I’ve played around with tube buffers once or twice–these normally simple devices add a valve stage to your playback chain so that you can enjoy a more “tubey” sound. In most cases these are simple boxes with a single valve–a Chinese-sourced one I once tried retailed a little more than $100 USD. But when Dan Wright of ModWright Instruments tackles the idea of a tube buffer with a product named Analog Bridge, you know that we’re talking about a new level of design sophistication.
Dan, of course, has plenty of experience modifying various digital players with tube output stages. If I remember correctly, that’s how ModWright began. The ModWright Analog Bridge ($2,900 USD) is a fascinating, well-built unit that is much more attractive than the other little black box tube buffers–it looks like a tube amplifier. The Analog Bridge has two selectable RCA inputs and two RCA outputs (XLR and fully-balanced are both options), and that allows the user to choose between 6922 or 6SN7 tubes from completely separate circuits.
The power supply of the Analog Bridge is internal, and tube rectified with a 5AR4. It is unity gain with no volume control, but you can build a very simple system with just a digital source that has its own volume control. It’s a very flexible unit, unlike most tube buffers.
In a series of A/B comparisons, we discovered that the Analog Bridge is highly dependent upon the source material. In some cases, there is very little sonic difference between having it switched in and out of the system, but we found a cut where the effect of the buffer was quite noticeable–Shelby Lynne’s Just a Little Loving. With the Analog Bridge, the sound was open and textured, but when Dan switched it out I heard a distinct hardening in her voice.
The system was remarkable to begin with–SME turntable, Revel speakers, Mytek Liberty DAC, Cardas cables and, of course, ModWright amplification. So it wasn’t good versus better as much as tube versus solid-state, and whichever one you prefer. I’ve always enjoyed the idea of flicking a switch and moving between the two types of circuitry, but I suspect the Analog Bridge takes this to a new level with its flexibility and thoughtful design.