The Replay Box: a re‑amp device with tonal options to explore.
These high‑quality boxes promise to add more to your rig than most DIs and re‑ampers.
Based in Baton Rouge, Louisiana, United Studio Technologies were founded with the aim of opening up access to “gear built like the original classics”. Having opened their account with reworkings of two popular vintage microphones, they’ve now released another product pairing: the passive, transformer‑based Vintage Direct Box and Replay Box re‑amping interface.
Appearance
Each of these devices sits in an identical, brushed‑aluminium enclosure, whose recessed front and rear panels carry matching control and connector layouts. Internally, the Vintage Direct carries one transformer, whilst the Replay has two. These and all other components in both units are of extremely high quality, right down to the three resistors in the Vintage Direct’s switched attenuator that are made by a supplier to NASA.
The front panel of the Vintage Direct carries a centrally positioned row of three miniature switches. These activate, from left to right: 12dB of output attenuation; an output polarity reversal; and a ground lift. To their right, a three‑position rotary switch selects between the three secondary windings of the unit’s transformer to deliver, in conjunction with the 12dB output attenuator, six output level options from ‑42 to ‑22 dB in 4dB steps. The Vintage Direct’s rear panel carries a balanced male XLR for the DI output, and two quarter‑inch (6.35mm) jack sockets, one for the instrument input and the other for a pass‑through of the input, for onward connection to an amp, effects processor or pedalboard.
The rear panels of the two boxes share broadly the same layout, though obviously the I/O support different functions.The Replay Box’s leftmost front‑panel switch toggles between the unit’s two transformers, to offer either Transparent or Harmonic colour options. The rest of the switches on the front panel have the same functions as those of the Vintage Direct. The output level control’s rotary potentiometer, in this case labelled Level rather than Output, has a practical range of ‑75 to +4 dB, beginning at full attenuation. At the unit’s rear, you’ll find a balanced female XLR input connector that accepts +4dBu line‑level signals; a quarter‑inch jack socket that can act either as a pass‑through of the signal entering the XLR input or (if the XLR is not in use) an input; and a quarter‑inch jack socket that carries the Replay Box’s output signal from the selected transformer.
Transformers
The transformers in both the Vintage Direct and the Replay Box are the fruit of a collaboration between United Studio Technologies (UST from here on) and studio engineer Chad Kelly, whose 20 years of experience in the design, development and production of boutique, hand‑built passive transformer‑based DI and re‑amplification boxes lies at the heart of these new units.
In the Vintage Direct brochure, the direct inspiration of the transformer in the Vintage Direct is given as the UTC A12, a 1960s transformer that featured three separate secondary windings. Over a period of several years, Chad Kelly iterated that design, settling eventually on specifications that were as close as possible to the original, and the design utilises the separate secondary windings to deliver three different output levels. This years‑long development effort resulted in United’s US‑made 5078, which is fitted to the Vintage Direct and which the company claim is one of the largest transformers being used in a current, commercially available DI box.
United’s US‑made 5078 is fitted to the Vintage Direct, which the company claim is one of the largest transformers being used in a current, commercially available DI box.
The Replay’s Transparent transformer comes from the SAE ReAmp that Chad Kelly produced and sold successfully for approximately 20 years under his Signal Art Electronics banner. That unit’s original transformer, designed by Kelly, was a transparent, unity‑gain transformer. Later, Kelly realised that the ReAmp required more gain to handle operation at +4dBu, which resulted in another US‑made transformer, United’s 5043 step‑up transformer. This has 3dB of additional passive clean gain available above its +4dBu input from your audio interface or recorder.
The Replay Box allows you to switch between two different transformers, one sounding cleaner, the other more characterful.The Replay Box’s second, harmonically richer transformer comes from the SAE AngReAmp (if you haven’t got the joke in the name yet, try saying it quickly...). Chad Kelly had experimented with using an inductor to add warmth to the ReAmp’s transparent transformer, a concept that had worked but which significantly reduced the signal level. Fortunately, Kelly discovered an obscure telecommunications transformer and used it in what he describes as “a pretty unorthodox way”, to create a version of the SAE ReAmp that was christened the AngReAmp by one of its first purchasers. This unit’s transformer was created to deliver a gentle high‑frequency roll‑off, fatter low mids and increased harmonic and phase distortion in the sub‑bass region, resulting in a more forward and warmer overall tone and an additional 5dB of passive gain.
