FAST FACTSAEA TRP Ribbon Microphone Preamplifier
Two-channel; high-pass filter; phase reverse; Fred Forssell design
- Amazingly quiet
- High gain
- Sound quality
- No power switch
A great value in a non-phantom-powered mic preamp
I bought and reviewed an AEA R84 ribbon microphone in 2003, and ever since I've been searching for its perfect preamp. I admittedly have a whole bunch of boutique preamps in my studio, but most of them are dedicated to stereo pairs of other microphones. My R84 needs a lot of gain and — even more importantly to the quiet acoustic sources I usually record — it seems not to tolerate long cable runs in my studio without picking up a small amount of hum.
I've found only two preamps in my studio to date that both amplified it without adding a lot of noise and did not change its perceived frequency response. They were one of my pair of Manley MicEQ500s (usually dedicated to a pair of tube AKG C60s hanging over the Mason & Hamlin piano) and a Yamaha i88x (an mLAN unit I had here for a while during the time I was reviewing the Yamaha 01x mixer). The Yamaha preamp was dead quiet and made the mic sound good, but it didn't even have real analog outputs; I had to use an insert point. The Martech MSS-10 (PAR, 10/97), another seemingly obvious contender, makes my big Neumann M 249s or U 47 (or the new M-Audio Sputnik) sound punchy and silky despite its high gain and low noise. But it had a low enough input impedance characteristic to seriously reduce my R84's low end, despite flattering most of my other vocal mics.
I mentioned my preamp dilemma to AEA's Wes Dooley last spring, and he told me to just wait a month or so and he'd have a surprise for me. So I was elated come June when I received a prototype unit of "The Ribbon Pre," heretofore referred to as "TRP." It was small, stereo and (one channel of it) immediately became the R84's dedicated mic preamp; I purchased it on the spot, despite its prototype status.
The AEA Ribbon Mic Preamplifier is a high-gain and high impedance, minimal-path FET mic preamp. It's designed by Fred Forssell, who's designed many well-known high-end vacuum tube and solid state preamps, plus equalizers for various manufacturers (as well as for his own company, whose equalizer I reviewed in PAR, 9/97). AEA advertises that this low-noise two-channel preamp is intended for ribbon, moving coil and tube microphones that do not need phantom power circuitry. This "lack of a feature" allows for numerous electronic improvements that result in simpler circuitry. It also rids the unit of the ubiquitous phantom power blocking capacitors found in most other preamps. Zener diodes on the input protect the input stage if external phantom power is applied from elsewhere.
TRP is a two-stage transformerless solid state amplifier. The gain in its first stage is adjustable from +6 dB to +63 dB by a 12-position Grayhill switch. Another 20 dB of fixed gain is available after the output level potentiometer. (This is similar to the configuration of the MSS-10, though it uses a circuit with input and output transformers.) TRP also features polarity reversal and high-pass filter switches and LEDs that show operating and overload level metering. It has two sets of outputs: balanced XLRs at +4 dBm and unbalanced 1/4-inch connectors at -10 dBm [AEA says shipping models will have outputs of +4 dB (balanced) and –2 dB (unbalanced); Fred's was a special prototype. — Ed.] A nice touch is its laser engraved legends and single line schematic on the top cover, reminiscent of old-school Roland equipment. TRP is a half-rack-wide unit, one rack unit high (8.5 inches x 8.5 inches x 1.7 inches), and weighs a mere two pounds. Its hefty external "line lump" power supply (which produces ±17.25 VDC) weighs another pound and a half.
I initially just used channel one of TRP with my R84, since it made it sound so good. The sound the R84 produced was as quiet as my quietest tube mics and, more remarkably, seemed more "hi-fi" than it had previously been (in that it appeared to have higher highs and lower lows). I thought to myself, "I haven't really heard this mic until now." I eventually started to get curious about how TRP, with its ultrahigh input impedance and special minimalist circuitry, would handle my other mics.
