A few months ago I bought my first ever tube phono preamp to use with my turntables. In this article, I will share my experience with how it sounds and compare it to my solid-state phono preamp.
The preamp I bought is the Pro-Ject Tube Box S2. Prior to my purchase I did a lot of research on affordable tube preamps and it seemed to me that the Pro-Ject Tube Box S2 more or less represented the entry point for decent tube phono preamps.
There are many cheaper tube phono preamp options available, but I didn’t find enough evidence that they offer the performance I am ultimately looking for. They all seemed to receive quite mixed reviews. So I ended up dismissing all the popular options I found that cost less than the Pro-Ject Tube Box S2.
There are, needles to say, much more expensive options as well. Many hardcore vinyl enthusiasts that fancy tube amplification use tube phono preamps that costs many times what I paid for the Tube Box S2. And would probably not even consider the Tube Box S2 a “real” tube phono preamp.
I wanted a tube phono preamp of decent quality, but I don’t really have the budget to throw thousands of dollars on a preamp.
So the Pro-Ject Tube Box S2 stood out as the perfect balance between cost and performance for me.
And I am quite impressed with how it performs. More on that in the comparison section below.
I think it is a tube phono preamp of interest for many vinyl lovers that care about sound but don’t have astronomic Hi-Fi budgets. Like myself.
The Pro-Ject Tube Box S2
The Tube Box S2 features a fully discrete circuit design (no use of op-amps) and has replaceable tubes that allow for tube rolling and sound shaping.
I have not seen the circuit schematics myself, but I have seen several audiophiles state that the tubes are used for the output stage and not just for buffering. I believe that is a fact, but I can’t guarantee 100%.
The Tube Box S2 supports both MM and MC cartridges, has adjustable gain and many settings to adjust input impedance.
Below is a quote from Stereoplay’s review of the Tube Box S2 in 2018:
Value blast! Flexible adjustable phono stage with interchangeable tubes. Doesn’t softer, but excites with a dynamic, punchy sound and great spatial representation.
Here is a review of the Tube Box S by Techmoan on YouTube. An interesting watch if you have the time.
Cheaper Options
The other tube phono preamps I research includes the Nobsound Little Bear T7, the Bellari VP130 and the Nobsound Little Bear T11. They are popular phono preamps that are discussed a lot in the vinyl community. And they are all significantly cheaper than the Pro-Ject Tube Box S2.
The Tech: Tube Preamps vs. Solid-State Preamps
A tube preamp uses vacuum tubes to increase the amplitude or power of a signal.
While a regular (solid-state) preamp use transistors and operational amplifiers to do that job.
In a tube phono preamp the circuitry needed to amplify and RIAA correct the PHONO signal is built around vacuum tubes. While this circuitry is built around transistors (or operational amplifiers) in a regular solid-state phono preamp.
Affordable tube phono preamps, like the Pro-Ject Tube Box S2, are usually hybrids. Which means that the circuitry includes both transistors and tubes.
Tube amplifiers respond differently from transistor amplifiers when signal levels approach and reach the point of clipping. In a tube amplifier, the transition from linear amplification to limiting is less abrupt than in a solid state unit, resulting in a less grating form of distortion at the onset of clipping. (Source: Wikipedia)
And this is the main reason why so many studio musicians, guitarist and home stereo enthusiast prefer tube amplification. The softer clipping that tubes provide results in a warmer and more pleasant sound character.
Another difference between the two technologies is that tube phono preamps usually work with tubes from a variety of different manufacturers. And different tubes often have quite different sound characters.
So, with a tube phono preamp you will have the option to roll tubes to change and balance the sound of your stereo. An option you won’t have with a regular solid-state phono preamp.
Not having that option may save you a lot of money over time by the way…
If you want to read more about the pros and cons of a tube phono preamps, please visit my Pros and Cons of Tube Phono Preamps article.
Sound Comparison: Tubes vs. Solid State
The solid-state preamp I have used for comparison is the award-winning Rega Fono Mini A2D.
If you have read some of my other preamp related articles here on Vinyl Restart, you probably know that I am a big fan of the Rega Fono Mini A2D that has been my trusted preamp for a long time.
The Rega Fono Mini A2D is a very good solid-state preamp that costs about half the price of a Pro-Ject Tube Box S2.
So, how do the Tube Box S2 sound compared to the less expensive solid-state Rega Fono Mini A2D?
Does the tubes make the music sound smoother and warmer?
Yes. Definitely.
The Tube Box S2 makes the music more pleasant and enjoyable to listen to in my ears. And basically without any downsides. The Tube Box S2 fully match the impressive dynamics and precision of the Rega Fono Mini A2D, but adds more warmth and character.
The Rega is quite warm sounding solid-state preamp in my opinion. But the Tube Box S2 take it to the next level.
In short, the Pro-Ject Tube Box S2 does exactly what I hoped a relatively affordable tube phono preamp would do. It adds warmth and character without taking away clarity, precision, or punch in the low end.
The sound difference between two decent solid-state (transistor based) phono preamps are usually marginal, in my opinion.
A solid-state phono preamp is a quite basic circuit, and if it is of good quality, there is not much more to gain by replacing it with a different or more expensive one.
I actually have a whole article on that topic, Does an Expensive Phono Preamp Sound Better?
The difference between the solid-state Rega Fono Mini A2D and the Pro-Ject Tube Box S2 is, however, not marginal.
They sound quite a bit different.
The level of extra warmth and character that was added by the tubes of the Tube Box S2 honestly surprised and impressed me.
Conclusion
Let’s go back to the initial question.
Does a tube phono preamp sound better?
I guess that is subjective, but based on my comparison between good solid-state phono preamp and a relatively affordable tube phono preamp, I will say that the tubes adds significant warmth, smoothness and character. Without noticeable downsides.
If that is what you looking for, I will say that a tube phono preamp does sound better.
We can objectively say that it sounds different.
And that the Pro-Ject Tube Box S2 sounds better if you like the way it sounds different.
Personally, I like the way it sounds different and I will probably have the Pro-Ject Tube Box S2 connected to my turntable for a long time. It is now the favorite gadget in my steadily growing list of vinyl gear.
Click here if you like to check current Pro-Ject Tube Box S2 pricing on Amazon.