On Test
With a selection of active and passive acoustic and electric guitars and basses plugged directly into it, and its balanced XLR output connected to a microphone input on my RME audio interface, the Vintage Direct (which can handle a maximum input level of +10dBu) delivered clean, clear, accurate results, whose character was subtly enhanced by the sense of weight and increased presence that characterises classic transformer‑derived harmonic distortion. There was never any shortage of output level, even with low‑output magnetic pickups, and I found myself occasionally having to dial back the Vintage Direct’s output to keep the RME in its sweet spot.
If you’re not fixated on obtaining the cleanest sound possible from your instruments, you could experiment with pushing the input of the Vintage Direct and taming its output with the attenuator, or you could always connect the Vintage Direct to a valve‑based mic preamp and then push that to add character to the dry sound. Those particular approaches should also work very well with keyboards, synths, bass guitars and electronic drums, as there’s no need to restrict the benefits of the Vintage Direct to any particular instrument; if it has an instrument‑level output, it can be connected.
To audition the Replay Box, I set up a minimalist, all‑analogue signal chain that began with a vintage active Countryman Type 85 (the cleanest DI I own) running into one channel of my Pendulum Audio SPS‑1 microphone preamplifier. The balanced output of that channel then fed the Replay’s balanced input, and the result was split between a high‑end headphone amplifier/monitor controller that I’m currently reviewing, and a hand‑wired Fender Vibrolux Reverb clone.
Playing through that chain delivered a very clear, detailed, neutral and, just as advertised, ‘transparent’ sound. Routing a pre‑recorded Vintage Direct DAW track from the RME to the Replay via the SPS‑1’s insert return immediately brought back the sound of the Vintage Direct. Replaying that track through the Vibrolux didn’t take much setting up, being simply a matter of setting up the interplay between the Replay’s output level control and the Vibrolux’s channel volume and tone controls to give me the edge‑of‑breakup sound that I like to hear.
I’ve never heard transformer‑derived harmonic distortion that sounded as good as that from this transformer.
Switching to the Harmonic transformer revealed the Replay’s secret power. I’ve never heard transformer‑derived harmonic distortion that sounded as good as that from this transformer. While the Vintage Direct’s transformer delivers a noticeable but relatively subtle enhancement, the Replay’s Harmonic transformer pushes the source sound to the fore by giving it much more weight, presence and size. Guitars connected to the Vibrolux through this transformer (I used the Vintage Direct connected to the SPS‑1 to drive the Replay) felt subjectively larger and more open to me than when directly connected. I also found that I could use the Replay quite successfully as an enhancer on a piezo pickup‑equipped acoustic guitar, which opens up another avenue of experimentation.
Boxes To DI For?
There’s absolutely no doubt in my mind that United’s transformer‑based passive Vintage Direct and Replay Box are superb units that deliver very high levels of performance that more than justify the asking price, and they should both be on the RADAR of any serious engineer or musician. Being the more expensive of the pair, the Vintage Direct DI perhaps appeared at first glance to offer less value for money, but once I’d worked with it that first impression disappeared quickly: although it costs approximately twice the price of my Countryman Type 85, it delivers a level of detail that I don’t hear in the Countryman. To me, that alone is worth paying extra for. The Replay just offers excellent value for money, whether you’re into re‑amping electric guitars and basses, acoustic instruments, keyboards, synths, percussion... or even vocals! That wonderful Harmonic transformer alone more than justifies its price, in fact, while its Transparent companion ensures you also have instant access to the original dry track for comparison or use. Had the distributor not needed them back so urgently, I would definitely have snapped up both these little boxes in a heartbeat... and I still might!
Alternatives
The closest DI to the Vintage Direct that I could find at the time of writing was a clone of Bruce Swedien’s UTC‑10X‑based DI, as used on Thriller, and costing almost three times the price! For less money, you’ll find good‑quality passive alternatives from the likes of Telefunken and Radial. I couldn’t find a direct competitor to the Replay, but companies such as Walrus Audio, Radial and Palmer offer lower‑cost options. Little Labs’ Redeye 3D Phantom passive combination re‑amp box and direct box would be worth considering if you’d prefer a compact, one‑box alternative.
Pros
- Both sound utterly superb.
- Both have clinical and creative applications.
- Superb value for money, given the performance.
Cons
- You may want two of each!
Summary
Two superb‑sounding, minimalist, transformer‑based passive units that, between them, make recording and re‑amplifying electric and pickup‑equipped acoustic instruments an easy and creative process.
Information
Vintage Direct Box £479, Replay Box £369. Prices include VAT.
Sound Service UK +44 (0) 330 122 2500.
Vintage Direct Box $399. Replay Box $299.
Rad Distribution +1 845 378 1189.