• Account
  • View Shopping Cart

Menu Search View Shopping Cart Call Us

Thermionic Culture Phoenix Mastering PLUS Compressor  From Thermionic

Stereo Valve Compressor

Thermionic Culture


"Experience the Difference"

Sound Pure's 3-Year Warranty

Our Free 3-Year Warranty!
In addition to the standard included manufacturer warranty, virtually all new products carry our exclusive, industry-leading, absolutely free, Sound Pure 3-Year Warranty, which includes PARTS & LABOR. This high-value perk is our way of providing the ultimate in added value to enhance the unique personal touch our small, dedicated team contributes to each purchase.
Learn more »

Lifetime Support

Free Lifetime Technical Support!
Our small team of dedicated experts is here to help the original purchaser for the lifetime of the product. Why? Because we care about building real relationships with our customers for life and stand behind every product we sell.

Free Shipping

This Product Ships Free!
Products ship from our well-located, climate- and humidity-controlled warehouse absolutely free (inside the continental USA). Low-cost international shipping options exist for most products.
Contact us for details »
Contact us for up-to-date delivery estimate.
Payments as low as $141/mo.

Manufacturer's Description from Thermionic

This is the latest development in the evolution of the classic Phoenix compressor, first introduced in 1998. After requests from mastering engineers the Master Phoenix was introduced in October 2006. This was more recall-able with indented pots and slightly different power supply and metering circuit, in which trimming the meter alters the current through the compression valve so compensating for valve ageing.


The compression curve of the mastering Phoenix is slightly gentler than that of the standard one, but it does have a more "positive" effect. This earlier version has 6dB lower gain compared to the standard Phoenix.


The Master Phoenix is in use in many studios and mastering suites around the world, and we do know that one of its users, Ray Staff of AIR London Studios won the MPG award for Best Mastering Engineer in 2009.


The new Mastering Plus is a much upgraded version employing precision Elma switches for the Gain and Threshold and Alpha switches for Attack and Release. Omeg indented pots are used for the Output Level for fine control.


Side Chain Bass Cut switches, which have become an essential mastering tool have been retained. In stereo mastering, with the link switch in, there are effectively 5 frequency options as the compressor side chain will work at the average of the switch positions.


A Standby switch is introduced to prolong valve and component life and this has had an unexpected effect, see. *


Mullard and Siemens NOS valves are used exclusively for lower noise and long life stability.


The Gain is now identical to that of the standard Phoenix so that extreme compression effects are possible .


Easy adjustment of Meter Zeros, especially important in stereo mastering, is now enabled by front panel access to the trim controls, situated between the 2 meters.



*some users have found that analogue tape type distortion is created when the unit is operated with Standby on.This was unintentional but some people may find it interesting.



 ♦ All valve signal path and side chain, point to point hand wired in England.

 ♦ Subtle control with 'soft knee' compression more compression effects when pushed hard.

 ♦ Stereo link for mix buss compression.

 ♦ Side chain filters to enable compression of all frequencies except bass.

 ♦ Flat frequency response over full audio range and beyond.

 ♦ Very low phase shift and harmonic distortion (unless pushed hard).

 ♦ Push-pull design gives a natural warm sound with high output level.

 ♦ Output trim controls for fine adjustment or lower level operation.

 ♦ Balanced ins and outs with custom made Sowter transformers.

 ♦ Bypass switch on each channel removes all electronics.



 ♦ Elma switches for gain and threshold controls.

 ♦ Alpha switches for attack and release controls.

 ♦ All Mullard and Siemens NOS valves.

 ♦ Easy recall- ability.

 ♦ Zero adjustment on front.

 ♦ Precise calibration.

 ♦ More gain than earlier Master Phoenix.

 ♦ Standby switch to prolong valve life.

 ♦ Distortion effects can be created with standby on.


Thermionic Culture

About Manufacturer

Thermionic Culture is focused on producing the very best all valve design audio products. In this day and age of mass-produced solid-state audio equipment it's a refreshing change for a company to constantly strive for the ultimate all valve signal path.

The owners/key people involved at Thermionic Culture are totally dedicated to valve audio equipment, all having many years experience in recording and working with valves. Company founder and designer Vic Keary built his first studio in the late 50's and went onto building Maximum Sound Studios which was later bought by Manfred Mann and renamed The Workhouse, Chalk Farm Studios, and the all valve based studio Chiswick Reach.

Jon Bailes, Thermionic Culture's co-founder is responsible for the mechanical design & visual appearance. Jon has a wealth of experience as a Chief Designer in the electronic manufacturing industry .

Nick Terry engineers on many current albums and singles working recently with artists such as McAlmont & Butler, The Libertines. All this 'real world' experience is an invaluable aid to creating all valve equipment that other artists will no doubt appreciate.

Audio amplification, compression, mixing and equalisation took a backward step when solid-state technology was introduced. Valves are much more real and natural when amplifying and processing audio. We use no transistors or ICs in the signal path. Solid state is relegated to where it works best - in power supplies, although we do use a valve voltage regulator in The Culture Vulture's HT supply.

Some of our circuits take ideas from the 1940s to '60s and refine and update them to produce the low noise and distortion which are expected now. Other circuits are really original! To achieve high standards we use modern components such as 1% metal oxide resistors and polypropylene capacitors where their use is a positive advantage, but we avoid Hi-Fi type gimmicks such as gold plated XLR connectors. We take pride in the construction and reliability of our equipment. To date it is all hand wired using the best quality components. We give a 2-year guarantee against manufacturing defects, though we can only guarantee valves for 1 year. Many valves we use, are Military/Industrial grade. Also, we select and match (where necessary) all of the valves that we supply so a far longer life span can be expected


Max. o/p level (MOL): +19dB into 600Ω

+24dB into 10kΩ

Max gain: 30dB.

THD (at no compression): better than 0.06 % @ 100Hz &



Noise, IEC weighted: better than 100dB below MOL.

Input impedance: 15kΩ.

Frequency response: <1dB variation over range of

12Hz to 56kHz.

Attack time: 0.004s to 0.12s

Release time: 0.04s to 2.4s

Output impedance: 600Ω

Distortion will increase with compression, typically 0.2% & 0.25% at 1kHz & 100Hz with 8dB compression. Attack and release controls are somewhat interdependent, for instance a change of attack setting may affect the release time slightly. Therefore, no times are given on the front panel.


Input/Compression: PCC85 (equiv. 9AQ8)

Output: ECC81 (equiv. 12AT7, CV4024)

Side chain detector: EB91 (equiv. 6AL5, CV4025).

Works Great With