Having decieded to swapout the speakers in my Recto 4X12 I thought I would share the project with The Board. I hope the information is found useful.
*** DISCLAIMER *** If you follow these steps and blow up your amp or cabinet it is not my fault !!
Installing Eminence Delta Pro 12A speakers into a Mesa Rectifier 4X12
1. Start by removing the jackplate and turn it 90 degrees and pass it through the back of the cabinet and rest it on the sound post that runs from baffle to back, just below the jackplate cut-out. It’s a tight fit but should pass through easily when fit from corner to corner.
2. Now remove the back of the cabinet. Next, remove the 9 grill screws (circled in red) and remove the front grill.
3. Now get out your soldering iron and remove the wiring from the original speakers. Each side of the cab has two speakers in parallel which are joined in series at the jackplate. DO NOT unsolder any wires at the jackplate. Make note of the polarity (white is +) and how the cab is wired. Draw yourself a diagram. Don’t over-heat the speakers terminals, heat them just enough to remove the wires. Put the jackplate somewhere safe.
4. Next lay the cabinet face down on some cardboard or an old blanket. Remove the 4 nuts (circled in red) holding in the original speakers and carefully remove the old speakers and put them somewhere safe.
5. Stand the cabinet upright and remove the original speaker bolts. They will unscrew out of the baffle.
6. Here is the new hardware I used for installing the cast frame speakers. It consists of a #10-24 X 1 ½ “ bolt, #10 split lockwasher, 1” fender washer with about a third removed to clear the speaker basket and a #10-24 X 9/16 “ T-nut.
You could also just replace the original screws with longer ones if you do not want to use T-Nuts. Be sure to use a washer on the front of the baffle board (under the head of the screw) to help distribute the additional weight of the cast frame speaker. Also, use locknuts to keep things tight.
EDIT Aug. 2016:
I've found that the combination of T nuts & Loctite can make the T nuts spin in the baffle board when trying to remove a screw. I actually had 2 on one speaker do this to me. I now recommend that the original screws be replaced with #10 screws (installed the same as the old ones) and washers/Nylock nuts.
7. Carefully drill out the old mounting bolt holes to accept the T-nuts. For me it was a 9/32” drill bit. Drill slowly and make sure you follow the original hole, staying square to the baffle-board. In this pic you can see one of the T-nuts already installed. You can see how it is also trimmed to clear the speaker cutout. I also removed one of the teeth in the nut so as not to have one close to the edge of the cutout, splitting the wood. Gently tap in the T-nuts from the outside of the cabinet until they are seated against the Baffle Board
This is what I removed from the T-Nut to clear the speaker cut-out. Do this BEFORE you install the T-Nuts.
Here are all the T-nuts installed
8. Now lay the cabinet back down on the floor and unpack your new speakers.
I’m a gigging musician and my cab gets moved around a lot, not to mention the vibration of use with a Recto. To make sure the speakers stay mounted to the baffle board I used thread locker on all the screws in addition to the lock washers. Be sure it is the removable type!
9. The directions will tell you to apply the thread locker to the screws, but if you do this the stuff will just get wiped off as you pass the screw through the mounting gasket on the speaker. Instead, apply the thread locker to the T-Nuts. I used a cotton swab that I pulled most of the cotton off of so it would fit easily into the T-Nut. Use enough thread locker to fill two or three threads. Put the thread locker in at least 2 of the T-Nuts. I did all 4. Do one speaker opening at a time so the thread locker doesn’t set-up and make it hard to start the screws by hand.
10. Now, carefully position the new speaker over the opening, lining up at least one of the screw holes to get started. Put the lockwashers on the screws first, followed by the fender washers.
11. Install the first screw by hand, being careful not to cross-thread the screw. Leave the screw loose so you can move the speaker as you lineup and install the remaining screws. Once you have all the screws installed, tighten them by hand in the order shown in the picture. DO NOT over tighten them, tighten them securely with a hand screwdriver. Tighten each screw a little at a time, making 2 -3 passes until they are all tight.
Repeat steps 9 - 11 and install the remaining speakers.
12. Stand the cabinet upright and wipe off any excess thread locker that has run out of the T-Nuts. You can also cover the T-Nuts with some black tape so they will not be noticeable through the grill cloth. Re-install the speaker grill.
13. Now it’s time to re-connect the wiring. If your speakers have standard solder terminals, simply reconnect the original wires exactly as they were removed. You can re-solder them (recommened) or use push on terminals, the choice is yours, just make sure that you provide a secure connection and MAINTAIN POLARITY (ie. positive to positive, negative to negative).
The Eminence Delta Pro 12A’s I am installing have binding post terminals so I had to come up with a secure alternative to soldering.
