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Charisma 2
Model 9733

SPL Charisma
Tube Processor

Pro Audio Review, USA
Jan Stevens

The Charisma from Sound Performance Laboratories (SPL) is an eight- channel tube processor designed to warm up digital recordings. The unit has eight tubes, eight available channels, and claims to give digital recordings the sound of a two-inch analog 16-track. The Charisma also allows the user to change the tube sound from soft to hard, creating sounds similar to analog tape saturation. The eight-channel configuration enables a tube interface betrween your signal source and any eight track digital machine or hard disk system.

Features

The unit comes housed in a groovy, retrolooking two-space rackmount. Each of the eight channels has three knobs and a bypass switch. The top knob, the "drive control", sets the amount of level that drives the tube. According to the manual, increasing the drive control results in more tube distortion and added harmonics. In the higher drive levels tube limiting occurs. This limiting is an extra bonus and helps prevent overloading and elipping as when recording live drums and vocals.

The second knob, the "Charisma controlÒ, varies the tube sound and saturation. Adjusting the Charisma in the "softÒ range brings in the harmonic distortion very slowly. This setting can be compared with the soft-knee setting on a compressor. Adjusting the Charisma in the "hardÒ range brings in the tube processing faster. The hard setting is comparable to a hard-knee compressor and the resulting sound is punchler. The "output controlÒ compensates for the level increase when higher drive values have been used. There are also eight bypass switches for each channel.

As the drive control is turned up, the process light begins to flicker; that means you are now beginning to saturate the tubes. Harmonic overtones, the manual states, are then heard, as are the very beginnings of tube limiting. That limiting will have a soft-knee or a hard-knee type of curve depending upon where the charisma control is. Turning the drive control up produces more harmonic overtones. The more drive that is dialed up, the more harmonic overtones are created up the scale. By further increasing the drive levels the sound can be pushed into a kind of warm distortion. The drive control pushes the rubes into saturation, which limits and creates overtones series.

The Charisma control changes the limiting wave form from soft knee to hard knee depending on the position of the control. The result is either a harder, more punchy, crispier sound or a softer, rounder type of sound. When the drive control is turned up to the point where the "maximumÒ light comes on means that the maximum capability of the tube plates and the maximum overtone series have been reached. At this point the unit can be pushed into real-time distortion, which is definitely audible. The Charisma is very quiet and there is a definite feeling of quality in the knobs and construction.

The Charisma is equipped with balanced 1/4Ò TRS jacks for both inputs and outputs. 1/4Ò unbalanced jacks will also work (tying the ring to ground). Balanced is strongly suggested to take advantage of the quality balancing input circuits int he unit which relieve hum an any radiated unwanted noise. A very cool feature which I appreciate is that the numbers are printed upside down on the back of the unit. This makes hooking up the unit easy.

Although there is no digitally controlled memory on the Charisma, bringing back your settings is fairly simple. This is because the knobs are carefully marked, and there are only three buttons per channel! Having eight channels makes doing things like drums a breeze.

The eight-channel version, priced at $ 1.699, seems expensive, but keep in mind that you are getting eight channesl of processing. A two-channel version is also available for $ 799.

In Use

In order to determine how the unit sounded, I tested it in a number of situations. It is obvious that sound processing is subjective, but the scenarios I chose are fairly common to everyday studio situations. The gear that I used for the test was an AKG 414 directly plugged into Mackie 8-bus console going to a TASCAM DA-88. Subjective as it is, this combination of this gear for my ears tends to bring out all of the chill and brittle high end that I was attempting to warm up with the Charisma. Monitoring was dons on Genelec 1031s.

The first test I did was with an Shure SM57 on a snare drum. I set up the controls so that the input and output levels matched. As I began to monitor the snare drum I slowly turned the drive control up and the process light began to illuminate. To compensate for the increase in level I turned the ouput control down. My immediate impression was that the sound had more presence and punch. At the harder setting, tube limiting began and the sound got even punchier.

As mentioned earlier, adding more drive to the tube adds color to the sound. This coloring effect is a result of the added harmonic content that the Charisma gives the signal. I could actually hear a slight coloring of the sound at even the most passive levels of the box. I found that for the snare, a hard setting on the Charisma control worked best. The effect was that on the louder snare hits the processing jumped in an I got a sound reminiscent of tape sturation. This of course was due tot he tube limiting effect and the added harmonic that enter at the point of limiting. When I pushed up the drive to extreme levels the signal went into a cool-sounding tube distortion Ð more on this later.

My next test was an bass. I recorded it directly into the board and used a soft setting with a medium high drive level so that the Charisma operated just a little. I adjusted the Charisma control so the peak level of the bass did not create too much tube distortion. I noticed that a warm fuzziness was added to the sound as the Charisma gently kicked in. The additional higher harmonics gave the subtle impression of new strings. Again, with the added harmonic content, the Charisma added a coloring to the sound. The digital signal was clean and precise and the Charisma-processed signal was warmer and fuzzier.

My next test was on an acoustic guitar miked with an AKG 414. I set the Charisma control at soft setting with a medium drive level up to 12:00. With a touch of prcessing the Charisma again added a nice warmth and presence to the sound.

Next I tested it on a lead synth sound plugged directly into the console. I tried pushing the drive control into the tube distortion zone and it created a great screaming tube-distorted sound Ð definitely cool for a lead synth sound that jumps out of the track. With this processing, the harmonic structure of a signal can be changed to create some new and different kinds of sounds.

After conducting these tests it became apparent that it would be cool to record a complete hard-hitting rock cue with an dwithout the Charisma. Doing tests out of the context of an actual song setting is fine, but it is not the whole picture. What became immediately evident was that without the Charisma the bass and drums sounded clear and very digitally accurate.

With the Charisma the bass and drums had more bits and more meat to the signal. For me, that is more in character with the rock-and-roll sound. Again, although the sound was meader and fuller, the Charisma does color the sound. It is not neutral and it does have a definite sound quality and color to it. This warm distortion that the Charisma gives recordings is an identifiable sound that can be increased or decreased or made to come in softer or harder.

Summary

In the case of the Charisma I suggest listening before you purchase. For my ears, the unit warmed up everything I put into it, but I felt that it did color the sound even with the smallest amount of processing. Some musicians on the session liked the added color, others did not. In practice I found that a combination of clean and Charisma-prcessed instruments worked best. Drums and bass in a rock-and-roll setting would be one of my choices for processing with the Charisma.

"TubeÒ is definitely an industry catchword at the moment. It seems like everybody is sticking a tube somewhere in their audio chain. They can be found in preamps, compressors, and plug-ins, all in the quest of warmth and less edge. The Charisma is one of these units worth checking out - just audition it first.

Jas Stevens composes and produces music for film, television and commericals. Some of his clients include NBC, ABC, CBS, Mattel Toys, HBO, and Showtime. He is also a contributor to Pro Audio Review.

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