Can you convert an amp into a extension cabinet?

[DM3MD]

Hi all,
Would you mind lending some advice? Can I remove the power amp section of an SWR Strawberry Blonde amplifier, chop the top so it’s flat, pull the speaker and re-route wires, and wire in a jack so it plugs in the back...and now it’s an extension cabinet? Would this even work?

 

[abarson]

You can simply install an external jack and switch between the built in head and an external head. No need for chopping.
What's wrong with it the way it is?

 

[jthisdell]

Yes I had an old combo with a dead head, took out the amp and wired in an input jack. I would sleep de my new head in the shelf where the combo amp used to be.

 

[MattZilla]

Modifying the existing enclosure and making it look professional and not like a nasty basement hack would be at least, if not more work than just building a fresh cab from scratch.

 

[Downunderwonder]

You can simply install an external jack and switch between the built in head and an external head. No need for chopping.
What's wrong with it the way it is?

If the switch wound up in the wrong place you get a 2nd blown up amp. Best not.

 

[DWBass]

I did it to an old Fender BXR200 combo. Amp went on the fritz. I removed it and installed a jack on the back.

 

[Bodeanly]

I did it with an SWR Basic Black. Wired the speaker straight to one of the jacks already on the back.

 

[DM3MD]

I’m definitely NOT trying to make it look like a hack job. What I am trying to do is set another Strawberry Blonde amp on top of it, run a cable down from where it says “extension cab” and plug that in to the back of the modified amp...thus creating a micro stack with 2x10’s.

I had not considered building one from scratch!

 

[pht2356]

I did it with an SWR Basic Black. Wired the speaker straight to one of the jacks already on the back.

Done it a few times. Easiest way based upon what you want

 

[toomanyslurpees]

So you’re thinking of having one combo amp and an extension cabinet that will look like two combo amps? The extension cabinet having a gutted head that serve as the home of the input jack? Can’t see any reason why not if I’m picking up what you’re putting down...

 

[DM3MD]

You are exactly right. That’s exactly what I’m trying to do! Now, how to do it...

So you’re thinking of having one combo amp and an extension cabinet that will look like two combo amps? The extension cabinet having a gutted head that serve as the home of the input jack? Can’t see any reason why not if I’m picking up what you’re putting down...

 

[Downunderwonder]

You are exactly right. That’s exactly what I’m trying to do! Now, how to do it...

I suggest running a very sharp knife down the cut lines clear through the tolex before doing any sawing. This will leave a clean edge after sawing.

Practice cutting on the top. Clamp a guide board to it and draw a line against it. Run the circular saw into the cab, be sure to be hard up on the guide. Now you can measure back exactly ( to the 0.1mm ) where to mark for the guide so the saw cuts immediately north of your cuts in the tolex when doing it for real.

 

[toomanyslurpees]

No, we're missing the point (or I might be missing the point still), no sawing or chopping... Does your back panel look like this one?

You could just take the chassis out of the cab, take the guts out, if you wanted to leave the knobs, leave the pots and associated circuit board (I'm assuming) and just have two quarter inch jacks jumpered together right where the cab presently plugs in and the extension cab output is now, then putting the gutted chassis back in the cab, that way you could plug the cab in on the dead amp just how it is now and the extension cab output would now be the gutted amp's input... If you wanted to really be fancy you could wire the gutted amp's power light to a battery and scare the guys that think you're plugging an output of the good amp in the output of another good amp (the gutted combo)

My two minute microsoft paint verion:

 

[Downunderwonder]

No, we're missing the point, no sawing or chopping... Does your back panel look like this one?
View attachment 3418546

You could just take the chassis out of the cab, take the guts out, if you wanted to leave the knobs, leave the pots and associated circuit board (I'm assuming) and just have two quarter inch jacks jumpered together right where the cab presently plugs in and the extension cab output is now, then putting the gutted chassis back in the cab, that way you could plug the cab in on the dead amp just how it is now and the extension cab output would now be the gutted amp's input... If you wanted to really be fancy you could wire the gutted amp's power light to a battery and scare the guys that think you're plugging an output of the good amp in the output of another good amp (the gutted combo)

My two minute microsoft paint verion:View attachment 3418565

Methinks 'tis you who miss the point. Ampless topless combo will weigh much less and the surgery be nearly invisible stacked bitchinly below the good one like it was meant to be there.

 

[toomanyslurpees]

I could be missing the point... a gutted head would be light and easier than surgery... surgery could induce stacked bitchingness.... I do concede...

 

[Ostie]

Yes I had an old combo with a dead head, took out the amp and wired in an input jack. I would sleep de my new head in the shelf where the combo amp used to be.

Yep i did this with a 1 x15 combo when the amp died. Yanked it out and wired the speaker to a jack on the back. Works great.

 

[Riff Ranger]

I don't know much about this combo, but if it has a 1/4" speaker cable that you can unplug from the back of the one you want to use as an extension cab, you can unplug it from there and use a 1/4"male<->1/4"male coupler and a stand-alone speaker cable from the jack on the one whose amplifier you want to use. I have considered doing this with two Mesa Buster combos (because I'm super paranoid about blowing tubes), but have yet to acquire a second Buster. The coupler costs maybe 10 USD tops and, as long as the ohms work out, doesn't risk anything or require any major effort. It's probably a better fit for your situation than mine because I can't imagine that even two of those strawberry blondes are anywhere near as heavy as my single Buster, haha.

 

[Downunderwonder]

I don't think SWR would have played this game so mainly for the benefit of others to come...

Some combos have 4 ohm drivers and an extension out that puts the extension cab into series. Defeating that series and adding a parallel cab would blow it up.

OP should still check what drivers he has. Some people flip gear after replacing stock driver with any random.

 

[chadface]

Any way you can flip it upside down? Put the part you cut up on the bottom?

 

[DM3MD]

Thank you all for your replies. You guys are awesome and I appreciate your help!

The amp is an 8 ohm amp, and it says the external speaker must be 8 ohms. So, it should be a doable.

As far as the the end result, it should be the functional amp on top, and the modified amp below it...thusly creating a bitchin’ little micro acoustic stack.

I’m gaining confidence to begin this project...somebody stop me or root me on here!