2 thoughts on “REISONG A50 MKIII 300B Tube Amplifier”
The Reisong A50 MKIII (also known as the BoyuuRange A50) arrives with a reputation that precedes it. In a market where single-ended triode (SET) 300B amplifiers routinely command thousands of dollars, this unit stands out as an impossibly affordable tube amp, costing just $849 at the time of writing. For audiophiles on a budget, the temptation of securing that legendary 300B glowing warmth for a fraction of the usual cost is almost irresistible.
But as the old adage goes: if it seems too good to be true, it usually is. Out of the box, the Reisong A50 MKIII is a nice-sounding amp, but it arrives plagued by significant issues that prevent it from achieving true high-fidelity greatness.
The Myth vs. The Reality
If you read or watch mainstream audio coverage, you’ll find a staggering disconnect between reviewer hyperbole and bench-test reality. I was incredibly surprised by some big-name audio reviewers claiming that the stock amp delivers a “huge, expansive soundstage,” that it “isn’t slow sounding or dull,” and that the “bass… has a weight, solidity.”
To be blunt: based on the out-of-the-box build, the amplifier simply cannot do any of that. In reality, the soundstage is heavily limited due to a severe, early roll-off in the high frequencies, caused by poorly constructed, low-quality factory output transformers. Seeing influencers rave about its stock performance leaves only two logical conclusions: either the imagination of those reviewers is running entirely wild, or they’ve been paid for their praise.
Compounding the sonic limitations are serious quality control concerns. The first unit I received suffered a catastrophic power transformer failure within just 20 days of ownership. Luckily, it failed within the Amazon return window, allowing for a swift replacement—but it’s a stark reminder of the corner-cutting required to hit this price point.
Unlocking the Potential: Making It Sing
Despite these glaring shortcomings, the Reisong A50 MKIII does possess the underlying potential of delivering that elusive 300B magic. It just falls completely short of it in stock form. Part of the problem lies in the glass itself; the tubes that the amplifier comes packaged with are the cheapest possible choices. While the choice of the stock Shuguang 300B output tubes could still be overlooked, the 6SN7 driver tubes used here are of the lowest quality imaginable. They create a very major bottleneck in the tube sound and need to be replaced as soon as humanly possible.
To transform this budget box into a giant-killer, two critical phases of modifications are required:
1. Rewiring the Schematic: The factory circuit layout throttles the tubes and introduces premature clipping. The solution is to completely overhaul the internal wiring. Following the step-by-step documentation on Skunkie Designs (skunkiedesigns.com/boyuurange-a50-mods), the schematic can be brought up to proper operating specifications. This modification is fairly straightforward, and it successfully removed the very early distortion—a fix I confirmed on the bench using a QuantAsylum QA403 audio analyzer.
2. Replacing the Transformers: Fixing the circuit only solves half the problem; you still have to address the bottleneck at the speaker outputs. To fix the compressed soundstage, you have to rip out those factory output transformers entirely and replace them with premium Hashimoto HC-203U transformers.
However, it must be noted that even after all of these upgrades, the final result is still not absolutely perfect. There remains an audible hum when the amplifier is paired with sensitive speakers (90dB and up). Completely eliminating that residual noise floor would require major, deep-level changes to the power supply design.
Final Verdict
Out of the box, the Reisong A50 MKIII is a flawed, highly compromised budget amplifier wrapped in a pretty chassis. It does not live up to the breathless praise of mainstream reviewers, and its stock transformers and questionable reliability make it tough to recommend to a casual plug-and-play user.
However, for the DIY enthusiast, it represents an incredible foundation. Once you fix the schematic and upgrade the iron to Hashimoto transformers, the narrative completely flips. Not counting your investment of assembly time, the total cost after mods comes out to around $1,600 – doubling the initial price. At that price point, this amplifier can easily give most high-end 300B amplifiers a serious run for their money. It ceases to be a budget compromise and becomes a genuine audiophile powerhouse.
