How to install a second input for a cabinet

Tokai Forum

Help Support Tokai Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
A

Anonymous

Guest
I am playing at home with my Gretsch G5222.The amp is completely modified with an alnicomagnet kit,the 6" speaker inside has gone for a weber 8".The speaker is connected inside to the speaker input.

Switch023.jpg


Normally the back is closed.I can reach the plug but it's a little tricky.The idea was to install a second input outside to connect my cabinet easyly with the amp.There should be a switch as well to cut the internal speaker when it is connected to the cabinet.I installed a second input,visible right beside the volume knob.

Switch024.jpg


The second socket is parallel to the first one,the 2 cables are only bridged from one socket to another.
When I connect the cabinet to the new input everything works fine.When I switch to the weber speaker inside I have much less volume and a kind of distortion,scratching,not sounding good.Seems that I cannot only install a second socket absolutely parallel to the first one.Any idea to solve would be welcome :wink:
 
With a valve amp you need to make sure the impedance of the output transformer is matched to the speakers. I don't know what the impedance of the internal and external speakers you are, are they the same? If so you should only run either one or the other, not both at the same time.
 
That is the reason why I installed the switch : with cabinet the internal speaker is switched off,without cabinet I play over the internal speaker.But when I use the internal speaker,the cable to the cabinet is not connected,only the internal speaker is active.And scratching like hell...
The internal speaker has 4 ohm,same for the cabinet
 
As soon as I cut off the cable between both sockets,I can plug in the internal speaker and it sounds normal.Same with the cabinet.Only with both sockets parallel it doesn't work
 
t.olsen said:
As soon as I cut off the cable between both sockets,I can plug in the internal speaker and it sounds normal.Same with the cabinet.Only with both sockets parallel it doesn't work

Strange! So you are saying even without a speaker connected to the second output it still affects the sound? This sounds like the +ve connection is finding its way to ground, or a possible ground loop issue, try un-screwing the second output from the chassis, or using an insulated socket like a cliff socket rather than the switchcraft style, and see if you have the same problem.

Any chance of a picture of how it's wired up from the inside?
 
Hi John,It is a switchcraft socket..too late for pics,I changed the mods back to one socket only but I use the outside socket now,not the one I just cannot reach inside.I take the cable from the internal speaker out now through a hole in the backplate if I need it.Most time it is connected to the cabinet but when I take the amp to another place I will use the weber inside.I only have to think about always connecting one speaker to the output not to destroy the amp.But I still don't understand It :roll:
 
t.olsen said:
Hi John,It is a switchcraft socket..too late for pics,I changed the mods back to one socket only but I use the outside socket now,not the one I just cannot reach inside.I take the cable from the internal speaker out now through a hole in the backplate if I need it.Most time it is connected to the cabinet but when I take the amp to another place I will use the weber inside.I only have to think about always connecting one speaker to the output not to destroy the amp.But I still don't understand It :roll:

I would definitely try a cliff jack (like on marshall amps) that is insulated from the chassis, the switchcraft jack is grounded because it is metal which means the output transformer is grounded in two seperate places, I think this could be the problem.
 
I will try it with a plastic washer to isolate it from the ground.just to make sure that is the reason and go for a better socket then
 
t.olsen said:
I will try it with a plastic washer to isolate it from the ground.just to make sure that is the reason and go for a better socket then

A plastic washer might not work as the socket could still touch the chassis where it goes through the hole, give it a try though it might just fix it!


Good luck :D
 
Most important is I did not kill my amp :lol:
I will check it but it is strange..
 
t.olsen said:
Most important is I did not kill my amp :lol:
I will check it but it is strange..

Yes killing an amp through tinkering is never good!! Report back if you have any luck!
 
I had another try...took the new input completely out of the amp and connected the pins only with 2 wires with crocodile clamps to make sure not to have ground connection.By the way,the original socket is fixed at a place where the paint has been removed for a good ground connection,so seems that is needed.Anyway,the result is the same : when connection the internal speaker to the normal input it sounds as it should,when connecting to the new input scratching distortion and volume loss.
No idea why :roll:
 
You got me beat!! How is your switch wired? You could use a double pole switch to totally disconnect the second socket when using the internal speaker.
 
This is what it looks like

Switch032.jpg


A double switch would help but first I have to find out why one of 2 parallel inputs is working fine while the second is not.I have to know to avoid sleepless nights :lol:
 
Problem is solved ! I woke up this morning at 6.30 and had the right idea :
It is visible that 2 contacts of the socket are connected with a piece of wire.The result is a short circuit between + and - if there is nothing plugged in.I installed a second socket with the same bridge but when I used my internal speaker,there was no cable plugged in from the cabinet and the result was a short circuit between black and white wire on the foto.All I had to do was remove the wire between the socket contacts and that's it :lol:
 
Yes,it was too easy to find out...that shows that the best is always take a look first at the layout to make clear how parts work together and what is the sense behind it.It 's fine now :wink:
 
But this was only one reason for sleepless nights...this is the main reason :

Bild052.jpg


Needs more oil than gasoline...
 

Latest posts

Back
Top