Alpa Audio Lab Single Ended 300B Monoblocks

January 2026

300B is a tube that I feel pretty knowledgeable about by now. As of today, I’ve owned or had extended loan of 18 300B amplifiers, a statistic that I’m not particularly proud of. Because I don’t feature equipment on the website that doesn’t make the cut, only 12 or 13 of those amps are presented here. And of those, only two have stood out to me over the years as having been really exceptional. Those two amplifiers; a pair of Bez mono blocks and John Hogan’s unusual fi-primer creation both stood out (sadly in retrospect) as having had something really special and magical about their sound. And now Dear Reader, there is a third; the amazingly robust but intimate sounding Alpa Audio Lab 300B.

The Alpa 300B mono blocks shown below are a bit of a mystery. Korean-made amps, I had never heard of Alpa, (which I assume is old style Kunglish for Alpha). I had to get some help inside Korea to find any real information about them (thank you John), and even then there isn’t much. The story seems to be that the Alpa line of amps and preamps were made by a Mr. Cheong in Daegu South Korea back in the 90’s. The only real information I’ve seen is an ad for a pair of used 300B monoblocks and a tubed preamp based on the Marantz 7, selling as a package for around $10,000 back in 2014.

Background aside, these heavy duty Shindo-inspired monoblocks may just be the best sounding 300B amps that I’ve owned so far. I have no idea about the parts in these, but the chassis is magnificently heavy-duty folded sheet metal, almost military grade. And with built-in volume control these simple, and to me extremely beautiful amplifiers bring the music and the emotion and the soul of the program material right into my room in big vivid pictures. 300B has the ability to really throw down some romance and these amps do not disappoint in that respect.

Honestly I kind of figured I was done with 300B. The Bez and Hogan amps had sounded great, and really all of the others featured here on the website sounded pretty darn good too. But at some point after so many amplifiers there is an upper echelon that only a few occupy, the winner’s circle so to speak. And 300B didn’t really have a place there that some bargain-priced oddball TV tube probably didn’t deserve more. But when a friendly Canadian audiophile reached out offering to send down this pair of vintage Korean 300B amplifiers, (thank you Den!) I couldn’t resist. And a few days after they arrived, I purchased them. I knew in the first few moments of playing that these were different.

In play the Alpa 300B monos are just phenomenally good. One thing that’s clear immediately upon firing these amplifiers up is that they produce a very big sound. On my open backed Telefunken speakers there is a freedom and openness to the sound that I always enjoy, and in this case its 20% bigger than many of the other amps I’ve experienced. Not quite as big and vibrant as my new Tektron Type 50 monoblocks, but a little growlier for want of a better term. The image is well defined and grounded. The Alpha 300B get up close and personal, but slightly more magnified. It can be startling, and rivals the big Psvane 845 mono blocks for quick transitions with natural feeling, alive vibrancy.

Looking back at the Bez monoblocks, also a 3 stage design, I do wonder that it might be the 3 stages in these amps that make them so special. In the Alpas, the first stage is a red metal RCA 5693 then into a 6V6 that feeds the 300B power tube. Tube rectified of course, with 5R4 or 5U4, in my case with a pair of Bendix potato masher 5R4. I was very lucky in that I had a nice spread of 6V6 and 300B tubes on hand to try in this amplifier, and in the end I found that I like the EML and Sophia Electric Royal Princess tubes the best. With the super fine sounding Brimar 6V6 tubes in place, I can’t help but feel that those special little bottles are really helping the 300B achieve the sound that I’m hearing.

The Alpa 300B have so many of the qualities that I really value. They are extremely well made, perhaps long ago and in small numbers, by someone who really thought and cared about what they were doing. Now that I spend some time listening in mono I appreciate having monoblocks. And with built in volume control these Alpa monos offer a lot of flexibility without compromise. They are easy to recommend from a fidelity standpoint, but I just don’t know whether there is another pair out there. And I’m keeping mine, at least for now. Perhaps be on the lookout for a 3 stage 6V6 driven 300B design like this, and it might offer a similar sound profile. Best of luck, and happy listening.

Hand made in Korea in the 1990’s, this pair of amplifiers sure have a story to tell, and look to have been around the block a time or three. There are no shortage of scrapes and bumps, and some odd peeling of the Shindo/Altec inspired green paint. But all of that just adds to the wonderfully heavy duty aesthetic that they have. I really like these amplifiers!

5693 into 6V6 into 300B. I’ve tried a few different 6V6 in these amplifiers and unsurprisingly to me the RAF Brimar 1950s tubes are clearly the best. If you have an application using 6V6, I highly recommend them. They were the clear winners in my Handel single ended amp as well.

Sophia’s Royal Princess are one of the best 300B I’ve heard to date. Along with the EML solid plate 300B, they are the top choice for me in these amps.

8 and 16 ohm taps.

Here are some interesting tubes, Stradi 300B, also made in Korea. A kind of modern reinvention of the very rare German Ed tube from the 1930's. Rich at Treehaus Audio Lab sent a pair for me to experience for a few weeks, thank you! They sound very clear and clean, and I found them to have a little more of a 2A3 profile in my amps. I liked them and really look forward to more from Stradi.

Sovtek, Sophia and Stradi 300B.

The somewhat leaner push pull Feastrex CV4055 and Lance Cochrane EL84 made an interesting contrast to the bigger and more saturated Alpa 300B.

On the other hand, single ended RE604 can be an even bigger and more saturated sound!

At the budget price point, I like the old Sovtek 300B better than most of the new Chinese tubes. It sounds like a 300B.

Emission Labs 300B. It’s hard to beat Emission Labs for a tight, taut and “modern” sound. For me, they set the standard for build quality. And what an incredible looking tube with the fins and big heavy glass envelope. EML is an example of actually getting what you paid for.

For a year or so my wife and I rented a small second home closer to her office, so that we could avoid a long commute and spend more time together. In the limited space I just couldn’t fit two large speakers, and I’m no longer a micro monitor guy. So rather than sacrifice speaker quality, I went with a mono system. The Alpa were perfect for this, and alongside a McIntosh A-116, I spent many days and evenings listening on a variety of mono speakers and with a wide array of 300B tubes. Only needing a single is definitely an advantage!

Nice and simple. Mono is a great choice for a room or space like this. Here I’ve repurposed my folding baffle with a nice teak front and a cutting board top that supports the amplifier. Attached to the inside wing is a compact Bellari preamp that I used with the McIntosh amp, and as a phono preamp. I thought of it as a kind of open baffle juke box.

Ray Reserve 300B.

LinLai Elite 300B.

Psvane T2 300B.

Here is some serious competition! A push pull 12W6GT by Nature Coast Electronics. Both the 300B and some of the TV tubes like this 12W6GT (or an old favorite the 6BX7), all sound big and fleshed out and vibrant. The 300B version of it tends to be larger in scale but a little more diffused, whereas the TV tubes are tighter and perhaps a little smaller, but more sharply defined. Crispier. Both are really good; it comes down to a matter of preference. And not to harp on it too much, but a pair of one tube is $6 or even less and a pair of the other is potentially $3000 or even more. At that difference there should be some sort of magical quality that I just don’t feel exists.

As you can see, I’ve heard the Alpa 300B against quite an array of amplification. It's tough around here! Pictured with Psvane’s Reference SE 845, an incredible space and presence machine. And on the left is Don Allen’s lightning bolt push pull 6BX7.