The 6N1P Balanced Preamp is our first Balanced Preamp Kit and was designed to drive our unique Pure Class A Solid State Monoblocks.
So what’s special about this preamp compared to everything else on the market? Well the first thing is that it is ALL Vacuum Tube, not a single transistor in sight! The Phase Splitter, Preamp Stage, and the Cathode Follower are all tube driven.
It’s also using commonly available tubes with the recommended complement being 3 x 6N1P-EV and 2 x 6N6P.
But you can also change the sonic profile by rolling in other tubes in the V1 and V2 gain stages including the 6N1P, 6DJ8, 6922, 7308, 6BZ7, 6BQ7. Or even the lower gain 6CG7 and 6GU7!
Note: Unlike other balanced preamps, the 6N1P Balanced Preamp acts as four independent amplifier channels and does NOT sum the signal. This means that an Balanced Input Signal is simply amplified and then output through a low impedance cathode follower.
A quick heads up though, this preamp is BIG! It’s our largest one yet, Measuring just under 12″ x 12″ (30 x 30cm).
For complete specifications please see the Owner’s Manual.
jahozafat (verified owner) –
Details details details, all the sweet details:
This Preamp has an immediate and responsive sound. I felt the Instruments sounded impressively real. I noticed string instruments especially had a noticeable detailed realistic fullness to them. Percussion instruments came to life with a little extra textured detail. The bass has an amazing richness. I kept thinking to myself while listening it had a certain sweetness to it especially in the bass.
It seemed to me while listening that this preamp had a slightly larger soundstage than my other preamps. The space between the instruments is noticeable. The room reverb of the recording studio is so apparent. This may be due to the immediacy I mentioned earlier giving the individual instruments and voices more room to breathe.
Like always the build videos make putting this beautiful piece of musical art together a dream. Jim and Charles do an amazingly job ordering the build steps in the most logical way. This build in particular has a lot of parts so the build order makes it easy to get harder to install parts in at the right time. I absolutely love building MTA Kits. The feeling I get having put it together myself brings so much joy to the listening experience knowing I had a part in making the sound I am hearing. The more I build Mellow Tone Kits the more I understand how they work and I am so grateful for the experience.
I tested this 6N1P balanced preamp first with my Pro-Ject RPM genie turntable with ortofon bronze cartridge, Universal 6or12SL7 Phono preamp, and OTL headphone preamp. Next I switched to Schiit Aegir Monoblock amps via XLR out. Then finally I switched the input to a Schiit Bifrost DAC to try out some digital sources. I normally prefer all analogue signal paths when I can. This balanced preamp handled my digital tracks through the Bifrost DAC beautifully. As I write this review I am enjoying some of the tracks I only own digitally and it’s like I hearing them for the first time. I never thought I would be listening to Dubstep on a tube preamp.
Thanks again Jim and Charles for creating another incredible preamp. I can’t thank you enough for introducing me to real audiophile sound. When I dipped my toe into this rabbit hole of beautiful sound I never realized how far it could go.
-Gary West
jeff.noblin (verified owner) –
6N1P Balanced Preamp Review
My name is Jeff, and I am reviewing the Mellow Tone Amps 6N1P Balanced Preamp. This is my second build of one of Jim and Charle’s kits. I reached out to the guys to be a Test Builder of this preamp for a few specific reasons. First, I was looking for a preamp with both balanced and single-ended connectivity. Second, a preamp that had a variety of tube options available to tweak sound characteristics to my taste. Third, a kit project that had good documentation and a published schematic as to help learn about non-inverted and inverted signal paths. Fourth, a preamp that adds a tube flavour to my solid-state amp that I use to drive floor-standing speakers.
