# EVM12L



## Theon (Nov 15, 2017)

Trying to diagnose a problem with my speaker.
Touching 9 volt battery to ground and neutral wire caused cone to pulse.

Placed input jack leads into compression tabs.
Plugged cable in no energy or sound.


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## oldjoat (Apr 4, 2019)

ummmm ... a bit cryptic

the 9V has enough power to move the speaker . ( so speaker is working )

input jack leads ( from guitar I'm assuming ) doesn't have enough power to move earphones , let alone a larger speaker .
or if it's a speaker patch cord , the jack end may be broken internally or shorted. test the cord with a meter .

try using an old radio to power the speaker instead .

or use another known good amp, disconnect the internal speaker and run 2 wires out to the speaker .

some pic's would be nice .


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## greco (Jul 15, 2007)

oldjoat said:


> some pic's would be nice .


For sure!


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## Theon (Nov 15, 2017)

"Umm .. a bit cryptic"
I know!
Attached ground wire (Black) to input jack ring then neutral wire (Red) to input jack hot.

Plugged cable from amps external speaker jack into extension cabinet. No sound!

I have switched the cables from one jack to the other on the amp. Combo cabinet speakers attatched to amplifier have sound with both connections.

Using an empty (no chassis) combo cabinet underneath a head.
Connecting the 2x12 speaker with a split cable.

Here is a photo of the setup I am trying to hookup to the extension cabinet.



I have since taken the wiring harness apart.
Try to reattach and snap a photo to upload.


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## greco (Jul 15, 2007)

Your pic wasn't clear so I reposted it here.

Why not wire the speakers together in series or parallel and then run one (single) speaker cable from one of the speakers up to the amp? 
What is the impedance (in ohms) of EACH speaker? This is important to know for the wiring.


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## Theon (Nov 15, 2017)

"Why not wire the speakers together in series or parallel and then run one (single) speaker cable from one of the speakers up to the amp? What is the impedance (in ohms) of EACH speaker? This is important to know for the wiring".

Thank you for reposting the photo Greco.

Amp head and 2x12 speaker cabinet in the photo is my everyday combo. They work fine together.

I am trying to test an extension cabinet with the amps external speaker output. 1x12 extension cabinet is a repair project I am finishing up.
Want to see if it functions properly.


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## greco (Jul 15, 2007)

Theon said:


> Thank you for reposting the photo Greco.


No problem. Beautiful looking gear!



Theon said:


> Amp head and 2x12 speaker cabinet in the photo is my everyday combo. They work fine together.


OK. The wiring looks unusual/atypical to me...but if it works fine, all is well.



Theon said:


> I am trying to test an extension cabinet with the amps external speaker output. 1x12 extension cabinet is a repair project I am finishing up.
> Want to see if it functions properly.


Can you take a pic of how it is wired? ...or is it working now?


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## Theon (Nov 15, 2017)

greco said:


> No problem. Beautiful looking gear"!
> 
> Thanks for the kind words Sir!
> 
> ...


It's working fine. The cabinet I need to upload a photo of is the problem.


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## Granny Gremlin (Jun 3, 2016)

Can't quite see the pic too well, but it looks like the harness from the amp to the ext cab is like a Y cable. Assuming that is parallel wiring for the 2 speakers ( more standard/common), but if for some reason it is series that would explain why it doesn't work with only a single speaker plugged in (need both speakers connected to complete the circuit). And that's assuming I understand the description of what was attempted correctly - which I am not sure I do.

I recommend you mimic that setup pictured above with the ext cab, but instead of using that existing cable, find the shortest 1/4" cable you have that's long enough (even a guitar cable) that is known to be working (test it) and use that. You can kludge some leads onto the 1/4" jack on the other end if you don't wanna rip it off bc you don't solder (if you do solder just wire up a 1/4" jack to 2 wires). I'd use alligator clip leads that I have, but even some bare wire, 1 ea, wrapped around tip and sleeve of the jack at the speaker end (tape up the sleeve one to keep it in place and insulate from the tip, which will stay put on account of the indent) will do to prove the point.

... wait does the ext cab already have a 1/4" input wired up? if so try that (again with any old guitar cable - won't hurt it and tone suck is not an issue right now). If that doesn't work then as above connecting direct to the speaker.

That'll tell you what the issue is.


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## greco (Jul 15, 2007)

Theon said:


> The cabinet I need to upload a photo of is the problem.


