACs in the coming months by swapping with each other.
    Will this work with my Amp?
    No, I mean will it pair well with it?
    Probably. Many of us favor the Garage1217 amplifiers for their price/performance ratio and ability to further tune the sound with an additional tube stage in the chain.
    I personally found the combination of the MHDT Labs Atlantis and Garage1217 Project Sunrise III satisfying enough that I sold my Audio-GD Master-11 in order to have the same setup at both work and home (before you ask: The Master-11 is better overall, but twice as expensive).


    1. s1rrah - Head-Fi: Stockholm 2 (June 2014)
    2. Positive Feedback: Stockholm 2 (January 2014)
    3. SoundBsessive: Stockholm 2 (January 2014)
    4. TNT Audio: Stockholm (October 2012)
    5. Digital Audio Review: Havana Balanced (February 2011)
    6. Digital Audio Review: Paradisea (August 2010)
    7. Positive Feedback: Havana (November 2009)
    8. Enjoy the Music: Havana (December 2008)
    9. Positive Feedback: Paradisea+ (July 2008)
    10. Enjoy the Music: Paradisea & Constantine (April 2006)

    Other Resources

    1. MHDT Laboratory Audio Devices Official Site
    2. Basshead.Club: Drivers and Manuals
    3. DIY Audio Blog: Modding the Constantine
    4. DIY Audio Blog: Modding the Paradisea
    Let me know of any other reviews or resources you know about.
    In a few weeks I hope to review the Atlantis. I imagine @s1rrah and @Soundsgoodtome will have Pagoda reviews sometime soon.
  3. Luckbad


    I'd like to compile a resource for tube rollers here for 5670 tubes (as well as experience of those who use the Garage1217 6SN7 -> 5670 adapter).
    Please post impressions and characteristics in this thread and I'll compile comments for each tube here.
    For now, this is just information from the official MHDT page.
    1st Class
    WE396A / WE2C51 (D getter, JW Military version)
    Bendix 6385 (expensive)
    Tesla 6CC42 (D getter, rare but sometimes will show up in the market)
    JJ 6386 (expensive, new production)
    2nd Class
    WE396A/2C51 (O getter)
    Tesla 6CC42 (O getter, rare but sometimes will show up in the market)
    Tung-sol 2C51 (they invent this tube, 1950s, D getter)
    Raytheon CK5670 (1950s, D getter)
    RCA 5670 (1950s, D/Plate 2 supporting rod getter)
    GE 5670 (3 mica structure, mostly 5 stars tube)
    3rd Class (after 1960s)
    GE 5670
    RCA 5670
    Tung-sol 5670
    Sylvania 2C51
    Sylvania 5670 (sometimes marked Mullard)
    RTC 5670
    Philips 2C51

    4th Class
    Russian and Chinese 6N3P, -E, -EB, -EV 
  4. s1rrah
    I am a fan.
  5. Soundsgoodtome
    Been turning people to MHDT Dacs, went as far as to put a tour (below). There needs to be more publicity on these DACs as they, imo, compete very well at their price level. Hopefully the tour will help get the word out. These DACs are extremely versatile in tuning, with a simple switch of a tube. Details, clarity, resolution, etc are all top notch. Great thing about a the R2R NOS and tube-buffered DACs is it's ability to match with a lot gear. Pairing with a solid state will usually create a euphoric sound but still keeping things tight. Pairing with a tube hybrid amp you can further make the sound even more tube-rich, even more so on straight tube amp.

    Another great with these DACs, which seems to have captured many in the speaker world (many early reviews after all are from speakerphiles), is it's ability to add a tube sound to most solid state speaker amplifiers.

    Luckbad likes this.
  6. ericr
    Here's a bit I posted over on the Pagoda thread that maybe makes more sense here:

    After a fair bit of rolling (in my Paradisea 3) the Bendix 2C51 is the champ and the WE 396a is a close second (it is the D getter though not the earlier JW version). Currently I also have the Stockholm 2 that Soundsgoodtome has on tour and it has a Bendix in it as well. I've not yet rolled with the S2 though.

    For me the Bendix gives these MHDT DACs a solid combination of tonal accuracy, detail, tightness of bass, treble extension and excellent openness / soundstage / separation / placement. In my Project Ember amp I'm running the Sylvania 6SN7W which is well known for characteristics much like I just attributed to the Bendix.

    These drive my 64 Audio A12 with the ADEL technology - a combo that putting me awash in an natural, realistic, and yet very impactful flow of music.

    One happy listener!
    Luckbad likes this.
  7. HighNFidelity
    Remarkable job Luckbad!
    I truly appreciate the sincere efforts from you and fellow compilers.
    An elaborately detailed and thorough thread compilation of useful information for current as well as prospective MHDT ladder heads is welcome.
    Also, have you or anyone else had the chance to audition the LM Ericsson Swedens in any of your MHDTs?
    Luckbad likes this.
  8. Luckbad
    I imagine some others have. I've only used the GE JAN 5670, GE 5 Star Triple Mica, WE JW 2C51 and WE 396A (non-JW).
    Since I sold you my best matched pair for your balanced Pagoda, I'm actually using a really great non-JW version now. It sounds like just the JW version. It's a D-getter from 1942 that measures at 140% of NOS (!).
    I'm on the lookout for other great testing 396As but this one oughta last me for a few years.
    These are on the way to you soon:
  9. ericr

    That's one I'm keeping an eye out for.
  10. Soundsgoodtome
    I've got a pair of AEG 5670 incoming which should be comparable to the Bendix 6385/2c51.
  11. Luckbad
    Never seen anything about the AEG 5670.
    I'm trying to decide if I want to get an RCA 5670. Anyone heard both the Command and normal version of these?
    I might need to offload a couple more of my WE 396A / 2C51 tubes. I have enough to last me like 20 years now.
  12. Soundsgoodtome
    The aeg is supposedly comparable to the Bendix 6385 according to S1rrah and the gent selling them out of Europe. The aeg, which is somewhat impossible to find cost new around $40 for 2 with intl shipping.

    Looking forward to trying em when they arrive. I'll pay impressions with the Pagoda.

    Also, I've yet to try it but the 6sn7 is another world of possibility with even richer sounding tubes. With the proper adapter from Jeremy at Garage 1217, one can dive into the world of tubes readily available for usually around $20-$30 with great sound.
    Luckbad likes this.
  13. Luckbad
    Did anyone ever get an answer from Jiun regarding 6SN7 tubes and whether it's safe/smart to use them long term?
  14. Soundsgoodtome
    I was told by Jiun 600mW heater draw from the tube is fine on the DACs. Not sure if there are 6sn7 tubes with more but I believe most is at that rating. The bendix 6385 is at 500mW
    Luckbad likes this.
  15. Luckbad

    Gonna start looking into good 6SN7 tubes for tube buffers.
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