The Nobsound MS-10D is NOT a "true" tube amp. Exactly as the previous reviewer wrote, it is actually a 60W per channel Class AB solid state amp (using two Fairchild TIP41C and two TIP42C transistors) with tube buffer stage. A tube buffer, also known as voltage or...
The Nobsound MS-10D is NOT a "true" tube amp. Exactly as the previous reviewer wrote, it is actually a 60W per channel Class AB solid state amp (using two Fairchild TIP41C and two TIP42C transistors) with tube buffer stage. A tube buffer, also known as voltage or cathode follower, is a passive pre-amp whereby the high output impedance of the source (for example CD player) is reduced so that it can be properly transferred to the lower input impedance load.
If you are concern about tube availability, this amp uses two 6N1 and two 6P15 (6P1 for US version), which are very easy to find and they are inexpensive. I strongly recommend replacing the stock Chinese Shuguang/Beijing tubes with either Russian or Bulgarian tubes of the same series. One of the owners (Stephen Smith) has successfully replaced the stock 6N1 with Telefunken ECC85 and stock 6P1 with Russian 6N1N-EB.
Even with stock tubes installed, I am pleasantly surprised by its good sound. Although a solid-state amp, the sound has "tube-like quality" - thanks to the tube buffer which adds body and mellow the sound. After replacing the stock Chinese tubes with Russian ones, the sound especially the highs and mids are smoother, warmer. The lows have more authority and fuller. Overall tonality is very balanced. The stock Chinese tubes sounded etched and a tad too lean for my listening preference (I reckon some people might like this kind of sound).
Soundstage extend beyond my speakers. Imaging is three-dimensional, spacious and precise. There is "air" at the top-end with the Chinese tubes, however, this "air" disappeared after I replaced them with Russian ones. I am fine with that as long as the music is soothing to my ears.
For those of you who use headphones, this amp has absolutely no problem driving my AKG K270 and Sennheiser HD650. Between the two, I prefer the AKG-Nobsound combo.
One thing I dislike about the amp is the flexible but flimsy, rather short power cord. If only it comes with an IEC socket instead (so I can use "audiophile-grade" power cord).
Bottomline is the MS-10D amp offers great sound at great value. If you can live with the fact that it is a solid-state amp with tube buffer, I am very sure you will like it very much.
FOLLOW-UP 1: Nobsound just launched the MS-10D Mark II with built-in Bluetooth connection and USB 2.0 input for about $50 extra.
Check it out here:
Nobsound® MS-10D MKII Hybird Tube Amplifier with Bluetooth/USB/Headphone for Hifi
FOLLOW-UP 2: I noticed there are two versions of Nobsound MS-10D (non-Mark II) on the market now:
- Version 1 has a tiny blue LED ABOVE the power switch
- Version 2 has an orange-yellow light AROUND the power switch
I dismantled both versions and found their circuits are vastly different. Both using the same Fairchild TIP42C transistor chipset. Version 2 supplies lower voltage to the tubes (6.3 volts vs 8.5 volts), so technically-speaking the tubes will last longer. Also, version 2 has better DC power regulation. Sound-wise, both are similar except that I have to turn the volume knob to 10 o''clock position for version 2 to get the same loudness at 8 o''clock position for version 1. The VU meter of version 2 is less active as well.
FOLLOW-UP 3: I have got the opportunity to get my hands on the Mistral MM-1 amp. Even though both the Nobsound and Mistral look "almost" identical (with the latter in darker gold faceplate), their internal components are very different. The Mistral uses two Texas Instruments LM1875 chipsets (rated at 30W) whereas the Nobsound uses four Fairchild TIP-42C chipsets (rated at 65W). The circuit layouts are different too. In short, the Nobsound has a slightly better designed circuitry than the Mistral. Sound-wise, I feel the Nobsound is cleaner and more dynamic. The Mistral is more musical. Built quality-wise, both amps are on-par. The Nobsound (version 2) is trickier to disassemble.
FOLLOW-UP 4: Over the weekend I replaced the 10K ohms potentiometer of the Nobsound MS-10D version 1 with a 50K ohms one to match the loudness of version 2. It works! So, I conclude the loudness issue with version 1 is due to a lower resistance potentiometer used.
FOLLOW-UP 5: A friend of mine brought his Nobsound MS-10D amp to me for a "partial" mod.
These are the things I did:
1. Replaced both reservoir caps to Panasonic FR 6,300uf 35v.
2. Resoldered all critical signal points using Cardas quad eutectic silver solder
3. Replaced all jumper wires with either 24 or 18 AWG pure silver wires
4. Replaced both stock Chinese 6N1 tube with Russian 6H1n tubes (his idea)
- Better high frequency extension (extremely prominent)
- Midrange is laid back. Not as full as using stock 6N1 tubes
- Cleaner and tighter bass
- More transparent and open sounding
- Soundstage widen
- Quieter, darker background
Verdict: My friend is very pleased with the mod. However, I prefer the fuller, more lustrous mids of 6N1 tubes.
FOLLOW-UP 6: Recently, the power switch on one of my Nobsound amps failed. It could not "latch" proper. As a result, it could not hold itself in the "ON" position. To share with fellow Nobsound MS-10D owners, the name of the switch is "KDC-A10-10B AC 250V 10A SPST Push Button Power Switch". Don''t worry. Even though it states "250V", it works with 120V too. Soldering is required. You may want to replace the heat shrink sleeve at the same time.
FOLLOW-UP 7: I just came back from a friend''s "man cave". The entire afternoon my friends and I (4 of us) were comparing a stock Nobsound MS-10D, a Rotel RA-02 (US$500) and a Gryphon Atilla 2 (US$11,000). All 3 are integrated amps. I am very pleased to say the Nobsound performed superbly against the two heavy contenders. The Nobsound excels in midrange and highs. Of course, the 11 grand Gryphon is the overall winner but Nobsound is not far behind. The Rotel is a love-hate amp. It performed well in certain music genre but poorly in another.
My friends were shocked that such a budget amp could sound so good.
FOLLOW-UP 8: Nobsound MS-10D MK2 is now available in gunmetal black with glossy black piano finished side panels.
FOLLOW-UP 9: Some of you may have notice I changed my review from hybrid amp to solid-state amp with tube buffer. I sent the Nobsound MS-10D to a friend (who is a tube amp designer and enthusiast) to take a look and he concluded the 4 tubes are used as buffers as there is no voltage gain.
FOLLOW-UP 10: Nobsound will release their latest 80 watts Class AB hybrid integrated amp DX-925 soon. Expect to cost between $250-300.