Rogue waves in the Roadwaves.

Thus far, "Roadwaves" has been a interesting project. Both as a band and personally as a recording engineer, I had never experienced anything so rigorous, challenging, strenuous, and as rewarding as the recording of this album. Despite the numerous setbacks, both scheduling, performance and equipment-wise, it has been a great experience and I haven't learned so much in such a short amount of time about musicianship, recording engineering, producing, and I guess, just being a human being. 


Since my fairly documented amplifier failure a couple of weeks ago, the band and me have decided to go forward with the project recording Alec's bass parts as my amplifier awaits completion. We have attempted to record some bass over top the completed drum tracks, but weren't all too satisfied with the resultant sounds. So this second time around we came up with some pretty cool, simple solutions to some age-old questions we had recording bass.


DI versus AMP. Why not both?


Bass guitar (and other low-frequency dominated instruments) do not have as much directionality in a stereo field as instruments that include higher frequency components, such as guitar, snare drum, cymbals, etc. Since about the mid to late 1960's, it has been a common practice to record the electric bass guitar directly through means of a impedance balancing transformer, more commonly known as a "direct inject" box, or DI. This gives a clean, electronic representation of the bass guitar sound as what come straight from the bass guitar's pickups (well, routed through the volume and tone controls on the instrument too). The DI does away with the anomalies associated with bass amplification, speakers, microphones, the environment of the recording space, and the distance the microphone is placed from a speakers, giving a drier, up front, and direct sound, which can sound sterile on it's own. 


Another practice is to mike the bass amplifier with a quality microphone; a Sennheiser MD421, AKG D112, Electrovoice RE20 or something of the like. This normally yields a "live, in the room" type sound, which is typically more natural and fuller, though can be hyped in certain frequencies or suffer from distortion as a result of the amplifier or speakers, or phase issues because of distance of the microphone from the speakers. Some engineers however swear by the amp and microphone technique, since it is most true to form when seeing a band perform live.


With modern digital (especially DAW based) recording platforms, higher track counts, almost unlimited track counts are possible, which allows the engineer to record multiple signals dedicated to a single instrument. This can be very useful for bass, allowing the engineer to record both direct and miked bass sounds, and blend them to taste in final mix down. With recording both, it is very, VERY important to observe phase relationship between the direct and miked signals. You should avoid as much as possible phase cancellation and/or phase reinforcement which may cause uneven frequency response of the bass, to avoid a week or otherwise boomy sounding bass sound. 


THE ROGUE WAVE.


So Alec and I settled on a scheme where the direct signal would provide a clean bass sound that would represent the full frequency response of his Fender Jazz Bass, while the amplifier would provide a more focused, mid range sound. The amp would be driven a little harder through means of a Boss Super Overdrive or EH Big Muff in order to add some harmonics to give the bass a more pronounced sound in the mix. The challenge was to record a clean DI signal that would be unaffected by the distortion pedals that were on the front end of the bass amp.


Since I didn't have an instrument-level signal splitter box (or any type of splitter for that matter) we used a somewhat unorthodox, if not "incorrect" method. The signal would leave the Jazz Bass, into a DI box, through an XLR cable to my Yamaha MG12 mixer, of which would be then (through one side of the stereo buss) routed through an ART tube compressor then to the A/D conversion. Part of that bass signal would be tapped from the mixer channel via an AUX send, through another instrument cable to a distortion pedal, then to the bass amp. Thankfully this particular amp, a cheap 30W Carlo Robelli bass amp with a single 10" speaker, had an active pickup input. Though line level is not quite the same as a bass with active pickups, the signal level would be closer active level than passive instrument levels. From there, the bass amp was close miked with a Sennheiser MD421 in close proximity with careful attention to phase relationship with the DI signal. The whole setup was then covered in a heavy packing blanket in order to minimize room reflections on the miked bass amp sound.


Note: using a mixer AUX to send an instrument signal is not the recommended way to go when multing a signal to used as both a direct signal and one to be the input signal for an amplifier. A re-amp unit would be much better at doing this, because of impedance and signal level differences.  In our situation, it was all we had, and honestly, sounded pretty darn good for how primitive the method is. 


Oh yeah, here are some pics of the session. I will post the pictures of the DI/mic signal chain in the near future. 

Alec and the Jazz Bass.

Alec and the invisible engineer... I guess I can't take photos and be in the shot at the same time.

My modest, yet effective recording setup. Yamaha MG12, ART VLA compressor, M-Audio Fast Track 8R, and Mac Book Pro armed with Pro Tools 8

ART Pro VLA II Compressor Review.

ART Pro VLA II Leveling Amplifier and M-Audio Fast Track 8R.

