Combo Guitar Amplifier Cabinet Swap

Introduction: Combo Guitar Amplifier Cabinet Swap

About: I'm just a compulsive DIYer that plays guitar and tries to fix just about everything around the house and garage. Sometimes I even succeed!
I came about this project due to a problem I was having with a solid state Jay Turser Classic 25r combo amp (25 watts, 10” speaker).  The little guy had a bad hum and I was not able to totally eliminate it after replacing a number of capacitors (but it did sound quieter).   Plus the sound of the Turser amp/speaker combo was just OK at best.  But I really liked the look of the Turser cab and didn’t want to give that up.

So my basic goal was to pull out the old amp/speaker and replace it with something that sounded nicer and didn’t ruin the look of the Turser cabinet.  This unit was only going to be used as a practice amp, so I did not need something expensive or involved (e.g. TUBES).  I needed a solid state amp, with about the same number of knobs due to the size of the control panel.  The biggest problem would be if the circuit board was too big, so that became one of my check-off items that had to be met.  Originally, I thought I had use the original control face plate, but this was just something I had to get a little creative with.

I happened across a used Peavey Envoy 110 (40 watts, 10” speaker) at a local Guitar Center ($50).  This one had the sound I was after and seemed more robust overall.  It had a nice 10” Peavey speaker (the Turser had a cheap/generic Celestion “Red” label, Tube 10), two channels and reverb.  It actually had a few more features that I didn’t worry about making functional on the new configuration.

Skills and Tools:
• Soldering – soldering iron, solder, de-soldering tool
• Drill – various bits (I used a drill press for the control panel, but you don’t have to)
• Metal cutting – rotary cutting tool
• Heat gun
• Stamping materials – ink, stamping kit
• Painters tape
• Metal cleaning chemicals – naptha, polishing compound
• Misc wire, shielded cable

• Safety glasses for drilling, cutting metal and soldering (solder can pop!)
• Gloves are always good idea when working with metal
• Ventilation for soldering operations

So let’s get started…

Step 1: Part 1: Receipient Cabinet - Rough Fitting

The most critical step is this was to make sure the circuit board from the new amp would fit in the old cab.  I took everything about of both cabinets and then started rough fitting the new pieces in place.  The circuit board fit with about 1/2” on each side to spare!
The Peavey speaker was a direct replacement (it had a minor tear in the surround that had to be fixed first – there’s plenty of sites that describe that easy fix, so I won’t go into that here).  The reverb tank just goes in the bottom.

Step 2: Part 2: Modifying Old Chassis and Moving the Controls

The Peavey chassis was just too big to fit – so I didn’t even worry about how that might work.  But I figured that if I could reuse the old chassis, then the attachment points, etc. would be easier to deal with. 

When I started this project it became pretty obvious that I would need to reposition the knobs/jacks/etc.  That part was just a couple of nights of de/re-soldering.  One of the things that really struck me was how nice the Peavey controls are secured on the circuit board compared to the Turser. 

The Turser had two inputs, 9 pots and a couple of small buttons.  The Peavey had one input, 10 pots and four large buttons.  So I had to make some choices as to what would physically fit in the same space as the Turser face plate.  We’ll walk through how that part was handled when we get to the faceplate part of this project.

I added a couple of comparison pics between the Turser and the Peavey just for fun.

Step 3: Part 3: De-Soldering and Re-Soldering

Now the tedious part.  I de-soldered each pot.  Each pot had four anchor points and three electrical connections.  The first pot was a bear, but after I figured out the angles and how much pressure, etc., it got pretty easy.  The main point here is to take your time and figure out how they originally attached things so you can reverse the process… more or less.  The end product was loose pots with 2-3” leads to the circuit board.

Step 4: Part 4: Control Panel Faceplate

As I said before, the Peavey had more pots and buttons than the original amp.  So the faceplate was probably the most challenging part of this deal.  Since I was retrofitting the Peavey amp into an existing space (and chassis), I had to make some decisions as to what I wanted in the final product.  The Peavey had three buttons that I personally wouldn’t use (6 db input switch, 2 additional gain stages).  So those were easy to ignore.

The original faceplate had 9 pot positions (the Peavey had 10 pots), I figured I’d use the 9 positions for the two channel controls and then put the reverb somewhere else.

The buttons (not the pots) were a problem because of the number of attachment points and how they were designed.  I didn’t think I could have easily desoldered those and just move them.  So the buttons were to stay on the circuit board and I would work around them.

The good part was that the only button I needed to keep functional was the channel selector.  This button could be controlled with a foot pedal connected to a rear jack…  which meant I could rig up a switch to put on the faceplate.

I used a brass sheet ($5) to match the original metal.  This was 12” wide – just a little shorter than the original faceplate, but long enough to fill the exposed space on the control panel.  The height was essentially the same as the original.  So I didn’t have to cut the brass plate, just some drilling.

Step 5: Part 5: Faceplate Printing

Getting printed type on the metal was a fun challenge.  It turned out that I could get a customizable stamp kit to make the control labels and use a somewhat unique ink to make it stick properly.  The ink is from a company called “StazOn” ($5) and the stamp kit is “trodat” ($20?).  Both of these came from Michaels (hobby store).  I was a little hesitant to buy these, but I think they will be handy for future projects.  Gives you sort of a cool, retro 50’s, military look for your labeling.

Step 6: Part 6: Specialty Cables

I had to make a few unique cables to make everything work in the new chassis.  I had to buy the two toggle switches ($4 each?).

Step 7: Part 7: Final Fitting and Assembly

This part went very smooth. All the special cables worked fine.  The only issue I had was with heat.  During my initial testing and playing, the heat sink was getting pretty hot.  So I thought I needed a fan and added one.  But that just added fan noise and a bad 60hz hum in the amp.  So the fan was disconnected.  Seems like just having the opening back there is enough to let air through to cool it off.

This is where using the original chasis really paid off.  I only had to do a little modification to the chasis and I still get to use all 6 mounting screws for the chassis without further modification or adding holes to the cabinet.

Step 8: Part 8: Closing Thoughts

I’m really happy with how this turned out.  The amp sounds great and still looks nice in the living room.  The main thing I would do different is not add the fan and just maybe have some kind of vent instead.  It does weigh a little more, but nothing significant for an amp this size.  The last step is to sell the Turser amp/speaker/reverb tank guts and the empty Peavey cabinet to recoup some my expenses.

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    6 years ago

    thats pretty awesome!!!!


    7 years ago on Introduction

    Great job, and thanks in advance!

    I am planning on stripping out my Bandit 112 and recovering it to make it look nicer, and I thought while I did that I would reposition the chassis to give it the vintage look, a tech friend of mine recomended mounting the chassis in the same fashion you have and now I know you've done it I am more confident that it'll work.


    Reply 7 years ago on Introduction

    Sounds like a fun project - If you think of it, post some pictures when you get done!


    7 years ago on Introduction

    Great job! I wondered about how to print onto a control plate. I was considering using the computer to print on to a waterslide decal and then lacquering over the top, but the printing set idea seems to work really well. Thanks for sharing - I'm really impressed with how this turned out!


    Reply 7 years ago on Introduction

    I like the decal idea. I can't remember why I didn't do that, but using the ink stamp gave it an old-school feel.


    Reply 7 years ago on Introduction

    I like the decal idea. I can't remember why I didn't do that, but using the ink stamp gave it an old-school feel.