background image

 
 

4) REAR PANEL CONTROLS 
 

 

 

1)

 

SEND

 

¼

” instrument jack 

2)

 

RETURN

 

¼

” instrument jack 

3)

 

IMPEDANCE SELECTOR

 three-way rotary selector 

4)

 

SPEAKERS

 

¼

” speaker jacks (x2) 

5)

 

BIAS TEST 

probe jacks (x2) 

6)

 

COM

 probe jack 

7)

 

FULL / HALF 

2-way toggle switch 

8)

 

HT FUSE 

 

9)

 

MAINS

 

FUSE

  

10)

 

MAINS

 IEC cable inlet 

 

SEND

 

¼

” instrument jack can be used to directly interface the preamps of the JCM800, thereby bypassing the power amplifier.  

Conversely, this is usually used as the SEND of the effects loop.  Plug the input of your effects unit, or interface device (ex – C-
lator, Klein-ulator) into this jack using 

¼

” instrument cable.   

 
RETURN

 

¼

” instrument jack can be used to directly interface the power amp of the JCM800, thereby bypassing the preamp 

and using the amplifier as a power amplifier.  Conversely, this is usually used as the RETURN of the effects loop.  Plug the 
output of your effects unit, or interface device (ex – C-lator, Klein-ulator) into this jack using 

¼

” instrument cable.   

 
 

Summary of Contents for JCM 800 2204

Page 1: ...1 JCM 800 2204 50W GUITAR AMPLIFIER User s Manual...

Page 2: ...s based on the British amplifiers built in the late 1970s and 1980s Their iconic sound is signature to countless records ranging from blues to classic rock fusion and heavy metal While their lineage i...

Page 3: ...peaker cabinet using 1 4 speaker cable 4 Set the IMPEDANCE SELECTOR to the match the impedance of your speaker cabinet 5 Set all rotary tone and gain controls on the front panel to 12 00 clock face 6...

Page 4: ...h powers the 2204 on and off With the toggle switch in the DOWN ON position the 2204 is on In the UP position the 2204 is OFF STANDBY applies high voltage to the vacuum tube anodes and screen grids du...

Page 5: ...add sparkle and clarity to your tone BASS adjusts low frequencies MIDRANGE adjusts the mid frequency response TREBLE adjusts the high frequency response MASTER VOLUME sets the overall volume PREAMP G...

Page 6: ...y bypassing the power amplifier Conversely this is usually used as the SEND of the effects loop Plug the input of your effects unit or interface device ex C lator Klein ulator into this jack using ins...

Page 7: ...plifier FULL HALF switches the power output of the power amp For the 100W JCM800 half mode is approximately 50W and for the 50W JCM800 this is approximately 20W HALF mode configures the power tubes to...

Page 8: ...RNAL BIAS JACKS AND ADJUSTMENT From left to right V1 JJ 12AX7 ECC83S input stage 1 and gain stage 2 V2 JJ 12AX7 ECC83S gain stage 3 and tonestack driver V3 JJ 12AX7 ECC83S phase inverter for power amp...

Page 9: ...9 In this diagram we have color coded features for simplicity 1 Blue arrow bias adjustment potentiometer 2 Green arrow bias probe jacks left V4 right V5 3 Red arrow black probe jack ground COM...

Page 10: ...ed probe jack on the right Write down your measurement 6 Adjust bias adjustment blue arrow SLOWLY until your DMM reads approximately 36mV see calculations following page 7 Remeasure V4 bias and adjust...

Page 11: ...your amplifier Extremely high voltages are present and vacuum tubes reach high temperatures during use The risk of electrical shock and or skin burns should ALWAYS be kept in mind Therefore bias at y...

Page 12: ...ce than pedals and thus can sometimes function fine without a buffer before them In addition some of these rack mounted effects can pad the volume they receive preventing it from overloading Pedals do...

Page 13: ...ESR electrolytic capacitors and those used in our British series 1 2W carbon composition resistors 1W carbon film resistors TAD Mustard capacitors high voltage silver mica capacitors Belton tube socke...

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