Vacuum tubes are the remnants of an era of technology that is long gone. They were the predecessors of the modern transistor, yet, vacuum tubes continue to ensnare the senses of audiophiles around the world, which hold them in high regard for their almost magical qualities. Tube amps (or valve amps as they are referred to in some regions) can usually go for quite a steep price, and the really cheap ones will usually be badly constructed designs with sub-par vacuum tubes.
Today, I have the Little Dot MK II with me for review – a tube amp that ships with 4 vacuum tubes in a 300W design for the unbelievable price of $179. The review sample was provided to us courtesy of Gearbest who are offering the Little Dot MK II at a super-discounted price of $133 for a limited time just for our us. So if after reading this review, you are looking to buy one, be sure to avail the discount.
I have to admit, I don’t think I have ever been more excited to review an amplifier, and before I get carried away, a general introduction of this amazing technology is in order; so without any further ado, lets dig in.
A long exposure shot to showcase the glow of the Little Dot MK II.
1. A short introduction to the magical world of tube amps
Modern amplifiers are all built of little transistors. These digital devices are the building block of pretty much any modern electronics and offer a very high level of control and power over the application in question. When talking about transistor based amplifiers we have to keep two things in mind, 1) that they will offer completely sterile amplification of the source and 2) the amplification in question introduces something called clipping at higher volumes, which isn’t really a desirable trait at all. To quote Ken RockWell:
Tube amplifiers have much more distortion than solid-state amplifiers, but most of it is second-order, which is quite musical. That’s why it’s called “harmonic” distortion.
Second-harmonic distortion is exactly the same note, an octave above. Ditto for higher-order even harmonics; they are also the same note more octaves above.
Even-order harmonic distortion can be so pleasant that back in the 1970s the Aphex Aural Exciter was very popular in recording and broadcast specifically because it was designed to generate and add these harmonic distortions!
Long story short, tube amps have a little extra something that modern day amplifiers lack. This distortion is something that is favored by most audiophiles around the world and is highly coveted. Audio trends are generally regressing, with the turntable making a comeback but it is the tube amp that is the real star of the show.
While this will obviously be a mostly subjective review, I have tried to explain the difference in the sound and tonal quality wherever possible. While it is almost certainly not a substitute for hearing it yourself, and will not give any idea of the absolute quality, it should give you an idea of the relative differences between the two mediums.
A closeup of the 6JI driver tube.
2. Unboxing and Contents
The Little Dot MK II came packaged in a plain cardboard box. The box itself only had the packing foams and the actual product, no box art is present. This is actually something I really appreciate. Instead of wasting cost on fancy box art, when targeting a budget price point, companies should focus only on the product itself. At these low price points, an increase in the production budget of a few dollars per unit can mean the difference between a seemingly high quality product and a low quality one.
Another thing that I would really like to applaud Little Dot on is the packaging style of the Little Dot and its tubes. Probably the first and foremost concern of anyone buying a Vacuum Tube based device off the internet is that the tubes are inherently fragile and couriers are quite notorious for manhandling packages. The good news is, all the vacuum tubes of the Little Dot MK II are removed from their housings and packaged separately. And they are so secured that nothing short of the package being entirely crushed, would leave a mark on them. So if you are worried about the tubes breaking during shipment, know that thanks to the packaging inside, the courier can mishandle the package as much as they want to.
Inside the plain cardboard box you will find:
1x RCA to RCA Audio Cable
1x 3.55mm to 6.3mm Adaptor (in the RCA packaging)
3x Jumper Caps (in the RCA packaging)
2x 6JI Driver Tubes
2x 6N6 Power Tubes
1x Little Dot MK II Amplifier
The company has provided a complimentary RCA cable as well as a 3.55mm to 6.55mm adaptor jack – and the gesture is appreciated. If you are going to be using the tube with your mobile or any other device that gives an output through 3.5mm jack, then you are going to need an additional 3.55mm to RCA cable. Without that, the amplifier will only work with a source that can output in RCA.
The company has also provided jumper caps for tube rolling (more on that given below) and the little buggers are super easy to lose considering they are very tiny and packaged along with the RCA cable. If you are thinking of upgrading the tubes at a later date, make sure to store these somewhere safe (and memorable).
3. Overview of the Little Dot MK II
The Little Dot MK II itself is a sturdily built device with a black metallic frame and inconspicuous looking white paint. The amp has quite a heft to it and feels heavy enough in your hand. The weight is distributed mostly to the transformer housing. The device has a single volume knob on the front along with a blue LED and of course, the 6.3mm port. At the back you can find the input and output RCA pots as well as the power button. The specifications of the amp are as follows:
Input: Gold-Plated Unbalanced Phono (RCA) Jacks
Output: 1/4″ Gold-Plated Stereo Headphone out
Driver Tubes: 6JI
Power Tubes: 6N6
Frequency Response: 20HZ – 50KHz (-1dB)
THD+N: 0.1% (50mW into 300 ohms)
Suitable Headphone Impedance: 32 – 600 ohms
Pre-Amplifier Output Impedance: 10K ohms
Power Output:
300mW into 300 ohms
200mW into 120 ohms
100mW into 32 ohms
Average Power Usage: 28 watts
Dimensions: 210mm (length) by 110mm (width) by 130mm (height)
Weight: 2.5 kg or 5.5 lbs.
