Fender Twin Reverb Amplifier Speaker Grille Replacement

Here's a look at the Fender Twin Reverb amplifier before starting.

Here's a closer look at the old frame.  One can see it's a bit warped at the bottom, and there are three locations where the particle board was broken and repaired in the past.

This is a closer look at the front of the knob in the worst condition.  More about the knobs later.

The amplifier without the grille cover.

Here is the Tube Location Diagram from inside the amplifier.  From what I've read on the Internet on several websites, sometimes there is a code stamped on the tube location diagram that you can break down to determine when the amplifier was manufactured.  Unfortunately, this diagram does not include the stamp.  However, an Internet search on "patent 2817708" and "patent 192859" turned up some details.  Also a search on "047944".

I also read where another way to get a close estimate of when your amplifier was made is to read the date codes on the transformers.  The code can supposedly be found on the power transformer, output transformer, choke, and reverb transformer.  I was unable to see any codes on one transformer and did not look for the others.  It's possible some of the transformers may be in the chassis and I didn't want to go that far.

Next was a trip to Menards to buy a piece of smooth interior grade plywood that was ½" x 24" x 48".  I then marked the frame design on the plywood in pencil, although it's somewhat hard to see in this picture.  Prior to taking this picture I cut the overall frame out of the 24" x 48" piece.  The radius used in the corners of each opening was 1".  The radius on the old frame was about ½", however, I went larger in order to provide additional strength in the corners.

Here's another look at the newly cut plywood frame from directly above.

After cutting the speaker grille frame and testing the size I was ready continue with the project indoors and clean up the mess I made in the garage.

In the process of cleaning up and preparing the Music Room and an adjacent Storage Room, I've gone through boxes and boxes of stuff, including many VHS tapes, CD's, Cassettes, and there are even two boxes of old 8-Track tapes I need to do something with.

Every so often I feel like hearing some Crosby, Stills, Nash & Young.  I had an old CSN&Y cassette and an old boom box handy so I popped the one shown above in and listened to it over and over while I continued working on this project.

Two coats of flat black latex paint were then applied to all surfaces and edges of the frame.

In addition to the frame, I noticed the Fender logo was missing some sections of the black background finish.  So, with a little flat black paint and a fine art brush I touched up the background of the logo.

Two more items include an ARROW T50 Staple gun that I have owned forever and that you can still buy staples for.  How many things like that can you identify these days?

The second was a package of ARROW T50 ¼" Staples that I also bought from Menards.

I already had several boxes of ARROW staples but they were all longer sizes than ¼".  Longer staples would make the following steps more difficult as it would be hard to get the staples to go into the plywood all the way.

Here is a close up of the Velcro strip in a corner location.

You might wonder what the frame is setting on now in the picture.  I had a couple pieces of 1" x 12" painted pine shelving boards available from a previous project, and I set them on the card table to provide a good solid surface for stapling.  The card table has a bit of a soft surface that could make it a little harder to get the staples to go in all the way.  The solid surface helps the stapling go better.

Before going further we should review a few notes about the grille cloth, direction, and stretching.  The dark area in the diagram above represents the 26" x 48" Precut piece of Genuine Fender Black PVC Grille Cloth.  The yellow dashed line represents the general area of the piece that I cut from for the speaker grille.

This model/type of grille cloth has a slight ability to stretch in the long (roll) direction and not too much ability to stretch in the short dimension.  So, this is why the section I cut was with the long direction and not the short direction.  I also noticed that the pattern in the cloth in the long direction matched the direction of the black grille cloth of my small Fender practice amplifier, and I wanted the two to match.

The piece of grille cloth I received had a little bit of irregularity in the pattern on the long edge, and that's why I avoided a couple inches in the long direction near the edge.  On the short side on the left I held back about an inch because it didn't look like the short edge of the cloth was cut squarely.

I used the lines in the grille cloth as a guide for cutting in order to try and keep the rectangular area square 90°.

Wrap the grille cloth around the frame in the middle and staple at locations 1, 2 & 3.

On the opposite side, try to stretch the grille cloth as much as you can, take another look to see if the frame still lines up with the lines in the grille cloth, and staple at locations 4, 5 & 6.

On the 1, 2 & 3 side, staple the rest of the grille cloth and try to keep the lines straight in the cloth.

On the 4, 5 & 6 side, try to stretch the grille cloth and staple the rest of the cloth on that side.

Repeat the steps on the long sides of the frame.

Here is a close look at where the grille cloth meets the Velcro at a corner.

Once again, where the grille cloth meets the Velcro, staple the cloth close to the Velcro, but don't overlap the Velcro.  Wrap the cloth at tightly as you can at the corners.

Then cut the grille cloth so it doesn't overlap the Velcro.

The next step includes reviewing the "Holes For Logo" details on the Speaker Grille Frame Plan to refer to the dimensions on where to locate the holes for the logo screws.  Using a tape measure I measured to where the hole on the right side of the logo should be located.  Using the Scratch Awl I carefully and very lightly poked through the cloth repeatedly until I located the hole.  After finding the hole I placed a toothpick in the small hole to hold the location.  I then repeated the process for the two screw holes on the left, as shown above.

I wish I would've taken close up pictures of these two areas of damage.  In both locations the black "Tolex" covering the amplifier was partially torn away from the cabinet, but thankfully not torn off and missing.

The two damaged areas were repaired using WELDBOND Glue and masking tape.  Glue was placed on the back side of the Tolex.  The Tolex was pushed tightly against the cabinet.  Excess glue was removed with a lightly damp paper towel to prevent glue on the outside surface of the Tolex.  Then, masking tape was placed over the damaged areas to hold them tightly to the cabinet.  The tape was left on the damaged areas overnight and then removed.  I was happy with the result.

Two new knobs were ordered to replace the two damaged knobs.  Finding replacement knobs was a bit tedious.  I was actually looking for used Fender Twin Reverb knobs of the same age so they would match the knobs on the amplifier in terms of a slight lack of shininess.  Earlier on this page I showed the back of the existing knobs.  I found someone selling three used knobs of the same age and the back of the knobs matched exactly, however, they were selling them for $75 plus shipping!  That was too far for me to go.  Some replacement knobs are not genuine and reviewers reported the knobs they bought were a bit different.  After lots of searching and giving up hope of finding reasonably priced used knobs, I bought two new genuine Fender replacement knobs that reviewers reported matched their old knobs pretty well.  The knobs I bought from "amplifiedparts" on eBay look pretty good.