MHDT Labs: R-2R NOS Tube DACs

[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.
 
http://dhost.info/mhdtlab/
 
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

 

Models​
Spec
Input Capacity USB (Max)​	16bits/48kHz​	24bits/192kHz​	24bits/192kHz​	24bits/192kHz​	24bits/192kHz​	24bits/192kHz​
Input Capacity SPDIF (Max)​	24bits/96kHz​	24bits/192kHz​	24bits/192kHz​	24bits/192kHz​	24bits/192kHz​	24bits/192kHz​
Output  Format​	16bits​	16bits​	16bits​	20bits​	24bits​	24bits​
Digital Receiver Chip​	CS8414​	CS8416​	CS8416​	CS8416​	CS8416​	CS8416​
USB Chip​	CM102AS+​	CM6631A​	CM6631A​	CM6631A​	CM6631A​	CM6631A​
DAC Chip​	PCM56P-J​	PCM56P-J​	PCM56P-J​	AD1862-J​	PCM1704​	AK4396​
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​	Current Out  AD847AQ as I/V​
Tube Buffer​
Output level​	2.6V​	2.6V​	3.0V​	3.0V​	3.0V​	2.8V​
Output impedance​	32 ohms​	32 ohms​	32 ohms​	32 ohms​	32 ohms​	32 ohms​
Inputs Available​
USB Input Topology​	USB1.0​
USB Driver for Win XP/W7/W8​	No Needed​
USB Driver for Linux/Mac​
Dimensions clear (WxDXH) ​
Dimensions w/ socket ​
Weigth​
Box Color Avialable​	Silver Only ​

[td=colspan:7]

Mhdt Labs DAC Families ​

[/td] [td=rowspan:2]

Havana​

[/td] [td=rowspan:2]

Havana 2​

[/td] [td=rowspan:2]

Stockholm 2​

[/td] [td=rowspan:2]

Atlantis​

[/td] [td=rowspan:2]

Pagoda​

[/td] [td=rowspan:2]

Steeplechase​

[/td] [td=colspan:2]

Voltage out
 DAC's Internal OPAMP ​

[/td] [td=colspan:3]

Current Out
Discrete Transistors I/V,  No OPAMP, No feedback​

[/td] [td=colspan:6]

Tube Buffer with 5670/2C51 ​

[/td] [td=colspan:2]

3 Inputs -- USB/ RCA/Optic​

[/td] [td=colspan:4]

4 Inputs -- USB/RCA/BNC/Optic​

[/td] [td=colspan:5]

USB2.0​

[/td] [td=colspan:5]

Yes, Needed​

[/td] [td=colspan:6]

No Needed​

[/td] [td=colspan:2]

260X150X60​

[/td] [td=colspan:4]

276 x 150 x 60 mm​

[/td] [td=colspan:2]

280X170X60​

[/td] [td=colspan:4]

295 x 170 x 60 mm​

[/td] [td=colspan:2]

1.8Kg​

[/td] [td=colspan:4]

2Kg​

[/td] [td=colspan:2]

Black Only​

[/td] [td=colspan:3]

Black/Silver Selectable​

[/td]

 

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

http://www.basshead.club/audio-gear/mhdt-laboratory-audio-devices/
 

Current drivers and manuals for MHDT Laboratories Audio Devices R-2R (resistor ladder network) NOS (non-oversampling) DACs (digital-to-analog converters).

MHDT Labs USB Drivers (CM6631A)

1. CM6631_6631A_1.03(CR) (Windows XP, Windows 7, Windows 8)
2. CM6631_6631A_1.15(CR) (Windows XP, Windows 7, Windows 8, Windows 8.1)
3. CM6631A_WIN10-1.01(CR) (Windows 10)
4. CM6631_6631A_1.01(CR) (Windows XP, Windows Vista, Windows 7, Windows 8)

MHDT Labs User Manuals (Atlantis, Pagoda, Pagoda Balanced, Stockholm v2, Stockholm V2 Balanced):

1. MHDT_User_Manuals

Icon for use in your list of Playback Devices:

 

My MHDT Labs Atlantis

R-2R NOS AD1862N-J Tube DAC
 

 

[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)?