OK ...Sorry...My misunderstanding.
If I send you a PM with my email address, do you have a pic you can send me?
I'll post it for you.


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## jb welder (Sep 14, 2010)

One thing I will say is if that is the head you are using, there must always be something plugged into 'main' speaker jack. If 'main' is empty, and you plug only into 'ext', there will be no sound.


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## Theon (Nov 15, 2017)

@Granny Gremlin
Thanks for your reply and info.
The extension cabinet I am trying to test was damaged in shipping. It's a project.

I just checked the EVM12L speaker wires and believe it was incorrectly wired to the old input jack.
Plan to give it another go tomorrow.


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## greco (Jul 15, 2007)

Good Luck with it. Please let us know.


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## Theon (Nov 15, 2017)

jb welder said:


> One thing I will say is if that is the head you are using, there must always be something plugged into 'main' speaker jack. If 'main' is empty, and you plug only into 'ext', there will be no sound.


Thank you for the reply and info @jb welder!

Yes I am aware the main speaker jack must always have an input.


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## Theon (Nov 15, 2017)

greco said:


> OK ...Sorry...My misunderstanding.
> If I send you a PM with my email address, do you have a pic you can send me?
> I'll post it for you.


Thanks for your offer @greco! 
Using Photobucket now. Posting a photo tomorrow.


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## Theon (Nov 15, 2017)

greco said:


> Good Luck with it. Please let us know.


Thanks for the kind words! I will let you all know.


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## oldjoat (Apr 4, 2019)

OK ,,, speaker switch is in 16 Ohms position ... so the new speaker should be 16 ohms ( to match impedance ) ... or less ... 4 or 8

connect the new speaker to the patch cord you've built 
then touch one pole of the 9V battery to the sleeve (outside conductor ) of the patch cord male jack and the other pole of the battery to the TIP of the jack ....
should get a click from the speaker if the cord and speaker are working OK .
no click = broken wire in your patch cord OR a wire is shorted somewhere in your wiring to the new speaker.

do NOT use your tube amp to test this until you have sorted out the speaker/patch cord problem

running a tube amp without a speaker load ( broken wire ) will cause runaway on the output section and blow the fuse ( very high impedance)
if the speaker / cord is shorted , the tube amp will take it no problem ( low impedance)

solid state amps are just the opposite , shorted speaker overheats the output transistors
no speaker load and the transistors run cool.


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## Theon (Nov 15, 2017)

Thanks @oldjoat!
The uploaded photo was an old shot of my setup.
Switched down to 8 ohms while testing the extension cabinets speaker.


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## Theon (Nov 15, 2017)

You guys are the best. Thanks to all for your helpful advice. Getting back at this tomorrow.


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## greco (Jul 15, 2007)

Has explaining all this exhausted you yet? (j/k)
We posted at virtually the same time..ironically.


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## Theon (Nov 15, 2017)

greco said:


> Has explaining all this exhausted you yet? (j/k)


Not in any way @greco!
Helpful information is never exhausting.
Very appreciative for the detailed explanations.


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## nonreverb (Sep 19, 2006)

Theon said:


> Trying to diagnose a problem with my speaker.
> Touching 9 volt battery to ground and neutral wire caused cone to pulse.
> 
> Placed input jack leads into compression tabs.
> Plugged cable in no energy or sound.


When you say the cone "pulsed", you mean it creates a oscillation with the battery constantly connected or when you connect/disconnect the battery from the line?
If the latter (which I suspect), then your speaker is operating.


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## Theon (Nov 15, 2017)

nonreverb said:


> When you say the cone "pulsed", you mean it creates a oscillation with the battery constantly connected or when you connect/disconnect the battery from the line?
> If the latter (which I suspect), then your speaker is operating.


@nonreverb Touching 9 volt battery to the speaker wires caused oscillation. Speaker moved forward.


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## oldjoat (Apr 4, 2019)

oscillation means back and forth repeatedly.

if it just move forward (or backwards) and stayed there as long as the battery was touching , it is not oscillation.

it does mean the speaker responds to power being applied.

so you have a short or a broken wire between the amp and the external speaker


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## Theon (Nov 15, 2017)

oldjoat said:


> oscillation means back and forth repeatedly.
> 
> if it just move forward (or backwards) and stayed there as long as the battery was touching , it is not oscillation.
> 
> ...


Got you! Speaker responds to power for sure.
Tried the battery test once again before hooking up a harness. Speaker cone moves as normal one try then only pulses outward the next.

Time for a visit to a tech.


