JC 120 Line IN

rpape2601 · 08-08-2009, 02:32 AM

Anyone know how to add a line in to an older Roland JC 120. I want to be able to use a stereo effects unit directly to the power amp side, bypassing the JC 120 preamp? The amp's SN 697711, not sure of the age, probably 79 or 80

booj · 08-17-2009, 06:38 AM

The volume pots are concentrick 100k/10k. Try inputting the signal through a 1-1-ufcap and a 10k resistor to the hot side of the 10k section.

SAB · 08-18-2009, 07:03 PM

I had a '77 or '78 model in the late '80's, & I believe I split the path at C26 & C126, but I may be mistaken.

I used the 4 jacks (2 ext. speaker, line out, & footswitch) on the back for stereo out & stereo in. I hooked up a DIN or MIDI jack to control the reverb, chorus, & distortion.

Since the 4 jacks are all normally closed jacks, they worked perfectly.

Initially, I used the amp's preamp & inserted a Quadraverb in the loop. Later on, I switched to a tube preamp into the Quadraverb, totally bypassing the JC120 preamp.

Another suggestion would be to switch out the Roland speakers Celestions or speakers of your choice.

Steve

08-08-2009, 02:32 AM	#1
rpape2601 Junior Member Join Date: Jul 2009 Posts: 3	JC 120 Line IN Anyone know how to add a line in to an older Roland JC 120. I want to be able to use a stereo effects unit directly to the power amp side, bypassing the JC 120 preamp? The amp's SN 697711, not sure of the age, probably 79 or 80

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08-17-2009, 06:38 AM	#2
booj Senior Member Join Date: Jun 2008 Posts: 349	The volume pots are concentrick 100k/10k. Try inputting the signal through a 1-1-ufcap and a 10k resistor to the hot side of the 10k section.

08-18-2009, 07:03 PM	#3
SAB Junior Member Join Date: Aug 2009 Posts: 1	I had a '77 or '78 model in the late '80's, & I believe I split the path at C26 & C126, but I may be mistaken. I used the 4 jacks (2 ext. speaker, line out, & footswitch) on the back for stereo out & stereo in. I hooked up a DIN or MIDI jack to control the reverb, chorus, & distortion. Since the 4 jacks are all normally closed jacks, they worked perfectly. Initially, I used the amp's preamp & inserted a Quadraverb in the loop. Later on, I switched to a tube preamp into the Quadraverb, totally bypassing the JC120 preamp. Another suggestion would be to switch out the Roland speakers Celestions or speakers of your choice. Steve

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