Stereo Compressor

The Kultube is a stereo compressor with three specialties:

Compression is done by a custom-made discrete Class A gain cell instead of industrial VCAs, the unique Progressive Time Control (PTC) automatically optimizes Attack & Release and an adjustable tube saturation.


1.628€ incl. AD 24/192

Recommended Retail Price
including 19% VAT
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SPL has developed discrete, very high performance gain cells that are used instead of the usual VCAs and the Kultube is the first product to use them.

They ensure the highest level of musicality and clarity in signal processing and demonstrate significantly improved distortion values over VCAs.
The adjustable tube saturation of the output stages combined with automatic output level re-adjustment produces tube sound effects that range from the delicate to the raucous.
With the unique Progressive Time Control (PTC) option for attack and release, time constants can be optimised by unique circuitry that reacts both to the input signal and to the user settings - for example, fast impulses are intercepted by an attack time as fast as 20 us.

PTC can be seen as an interactively controllable automation which is not based on fix presets but reacts to the audio material in a musically useful way.
The Kultube user has a unique range of powerful compression tools always available, from subtle unobtrusive compression to very obvious ‘effect‘ compressions. Used conventionally or as an effect, in professional recording or mastering applications, the Kultube combines outstanding audio quality with the acclaimed musicality and user-friendliness that SPL units stand for.

Applications cover those of a classic compressor for vocals and instruments, in both mono and stereo, through stereo operation for subgroup processing to stereo mastering and multi-channel/surround projects.
In master/slave mode, any number of devices can be controlled from one master unit.
  • Stereo compressor with discrete, Class A gain components (instead of industrial VCAs)
  • Single track or subgroup/summed signal processing in studio and live recording
  • Stereo and multi-channel applications
  • Adjustable tube saturation with automatic output level adjustment
  • Selectable soft or hard knee characteristics
  • Unique decompression mode
  • Large VU meter displays gain reduction or (mono summed) output level
  • Switchable side-chain inputs on the front panel
  • Slave mode for multi-channel operation
The Kultube can be equipped with a 24/192 AD Converter and I/O transformers from Lundahl.
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Frequency response (100 kHz = -3 dB): 10 Hz-100 kHz

THD & N (at 0 dBu): > 83 dB

S/N (A-weighted): 90 dBu

Input impedance: 20 kOhm

Max. input level: +22 dBu

Max. output level: +24 dBu

Output impedance: = 50 Ohm

Common mode rejection (at 0 dBu):

1 kHz: > 75 dB
10 kHz: > 65 dB

Power supply

Toroidal transformer: 30 VA
Fuses: 400 mA (230 V/50 Hz) / 800 mA (115 V/60 Hz)
Maximum power consumption: 40W


Standard-EIA-19 inch/2U housing
W x H x D: 482 x 88 x 210 mm; 19" x 3.46" x 8.27"

Weight: 4.3 kg, 9.5lbs

0dBu = 0.775V. Subject to change without notice.