Review and Measurements of Little Dot MK III Tube Headphone Amplifier

[milosz]

One of the reasons for tube headphone amps is that many very good headphones are ELECTROSTATIC, which operate at high voltages and are mostly a capacitive load. Tubes operate at high voltages and are tolerant of capacitive loads generally speaking. An electrostatic headphone wants a big voltage swing and almost no current, which task tubes happily accomplish. In addition, properly used to drive a load that does not require much current a triode tube is perhaps the most linear active device ever made.

For dynamic or planar headphones, tubes don't have the kind of inherent suitability that they have for electrostatic 'phones.

BEST headphone / amp combo I ever heard was a GIlmore DIY T-2 and original version Stax SR-007's. Better than any Focal, Abyss, etc headphone I've ever heard. (Disclaimer: I have not heard the Sennheiser Orpheus 'phones or amps)


[EDIT 9/2/19 FYI I was here explaining that there ARE sound engineering reasons for using tubes in a headphone amp if it's intended for electrostatic headphones; I was not trying to claim that the Little Dot III is a headphone amp for electrostatic 'phones. ]

 

[Andrew LB]

Does anyone know which PCB version the tested amplifier is? I ask because there are big differences between the earlier PCB versions and the more recent ones that are much lower quality IMO. The ones with PCB 1.0 and 2.0 typically have Rubycon and Nichicon electrolytic capacitors and WIMA film caps, while the V4.0 and v5.0 use Nippon Chemicon and some generic crap films. There are lots of other differences as well, and its clear that the newer versions were made on the cheap.

Any channel imbalance is likely due to the volume pot. Cleaning it out and re-lubing it will help. I went a bit further and threw it in the trash and installed an Alps Blue Velvet. No more imbalance or buzzing.

 

[GGroch]

I bought one of these on ebay as a general purpose gain stage and HP amp. They can be 'hot rodded' in various ways with tubes, so rolling fun for tube perverts........They have sliders on the bottom to adjust the gain.......I find it most pleasant to listen to due to whatever subjective atrocities it commits. I would have expected it to measure like dog's breakfast. At the price I paid, with the pleasant listening and nice appearance, it was money I don't regret parting with.

I have owned a MK III for several years and totally agree with your assessment. I really like my MK III. I am certain that most or all of my appreciation has to do with tube rolling opportunities, its classy appearance, nostalgia, and its very cheap price.

Amir's tests prove any actual performance advantage is bunk. But as subjective beings audio science also proves that we appreciate audio with our minds as well as our ears. I know it's contradictory for me to enjoy this tube amp so much, while simultaneously ridiculing those who get pleasure from high end audio cables. Especially since most high end cables do not hurt performance. So my MK III is a guilty pleasure, but I love it.

 

[Azeia]

Does anyone know which PCB version the tested amplifier is? I ask because there are big differences between the earlier PCB versions and the more recent ones that are much lower quality IMO. The ones with PCB 1.0 and 2.0 typically have Rubycon and Nichicon electrolytic capacitors and WIMA film caps, while the V4.0 and v5.0 use Nippon Chemicon and some generic crap films. There are lots of other differences as well, and its clear that the newer versions were made on the cheap.

Nippon Chemi-Con is supposed to be good though, so I dunno what the issue is with that. Also, out of curiosity, where did you garner this info? Have you bought multiple units yourself or is there a forum where they've discussed and compared units?

 

[irrationophile]

If you don’t mind me asking, about how high in frequency can you hear?

https://www.szynalski.com/tone-generator/ (taking note of course of the frequency response of the gear used)

It doesn't matter when you are trying to listen for Harmonic/intermod distortion and noise. As for 'flatness' of sound or low/high freq. extension, nothing is more reliable than frequency response measurment which amir has already provided (although i'm not sure if this is phone output).

 

[jsrtheta]

I have owned a MK III for several years and totally agree with your assessment. I really like my MK III. I am certain that most or all of my appreciation has to do with tube rolling opportunities, its classy appearance, nostalgia, and its very cheap price.