The only other passive ribbon mics I own are a pair of vintage Beyerdynamic M-500s, which I use live for female vocals. I find these hypercardioid Beyer ribbons to really excel in that application. The little bit of noise their low output level brings out live in most preamps is rarely a problem, and their apparent built-in low-end rolloff is usually desirable (when it isn't it can always be cured by a little mid-bass boost). That's what I thought until I tried them with TRP. I just unplugged my R84, substituted one of the M-500s, and wow!
It had about the same output level as the R84 and, although it obviously lacked that mic's large ribbon creaminess, it definitely sounded like a completely different M-500. It was big, bright, and had plenty of low-end punch. I wish I had a Neumann KMS 105 around with which to A/B it, because it really did sound like an M-500 on steroids. The sound in my monitors, meanwhile, was dead quiet, and the Beyer still had that wonderful airy upper-midrange characteristic which many female vocalists love; it just sounded "bigger and better." I would bet that the still-available Beyer ribbons — like the 130, 260, etc. — would also shine with TRP. I no longer own any passive Royer ribbon mics (just their active versions), but I can't imagine an SF1 or stereo SF12 not sounding better (and quieter) with TRP than with just about any other preamp.
The only dynamic mic I own is a vintage Beyer M-88 and, besides requiring about 12 dB less gain from TRP than the ribbon mics, it sounded considerably better than an SM57 used with a cheap preamp, that's for sure!
I restored the R84 to TRP's Channel 1, and then started hooking up my tube mics to Channel 2. There was less of a difference between TRP and my other good preamps with tube mics than with the ribbon and dynamic mics. So I then started comparing preamps instead, keeping the mic invariant. One day I used my 3-micron U47; the next day (when I was writing the Sputnik article) I used the Sputnik.
Those who have been reading my mic preamp reviews since Pro Audio Review began publishing them might believe that I own only tube preamps. And, in fact, you'd be partly correct. I use my various Manley preamps and my D.W. Fearn VT-2 just about every day, but I also own three high-end solid state preamps, and it was those which I A/Bed with TRP. They are my "vintage" Millennia Media HV3C — the original model, with the built-in Apogee 500 A/D board (PAR, 11/95); my Dan Alexander stereo unit built with authentic Neve parts (PAR, 1/03); and the aforementioned single-channel Martech MSS-10. Here's where TRP stands in that lineup: the Dan Alexander preamp has the "heaviest" and most-colored sound (as would be expected) and the MSS-10, with its multiple modern transformers and specially-voiced circuitry, has a wonderful silky coloration that often makes it my preamp of choice for vocals. The TRP sounds nothing like either of those.
I'd place it instead in the "same sound universe" as the Millennia Media HV3C. The HV3C sounded a little bigger with some of my tube mics; the TRP sounded cleaner with others. But, in general, the two of them sounded similar. I'd say that TRP was more neutral, cleaner, airier if I had to put my finger on it, while the HV3C sounded a little bigger and bolder. And, since the Millennia Media preamp is such a standard around the world for classical recording, I'd consider that putting the TRP in the same category as the HV3C is giving it some pretty high-class company to keep.
For the ultimate vocal channel for my R84 — cost being no object — I hooked the TRP into the line input in my Manley Voxbox, substituting for its own 40 dB gain tube preamp (not a good match for the R84). This is now my dedicated voice system, as it's dead quiet, super clean, warm and — given the special EQ and dynamics adjustments of which the Manley is capable — that's a pretty hard to beat combination!
AEA's "The Ribbon Pre" fills a much-needed niche in the world of mic preamps. Its sound fits right in with the best of the clean, neutral, uncolored solid state preamps and, with its 30 kohm input impedance and extremely high (and quiet) gain, is destined to become a first choice preamp for engineers who use ribbon mics with quiet sources. It's additionally perfect for any tube mic for which one needs gain without coloration. In other words, it's the first universal mic preamp for non-phantom powered mics! Congratulations, Wes (and Fred Forssell): you've got a winner here!