P&R Audio Active DI Box
P&R are perhaps best known for their patchbays, but they also manufacture other accessories, the latest being this rather nifty active DI box. It may be powered either from an internal 9V battery or from a mixer mic input equipped with phantom power, the output being via a balanced XLR connector, giving a nominal mic level at 600 ohms. It is recommended that the battery be removed if phantom powering is used. A red LED indicates that phantom power is present, but as the circuit power is switched off when the input is unplugged, no light shows unless a jack lead is plugged into one of the two inputs. Changing the battery involves removing a few crosshead screws to get the cover off, but otherwise everything is quite painless.
Physically a little larger than most budget DI boxes, the P&R model features a bank of pushbutton switches along one side to provide a useful selection of input and output options. Amongst these is a non-latching battery check facility (very sensible), a choice of high or low input impedance (electric guitars require the high Z setting) and even a presence boost, again useful when working with guitars. There's also a setting which allows speaker level signals to be fed into the unit, though I'm a little concerned that it would be too easy to select the wrong setting, with the possibility of damaging the DI box if a high-powered guitar amp was being used. There is no inbuilt speaker simulation circuitry, so taking a DI feed from a guitar amp is only likely to be useful for clean rhythm or bass guitar sounds. Finally, there's a phase invert switch, which has no obvious effect when used in isolation, but if the DI box is part of a complex effects patch that needs phase inversion, then this facility is very useful.
There are two inputs, both on unbalanced jacks, and they are identical other than that one is ground lifted. Ground lift can sometimes eliminate hum caused by multiple earth connections, so when using the DI box to connect two mains-powered pieces of gear, this input will probably produce the quietest results. A further socket is wired in parallel with the input, allowing the DI box to take a feed from between two pieces of equipment without breaking the existing signal path. In use, the DI box is very quiet and works exactly as described. Using an electric guitar directly into the box (High Z, Presence on) gave a very nice rhythm guitar sound with just enough brightness and again, no audible noise. Because the Presence setting does impart some degree of high-frequency boost to the signal, it's probably best used only for guitars, as the already generous high-frequency content of drum machines and synthesizers could cause distortion. If in doubt, just try it and see if you get the results you want.
DI boxes are never over-exciting, but considering its low price, this one has to be considered a bargain, especially when you consider it sports some facilities not even offered by far more costly, pro-audio units.
P&R Active DI box £39.95 including VAT.
P&R Audio, (Contact Details).
Review by Paul White
Previous article in this issue:
Next article in this issue:
mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.
If you value this resource, you can support this project - it really helps!