The Little Dot MK II ships in two different variants, the 110v and 220v variant so make sure to match the power supply to your mains before you order. I live in a country where we have 220v, so that is the one I ordered. There are no gain switches given on the outside of the body, but there is indeed a way to change the gain (which you can find detailed later on in the review).
The Little Dot MK II features a cleanly soldered circuit on a high quality PCB.
The Little Dot MK II boasts a newly designed SEPP (single ended push pull) circuit (in similar vein to the rest of the MK-series tube amplifiers) greatly increases sound quality, dynamic range, output impedance, and harmonic distortion. The Little Dot MK II now also provides gain control of 3, 5, and 10 via internal DIP switches for fine-tuning so you can maximize synergy with almost any headphone you have, whether it be 32 ohms or 600.
Some cheap tube amps have what is called a hybrid design, where the power is provided by a transistor based circuit and the driver circuitry is tube based. Examples of these designs are the headphone amps with only a single vacuum tube (the driver tube). Not only does the Little Dot MK II have a fully tube based design (both power and driver elements are tube based) it actually has independent circuitry for the left and right channels.
So essentially, you have 1 power tube and 1 driver tube for the left channel and 1 power tube and 1 driver tube for the right channel. This is called an SEPP design (think of it as 2 + 2 design). I think I can safely say that you will not be able to find a more value oriented tube amp design anywhere on the market.
4. Setting up the Little Dot MK II
Setting up the LD MK II is pretty easy although you need to be mindful of the vacuum tube’s legs when plugging them in. The power tubes are slightly larger in diameter and will fill the ceramic bases immediately after the transformer. Insert the legs into the base plate and gently shimmy the vacuum tube into the slot. Repeat the process for all 4 tubes.
Once the tubes are all plugged in, you can now plug in the power cord and turn the amp on. The vacuum tubes will slowly light up with their iconic dull orange glow. Unlike some tube amps out there, the glow isn’t adulterated by any mood lighting at the base of the plate. The glow is 100% au natural. If you are someone who believes in burning in their vacuum tubes (although the set I received was perfect out of the box) then you can plug in a source of pink noise, plug in headphones, turn up the volume to maximum and let it run for a few hours. The manufacturer warns not to let the amp run for more than 6 hours at a time.
The amplifier is now ready for listening. Advanced set-up options like tube rolling and gain switches will be tackled with later on.
Note: In order to gain the maximum amount of “color” max out the Vacuum Amp first, and minimize all other digital gains. In other words, set a low source volume (low windows volume) and a very high vacuum amp volume. This will saturate the vacuum tubes and produce the warm organic tone that is coveted by audiophiles. Doing it the other way around, will simply amplify the horrible digital clipping that we are trying to avoid in the first place.
5. Testing as a Headphone Amp
Audiophiles that have a pair of high grade cans will be pleased to hear that the Little Dot MK II can support impedance of up to 300 Ohms officially, so if you have an expensive Sennheiser lying around, they will be a perfect match. For the sake of catering to a wide range of audience however (and also because I do not have a pair of Senns on me right now) we will be using a pair of 32 ohm studio monitoring headphones from ISK.
My testing methodology is going to be multi-tiered. Because of the way vacuum tubes function, a .FLAC is usually the best way to get your amp to shine, but since a lot of the audio experience is from plain ol web audio streams we are going to be giving them just as much weight. I am going to be comparing the ISK HD 9999 + Little Dot MK II set up to a vanilla setup (simple audio output from my motherboards inbuilt DAC) + ISK HD 999 and a powered setup with a high end amplifier powering the ISK HD 9999.
I have a few FLACs for this very purpose and I started off with them. The most noticeable improvement to the sound stage was that of the base. It was instantly much deeper and had a “shine” to it that did not exist before. Vocals were much clearer and at high pitches had that coveted ‘harmonic distortion’ quality instead of the digital clipping that we are usually used to.
The unpowered soundstage did not come close to the Little Dot MK II at all, and even my Onkyo (a $700 affair) was only able to keep up because it is vastly overpowered (1350 Watts) so I was using it at a low volume and therefore no digital clipping was introduced. Movies and web streams were vastly improved over a vanilla setup but offered very little improvement over a powered setup – so if you are thinking about a primarily web browsing scenario you will be able to get similar results with a good amplifier and some high quality equalization.
