Update to Yaqin MS-300C tube amp review about a year after purchasing:
I’m still quite happy with this Yaqin tube amp, even without yet upgrading the 300B power tubes. The most significant improvements have been: changing the rectifier tube and adding a bypass capacitor across the second pair of large caps after the rectifier. Both changes were immediately more noticeable than replacing all the pre-amp tubes, and I highly recommended doing both if you buy the MC-300C amplifier as those upgrades improved the clarity and “3D feel” of the sound field.
Replacing Rectifier Tube: The “preferred series” 274B from thetubestore, while having a bit too much heating element noise for my tastes, made a noticeable difference to the sound. The filament buzz is not microphonic and does not enter the signal path, so if you don’t mind it coming from the tube itself, then it gives a significant improvement to the presence of the entire soundstage; so much so that I found myself saying “Wow” again. The JJ 5U4GB rectifier tube is also noticeably better than the stock 5Z3P – not as good as the 274B, but the JJ 5U4GB is inexpensive and makes less noise, so it’s a trade-off of preference and situation.
Capacitor Replacement: To make the amp more cooperative with the rectifier tube – and see if I remembered how to solder – I changed some of the capacitors in two stages based on this post: Yaqin MS-300C Upgrade. First, the two F&T 80uF/450v immediately after the rectifier, a 330uF /16V to lengthen the warm-up time (now about 40 seconds), and the 4 original 22uF/450v with F&T 22uF/500v. A couple months later, the second set of large power supply capacitors were bypassed with a .1uF Solen Fast Cap, and since I didn’t really want to spend over $200 on PIO capacitors, I replaced the .47uF and .1uF caps in the signal path with some cheaper Solen Fast Caps as well. Those started a bit bright, but after 20-30 hours, either my ears or the capacitors softened and settled into a pretty darn good listening experience. Eventually, the Solens in the signal path will probably be replaced by Audiocap Thetas (total cost for that would be around $60 from Parts Express), but can’t see myself ever digesting the cost of Jensen PIOs. Nevertheless, even with the cheaper Solens, I can really crank up Rickie Lee Jones’s The Horses and clearly hear everything down to the quietest nuance.
“Aesthetic” Choices: The LEDs indicating input source were WAY too bright. People who buy tube amps want to see the glow of the tubes – not be blinded by LEDs – so I changed the resistors before each one. It took some testing with progressively higher values, but ultimately the blue LEDs required 220k, and the green/red power indicator 20k. After that change, this tube amp became much more visually pleasant in a dark room.
Finally, the strange-looking stuff: I couldn’t stand the power transformer and choke covers. Besides ringing like drums, the logo-like white writing on the top is cheesy. So I spent $7 at home depot for a sheet of underlayment wood and cut it to wrap the transformer covers, which solved both issues. Also cut about 1.5 inches off the steel choke cover to make it shorter, and replaced buttons and volume knob with hardwood… because, well… why not? It’s definitely not art, but it solved the transformer cover problems, and is without a doubt my own. If my carpentry skills ever improve, maybe I’ll try to make some that look a bit better.
ORIGINAL MS-300C TUBE AMP REVIEW :
Audiophile I am not, but I am a former recording engineer so have a little perspective. Previous owner of a couple smaller integrated tube amps, and abused the YAQIN MS-30L push-pull amplifier for about a year before buying the MS-300C. I was happy with the MS-30L, but chose to upgrade to the MC-300C because I wanted a Class A with 300B tubes. The MC-300C fit that bill without breaking the bank (about $1150 new).
The MC300C is a beast in that it weighs about 60 pounds. It’s very well built and obviously fun to look at – though I could do without the polished, mirror-like area, which only shows off my lack of cleaning skills. Since the 300B tubes aren’t cheap, I’m using stock PSVane 300B tubes that came with it. Even with the stock preamp tubes, the sound quality is impressive.