Today was a joyous day in my little world. A little box (actually it was a pretty big box, and quite heavy at that) arrived at my door this morning from our friends over at Sweetwater.com.

The ART Pro VLA II Leveling Amplifier is a rather inexpensive tube driven two-channel compressor/limiter. Vacuum tubes are all the rage lately, (when I say lately, meaning the past decade or so) and nearly every professional audio company seems to be cashing in on the craze. The audio recording world has been no exception. Many feel that digital recording sounds "cold" or "sterile," and many companies are adding tubes in the signal chain to add some "warmth" to the sound. Now I’m not completely sure how grounded these claims are, being that any quality analog piece of recording equipment, solid state or valve, will have it’s own sonic character. Solid state mic pres, such as ones made by API or Neve, or compressors such as the dbx 160a or the famous UREI 1176 will have plenty of warmth to go around, but we’ll save that discussion for another time.

First Impression

In my little world, the arrival of this ART leveling amplifier is nothing short of a godsend. As a home recordist, I have been using plug-ins for quite some time, but through experience found that working with analogue equipment was more inspiring and easier to get the sounds that I heard in my head. I heard a many good thing about the VLA II and decided to pick one up myself. Unwrapping the unit revealed a quality piece; it had detented pots with well marked descriptors and values, two large analogue VU meters with selectable input/output metering, gain reduction and output level displayed via LED meters, a bypass switch per channel to take the compressor circuit out of the signal chain, XLR and quarter-inch TRS input and output jacks on the back, all housed in a study, stamped metal chassis.

Totally spiking the output meter. Rawr!

The controls, per channel.

Without ado, I connected the VLA II to the I/O of my M-Audio Fast Track 8R interface and began running 2 Track stereo mixes through the unit. My immediate reaction was, “Boy, this thing really colors the sound!” And it does. It rolls a bit of the high end off and even with the Ratio set at 2:1 (the lowest setting) and Input Threshold set to have a gain reduction of only about 1dB to 2dB, compression was quite audible. With a little tweaking of the attack and release times, the compression was tamed and sounded very smooth and pleasing. The overall character however sounded a little too "tubey." Even when I backed off both the input and output gain, I would run into some slight distortion in sound of fizziness on the lead vocal.

Now I’m not completely sure where the sound coloration is taking place, but my guess is that the tubes have something to do with it. Being that this unit is advertised as a "vactrol" type compressor (in other words, a compression circuit that utilizes an optocoupler) chances are the tube itself has little to do with the actual signal attenuation, and more to do with the output gain stage (output level). This however still gives the tube plenty of room to impart it's own sonic character to the overall signal.

Diving In

Opening the unit up revealed the presence of two 12AT7 tubes, one for each channel. 12AT7s are lower gain (but higher current) than the more popular 12AX7 seen in guitar amps. Upon inspection I found the stock tubes to be Ruby Tubes. Being that the VLA II is the only unit I have tried with these tubes installed, I cannot make any reliable judgment on how good these tubes are. Poking around my parts drawer, I luckily found two Tung Sol 12AT7s and quickly popped them in. I love the way Tung Sol tubes have a nice, bright chime in guitar amplifiers, and I hoped that they would sound about the same in the VLA II.

Replacing the stock tubes with any high quality type (in this case a pair of Tung Sol) will help extend the frequency response, increase headroom, and help with overall clarity.

To my luck, they did! I wouldn't go so far as to say it was a "night and day" difference, but much of the higher frequencies that were attenuated with the stock tubes did not occur with the Tung Sols. They were significantly clearer, the bass tighter and more defined, and had much higher headroom... they didn't even distort if I drove the output level very hard (the picture where I'm spiking the output meter). The addition of the Tung Sol tubes really helped the unit out, but I could only imagine that any quality tube from RCA, Phillips, GE, Mullard, or GT would help the output stage immensely. Now don't get me wrong, I'm not knocking the Ruby Tubes at all. I think possibly the VLA II is designed with a lower plate voltage that in turn lowers the headroom, and maybe the Ruby Tubes are less adept to handle such conditions, but that's only a theory.

Concluding Opinion

The ART Pro VLA II as delivered is a good compressor/limiter especially if you want to add a certain vintage character to your recordings. It immediately gave more fatness to the bass frequencies, my guess about 200Hz and below. The only caveat is that some of the high end (especially above 9kHz) I felt was sacrificed, and the mids were not very defined overall. This is not however a criticism of the sound; it is still very useable and with some careful EQ treatments on the front end, will add just enough secret sauce to your mix.

With a higher quality tube replacement, I give the VLA II two big fat thumbs up. None of the high frequency gobbling, much better headroom, more defined mids, and bigger bass without sounding muddy or messy. What was a "character" compressor becomes a solid all around performer good for single sources and 2 Track stereo mixes alike.