I would like to touch on the kit assembly before going into the sound characteristics of the Balanced Preamp. The components arrived well packaged and without damage to my home in Tennessee in a timely manner with no import tariffs. The bill of materials and schematic are available online as well as frequency sweeps. The extremely well-annotated schematic and bare circuit board are the best I have ever encountered. The quality of components and the attention to the small details are something I have come to expect from MTA Kits but worth mentioning again for new customers. The online build video series is excellent, and anyone with a good foundation of kit assembly should not be nervous about attempting it. That being said, this preamp is much more than the sum of its parts and should be considered as a worthy addition to your system even if purchased as a completed preamp.
Upon completion of the preamp kit, with no hiccups or issues, I did my test measurements and installed my tube complement and settled down for my first listen. I started out using the single-ended inputs and outputs and must admit I was very surprised with my first impressions. Wow, the command of the bass was dramatic and powerful! Optimistically, I decided to move to the XLR balanced inputs and outputs. After all, that is one of the reasons for the purchase of this particular preamp. Again, the bass. Wow! I listened for a couple of hours in this first session with a variety of music but not critically, just enjoying and getting the feel of this new addition. My second session began the next night after work, and I planned on being a little more critical in my listening. From my experience, tube and component break-in should occur pretty quickly. I listened for about another hour, changing music and enjoying the new sound of the preamp. It was time to start listening to a few of my test tracks that I am very familiar with. I won’t bore you with my entire list of tracks and the other components in my system, but I will mention one of my go-to test tracks. The Chicago Transit Authority’s “I’m a Man”. The bass intro is a good way to determine the speed and accuracy of a system’s bass capabilities. It is also a good representation of real electric bass guitar without being overly in your face. Then the tambourine kick in as another layer with guitar and vocals to follow. In my opinion, you get a good idea of band placement and can hear how the layering of sound is handled. Again, the bass was dominating. I was beginning to be a little concerned that the midrange and treble were being a little overwhelmed by the lower octaves. Where was that tambourine cymbal sizzle? I also felt things got a little muddy when all the instruments were playing all at once. Oh well, maybe time to roll some tubes. After discussing with Jim my first impressions, I ordered a pair of 6CG7 tubes based on his recommendation. I continued to listen with the original tube set (Voskhod “Rocket” 6N1P-EV) while awaiting the arrival of the new tubes. By my fourth listening session, things changed pretty dramatically. I don’t know if it was the tubes or the preamp or both, but the overall sound settled down to a very even tone from top to bottom. I have completely changed my opinion. This setup was now very even. Bass was still great yet no longer overly emphasized. The sizzle and shimmer was back! I realize most will just chalk this up to getting used to a new sound or some type of confirmation bias. Everyone is entitled to their own opinion, but I am a pretty seasoned listener and have had many very good components throughout the years and can say without hesitation… This preamp and tube complement did take several hours to settle in. YMMV, but my suggestion is to give this setup at least 6 hours of listening before you make any assumptions or opinions. By the way, the new 6CG7 tubes also sound great! In my opinion, they are better for great midrange in smoother types of music, and the rockets are best for highly dynamic music like 70’s rock. I now go back and forth between the two tube sets with the Rockets getting the nod 70% of the time. I am a child of the 70’s rock scene, therefore, the tube choice.
To sum this review up, I would say this is a very high-quality and musical preamp worthy of your consideration. It has a great deal of flexibility in inputs and outputs as well as a good number of tube options available. My takeaway is it accomplishes all my objectives and adds just enough tube flavour to my solid-state amp to become a regular player in my system. For many, it might even be an endgame purchase. Don’t hesitate to purchase or build this preamp if you are on the fence.
Thanks, Jim and Charles, for another quality piece of gear.
bradleybcraig (verified owner) –
6N1P Balanced Preamp Review: Mellow Tone Amps Delivers Again
Background
This is my fourth Mellow Tone Amps build, following their GU50 Monoblocks, Phono Preamp, and Universal 6or12SN7 Preamp. Each kit has raised my expectations, and the 6N1P Balanced Preamp continues that trajectory. If you’ve worked with Jim and Charles before, you already know what to expect: thoughtful design, clear documentation, and a finished product that punches well above its price.
