In-Line Microphone Signal Booster…
I’ve long been a fan of using ribbon microphones — both in the studio and on the live stage. Traditionally, ribbon mic designs suffered from a certain drawbacks that made them less suitable for live use, including a large body, fragile construction and high prices.
Solutions
From its first mic design, the R-121 in 1998, Royer Labs took on these drawbacks with models that were compact and great sounding, and eventually debuted road-rugged models such as the R-10 (reviewed in the May 2018 FRONT of HOUSE), which uses an internal shock mount, 3-layer windscreen and a $499 price tag that appeals to live users. Problem solved.
This is not to say that ribbon mics are ideal in all applications. Most ribbon mics exhibit a figure-8 polar pattern, which can be problematic in some live applications, in terms of pattern control (stage noise pickup) and feedback avoidance. However, ribbon mics excel at some duties — including close-in guitar cabinet and horn miking — and in certain situations when used as stereo configurations, whether as spaced or coincident pairs as drum overheads, for example, as long as the ceiling is not too low. Another downside to ribbon mics is that the mics tend to have a fairly low output. Again, this is less problematic in studios with short cable runs, but this can be an issue in live use, where long cable runs and the possibility of mic splitting is more common.
Enter the dBooster
To address the level concerns, Royer designed the Model R-DB20 dBooster. Housed in a lightweight yet sturdy 3.6-inch aluminum case, the unit is an in-line, phantom-powered signal booster/impedance buffer that provides two levels of gain boost — either +12 dB or +20 dB selectable via an in/out pushbutton. Essentially, the unit defaults to a 12 dB boost and by enabling the switch, the total gain boost rises to 20 dB. The dBooster can be used with any passive (non-active) ribbon or dynamic microphone and maintains headroom and gain regardless of load.
There are a number of in-line gain boost devices on the market, but the dBooster sets itself apart from the rest. First of all, the selectable +12/20 dB gain boost feature gives the user more flexibility — although in most situations, depending on the instrument source, +12 dB was plenty.
Going Inside
As shown in Fig. 1, a look inside the dBooster reveals a lot. Rather than a simple FET design, it’s a low-distortion, fully Class-A approach that consists of multiple paralleled PNP semiconductors for low-noise performance, while presenting a high source impedance to the mic to minimize loading/damping effects to reduce coloration and improve headroom at the preamp.
Royer’s intent with dBooster was a design that takes the approach of the front-end of a high-end mic preamp. Gain is achieved via eight (four pairs) of low-noise bipolar transistors with four ganged on pin-2 and four on pin-3, an approach that results in even lower noise. The transistors are followed by an op amp on each pin, which isolate the transistors for a low-impedance output that’s ideal in live applications. Taking things a step further, dBooster incorporates a regulated power scheme and noise/RF protection — another appreciated touch for the live user.
Plug and Go
As with any phantom powered device (condenser microphone, direct box, etc.), you definitely want to make sure your input channel is muted when you engage the phantom power or change the gain setting. But other than that, operation is easy, although I would have preferred that the gain switch would be recessed to avoid accidental changes. The outer chassis seems road tough, the underside has a non-slip/non-scratch rubber panel, and the circuit construction and parts selection (including the Neutrik I/O XLRs) are high-quality throughout.
It should be emphasized that dBooster is not a microphone preamp. Its output is an low-impedance microphone-level signal (with increased gain, of course) that can drive any standard console or stagebox preamp. It’s use is not limited to ribbon microphones — and is equally useful on low-output dynamic mics, such as the Shure SM7B, or any dynamic mic when very long cables runs are necessary, without having to without sacrificing gain or performance while maintaining ample headroom.
In use, the gain — and plenty of it — was there, which was no surprise, but what I didn’t expect was that the dBooster had the effect of opening up the top-end of the Royer R-10 I was testing it with. Not that the R-10 has an overly attenuated top-end to begin with, but using the dBooster with the R-10 yielded a somewhat more airy HF response that was more like Royer’s top-end R-121. I’m not sure if this was due to improved loading or possibly some result of the Class-A circuit design, but either way, I liked what I heard and was impressed with the end result.
With a street price of $179, the Royer Labs dBooster Model R-DB20 in-line signal booster is an easy to use, affordable (and useful) gig bag item that is ideal for any ribbon mic user. By the way, it is made in the USA and carries a one-year warranty.
At a Glance
More Level, Less Noise
Royer’s Model R-DB20 dBooster is a signal booster/impedance buffer that provides two levels of gain boost — either +12 dB or +20 dB, selectable via an in/out pushbutton. The end result: more level, and less noise, for your ribbon and dynamic microphones.
Royer Labs dBooster
PROS
- Easy to use
- Clean, stable, low-impedance gain boosting
- Switchable +12/+20 dB gain settings
CONS
- Gain switch can be inadvertently changed
STATS
Gain: 12 dB or 20 dB switchable
THD+N: 0.0015% @ 20 dB setting; 0.001% @ 12 dB
Frequency Response: 20 Hz to 20k Hz (±0.25 dB)
Self-Noise: <11 dBA (20 dB setting); <15 dBA (12 dB setting)
Input Impedance: 3.6K Ohm
Output Impedance: 300 Ohms (at 20 dB setting)
Power Requirements: 48 VDC phantom
Weight: 6 ounces
Street Price: $179
More Info: www.royerlabs.com