The Reisong A50 MKIII (also known as the BoyuuRange A50) arrives with a reputation that precedes it. In a market where single-ended triode (SET) 300B amplifiers routinely command thousands of dollars, this unit stands out as an impossibly affordable tube amp, costing just $849 at the time of writing. For audiophiles on a budget, the temptation of securing that legendary 300B glowing warmth for a fraction of the usual cost is almost irresistible.
But as the old adage goes: if it seems too good to be true, it usually is. Out of the box, the Reisong A50 MKIII is a nice-sounding amp, but it arrives plagued by significant issues that prevent it from achieving true high-fidelity greatness.
The Myth vs. The Reality
If you read or watch mainstream audio coverage, you’ll find a staggering disconnect between reviewer hyperbole and bench-test reality. I was incredibly surprised by some big-name audio reviewers claiming that the stock amp delivers a “huge, expansive soundstage,” that it “isn’t slow sounding or dull,” and that the “bass… has a weight, solidity.”
To be blunt: based on the out-of-the-box build, the amplifier simply cannot do any of that. In reality, the soundstage is heavily limited due to a severe, early roll-off in the high frequencies, caused by poorly constructed, low-quality factory output transformers. Seeing influencers rave about its stock performance leaves only two logical conclusions: either the imagination of those reviewers is running entirely wild, or they’ve been paid for their praise.
Compounding the sonic limitations are serious quality control concerns. The first unit I received suffered a catastrophic power transformer failure within just 20 days of ownership. Luckily, it failed within the Amazon return window, allowing for a swift replacement—but it’s a stark reminder of the corner-cutting required to hit this price point.
Unlocking the Potential: Making It Sing
Despite these glaring shortcomings, the Reisong A50 MKIII does possess the underlying potential of delivering that elusive 300B magic. It just falls completely short of it in stock form. Part of the problem lies in the glass itself; the tubes that the amplifier comes packaged with are the cheapest possible choices. While the choice of the stock Shuguang 300B output tubes could still be overlooked, the 6SN7 driver tubes used here are of the lowest quality imaginable. They create a very major bottleneck in the tube sound and need to be replaced as soon as humanly possible.
To transform this budget box into a giant-killer, two critical phases of modifications are required:
1. Rewiring the Schematic: The factory circuit layout throttles the tubes and introduces premature clipping. The solution is to completely overhaul the internal wiring. Following the step-by-step documentation on Skunkie Designs (skunkiedesigns.com/boyuurange-a50-mods), the schematic can be brought up to proper operating specifications. This modification is fairly straightforward, and it successfully removed the very early distortion—a fix I confirmed on the bench using a QuantAsylum QA403 audio analyzer.
2. Replacing the Transformers: Fixing the circuit only solves half the problem; you still have to address the bottleneck at the speaker outputs. To fix the compressed soundstage, you have to rip out those factory output transformers entirely and replace them with premium Hashimoto HC-203U transformers.
However, it must be noted that even after all of these upgrades, the final result is still not absolutely perfect. There remains an audible hum when the amplifier is paired with sensitive speakers (90dB and up). Completely eliminating that residual noise floor would require major, deep-level changes to the power supply design.
Final Verdict
Out of the box, the Reisong A50 MKIII is a flawed, highly compromised budget amplifier wrapped in a pretty chassis. It does not live up to the breathless praise of mainstream reviewers, and its stock transformers and questionable reliability make it tough to recommend to a casual plug-and-play user.
However, for the DIY enthusiast, it represents an incredible foundation. Once you fix the schematic and upgrade the iron to Hashimoto transformers, the narrative completely flips. Not counting your investment of assembly time, the total cost after mods comes out to around $1,600 – doubling the initial price. At that price point, this amplifier can easily give most high-end 300B amplifiers a serious run for their money. It ceases to be a budget compromise and becomes a genuine audiophile powerhouse.
This might be helpful as well. Is a Budget 300B Amp Worth It? The Real Cost of SET