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## nonreverb (Sep 19, 2006)

Theon said:


> Got you! Speaker responds to power for sure.
> Tried the battery test once again before hooking up a harness. Speaker cone moves as normal one try then only pulses outward the next.
> 
> Time for a visit to a tech.


First, lets look at what is and what isn't. We now know the speaker works. To recap; The amp works with the other cab?


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## Theon (Nov 15, 2017)

nonreverb said:


> First, lets look at what is and what isn't. We now know the speaker works. To recap; The amp works with the other cab?


Yes, the amplifier works perfectly fine with the other cabinet.


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## nonreverb (Sep 19, 2006)

Theon said:


> Yes, the amplifier works perfectly fine with the other cabinet.


So we can now narrow it down to the plug, speaker cable, jack on the cab or the wires going to the speaker from the jack. Have you checked all the solder connections on the speaker cable (assuming it's not a molded type) and on the jack? I'm assuming you've tried a different speaker cable?


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## Theon (Nov 15, 2017)

nonreverb said:


> So we can now narrow it down to the plug, speaker cable, jack on the cab or the wires going to the speaker from the jack. Have you checked all the solder connections on the speaker cable (assuming it's not a molded type) and on the jack? I'm assuming you've tried a different speaker cable?


All cables are reliable and functional.
Rewiring ground/hot wires to input jack later today. I'll report back with photos. 
Thanks @nonreverb


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## Theon (Nov 15, 2017)

1st 2 photos are just for reference.
Using ring terminal connectors instead of the spring/compression tabs.

How does everything look so far guys?
Waiting for the word before soldering the wires.https://photos.app.goo.gl/UfKCvZV74rZiPMrLA


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## greco (Jul 15, 2007)

I would certainly consider tidying these wire ends before soldering.

Will that gauge of wire easily fit through the holes in the terminals if you tinned the ends of the wires first?

Is that a 1/4 inch jack of some sort? I haven't seen one like it....but my experience is limited.

Have you tested that you are connecting to proper terminals on the plug? 

Sorry if you know all about this stuff.


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## Theon (Nov 15, 2017)

greco said:


> I would certainly consider tidying these wire ends before soldering.
> 
> Will that gauge of wire easily fit through the holes in the terminals if you tinned the ends of the wires first?
> 
> ...


Placed those inside the holes for a reference.
All 4 ends of the wiring harness are tinned.

Musiclily brand 1/4 long barrel mono jack.
The photo was taken from the top as it's tightened down into the back panel. Angle makes it looks weird i know.
https://photos.app.goo.gl/bWEaRYKw26y7PUW96


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## greco (Jul 15, 2007)

Theon said:


> Musiclily brand 1/4 long barrel mono jack.


If you plug a cable into the jack do you get continuity from the jack terminals the tip and sleeve of the plug at the other end of the cable? Apologies for being Captain Obvious.


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## Theon (Nov 15, 2017)

greco said:


> If you plug a cable into the jack do you get continuity from the jack terminals the tip and sleeve of the plug at the other end of the cable? Apologies for being Captain Obvious.


About to solder the wires to the jack.
Back in a few.


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## Theon (Nov 15, 2017)

Soldered wires to input jack plugged cable from amp in...no sound from extension cabinet.
2x12 cabinet working perfectly. 

Had high hopes for this basket case.
Beige cloth ready to staple to the grill frame.

https://photos.app.goo.gl/mWZbqg4QKC9iG8AP6


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## greco (Jul 15, 2007)

The wires from this jack have continuity with the tip and sleeve to the plug going to the amp? The red wire is Ok going to either terminal?


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## nonreverb (Sep 19, 2006)

greco's right...That's a TRS jack which means it has 2 hot contacts. If you have it on the wrong one, it will short out the signal from the amp...and you won't have output.


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## greco (Jul 15, 2007)

Musiclily has confused you. 

It can be wired mon0 or "stereo" (see information in bottom right corner)


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## Theon (Nov 15, 2017)

greco said:


> The wires from this jack have continuity with the tip and sleeve to the plug going to the amp? The red wire is Ok going to either terminal?
> 
> View attachment 287674


Nothing happens when a cable is plugged into the jack. I understand what your saying.
Negative 9 volt battery touching to the cable's tip should cause movement.
The red wire is fine.


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## Theon (Nov 15, 2017)

nonreverb said:


> greco's right...That's a TRS jack which means it has 2 hot contacts. If you have it on the wrong one, it will short out the signal from the amp...and you won't have output.


