Cabinet wiring question.

George Dickens

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I was trying to find out if by changing the direction of an extension cab switch in a small ss combo, one wihich disables the internal speaker.
If by doing this would reverse operate, so that the combo can be used as an extension cab.
by doing this it would disable the amp rather than the speaker and allow the speaker to be free to use.
The combos amp would not have to be turned on or plugged into the mains.
Im thankful to a answer for this question.

The simple switch jack in question is wired as the one shown in the linked document.


https://www.singlecoil.com/docs/external.pdf


I previously mis-construed and mistakenly posted this question in another forum.

https://www.marshallforum.com/threads/combo-as-a-speaker-cabinet-unusual-wiring.124913/#post-2230854
 
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fitz288

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by doing this it would disable the amp
This would not disable the amp, it would disconnect the combo OT from the speaker circuit when you plug anything into the combo external speaker jack.
Technically, yes it would do what you want, but it's about as far from fail-safe as you can get.
If anyone plugged an extension speaker into the extension speaker jack and turned on the combo it would have no load.
There are other solutions that would accomplish your goal of using the combo speaker with another amp that are far better.
 

George Dickens

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This would not disable the amp, it would disconnect the combo OT from the speaker circuit when you plug anything into the combo external speaker jack.
Technically, yes it would do what you want, but it's about as far from fail-safe as you can get.
If anyone plugged an extension speaker into the extension speaker jack and turned on the combo it would have no load.
There are other solutions that would accomplish your goal of using the combo speaker with another amp that are far better.
I see- it is far from fail-safe , that is probably why I have never seen it.
thank you for the answer. Sorry for the confusing description prior.
The idea was to use the 6 inch - 8 ohm speaker in a Marshall MG10 Gold Series as an extension cab.
A full switch is probably the way or even a different jack type or perhaps an old style screw terminal to avoid any misuse..
 

fitz288

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The idea was to use the 6 inch - 8 ohm speaker in a Marshall MG10 Gold Series as an extension cab.
I'm not sure if there's some sort of power feedback danger to the MG10 by just adding an external jack to the speaker and running another amp to it.
I would point out that that little speaker is only rated at 10w, so obviously running a 2203 onto it from the amp's 8 ohm tap would be ill advised.
Along those lines, I'm also not sure how much the MG speaker is going to add to another amp as an extension speaker.
Another thing to keep in mind is the combined speaker load on the other amp, depending on how you wire the jacks.
Two 8 ohm speakers in parallel would be a 4 ohm load.
Make sure the other amp can handle this, in and of itself, regardless of amp watts.
 

George Dickens

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In thinking further on the subject.

"If anyone plugged an extension speaker into the extension speaker jack and turned on the combo it would have no load."

Well it is a new style amall 10watt solid state amp. It shouldnt matter should it?
The switch jack wants to see an amplifier output.
Another speaker wouldnt do anything to the speaker or the amp.

Basically Im looking for a simple way to use a combo for an ext cab when required.
If the switch jack can perform both functions it would be a plus.



My concern is the unused amp hanging off the neg terminal of the speaker switch.
If it would it interfere as the output from the parasite amps negative side went into it rather than being terminated there for the speaker only.
 

George Dickens

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I'm not sure if there's some sort of power feedback danger to the MG10 by just adding an external jack to the speaker and running another amp to it.
I would point out that that little speaker is only rated at 10w, so obviously running a 2203 onto it from the amp's 8 ohm tap would be ill advised.
Along those lines, I'm also not sure how much the MG speaker is going to add to another amp as an extension speaker.
Another thing to keep in mind is the combined speaker load on the other amp, depending on how you wire the jacks.
Two 8 ohm speakers in parallel would be a 4 ohm load.
Make sure the other amp can handle this, in and of itself, regardless of amp watts.


Well the intention would be to not use the donating amp except when the jack was not engaged. to either have it turned off or unplugged. A temporary extension cab which would be used for mic'd recording at very low ambient levels for example.
A less is more approach if you will.
 

fitz288

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Basically Im looking for a simple way to use a combo for an ext cab when required.
Out of curiosity, what is the "other" amp?
I ask because I think I have done something similar in a completely different way.
I once ran my Spark out from the headphone jack into a CODE100H input jack with a 1/8" TRS to 1/4" TS cable.
Set the Code to no preamp or cab sim and blasted the Spark out the 100w power amp through the 212 cab. :D
 

George Dickens

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Look at my comments in your first post.
Doh...!?! Absolutley now why didnt I think of that.
Ive even done it before... Jeesh I over complicate things sometimes.
thanks very much for pointing out this fine solution.
I just must overcome the fact it is a closed and sealed backed cab
Ill have to let the male from it amp hang out
 

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