1. Introduction

Grove Hill Liverpoolは、1960年代のアメリカとイギリスの最高級コンプレッションを現代に復刻させました。あなた間違いなくこのコンプレッサーを気に入ります。豊かで、レンジが広く、深みがあり、図太い。アコースティックギターに通して演奏すれば、鮮明に聞こえ、ボディサウンドに魂が宿ります。


2. Features

  • 1960 年代の オールチューブフィードバックスタイルコンプレッサー
  • デュアルトライオードをベースに、ゲインリダクション用のリモートカットミュチューブと 6AL5 真空管で再バイアス。
  • 忠実に再現されたソリッドステート電源は、30dB(最大)のゲインの増減でさえ、低ノイズと安定性を提供します。
  • 高調波歪みを導入することなく、広範囲の入力信号を処理することができます。
  • コンプレッションを使用せずに音楽的に快適な歪みを実現するために使用できます。

3. Original Hardware Specifications

Frequency Response
10Hz to 40kHz (+/- 1.5dB)

Frequency Response (vintage)
300 Hz to 15,000Hz (+/- 1.5dB)

Power Output
+20 dBm

Total Harmonic Distortion
0.08% at 1 KHz with output at 0dB

Noise Level
82 dBu below rated output

Noise Level
82 dBu below rated output

Source Impedance
Any up to 15,000 Ohms

Load Impedance
600 Ohms

30 dB in 5 dB steps – constant impedance

Maximum Compression

0dBm to +16dBm Output

Compression Ratios
⦁ 2:1 at 0dBm Threshold
⦁ 4:1 at +16dBm Threshold

4. Layout

1. Input Gain Knob

Unlike many other compressors, this control here plays two roles. It is used both for adjusting input level and to specify the desired average compression as indicated by the gain reduction meter.

2. Threshold Knob

Again, there are two functions to this knob. Its primary purpose is determining the output level at which compression commences. Secondary, it adjusts the ratio.

3. Attack Knob

The Attack Knob controls how much of the signal transient is allowed through before compression starts. There are 6 different speeds, labeled 1 (Fast) to 6 (Slow), with every second selection labeled ‘C’ — for turning off the compression. In these positions, the effect can be used as a line amplifier.

Attack Times
Knob Position


Attack Time

3 milliseconds
19 milliseconds
48 milliseconds
77 milliseconds
109 milliseconds
138 milliseconds

4. Gain Reduction Meter

Used for measuring the gain reduction which occurs as the result of compression.

5. Recovery Knob

The recovery control determines how quickly the signal rebounds after the input signal has fallen below the threshold. There are six Recovery positions labeled 1 (Fast) to 6 (Slow), with every second selection (labeled H) turning on the Hold function.

The Hold function is a unique feature of the Liverpool. It was added as a modification of the original compressor based on feedback from recording engineers. The Hold function is explained in more detail later in this manual.

Recovery Times
Knob Position


Recovery Time
127 milliseconds
447 milliseconds
917 milliseconds
1.9 seconds
3.4 seconds
6 seconds

6. Output Gain Knob

The output attenuator of the Liverpool is controlled from a six-position rotary switch. This method of attenuation allows for constant impedance on the output transformer as well as the load. The available choices are: 0dB, 5 dB, 10dB, 15dB, 20dB, and 30dB.

Mains Power On/Off Switch

In the hardware original, the power switch is used to turn the compressor On or Off. Here, it is used for bypassing the effect.

5. Hold Function Explained

When trying to process the initial attack of an audio track, the slow attack of the compressor will cause an audible thump to be produced. In such cases, the Hold function is used to “prime” the compressor with the required amount of gain reduction first, thus preventing the thump from occurring.

This is done by playing a track into the compressor, setting the controls as required, then moving the Recovery control to one of the Hold positions. This prevents the compressor release from taking place, maintaining the amount of gain reduction.

The track can then be stopped and played from the beginning. Once the initial attack of the first note has been processed, the compressor can be switched out of Hold and put back to the desired Recovery setting.

If the unit is compressing a track with room ambience, the ambient noise from the recording would swell up in volume at the end of the performance as the gain reduction returned from the compressed level to zero.

This can be avoided by switching the Recovery control to an adjacent Hold position after the last note has finished, which would stop the compressor release from taking place.

6. Interesting Facts

  • The original hardware is based on a Mu tube — an all-glass, miniature VHF, dual-triode, remote cut-off tube used for gain reduction. This tube is re-biased by a 6AL5 vacuum tube-rectified, side-chain control voltage, which causes the Mu tube to smoothly change its mutual conductance.
  • The benefit of utilizing a variable mutual conductance vacuum tube as the ‘heart’ of the compression is that a variety of input signals can be handled without introducing harmonic distortion.
  • The input control on the LIVERPOOL is located before the tubes and directly after the input transformer. As you advance the input control, you are hitting the input tube at the gain reduction stage with more signal. The signal is then amplified by the second stage.
  • Distortion can be creatively used by turning up the Input Gain Knob and turning down the Output Gain Knob while applying very little or no compression.

7. Contacts

Having difficulties with the Grove Hill Liverpool or anything else Antelope? Get in touch with us by the following means:

European Direct Support Line
+44 2039578550
10:00 a.m. – 10:00 p.m. (EET), Monday – Friday

USA Direct Support Line
+1 734 418 8661
7:00 a.m. – 6:30 p.m. (EST), Monday – Friday

Online (live chat and e-mail)
Antelope Audio Support Page

8. Glossary

Attack: Adjusts how quickly the compressor starts to work after the signal exceeds the compression threshold.

Release: Controls how soon the compressor will stop after the signal goes below the compression threshold.

Ratio: Controls how much compression is applied. For example, a 3:1 ratio means that every time the input signal crosses the threshold by 3dB, output signal will be attenuated 1dB.

Threshold: The Threshold is the level above which the compressor considers the signal too loud and starts applying compression.

Knee: Knee and Attack have a lot in common, but they are not the same. Like Attack, Knee controls how the compressor will react once input signal passes the threshold. Hard Attack makes the compressor engage immediately while Soft Knee shapes its attack time to make it slower and smoother.