Pendulum Audio Quartet II Tube Recording Channel
 by Mike Caffrey , Tape-Op March/April 2005

The Pendulum Audio Quartet II (Mercenary Audio Edition) sounds outrageously beautiful. The Quartet II is four independent analog processing elements: a tube mic pre, a tube EQ, a tube compressor and a solid state limiter. It takes up two rack spaces and has both XLR and 1/4 inch I/Os giving it more flexibility than any other multi-element deviceI've ever seen. Greg Gualtieri designed the Quartet II with the intent of having one piece that he could bring to a session and know that he could get a great sound out of anything he had to record. The Quartet II easily meets that goal.

The mic pre has what I've come to think of as the modern design - having both a gain control and an output control so that you can drive the input for extra coloration while controlling the output like the gain and master volume controls on a guitar amp. The impedance is switchable between 1500 and 10k ohms. One feature that I haven't seen before is switchable input transformers. The first transformer is labeled "Full" and the other is labeled "Focused" with the Focused transformer providing a little more gain. When switching between the two while miking a snare drum, I'd describe the difference along the lines of switching between Neve (Full) and API (Focused) pres. Both transformers sounded great on every source I tried them on and it wasn't always easy to choose which was the better option (a nice problem to have). The front panel has all the standard phantom, polarity and high pass filter (75hz or 150hz) controls. The are also switches for selecting mic or line (the single XLR input can be either) and DI inputs. One unusual feature is there are two 1/4 inch DI ins, (front/back) which are loaded differently so that they each have
their own tone.

The passive inductor based EQ has three unique bands and two modes. The low shelving band can boost and cut simultaneously like a Pultec (freqs: 20hz, 30hz, 50hz, 100hz and 120hz). The mid dip cuts only and has a continuously variable Q, labeled intuitively - "Broad" to "Sharp" (freqs: 200hz, 350hz, 500hz, 650hz, and 800hz). The high peak band boosts only, with a continuously variable Q like the mid band (freqs: .8k, 1.4k, 2k, 3k, 4k, 5k, 8, 10k, 12k, 15k and 18k). The EQ can be positioned before or after the compressor in the signal path and can be switched between its "Passive" and it's "Aggressive" mode which increases the saturation of theEQ and adds harmonic content.

The Delta Mu compressor is basically identical to a single channel fromthe Pendulum ES-8 compressor. It's an actual tube compressor, which is a rare thing because most compressors calling themselves "tube" don'tactually use a tube for gain control (just the output stage). It has 5 modes - Fast and Manual like the ES-8, and also Faster, Vintage (program-dependent) and Average (RMS) modes.

The peak limiter is the only non-tube element in the Quartet II (of course- in order for it to be fast enough) and can switch between JFET andMOSFET operation.

How does it sound? As I said earlier, beautiful. It's my first choice for a natural sound that's not devoid of character. The Quartet II has a tube vibe (the real tube vibe) that people aren't always familiar with. Tube gear is usually described as sounding warm, which it often does, but that's more often a result of the transformers and other circuitry (see Neve for an example of how circuitry crates warmth without tubes). It's not uncommon for this circuitry to add extra coloration through poor high end response, a muddy low end and large quantities of harmonic distortion- all problems that the Quartet II does not suffer from. As a result ofthe Pendulum approach to tubes, the Quartet II has a beautiful three dimensional quality that I've never heard from any other piece of recording gear. It was the first thing I noticed when I tried it out by running my Gibson SG into the rear DI. Between driving the pre a little, some simultaneous low boost and cut from the EQ and a few dB of compression in the average mode, I was able to get a sound reminiscent of a clean sound from a Fender Deluxe. It was such a nice tone that, had I been in a session, I would have considered tracking it and I've always hated direct guitar tones. As I played through my monitors (bone dry) I realized that the guitar sat differently than dry signals usually sit. It's hard to describe, but it was like there was an air around the sound. It wasn't obnoxiously forward like a DI sound usually is. It was kind of like it was hovering in the vacuum of space (vacuum tubes - coincidence?). It was clear that it was going to be great for sitting vocals in the mix, especially when going for a dry in your face sound which was the next thing I tried. That tube quality with a little peak limiting made it easy to sit the vocals forward in the mix and allowed me the option of leaving them dry without sounding awkward.

I invited John Lardieri of Twin A by for some vocal comparisons. We ran a TLM 103 through three paths. First a super mint, all original 1073 through an 1176. Then through an Avalon 737 and finally through the Quartet II trying both input transformers. John's first reaction was that the Quartet II sounded "richer" than the Neve and I definitely agreed. The Avalon sounded tinny and a little brittle next to the Quartet II. Both of these comparisons were made with the "Full" transformer. We then A/B'd the vocal through the "Full" and "Focused" transformers. They both sounded great. John preferred the "Focused" transformer because he likes his voice when it's less "husky" sounding. The "Focused" transformer had a slightly tighter low end and a little push in the mids. We also tried it on snare where it sounded full and robust and with a boost at 8K brought out out the snare rattle better than I could with a 1073. I tried duplicating thesound of my Shure Level Loc with the "faster" compression setting, and couldn't quite do it, but I was able to get a truly nasty distorted sound by turning everything all the way up. I tried bass DI'd through the frontand it sounded great. I experimented with guitar though a Pod which the Quartet II made acceptable. I couldn't find a use that the Quartet II didn't excel at.

Another feature that sets the Quartet II apart from every other recording channel I've seen, is that you can run all four components independently. The main I/Os are the XLRs, but there are also the 1/4 inch I/Os for each device in the path. So, for example, you could use it as a complete signal path while recording, and then when mixing you could use the EQ on oneinstrument, the compressor on another, the pre for it's transformer tone options on a third and the brickwall limiter on a fourth. It's important to understand that you're getting four separate top of the line pieces in one box, because you'll find that the Quartet II's price is in line with
purchasing the four devices separately.

The Quartet II was designed to be a jack of all trades. Often that means mastering none, but the Quartet II has mastered any use I could come up with. It's inherent Pendulum tube tone will make it a classic piece of gear and, in an era where studios are competing with each other as well as with home studios, the Quartet II is the caliber of gear that will give people a reason to hire you for a sound they can't get elsewhere. When you compare the Quartet II to other other pieces of gear at the same quality and price level (say a new reissue 1073) it's clearly an exceptional value. I'm also very curious how a pair would fare as as a masteringsignal path (I'd love to hear some non-L1/L2 limiting). Congratulations to Greg on another exceptional design and a nod to Fletcher at Mercenary Audio for his consistency with being involved the best gear. - Mike Caffrey