In all our dacs, tube is acting as a buffer.
So, the tube is a passive compnents in circuit and so a fixed set up (bias). No needs to adjust resistors' value for most tube.

However, the tube is working on -17.5 to + 17.5 volts, quite a very low voltage in tube's world.
5670 can works on this low voltage because 5670 was design and developed for minitary communication equipment during WWII. So, it can be work on hardest enviorment such as low battery source and hard vibration. All pencil tubes were designed to be used in air plane, they also have same characteristics like 5670. 6SN7 is a commercial tube, it may also works on our dac but sound must be another issue.

Best Regards,
Jiun
Mhdt Lab

 
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?

6N2P-EV is about the same as 6AX7.
This tube is good for high voltage and don't know how it sounded in low voltage's situation.
It will work on an unnormal condition like 6SN7.
 
If you know the best sounding of a tube is when this tube is near dying.  May be this is our proverb says "Sunset is beautiful but near dusk".  So, You can try but I doubt that the sound will be correct.

Best yours,
Jiun
Mhdt Labs

 
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: http://dhost.info/mhdtlab/tube.htm
 
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?
Yes.
 
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).
 

Reviews

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.

 

[Luckbad]

Tubes

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.
 

The burn in time will takes about 1 days for components and about one month for tube.
The tube will be a big issue in this process.  The installed tube GE 5670, date coded 1987,  is the last generation of western industry,  the golden tube ages.  In fact is a good tube but need quite a long time to burn in and aging.  The famous tube are all about 1950s' tube as they were well aging already just need burn in.
 
The tube, I will not recommend any since it depends majorly in taste. 
However, I will say that the western tubes are quite good due to their materials used in making tube and not recommend recent produced tube like Russian or Chinese 6N3 due to wrong materials are used.
 
Jiun-hsien,
Designer of the team Mhdt Labs

 
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 

 

[s1rrah]

I am a fan.

 

[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.

 

Spoiler: MHDT Stockholm V2 Tour

  Hello Head-Fi community, being a part of this site for some time now and expanding my musical journey as well as the different gear I've been able to listen to; I figured closing in on 5000 posts it would be a great time to put together a tour for one of the best discoveries I've made upon joining the hobby years ago. Looking at my list of gear on my profile will show you I've gone through quite a bit sources, phones, amps. Many I've thoroughly enjoyed through the sonic journeys. Up until today, one discovery in the journey I've made are the MHDT line of DACs. With very little coverage of this DAC, I offer to tour a self-purchased Stockholm V2 to share this little known gem of a company.

 

Spoiler: A bit about MHDT Labs:

MHDT Labs, a Taiwan based company, started producing their own multi-bit/R2R DACs in seeking pleasing but accurate sound to the 4 founders of the company. Their earlier models, Constantine and Paradisea, were some of the most musical DACs I've heard but without sacrificing a whole lot in detail and resolution. Fast forward some 10 years and they now offer several models ranging from AD R2R chips to the more common PCM1704.

The name MHDT comes from an acronym of the original 4 founders and the first letter of their Zodiac signs (Mouse, Horse, Dog, and Tiger). The acronym meaning was later changed to Music Heaven Development Team but given the time of the year and that Lunar New Year is upon us (Feb 7th on this side of the globe), I would prefer the original meaning of the acronyms of the name.

The original focus of the company is to create a musically pleasing sound that catered to the liking of the founders. What it has evolved into is an accurate recreation of sound and timbre of instruments and vocals while remaining musical to ones ears. Searching around the net will yield many reviews from many in the speaker side of audio but using these DACs with headphones has shown the amazing accuracy they're able to reproduce from the digital files.