Should I switch the hot to the other hot contact?


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## greco (Jul 15, 2007)

Theon said:


> Should I switch the hot to the other hot contact?


I'd try it. I can't tell from any of the the pic which terminal is "short" = "hot"


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## oldjoat (Apr 4, 2019)

possibly you are using a stereo jack and are putting the red wire to the 2nd sleeve terminal and not the TIP ?

the spec says MONO and Stereo jack . ( so it's really a stereo jack )

switch the red wire to the other short pin on the jack and re-solder it ... then try again


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## nonreverb (Sep 19, 2006)

You have the hot wire on the wrong contact. Swap it and it "should" work...if not, we'll proceed further.


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## Theon (Nov 15, 2017)

oldjoat said:


> why does the input jack have 3 terminals ?
> 
> possibly you are using a stereo jack and are putting the red wire to the 2nd sleeve terminal and not the TIP ?
> 
> ...


The ground(black wire) is attached to the sleeve.
Red has been attached to both short inner hot tips. No connection either way.
Best shots I could get. 
https://photos.app.goo.gl/cBdRnLUsYDeJ2WdR9
https://photos.app.goo.gl/sBFmTn1tLvq2xaon8


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## nonreverb (Sep 19, 2006)

Have a pic of the speaker cable?


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## greco (Jul 15, 2007)

nonreverb said:


> ...we'll proceed further.


Sorry, I'm now lost. Especially, if the tip and sleeve have continuity between the plug (at the amp "end") and the speaker terminals.

I will continue to follow with interest.



oldjoat said:


> possibly you are using a stereo jack and are putting the red wire to the 2nd sleeve terminal and not the TIP ?
> 
> the spec says MONO and Stereo jack . ( so it's really a stereo jack )
> 
> switch the red wire to the other short pin on the jack and re-solder it ... then try again


That is what we are trying to sort out.


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## oldjoat (Apr 4, 2019)

do not connect the 2 shorter "hot" pins together ( only use 1 or the other )
or that will short both "hots" to the ground

... 
OK . 
desolder the "jack" , touch the 9V to the 2 wires that were connected to the jack ... should get a speaker movement ... wires up to the jack are good 
no movement and one of the wires is bad .

if you get movement , by pass the female jack you bought , 
wrap the speaker wires around the external speaker patch cord male end that you are using to go between the amp and the external speaker .
one goes around the outer sleeve and the other to the "tip" ... you've just extended the speaker wires 

now touch the 9 v to the outer sleeve at the far end on the patch cord and then touch the "tip" with the other battery terminal.
movement means the cable and wiring is good but you have a bad female jack ( or wired it incorrectly)
no movement means the "patch cord" is bad


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## Theon (Nov 15, 2017)

nonreverb said:


> Have a pic of the speaker cable?


It's a standard Lava Tweed instrument cable.
Use it with to connect my guitar to amplifier input without issue.


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## cbg1 (Mar 27, 2012)

I would go back to those ring connectors...I am not fond of your approach there...those spring terminals are fine... EV knows what they are doing....
It is possible that you may have shorted the connections to the speaker frame...perhaps use the battery to test the speaker with your connections to make sure....

Good luck


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## greco (Jul 15, 2007)

Theon said:


> It's a standard Lava Tweed instrument cable.
> Use it with to connect my guitar to amplifier input without issue.


You should be using speaker cable! NOT instrument cable.


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## Theon (Nov 15, 2017)

oldjoat said:


> do not connect the 2 shorter "hot" pins together ( only use 1 or the other )
> or that will short both "hots" to the ground
> 
> ...
> ...


Throughout the process I've always had a wire connected to the ground. Switching wire between hot tips.

Even before wiring to the jack I performed the battery test. Nothing.

Think I need another jack as the original worked until it broke loose.


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## Theon (Nov 15, 2017)

greco said:


> You should be using speaker cable! NOT instrument cable.


I was under the impression any 1/4 cable would suffice. Does it really matter?


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## oldjoat (Apr 4, 2019)

Theon said:


> Even before wiring to the jack I performed the battery test. Nothing.


