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Grove Hill Audio LIVERPOOL, Operating Instructions Manual, Page: 20 / 22

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LIVERPOOL Tube Compressor 

Page 20 

 

 
 

 

 

 

 

 

Charges for unauthorized service and transportation costs are not 

reimbursable under this warranty, and all warranties, express or implied 

become null and void where the product has been damaged by misuse, 

accident, neglect, modification, tampering or unauthorized alteration by 

anyone other than Grove Hill Audio.   

 

The warrantor assumes no liability for property damage or any other 

incidental or consequential damage whatsoever which may result from failure 

of this product. Any and all warranties of merchantability and fitness implied 

by law are limited to the duration of the expressed warranty. All warranties 

apply only to Grove Hill Audio products purchased and used in the United 

States of America. 

 

Some states do not allow limitations on how long an implied warranty lasts, so 

the above limitations may not apply to you. Some states do not allow the 
exclusion or limitation of incidental or consequential damages, so the above 

exclusion may not apply to you. 

 

This warranty gives you specific legal rights and you may also have other 

rights which vary from state to state. 

Summary of Contents for LIVERPOOL

Page 1: ...LIVERPOOL Tube Compressor Page 1 Grove Hill Audio LIVERPOOL OPERATING INSTRUCTIONS TUBE COMPRESSOR Rev 3 0 ...

Page 2: ... Contents Section Page INTRODUCTION 3 MAINS CONNECTIONS INSTALLATION 6 FRONT PANEL OPERATIONAL NOTES 8 TECHNICAL NOTES 14 SERVICE ADJUSTMENTS 16 SPECIFICATIONS 17 TUBE SUBSTITUTIONS 18 WARRANTY AND SERVICE 19 WARRANTY REGISTRATION 21 ...

Page 3: ...y Copyright and other Intellectual Property Rights The whole content of this Manual is subject to copyrights All copyrights on the content of the Product Manual remain the property of Grove Hill Audio Any reproduction transfer alteration or utilization of this manual and of the logo of Grove Hill Audio for a public and or commercial purpose without prior written consent of Grove Hill Audio is proh...

Page 4: ...le The Grove Hill PCB with its excellent transformer design and component layout has been used to make a compressor which improved upon the original audio circuit with added features that make LIVERPOOL usable on many types of program sources from vocals drums and bass to mastering The heart of LIVERPOOL is the dual triode remote cut off Mu tube This is the gain reduction tube This tube is re bias...

Page 5: ...ed to promote long life of the internal components and consistent performance WATER MOISTURE This unit should not be used near water or moisture SPECIAL NOTES Even though the tubes have metal shields around them tubes may become loose during transit Straighten and press down each tube before you plug the unit into the mains socket Do not touch the tubes after the unit has been switched on as the t...

Page 6: ...tandard IEC mains cable The fuse is also located within the same assembly and should be changed if the voltage is changed to 230 VAC INSTALLATION 1 Set the voltage change over switch on the back of the unit to the voltage you are using Units are shipped set for U S A standard voltage 2 Be certain that the correct fuse is installed 3 Connect the input signal to the 3 pin female XLR on the rear pane...

Page 7: ... switched off on the unit 6 Connect a standard IEC mains cable to the IEC mains socket on the rear panel 7 Connect the IEC mains cable to a 50 60 Hz AC source of the proper selected voltage 8 Power up the unit and allow approximately 15 30 minutes for the unit to stabilize before using 9 There is a LINK connector on the rear panel This is used to connect two units for stereo operation Set all cont...

Page 8: ...trols The LIVERPOOL compressor has nine controls Seven mounted on the front panel two located inside the chassis 1 Input gain control 2 Threshold control 3 Attack control 4 Recovery control 5 Output attenuator 6 Mains Power switch 7 Cathode balance trim 8 Anode balance trim 9 GR zero trim ...

Page 9: ...ontrol voltage CV Gain reduction is done by making the DC bias on the first stage tube more negative So as the input is increased so does the CV and therefore the amount of compression The onset of compression is determined by the threshold and how far the input control is advanced The input tube has a limit as to how far it can be biased negative to reduce gain before it goes non linear and since...