Amir's tests prove any actual performance advantage is bunk. But as subjective beings audio science also proves that we appreciate audio with our minds as well as our ears. I know it's contradictory for me to enjoy this tube amp so much, while simultaneously ridiculing those who get pleasure from high end audio cables. Especially since most high end cables do not hurt performance. So my MK III is a guilty pleasure, but I love it.

I had one about five years ago, using it as a preamp to a yamaha integrated amplifier (preamp section on the Yamaha bypassed). I realize it measured horribly (as I knew it would when I bought it), but I found the sound seductive. At some point, for reasons that seemed rational at the time, I sold it (it lasted on Craig's List all of five minutes after I posted the ad). I never should have done that.

 

[watchnerd]

@amirm I have to commend you sir for a balanced review! It's unfortunate that the Littledot gear misses its distortion spec.


It's THD stays above 0.1% for most of its operation which is a good bit more than 0.15% quoted. Also though it has a healthy power output at 350 mw, man, it's not close to the 350 mw quoted in your tests. This is a real problem. It sounds to me like blatant lying by the manufacturer . And I'm seeing this all the time even in gear that measures very well. Inflated power specs! It's not right and I appreciate you doing it because it shows the world that there's falsehoods being advertised.

Regarding performance:
The Little dot spurious tones do intrude into potentially audible territory coming in at -55db.
But I appreciate the listening tests you did. You discovered that the audible impact was barely noticeable. Quite surprising to me honestly as I thought that would be significantly noticeable in music listening. This sort of combination of measurements and listening tests help people like me understand what kind of impacts measurements put out in real world music listening.

The Little dot measures rather poorly imo

with distortion spikes at -55 db
vs the JDS atom

with distortion spikes at -118 db (!!) - 63 db lower distortion!

Even at these high distortion values the audible impact in music listening appears to be seemingly very low.
I hope you continue to perform as many listening tests as you have time for so we can get a better idea of how measurements correlate to music listening.

To be honest, I am hesitant though, for me those distortion spikes and snr are simply too bad. I would probably bias myself in to disliking it if I ever purchased it simply because I know its real measurements.

Having said that, I once had my heart set on buying the Little Dot mk8. Whatta looker!

That's really nice looking.

I'll admit that if it was made by a brand I could trust with tubes (e.g. Luxman), I'd be so tempted....even though I don't really need a headphone amp.

But VU's!

 

[milosz]

That LittleDot MK8 is GARISH! All it needs is a HOOD ORNAMENT.

You want to see a headphone amp which exhibits what I consider good luxury-minimalist industrial design?

Have a look at this amp I built... based on Nelson Pass Zen amp; shedua wood side trim, volume knob ground from labradorite; 5/8 thick machined aluminum front panel with polished and beadblasted finished sections.... sounds OK, too, especially on Sennheiser HD800. Not quite enough power for HiFiMan HE6 but plenty for the various Audeze planars.

 

[watchnerd]

That LittleDot MK8 is GARISH! All it needs is a HOOD ORNAMENT.

You want to see a headphone amp which exhibits what I consider good luxury-minimalist industrial design?

Have a look at this amp I built... based on Nelson Pass Zen amp; shedua wood side trim, volume knob ground from labradorite; 5/8 thick machined aluminum front panel with polished and beadblasted finished sections.... sounds OK, too, especially on Sennheiser HD800. Not quite enough power for HiFiMan HE6 but plenty for the various Audeze planars.View attachment 32548

That's a nice bit of work! I could never build such a thing without a year of free time that I don't have. Really mad skills you have.

But where are the tubes and VU?

What glows or moves?

 

[dreadknot]

i dont know or cant find if you've reviewed the balanced version of this amp the LITTLE DOT MKIII SE BALANCED HEADPHONE AMPLIFIER an if its better or worse then the xDuoo TA-20 an if its cheaper, as im looking for a BALANCED amp for my cans that got at least 2watts at 32ohms and is under 300$ because id almost go for the Drop THX (THX AAA™) 789 even for 400$ but its just to much power for my needs other way it would be the sweet spot

 

[maxxevv]

SMSL SP200.

Check the review here on ASR.

 

[Shane D]

SMSL SP200.

Check the review here on ASR.

I second your recommendation. The landed price from China was MUCH cheaper than the 789 or 887, in Canada.
It took a while to adjust to the sound and I love it now.