6. Testing as a Pre-Amp
To test the Little Dot MK II as a pre-amp, I set up my Onkyo HT-R592 amplifier in AUX mode and plugged in the LD MKII via the RCA cable. The volume levels were as follows: 30% on source (Windows PC), 100% on the Little Dot MK II and 30% on the Onkyo. This setup was compared to my standard Windows PC + Onkyo combo.
The immediate difference is that the new tone is that the latter was much warmer with deeper bass and rolling highs. The Vacuum Tube when used as a pre-amp acts as a natural equalizer, coloring the output tone. Sounds and music that may sound sterile on a digital amp will get that missing “oomph” factor when used with a vacuum tube. That said, it goes without saying that this is not an accurate reproduction of the sound and should not be used for reference purposes in any studio environment.
As far as music goes, the results are really great. Guitar notes become inherently cruisnchy, drums get deeper and vocals get warmer. This is something entirely expected ofcourse, considering high end guitar amps are fully vacuum tube powered.
Movies also receive the same treatment although, the coloring quality of the tube amp might actually be construed as a downside on this one. Movie sound channels are designed to be mostly sterile and reference in nature and the coloring the vacuum tube will add may not be likeable for everyone.
I personally loved the LD MK II’s performance as far as music is concerned, but would not use it for watching movies. Since the amp is a stereo device, it would be moot point since DTS HD MA is still my go-to choice for cinematic pleasure.
7. Tube rolling and changing gain
If you want to play about with the “color” of the amp or simply want to upgrade to better quality tubes (the default ones are good enough out of the box!) such as Mullard’s Driver Tubes and Russian Power Tubes. This is called tube rolling and the general consensus out there is that a matched set of Mullard’s EF92/EF95 or Siemens Blue Glass 6AK5W as driver tubes and Soviet 6N6P Gold Grid power tubes will offer superior value in increasing the Little Dot MK II’s performance.
The red dip switches need to be changed in order to adjust the gain.
The Little Dot MK II also gains the driver tube-rolling options from the rest of the MK-series with the ability to roll 6JI, WE403A, GE5654, M8100, CV4010, EF95, etc at its factory jumper setting, and with jumper pins shorted, EF92, EF91, CV138, CV131, and all equivalents and drop-in replacements.
To use the jumper pins or to adjust the gain of the amp, you will need to access the inner housing of the tube amp. Wait for the amp to cool down (the power tubes can become scalding hot) and remove the vacuum tubes. The face is secured with X screws and you can open it up with a simple screwdriver. Once that is done, you can change the gain by changing the dip switches in the following fashion.
Switch 1 Position
Switch 2 Position
Gain
Recommendation
OFF
OFF
10
Low impedance and/or low sensitivity headphones
ON
OFF
5
Medium impedance/sensitivity
OFF
ON
4
Medium impedance/sensitivity
ON
ON
3
High impedance and/or high sensitivity
If the switches are not toward the E92 label the following driver tubes may be used:
WE403A
5654, CK5654, GL5654, 5591, CV4010, CV5216, CV8246, 6069, CV10442
EF95F, M8100, 6AK5W, CV10100, CV8159, CV8225, CV850
6J1
If the switches are on the side of the E92 label, the following driver tubes may be used:
EF92, 6CQ6, CV2023, V884, VP6, M8161
EF91, 6AM6, CV10327, CV138, CV1955, CV2195, Z77
CV131, 9D6, W77
2-pin sets: If the jumper caps are removed, you can use the 5654/6JI driver tubes (default). If the jumper caps are placed over the pins, you can use EF92 type driver tubes.
3-pin sets: Place the jumper cap over the middle pin and the pin to the side of the “E95” text to use the default 6JI/5654 tubes. Place the jumper cap over the middle pin and the pin to the side of the E92 text to use EF92 type tubes.
8. Conclusion
The Little Dot MK II isn’t going to win any awards for pure aesthetics, but in terms of functionality I think it’s safe to say that you won’t find any tube amp with better performance per dollar. You are getting four good tubes plus a great amp for the meager price of $133 (from Gearbest) as well as tube rolling options for future use. You can also check out their ongoing promotion on audio equipment. My experience, currently amounting to over a 100 hours, with the LD MK II was absolutely amazing.
The only down side that I have noticed is that there were a few instances where the volume knob caused one channel to be muted. Twisting and pressing the volume knob solved the issue quickly enough although I am not sure whether this was simply a QA mishap with my unit or an overall oversight. In any case, it was innocuous enough to not warrant any further despair.
If you are someone who is looking for a first and last Vacuum Tube Amp, this is the one for you. It will give an unprecedented amount of power to a vanilla setup and even help out as a pre-amp if you are already initiated. The only person I would not recommend these to is if you never listen to music and are not particularly interested in the tonal sound quality of the source – only its volume. In that case, you would be better off with a cheap USB DAC.
The post The Little Dot MK II Review – The Miracle Of A Sub $180 Vacuum Tube Amp by Usman Pirzada appeared first on Wccftech.