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LCA 2B Dual Channel Tube VCA Compressor

LCA2B - Description

The LCA 2B is an all-tube VCA compressor/limiter with two independent, linkable channels.

LCA2B is a true TUBE VCA compressor, using a tube as the VCA.( Voltage controlled amplifier.) This kind of compressor is also known as a Vari Mu compressor.


TUBE-TECH LCA 2B is one of the most powerful and versatile VCA compressors in the market:

LCA 2B is extremely versatile, and it works equally well on vocals, instruments and as a bus compressor.
Due to its very fast and smooth attack it is also perfect for drums and percussion.


There''s literally nothing the LCA 2B can't handle very well: 

Powerful bus compression ( It's a dream used for buss compression both inserted and parallel.)

+ fine single instrument and voice compression.


Check our Video: Parallel Snare Drum Compression


The action of the LCA2B is always easy to hear, so finding the right setting on this compressor is a not complicated.


LCA2B is designed to be the TUBE-TECH equivalent of the Fairchild 670, but only in terms of action, not the actual electronics.

It is designed with the Fairchild in mind, delivering similar action but retaining its transparency or high frequencies,

even when pushed to the limit.)

The fixed attack/release constants are duplicates of the Fairchild constants.


When you want even more control, power and wildness than our famous CL1B can deliver, try the LCA 2B.

The LCA2B has found its use in many top live Engineers' touring racks.


Read about Muse/ Marc Carolan FOH setup


LCA2B - Sound Samples

Tracks : Examples :
Female Vocal
Male Vocal
Drums A Power
Drums C Soft
Drums B Medium
Snaredrum A


LCA 2B - Controls and Features

LCA 2B Video










LCA2B Selected User Statements

Barb Morrison - American recording artist, Top 5 Billboard dance chart songwriter,

and Gold record producer.


Barb is known as producer for numerous artists such as Blondie and Rufus Wainwright, and as one half of the

production duo Super Buddha



"the LCA2B is one of my favorite compressors because of how versatile it is. i can get it warm and tubey for vocals but on the other hand it can deal with slamming drums as well. I've used it for both Debbie's vocals and Chris' guitars on a lot of the Blondie records I've done. whatever i use it on seems to immediately sit in the mix with perfection. its been a staple at my studio for almost a decade now." 





Link to three new Blondie Songs, featuring the LCA2B. ( Oct 2012 )



Joe Baressi on Compression

Quote from SOS atricle: Joe Baressi, "Recording Queens Of The Stone Age" 


When nagged further about the ins and outs of his wall-of-rock sound, Barresi soon lands on a not-so-secret ingredient. "I use a lot of compression, obviously, for example the EMI TG12413, Focusrite Red 3, Tube-tech LCA 2B, Dbx 160, Neve 33609 or 2254, things like that. I also spend a lot time riding the faders when I'm mixing, so I can retain some dynamics and separation and the individual sounds are still recognisable and hard. When you compress too hard you lose all your dynamics. I'm a big fan of parallel compression, so I'll often mix in non-compressed sound with compressed sound to maintain the transients. Or I may use the console compressor on the SSL on an individual channel and buss my whole drum kit to a Tube-tech compressor or something. Also, in general I try not to over-EQ stuff, unless it's to get a particular sound. I'd rather get the sound I want out of the microphone. It does start there. It all starts at the source."


Read the whole SOS article.

LCA2B - Technical Features




  • Tube VCA compressor/limiter
  • All-tube based push-pull amplifier
  • Frequency response @ -3 dB: 5 Hz to 50 kHz
  • Low noise: < -85 dBU @ 10 dB gain
  • CMRR: > 60 dB @ 10 kHz
  • Separate compressor and limiter
  • Output Gain: -6 dB to +10 dB
  • Interconnection of several compressors via two busses
  • Clickless In/Out relay
  • Conductive plastic potentiometers
  • Gold plated switches
  • Inputs and outputs are transformer balanced and fully floating
  • Linkable for stereo applications




  • Variable ratio (1.6:1 to 20:1)
  • Variable threshold (Off to -20 dBU)
  • Continuously variable attack and release times
  • Choice between 6 presets (Fairchild) and manual attack/release control
  • LED Gain reduction display




  • Variable threshold (Off to 0 dBU)
  • Attack: 0.8 ms - release: 0.5 sec
  • Separate Limiter On/Off switch
  • LED indication of limiter action


LCA2B - Technical Description

The TUBE-TECH LCA 2B is a two-channel unit with an independent

compressor and limiter per channel.


The unit is all tube based (except for the power supply and side chain circuit).

The VCA (1 dual triode) is placed between the input transformer and the output stage (2 dual triodes).

The audio signal is picked up after the VCA and fed to the side chain circuit. The control signal from the compressor and from the limiter is combined and sent to the link switch and to the control amp, which feeds the VCA. The two bi-directional link busses are accessible at two 1/4" stereo jack sockets on the rear panel. The channels can be linked together for stereo applications and also linked to other LCA 2B's via the two link busses and a standard stereo jack/jack cord. 

The compressor has six att/rel presets ( Fairchild time constants ) as well as manual control. The limiter att/rel is fixed. The LED display is fed from the control amp. The limiter LED is fed from the limiter buffer.The audio path is fully symmetrical from input to output. Input and output have fully floating transformers. All DC voltages are stabilized, except the anode voltage for the output stage.


FAQ: LCA2B Tube Compressor calibration

Like any other compressor, that uses tubes for theVCA, LCA2B occasionally needs calibration.


We recommend that the unit should be calibratedat least once a year.

In real life, depending on the compression tube (ECC81)  the LCA2B will often work perfect for a much longer period of time.


A quick test will tell you if calibration needed:

Turn the THRESHOLD for both compressor and limiter fully CCW. 

Connect a 1kHz tone at a level of 0 dBU (-4VU) to the input and turn the LIMITER THRESHOLD

slowly CW until the LIM led (RED) turns slightly on.
If the LIM led (RED) turns on abruptly or even starts oscillating, the balance should be calibrated.


This test can also be done with audio:

If the LCA2B needs calibration, the compressor starts pumping with this extreme setting.


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