Nobsound 6N8P Class A Tube Amp DIY Kit Review

Are you looking to build your own DIY amplifier kit? Nobsound might have what you’re looking for!

Yes, the Nobsound 6N8P + 6P3P Hifi Class A tube amp is here to push your analog building skills to their absolute limits.

All you need to build this kit is background knowledge of solid-state components and a dire aspiration to produce excellent quality music.

Here, we run you through everything you need to know about this kit, in addition to what other established hobbyists say about this amp.

Let’s get started!


The Most Polished DIY Kit On the Market

Right off the bat, you’ll notice that this kit does things a little bit differently.

Nobsound is a China-based manufacturer that is known to include, well, Chinese tubes and electronics.

However, the 5H8C vacuum tubes, coupled with the 5Z4P and two 6N8P tubes are of Russian origin, and we’ll admit that they’re much better than the Chinese variant. It seems that Nobsound went the extra mile to keep things at the highest quality, by including tubes and accessories that are not only well made, but also proven to be reliable.

Quality over quantity, but Nobsound had both covered from the get-go. You’ll find diagrams for the schematics, wiring, tube pin-outs, and transformer wiring. All the supplementary are there. Something we can’t say about most DIY kits out there.

That’s not all. This kit also comes with some extra nuts, screws, ties, wires, and adhesive bases, making this truly the most polished DIY kit!

Outstanding Sound Quality

When we were done building this kit, we were simply blown away by the quality of sound!

We were also pleasantly surprised by how loud this amp can get before we start hearing any distortion.

The highs were clear, the mids were excellent, and the bass was warm and mellow. You can get surprisingly loud sound using just 28 watts, which further showcases the quality of the material and electronic design.

What caught our attention was also how the vocals stood out against the competition. They performed much better than Lysignal Fever’s DIY amp and consistently produced deeper base and sweeter trebles.

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  • Tubes: One 5Z4P/5U4C + Two 6N8P/6H8C + Two 6P3P/6L6GC tubes
  • Power supply: 300 Volts * 2 & 6.3 Volts + 5 Volts + 3.15 Volts * 2
  • Signal / Noise Ratio: 95 dB
  • Distortion: Less than 1% at full power
  • Frequency: 10 Hertz – 70 Kilohertz at 3 dB
  • Output Power: 7 Watts per channel (2 channels)
  • Voltage: 100 Volts – 240 Volts
  • Size: 290 x 170 x 150 mm
  • Weight: 8 Kilograms
  • Actual Package Dimensions: 13.5 x 10.2 x 9.1 inches


We won’t deny that this is a fun piece of kit to experiment on.

This kit will be challenging at times, but once we assembled it, we found that the 8-ohm speakers produced outstanding sound with little to no hum at idle.

The total volume was great and easy to adjust. The channel separation was also incredibly engineered and the music had an overall astounding soundstage for concerts and gigs.

We loved the high-quality vacuum tubes and Russian NOS tubes as well. Every component included with this kit had somewhat of polish to it.

We should also mention that the chassis of this kit is of very high quality. Similarly, the output transformers were commendable, with a superb overall performance.


If you’re looking for detailed pictures and accurate wiring diagrams, you should probably look elsewhere.

First of all, the instructions were printed in Mandarin, so you’re not going to be able to assemble them without finding a proper English translation online.

This isn’t a walk in the park, either. You’ll run into a lot of conflicting schematics for this kit. You’ll also find that component values, and sometimes even wiring, vary from one user to another.

The assembly of this kit took us around 8 hours and stretched over 3 days. There were times when we were ready to abandon this whole thing and move on, but we persisted.

We also realized that the documentation didn’t cover a crucial phase inversion in the circuit. The output transformer’s red primary wire should connect to the output tube plate. The blue wire should also connect to the plate supply.

Users unaware of this issue will run into a very bad case of positive feedback. This will create a very loud squealing sound when you turn on the amplifier.

What Customer Reviews Say

The Nobsound 6N8P + 6P3P amp kit currently has 10 reviews on Amazon. Of the reviews, around 29% are 5-star reviews, and 15% are 1-star reviews.

Before you get discouraged by the mixed reviews, you should bear in mind that almost everyone who gave it a bad review couldn’t assemble it in the first place and therefore wasn’t judging the overall product rather than the failed assembly process.

The kit was constantly praised for the high-quality material throughout. Reviewers said that this amp was an outstanding value for money, considering what you get with the finished product.

One feature that got a lot of attention was how no audible distortion can be heard, even at very high volume. The humming was negligible, too.

Of course, the thing that practically prevented this kit from reaching the hall of fame was just how difficult it is to assemble. Most reviewers complained that they needed extensive knowledge with solid-state assembly to put this thing together. Even the users who built this unit successfully said that it took them days on end to put it together.

Finally, everyone took the time to complain about the Mandarin schematic diagram. Some reviewers posted their own translated versions of the diagram on google drive, but you should, of course, use them at your own responsibility. 

In Conclusion

If you’re willing to put your abilities to the ultimate test, this kit could be for you!

Is this going to be a fun project? Chances are, no, you’re going to walk away frustrated rather than satisfied with this kit. If you’re new to DIY kits, I’d recommend that you find a more be beginner-friendly amp kit instead of pushing your limits here in vain.

However, if you manage to put this thing together, after hours and hours of tireless assembly, you’re going to enjoy blasting your music at full volume, with no hum or noticeable distortion in sight!

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