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Roland JC120 Line Out/Speaker disable
Old 13th March 2018
  #1
Gear Head
 

Roland JC120 Line Out/Speaker disable

Hi folks. Another JC120 question.

Just wondering, is it ok to put dummy cables into the speaker outputs while using the line out on a JC120? Or should I disconnect the speakers? It's an idea for late night practice/recording.

Cheers!
Old 14th March 2018
  #2
Lives for gear
Adding cables to the speaker output jacks doesn't cut out the internal speakers. You could disconnect the internal speakers, but this will wear on the output transformers, but much less given it's a solid state amp.

For reference, here's a copy of your manual - oldie but a goodie! - https://static.roland.com/assets/med.../JC-120_OM.pdf

If you're using it for clean sounds, you may be better off just going direct into the board and then using a free Roland chorus plugin (something like this I've used - TAL - Togu Audio Line: TAL-Chorus-LX) vs. the mono line out of the JC120. My $0.02.
Old 18th March 2018
  #3
Gear Head
 

I got it sorted, cheers anyway!
Old 19th March 2018
  #4
Quote:
Originally Posted by nedorama View Post
Adding cables to the speaker output jacks doesn't cut out the internal speakers. You could disconnect the internal speakers, but this will wear on the output transformers, but much less given it's a solid state amp.

For reference, here's a copy of your manual - oldie but a goodie! - https://static.roland.com/assets/med.../JC-120_OM.pdf

If you're using it for clean sounds, you may be better off just going direct into the board and then using a free Roland chorus plugin (something like this I've used - TAL - Togu Audio Line: TAL-Chorus-LX) vs. the mono line out of the JC120. My $0.02.
It doesn't have output transformers. It has output TRANSISTORS and they don't care about being operated open, they just don't like shorts. At all.
Old 19th March 2018
  #5
Lives for gear
Quote:
Originally Posted by John Eppstein View Post
It doesn't have output transformers. It has output TRANSISTORS and they don't care about being operated open, they just don't like shorts. At all.
John - thanks for the correction.

For clarity then, disconnecting the speakers could short out the output transistors and thus don’t try this? Want to make sure OP and others have clear direction.
Old 20th March 2018
  #6
Quote:
Originally Posted by nedorama View Post
John - thanks for the correction.

For clarity then, disconnecting the speakers could short out the output transistors and thus don’t try this? Want to make sure OP and others have clear direction.
Wrong. Transistors don't give a damn if they've operated pinto an open. Operating them into a short (or too low an impedance) will blow them in a hot minute (or less.)

TRANSFORMERS don't like opens. Not transistors. Transistors simply won't conduct. No problem.
Old 1 week ago
  #7
Here for the gear
 

Follow up questions. Just bought a used JC-120 from ‘89. When I connect to the external speakers it does cut the sound to my main speakers, does this mean someone has done a mod to this amp? Is it ok to plug that directly into my board?

Also, the “line out” seems to be affected by the volume knob, I thought they would tap that line before going to volume. Any thoughts or advice would be awesome. Love my Rhoads through this thing, but I don’t want to mic it for home recording.
Old 1 week ago
  #8
Quote:
Originally Posted by nedorama View Post
Adding cables to the speaker output jacks doesn't cut out the internal speakers. You could disconnect the internal speakers, but this will wear on the output transformers, but much less given it's a solid state amp.

For reference, here's a copy of your manual - oldie but a goodie! - https://static.roland.com/assets/med.../JC-120_OM.pdf

If you're using it for clean sounds, you may be better off just going direct into the board and then using a free Roland chorus plugin (something like this I've used - TAL - Togu Audio Line: TAL-Chorus-LX) vs. the mono line out of the JC120. My $0.02.
JC120s don't have output transformers.

It should be fine. DO NOT let the speaker leads short together.
Old 1 week ago
  #9
Quote:
Originally Posted by PN4A View Post
Follow up questions. Just bought a used JC-120 from ‘89. When I connect to the external speakers it does cut the sound to my main speakers, does this mean someone has done a mod to this amp? Is it ok to plug that directly into my board?

Also, the “line out” seems to be affected by the volume knob, I thought they would tap that line before going to volume. Any thoughts or advice would be awesome. Love my Rhoads through this thing, but I don’t want to mic it for home recording.
There have been many revisions of the JC-120. It's probably normal for yours, but I'm not certain.

DO NOT plug speaker outputs into your board unless you enjoy supporting your local tech. Doesn't the amp have a preamp out?
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