 

[MorningDew]

This seems like the best thread for this question, if not, I apologize. The MKIII has the two gain switches allowing the user to adjust to headphone impedance accordingly. After some experimentation I've landed on a gain of 4 with the HD4XX (300 Ohm, 103dB/1Vrms) . I'm currently intrigued by some Grados (32 Ohm, 99.8dB/mW) which are at the other end of the impedance spectrum. If I were to own both does that mean I'll be forced to adjust the gain every time I switch headphones or am I putting too much stock in what the switches do? I also find it odd that changing the gain settings didn't much affect listening volume. Thank you!

 

[royiko]

High voltage solid-state devices are as well the limiting factor of performance for electrostatic amplifiers. But you need to know that electrostatic headphones are really different load. So solid-state don't really have much lower distortion.

You get some experience with LittleDot MK8 or MK6? How are they comparing to the A90?

 

[rafmart]

Has anyone used the hybrid version: MKIII+?
https://littledotus.com/?product=mk-iii-2
Any conclusion / summary?

 

[Shane D]

This seems like the best thread for this question, if not, I apologize. The MKIII has the two gain switches allowing the user to adjust to headphone impedance accordingly. After some experimentation I've landed on a gain of 4 with the HD4XX (300 Ohm, 103dB/1Vrms) . I'm currently intrigued by some Grados (32 Ohm, 99.8dB/mW) which are at the other end of the impedance spectrum. If I were to own both does that mean I'll be forced to adjust the gain every time I switch headphones or am I putting too much stock in what the switches do? I also find it odd that changing the gain settings didn't much affect listening volume. Thank you!

View attachment 60996

It is a weird little amp. I maxed out the gain, but felt it could not do justice to the DT880's (600 Ohm).
On the other hand my Grado GH2's sounded awesome out of it. Really surprised me. To add to the "tube magic", I also ran a Schiit Loki through the system to give it a more full sound.

After a few months I sold it on. And shortly after that I sold my Mapletree Audio Design Ear+ HDII amp. It was a very nice amp, but again, I could not find the tube magic. And it was more than triple the price of the LD MKIII.

I am still on the lookout for interesting sound signatures, but do love my iFi Pro iCAN and Violectric V220 (both bought used for about half of retail).

There is just something about the look of tube amps though...

 

[DonR]

For those interested in this amp, there is a thread here that has schematics and a wiring diagram for the volume pot, which is essential as the little wires going to the pot tend to break at the solder joints. If you hear a channel drop out, this is likely to be your problem.

 

[jdjung]

You know, I've had this amp for about ten years and bought it for $110 on Craigslist and it was the best investment I've made as a proclaimed audiophile. The person sold it to me because he kept getting noise from the RCA no matter what he was plugging it into. It was a ground loop noise. I currently have it setup with NO NOISE from a Qudelix 5k and stream my phone or computer directly by LDAC. I also have it hooked up this way to my Drop THX 789 as a preamp using the RCA's out the back. Given that noise on these tube amps can be different for different volume levels, this gives me more control to find the sweet spot by having the 789 raise the level of the tube amp. I have the balanced inputs on my 789 attached to my Antelope Audio Zen Q if I don't want to use the Little Dot Mk 3 as a tube preamp.

 

[DonR]

If you place a cell phone or cordless phone less than a foot away have you noticed any periodic noise? I had to move my handset 2 feet away to have it stop even though I have a cage for the tubes which helps but not enough.

 

[jdjung]

If you place a cell phone or cordless phone less than a foot away have you noticed any periodic noise? I had to move my handset 2 feet away to have it stop even though I have a cage for the tubes which helps but not enough.

Hey DonR, I know what you're talking about. It's the weirdest thing ever, I used to get noise from it from my phone when I had it hooked directly to a wall plugged DAC and had to be VERY choosey where I placed the amp. After I plugged the sucker into either Fiio BTR3 or the Qudelix 5K, It's just QUIET. Like no noise, no feedback, nothing just clean music, no distortion that I can notice and no weird glitchy noises! I don't understand it myself. I litterally just put my phone on top of my Little Dot Mk 3 and it's quiet.