OK 
so either a broken wire to/at the speaker , or your connections at the speaker are shorted to the metal frame of the speaker


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## oldjoat (Apr 4, 2019)

Theon said:


> I was under the impression any 1/4 cable would suffice. Does it really matter?


for very light loads the guitar cable will handle it ( about 20-22 gauge wires ... thin and light)

speaker patch cords are much heavier ( 16-18 gauge wires ... about twice as heavy and can handle more power )


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## Theon (Nov 15, 2017)

oldjoat said:


> OK
> so either a broken wire to/at the speaker , or your connections at the speaker are shorted to the metal frame of the speaker


Making a new harness tomorrow then switching back to compression tabs. Try something different.


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## Theon (Nov 15, 2017)

oldjoat said:


> for very light loads the guitar cable will handle it ( about 20-22 gauge wires ... thin and light)
> 
> speaker patch cords are much heavier ( 16-18 gauge wires ... about twice as heavy and can handle more power )


Should it make a difference for testing the speaker?


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## greco (Jul 15, 2007)

oldjoat said:


> for very light loads the guitar cable will handle it


Why would anyone take the risk? Speaker cables are easy to build/purchase.
You have lots of extra proper speaker cable!


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## cbg1 (Mar 27, 2012)

The instrument cable will work but can cause problems due to the fact that the conductors inside are of two different sizes


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## Theon (Nov 15, 2017)

greco said:


> Why would anyone take the risk? Speaker cables are easy to build/purchase.


A guitar cable is all I had in house.
Wasn't planning to use long term only for testing the speaker.


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## greco (Jul 15, 2007)

Theon said:


> A guitar cable is all I had in house.
> Wasn't planning to use long term only for testing the speaker.


You are forgiven...but only this time.


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## Theon (Nov 15, 2017)

greco said:


> You are forgiven...but only this time.


Thank You Sir! I will not make that mistake again. At least I didn't try putting 6L6's in a EL84 amps power section.

Some have tried...All have failed!


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## nonreverb (Sep 19, 2006)

There are two good reasons not to use instrument cable. One is that the hot wire gauge is small which can cause heat and a certain amount of line loss...Remember were transferring current here as well as voltage. Second is the capacitance that can be created across the entire cable due to the way the hot and shielding interact can do bad things to amps as well.


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## Theon (Nov 15, 2017)

nonreverb said:


> There are two good reasons not to use instrument cable. One is that the hot wire gauge is small which can cause heat and a certain amount of line loss...Remember were transferring current here as well as voltage. Second is the capacitance that can be created across the entire cable due to the way the hot and shielding interact can do bad things to amps as well.


Amazoning a speaker cable and another jack right now.


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## jb welder (Sep 14, 2010)

Theon said:


> Amazoning a speaker cable and another jack right now.


Good idea, I was thinking that new jack might be bad. Or it could have been overheated if you are not very experienced soldering. It looks like there is plastic rather than fiber spacer/insulator and it is easier to damage when soldering. You need a good hot iron and get on and off fast. Too weak of an iron means you have to keep it on there too long and it gets overheated.

Get the wires all in place but do another battery test before you solder. Plug your cable into the jack and touch the battery at the other end of the cable. If it moves the speaker then go ahead and solder it up.
Like the others said, don't use the instrument cable for any more than quiet testing.


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## Theon (Nov 15, 2017)

jb welder said:


> Good idea, I was thinking that new jack might be bad. Or it could have been overheated if you are not very experienced soldering. It looks like there is plastic rather than fiber spacer/insulator and it is easier to damage when soldering. You need a good hot iron and get on and off fast. Too weak of an iron means you have to keep it on there too long and it gets overheated.
> 
> Get the wires all in place but do another battery test before you solder. Plug your cable into the jack and touch the battery at the other end of the cable. If it moves the speaker then go ahead and solder it up.
> Like the others said, don't use the instrument cable for any more than quiet testing.


Thank you for the extra information my friend!


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## greco (Jul 15, 2007)

Please keep us updated with your progress.


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## Theon (Nov 15, 2017)

Update guys: Ordered a Seismic Audio speaker cable and a Switchcraft 151 mono input jack.

Attached black wire to long ground post and red wire to short hot. Placed wire ends into spring loaded/compression tabs. No reaction to 9 volt battery test or sound plugged into amplifier.

Thinking this speaker has a internal short.
I have exhausted all options. Tech time!

Thanks to everyone for being so very generous with your time and giving of knowledge.


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## greco (Jul 15, 2007)

Thanks for the update. 

Please let us know the Tech's findings and solution.

Good Luck with it. Hopefully the speaker can somehow be made to function (if it is the problem).


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## Theon (Nov 15, 2017)

Thanks for the well wishes @greco.
I'll report back after the tech has a look.


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