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Thermionic Culture Vulture Distortion Unit

The Thermionic Culture Vulture valve distortion unit is a strange bird. The manual's first page reads, Do not take this unit seriously. The Culture Vulture

The Thermionic Culture Vulture valve distortion unit is a strange bird. The manual’s first page reads, “Do not take this unit seriously. The Culture Vulture is a fun effects unit and has been designed for maximum pleasure!” Whether you want full-on distortion possibilities or subtle track warmth, this bird is worth a deeper look.

The unit’s spec sheet lists the distortion as 0.2% to 99.5% — very subtle to extreme effects, as you might expect from these numbers. The twin-channel all-tube Vulture makes use of pentode and triode modes that allow for both odd and even distortion effects. To call this box just a distortion unit is an understatement.


At first look, the labeling and function of the front panel controls on this hand-wired, well-constructed 2U rackmount box might not be obvious. A Bias control adjusts the current through the 6AS6 distortion valve that is displayed on the meter, calibrated in mA. Next to the Bias control is a three-position distortion switch with triode and pentode modes labeled T, P1 and P2. The drive and output level controls vary the amount of gain to which the input and output signals are subjected. Also included is a 12dB/octave lowpass filter set for 4 or 7 kHz. The Overdrive switch increases gain and bias. Beware of the left-to-right mirror image controls: It’s easy to reach for the wrong control when working in stereo. Inputs and outputs are by way of unbalanced ¼-inch jacks on the rear panel. Two output jacks per channel provide both +4 and -20dB operation. (Recommended load impedance is 10 kilohm.) Two instrument DI jacks on the front round out the connections.


Being an impatient engineer, I wanted instant gratification by just plugging it in, feeding the Vulture some audio food and twisting some knobs. To my horror, nothing useful happened. After reading the operating manual and receiving e-mail help from the distributor, Unity Audio Ltd., I discovered that a little goes a long way when setting up this unit.

Under “General Operational Hints” in the manual, I found that normal current setting is between 0.2 and 0.4 mA. More is warmer; less, the tube is starved and sounds thin. Analog tape distortion simulation occurs with a current of about 0.4 mA and using the triode mode. Unity Audio offered an additional list of basic settings that I wish were included in the manual: Drum Warmer, Drum Gating, Bass Warmer, Bass Overdrive and Guitar Overdrive. Because of the wide operating range of the controls and the unit’s flexibility, I found that they provided a good starting point for my adventure with the Vulture. But like an old analog synthesizer, when you find a setting you like, document it because there are no presets. The combinations are infinite.

Guitar Overdrive seemed like a logical place to start my discovery process. Less bias, more drive was the setting that gave a larger-than-life, very powerful rhythm guitar sound. I set it for triode mode, set the bias for about 0.5 mA of current and adjusted the drive until the meter dipped on audio peaks. I used this technique for bouncing multiple rhythm tracks in Pro Tools. This alone is worth the price of admission.

Acoustic Guitar was next on my list. I have used other enhancers on acoustics, but the Vulture with a low-bias setting in P1 mode and moderate drive resulted in some nice harmonic enhancement and a big warm tone.

Lead Guitar was the most fun — the variations are endless. P1 and P2 modes with about 0.1 mA created some amazing tones. Watch the meter bounce on the peaks when you adjust the drive. I ended up mixing my original amp track with the output of the Vulture together on the console for more control. I used this technique with several instruments with great results. Bass Guitar was enhanced with the P1 mode and the drive knob at 7.5 and bias at 5. For more distortion, try setting the drive at 11 — yes, the knob goes to 11!

Approach overhead drum tracks with caution: Phase shift and EQ can wreak havoc with a drum mix. I inserted the Culture Vulture and started with triode mode and the bias set to 4. I brought up the drive slowly until I heard it and then backed off a bit. After a lot of serious listening to the full mix using the bypass switches, I found a very nice added sizzle to the cymbals. “A little goes a long way” holds true here. Using it on a drum submix was the last experiment. Based on the results I had with the overhead tracks, I wanted to try the Vulture on the entire kit. Triode mode with drive at 7 and bias brought up slowly to about 4 provided a nice, fat low end reminiscent of good old analog tape.

Other recommended applications include using the Vulture to bounce existing digital tracks to add a little smoothing to analog and digital sampled keyboards, vocal effects and, in some cases, the entire mix.


You might not consider the Culture Vulture a necessary addition to your rack, but once you use it, you’ll hate to give it up. There’s really nothing to compare it to price-wise, so $1,995 might seem expensive. The fact that it’s hand-made and solidly built might make that easier to swallow. Once I figured out the Culture Vulture, I loved it. I spent several late nights exploring the possibilities. If you want to go back to the future of tubes and are tired of the presets in all those DSP boxes, give Vulture a try.

Thermionic Culture (, dist. by Unity Audio Ltd., [email protected].

Jeff Harris is the owner/operator of Artifact Recording Services in Chandler, Ariz.

Culture Vulture

Undocumented Settings From the Manufacturer

Warmer Drums

Drive = 9

Bias = 4

Type = Triode

Output = 6

No Overdrive Or Filter

Drum Gating

Drive = 8

Bias = 4

Type = Pentode 2

Output = 8

No Overdrive

Filter In Or Out

Warmer Bass

Drive = 7.5

Bias = 5

Type = Pentode

Output = 7

No Overdrive Or Filter

Bass Fuzz

Drive = 11

Bias = 1

Type = Triode For ‘Fuzz’, Pentode For ‘Fizz’

Output = 6

Overdrive In

Filter 7k

Guitar Fuzz

Drive = 11

Bias = 3

Type = Pentode 2

Output = 7

Filter 7k

Overdrive In