Basic MS-300C tube amplifier specs:
Tubes: 300B x 2 (power tubes), 5ZP3 (rectifier tube), 12AT7 x 2 and 6N8P x 2 (pre-amp tubes).
Output power: 8.5W per side – or 9.5W depending on which user manual you get, apparently. (That’s more than enough power… unless you own those ridiculous tower speakers with 10 drivers and a 60db sensitivity rating.)
Frequency Response: 5Hz – 56kHz
Signal To Noise Ratio: >84db
Other notables: remote control, pure-post stage, the typical YAQIN user manual with terrible English so you get a chuckle reading it, 4 and 8 ohm load, headphone o/p.
Yaqin MS-300C upgrade / modification note:
After about 100 hours of being perfectly happy with the stock setup, I replaced the preamp tubes: 12AT7 tubes with JJ gold pins, and the 6N8P tubes with Tung-Sol 6NS7’s. After a few weeks those have settled in quite nicely. “Wee bit smoother” is how to describe that change.
The power transformer developed a slight buzz (as all do; even if in the smallest amount). The real issue, however, is that the transformer and inductor covers are fairly resonant. At first I just put an big rock on the cover which mostly solved it. Eventually, I took the 20 minutes or so to open it up, take the cover off, and insert some isolation washers on the transformer mount, which solved the problem and something I’d recommend if your ears / mind tend to seek out buzz and hum.
After about 5 months of heavy use, one of the 300Bs also developed a very small hum – but I’m one of those “hum seekers”, and thus far no one else has noticed it. It’s really only really audible if leaning into the speaker. Swapped the tubes to confirm; pins and socket are clean, so I’ll wait until the holidays when there’s a shopping excuse to replace the stock 300Bs with the Gold Lions everyone seems to rave about.
Listening to the MS-300C Amplifier
After plugging in, warming up, and checking the tube bias (it was biased a bit hot out of the box), I ran it through some of the old records I’ve had forever and pretty much know how they sound.
They most certainly sounded better.
While the EL34B amp I’ve been using for awhile sounded good (and slightly wider with KT77’s in it), this amp with the 300B tubes immediately had a stereo image with a softer high end that feels as though it extends well beyond your speaker placement. Depending on the mix of the track, the stereo image is almost unsettling. There have been many times when I’ve been caught off guard by the 3D feel of a trumpet stab or a really wide synth.
What is also striking is this thing has handled any genre of music I can throw at it. Early Floyd, to debut Ricki, to mid Björk, to late Radiohead – the YAQIN MS300C just smiles and we both ask for more. Chris Wood’s bass is almost tangible, Etta’s subtle throat rasp demands a deep sigh, the air in Rosa Passos’ vocal floats in the room, and I’ve fallen in love with Bebe’s voice all over again.
I can’t afford to buy every record I want, so also stream a lot of music… this is where those who fancy themselves and “audiophile” smirk and insult, right? Nevertheless, the MS-300C either distracts from, or effectively masks the normal upper-harmonic ripples you hear in Pandora and Spotify streams. The encoding flaws are still there, but there’s so much more “goodness” in the sound that my ears, at least, don’t really care or notice anymore.
Depth is also much better than any other tube amp I’ve previous owned. Other amp / tube combinations often make strange trade offs between depth and width. What makes this special, though, is how the depth compliments the width. It’s not so much the two forces are pulling against one another as wrapping around (that’s the only way I can describe it).
Frequency balance, top to bottom creates yet more smiles. Even though most serious listeners scoff at the stock Chinese 300B tubes, these have a very impressive overall balance. Everything is there, nothing wolfs or sinks, and you can hear the whole mix without anything getting lost. If the track is too compressed the tubes will start to get “confused” – that could also be the rectifier tube trying to keep up, but it’s really the mixing engineer’s fault, anyway, not the tubes. ;)
Obviously, it’s no secret at this point that I like this amp. It’s well worth the price, even with the stock tubes. Take care of it and it’ll definitely take care of you.