A little disclaimer: their website is a bit of a throwback in terms of layout, just part of the company charm I suppose. Most e-mails are answered directly by Jiun himself and I believe the company while creating fantastic sounding DACs, may be a bit slow on the response as it is a smaller company compared to Audio-GD. That should not detract you from the company, however keep in mind if you do make inquiries. Lastly I'm not associated or affiliated with the company, just another enthusiast who really likes the products.

 
 
 

Spoiler: Why the MHDT Labs Stockholm V2?

There are several models in the MHDT Labs lineup and after a recent comparison between the Paradisea 3 (discontinued), Havana 2, and Pagoda, I've come to the conclusion that the Stockholm V2, which can be said to be the latest iteration of the Havana line using the PCM56P-J R2R chip minus the use of the internal opamp, would be a great candidate to tour as not only does it represent the MHDT house sound it also takes the level of clarity above previous models without sacrificing the lineage signature. I also own the Pagoda which does offer a level of clarity above the other units but at the sacrifice of some of the musicality and timbre that the company has well crafted into their signature, consider the Pagoda as the one-off in terms of of fitting into an 'audiophile' signature by straying from the house sound.

The Stockholm V2 is a non-oversampling tube buffered DAC that can handle files up to an 'audiophile' 24-bit 192khz but downsamples this signal internally to 16-bit which is then turned into an analog signal via the Ti/BB PCM56P-J chips. While the DAC is NOS and tube buffered, the DAC is not slouchy or heavy in color but only hints in warmth and has a sense realism in sound I've not heard in other gear.

The requirements to join the tour:
- Be a USA Head-Fi member
- Have at least 150 posts and have joined H-F prior to 2015 or know me personally / have met in person.

To sign up, write in a post of this thread with the following:
- List of gear you'll be using with the DAC including headphones, speakers, amps, and DACs in comparison.
- Your experience with audio gear and if you've had experience with an R2R DAC previously/currently. 
  -Also list if you're part of the music industry (engineer, musician, etc) or have some musical training on an instrument.

After sign-up has been closed, I will select 7 members within the list to participate in the tour, 3 have already been chosen and are local Head-Fi members/friends who have shown interest in person. This will make a faster start to the tour and get a few impressions rolling. I do ask that participants refrain from reading the written impressions/reviews until you've made yours, the power of suggestion is quite persuasive.

Details if you are chosen for the tour:
All participants must be in the USA, this makes it less complicated logistically. I ask that you write an impression however short or long of your notes or a full review of the unit when you are finished (although not required). Each touring member is required to pay for shipping to the next member in tour, which is to have tracking and full insurance. USPS or FedEx is to be used for shipping. Members keep the unit for 7 days, first day starts day after receiving the unit and item must be shipped on the 7th day to the next member (if 7th day falls on a Sunday it is to be shipped the next day). Upon receiving the unit, tour members are to report condition of the DAC within the same day with a picture of everything received.

More details in PM upon being chosen for touring. If you have any questions please feel free to PM me.
 
 
MHDT Labs Stockholm V2:
non-oversampling R2R DAC with a tube buffer. Complete discreet output with no opamps or digital filters.

 
Comes with GE 5670 stock tube but tour unit will be fitted with Bendix 2C51 NOS tube for better performance.

 
Unit is configured for 115V usage (switchable via jumpers to 230V)

 
Dual BB PCM56P-J with tube output buffer. Design output discrete with no opamps or filters in path.

 
Inputs are up to 24/192khz files via USB, Optical, RCA, or BNC spdif:

 

 

[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!

 

[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]

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?

 
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:

 

[ericr]

...
Also, have you or anyone else had the chance to audition the LM Ericsson Swedens in any of your MHDTs?

That's one I'm keeping an eye out for.

 

[Soundsgoodtome]

I've got a pair of AEG 5670 incoming which should be comparable to the Bendix 6385/2c51.

 

[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.

 

[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]

Did anyone ever get an answer from Jiun regarding 6SN7 tubes and whether it's safe/smart to use them long term?

 

[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

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.

 

[Luckbad]

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

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