The Build
Total build time was roughly 8-10 hours spread across several evenings. As with the previous three kits, the documentation and video tutorials were excellent – Jim and Charles have clearly refined their teaching approach over the years, and it shows.
Component and Chassis Quality were very good and well thought out. The main circuit board design, layout, and labelling were particularly impressive. Assembly felt logical at every step, with components falling into place exactly where you’d expect. There’s a real difference between a PCB designed by someone who builds amps and one designed by someone who only designs PCBs – this is clearly the former.
I built this one 100% stock, no upgraded parts or modifications. First power-up was clean, and all measurements came in within spec. No troubleshooting, no head-scratching – just plug in, verify, and listen.
Would I recommend this kit to a first-time builder? Honestly, this is a build for someone with some experience under their belt. That said, Jim and Charles have made it as approachable as a project of this complexity can be. With patience and basic building skills, a careful newcomer could absolutely succeed here.
The Listening Rig
– Source: Lumin U1 Mini streamer feeding a Playback Designs MPD-8 DAC, with Roon serving Qobuz
– Preamp: The 6N1P Balanced Preamp (running balanced circuit only for this review)
– Active Crossover: Sublime Acoustic K235 3-way
– Power Amps: Two Jeff Rowland Model 125s configured as monoblocks
– Subwoofers: Dual REL T/9x
– Speakers: Magnepan .7
– Room: 12 x 14 feet
– Cabling: Upgraded power and speaker cables, nothing exotic
– Tubes Evaluated: Stock 6N1P and upgraded Hit-Ray tubes
The Listening Experience
I started where you should start any serious preamp evaluation: “Time” from Dark Side of the Moon. The clocks and chimes intro is a torture test for transient response, spatial cues, and image focus, and the 6N1P Balanced Preamp passed beautifully. The clarity I heard in those opening seconds was something I had not previously experienced with my Schiit Freya+ running RCA “Bad Boy” 6SN7s – and that’s not a slight against the Freya+, which is a fine preamp. It’s a real statement about what this little kit can do.
From there I worked through Jackson Browne, Dire Straits, Adele, Tyler Childers, The Beatles, and Amy Winehouse. A few consistent impressions emerged:
Tonality: Warmth without thickness. Bass is clear and precise – no bloat, no smearing – and the midrange is immediately noticeable in the best way. Vocals and instruments in the mids feel present and just hang there in the room, clear and palpable. Tyler Childers and Amy Winehouse in particular benefited from this midrange presence, which gave their voices a life like texture.
Tube Rolling: The “Gold Set” 6N1P-EV tubes lean slightly brighter, while the “Platinum Set” 6CG7 tubes add a touch more warmth. Both are musical and enjoyable – the choice really depends on the rest of your system and your personal taste. Owners of brighter source components or speakers will probably gravitate to the Platinum Set; those wanting more sparkle will prefer the Gold Set.
Soundstage and imaging: This was where the preamp really announced itself. Stage width and depth were immediately apparent, with images locked into place and convincing layering front-to-back. The Magnepan .7s love a clean, low-noise source, and the MTA Balanced Preamp feeds them exactly what they need.
Noise and quirks: Noise floor is well managed. Channel balance is on par with what you’d expect from a much more expensive piece. No quirks, no microphonics worth mentioning, no surprises.
One caveat: I’ve only tested the balanced circuit so far, which makes sense given my fully balanced downstream chain. The single-ended outputs remain unexplored territory for me.
Verdict
The 6N1P Balanced Preamp is a clear upgrade from a mid-tier preamp like the Freya+, and it offers genuine tube-rolling flexibility for those who enjoy that hobby-within-a-hobby. It’s a build best suited to experienced kit builders, but anyone with patience and basic skills can succeed thanks to Jim and Charles’s excellent documentation.
For the price of admission, you get a balanced preamp with the kind of midrange presence, soundstage, and image focus that typically costs considerably more in a finished product. Four kits in, Mellow Tone Amps continues to impress.