Page 10: ...nt speeds labelled 1 Fast to 6 Slow with every second selection labeled C turning off the compression action In these positions the unit can be used as a line amplifier Attack times 1 3 milliseconds 2 19 milliseconds 3 48 milliseconds 4 77 milliseconds 5 109 milliseconds 6 138 milliseconds 4 Recovery Control The recovery control determines how quickly the signal rebounds after the input signal has...

Page 11: ... applied 1 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 The Hold control would be used in these cases to prime the compressor with the required amount of gain reduction and prevent the thump from occurring This was done by playing a track into the compressor setting the controls as required and then moving ...

Page 12: ...ned 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 5 Output Attenuator The output attenuator is a six position rotary switch This method of attenuation allows for constant impedance on the output transformer as well as the load The attenua...

Page 13: ...The anode balance pot is used to balance the anodes of the Mu tube This helps to reduce thumps and instability To adjust the anodes balance turn the pot fully CW and then fully CCW and then to the middle position Connect the negative lead of a digital multi meter to ground and the other one to test pin 1 of the 6BC8 tube socket and note the voltage them measure the voltage at test pin 6 of the sam...

Page 14: ... minutes Any adjustments such as meter calibration should be performed when the unit had time to warm up to operating temperature OPERATION The principle of operation of this unit is based around a Mu tube an all glass miniature VHF dual triode remote cut off tube This is the gain reduction tube This tube is re biased by the 6AL5 vacuum tube rectified side chain control voltage which causes the Mu...

Page 15: ...ems These balanced inputs and outputs will interface to unbalanced inputs and outputs automatically This is a prime benefit with transformers Alternative ground schemes are common in studios The two most used are cutting shields at either inputs or outputs to prevent ground loops and star grounding style This method does not use any AC grounds but supplies a separate ground wire from a central gro...

Page 16: ...chnician perform these tasks These are factory presets and need only be altered after a re tube or if a change in performance is suspected 1 Cathode Balance Refer to item number 7 in the Operation and Use of Controls section 2 Anode Balance Refer to item number 8 in the Operation and Use of Controls section 3 Gain Reduction Zero Adjust Refer to item number 9 in the Operation and Use of Controls se...

Page 17: ...el 82 dBu below rated output Source Impedance Any up to 15 000 Ohms Load Impedance 600 Ohms Attenuation 30 dB in 5 dB steps Constant impedance Maximum Compression 30dB Attack Times msec 3 19 48 77 109 138 Recovery Times msec 127 447 917 1 9 sec 3 4 sec 6 sec Threshold 0dBm to 16dBm Output Compression Ratios 2 1 at 0dBm Threshold 4 1 at 16dBm Threshold Tube Complement 6BC8 6BZ8 or approved equivale...

Page 18: ...ualified technician The 6BC8 can be substituted with a 6BC8 6BZ8 ECC189 6N1 P or PCC189 The 6AL5 can be substituted with an EAA901S D77 EB91 5726 or 6058 Substitution of the 6CG7 is not recommended Although substitute tubes will perform well for optimum results use the same model tubes as supplied ...

Page 19: ...by the factory If you believe this to be a new unit then please contact the factory with the details of purchase This warranty is provided by the dealer where the unit was purchased and by Grove Hill Audio LLC Under the terms of the warranty defective parts will be repaired or replaced without charge excepting the cost of tubes No warranty is offered on tubes unless the warranty registration sheet...

Page 20: ...soever which may result from failure of this product Any and all warranties of merchantability and fitness implied by law are limited to the duration of the expressed warranty All warranties apply only to Grove Hill Audio products purchased and used in the United States of America Some states do not allow limitations on how long an implied warranty lasts so the above limitations may not apply to y...

Page 21: ...Ilwaco Ave NE Renton Washington 98059 Registration entitles you to product support full warranty benefits and notice of product enhancements and upgrades You need to complete and return the following to validate your warranty and registration MODEL ___LIVERPOOL____ SERIAL No ______________________ PURCHASE DATE _____________________ SUPPLIER _________________________________ ...

Page 22: ...EPHONE NUMBER ___ ______________________________________ EMAIL__________________________________________________________________________ ANY SUGGESTIONS TO IMPROVE THIS PRODUCT ______________________________________________________________________________ ______________________________________________________________________________ _________________________________________________________________...

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