14. Using some good quality 16ga speaker wire, cut a 12 to 15 inch length pigtail for each speaker. Strip a good 2 inches of insulation off of one end of the pigtail.
15. Slip a 1 inch length of heat shrink tubing down over one end of the stripped wire. Pass the wire through the hole in the binding post, stopping about 3/8” from the insulation. Bend the inserted wire back towards itself forming a loop as shown.
16. Wrap the end of the wire on to itself forming a sort of noose. Wrap tightly 3-4 times. Tighten the binding post firmly BY HAND. Don’t use pliers, you will cut through the wire for sure.
17. Slide the heat shrink up to the binding post and carefully apply heat to secure the wire.
18. Repeat steps 15-17 for the second terminal.
19. Slip a 1 inch length of heat shrink tubing onto the pigtail to keep the wires together. Stop a couple of inches from the binding posts. Apply heat to secure.
20. Repeat steps 15 – 19 for the remaining speakers.
21. The cab is wired with a pair of speakers in parallel, then the two pairs in series. Connect the right pair in parallel then connect the pair to one set of black/white wires from the jackplate. WATCH THE POLARITY! Use solder and some heat shrink tubing for the most reliable connection. DO NOT JUST TWIST THE WIRES TOGETHER AND TAPE THEM. Repeat for the left pair.
22. I chose to gather the wiring together and secure it to the soundpost with a cable tie. The last thing you want is for the wires to rattle around inside the cabinet or rub against the speaker cone. Just make sure the wires are long enough for the jackplate to pass through the back of the cabinet when it is back on.
23. Place the jackplate on the soundpost. Re-install the back of the cabinet being careful not to over tighten the screws. Reach through the jackplate hole and pull the jackplate through. Install the jackplate to the back of the cabinet.
24. Plug in your amp and enjoy your new speakers. Start with low volume playing for ten minutes or so before you crank it up for the first time.
Dom
*** DISCLAIMER *** If you follow these steps and blow up your amp or cabinet it is not my fault !!
Installing Eminence Delta Pro 12A speakers into a Mesa Rectifier 4X12
1. Start by removing the jackplate and turn it 90 degrees and pass it through the back of the cabinet and rest it on the sound post that runs from baffle to back, just below the jackplate cut-out. It’s a tight fit but should pass through easily when fit from corner to corner.
2. Now remove the back of the cabinet. Next, remove the 9 grill screws (circled in red) and remove the front grill.
3. Now get out your soldering iron and remove the wiring from the original speakers. Each side of the cab has two speakers in parallel which are joined in series at the jackplate. DO NOT unsolder any wires at the jackplate. Make note of the polarity (white is +) and how the cab is wired. Draw yourself a diagram. Don’t over-heat the speakers terminals, heat them just enough to remove the wires. Put the jackplate somewhere safe.
4. Next lay the cabinet face down on some cardboard or an old blanket. Remove the 4 nuts (circled in red) holding in the original speakers and carefully remove the old speakers and put them somewhere safe.
5. Stand the cabinet upright and remove the original speaker bolts. They will unscrew out of the baffle.
6. Here is the new hardware I used for installing the cast frame speakers. It consists of a #10-24 X 1 ½ “ bolt, #10 split lockwasher, 1” fender washer with about a third removed to clear the speaker basket and a #10-24 X 9/16 “ T-nut.
You could also just replace the original screws with longer ones if you do not want to use T-Nuts. Be sure to use a washer on the front of the baffle board (under the head of the screw) to help distribute the additional weight of the cast frame speaker. Also, use locknuts to keep things tight.
EDIT Aug. 2016:
I've found that the combination of T nuts & Loctite can make the T nuts spin in the baffle board when trying to remove a screw. I actually had 2 on one speaker do this to me. I now recommend that the original screws be replaced with #10 screws (installed the same as the old ones) and washers/Nylock nuts.
7. Carefully drill out the old mounting bolt holes to accept the T-nuts. For me it was a 9/32” drill bit. Drill slowly and make sure you follow the original hole, staying square to the baffle-board. In this pic you can see one of the T-nuts already installed. You can see how it is also trimmed to clear the speaker cutout. I also removed one of the teeth in the nut so as not to have one close to the edge of the cutout, splitting the wood. Gently tap in the T-nuts from the outside of the cabinet until they are seated against the Baffle Board
This is what I removed from the T-Nut to clear the speaker cut-out. Do this BEFORE you install the T-Nuts.
Here are all the T-nuts installed
8. Now lay the cabinet back down on the floor and unpack your new speakers.
I’m a gigging musician and my cab gets moved around a lot, not to mention the vibration of use with a Recto. To make sure the speakers stay mounted to the baffle board I used thread locker on all the screws in addition to the lock washers. Be sure it is the removable type!
9. The directions will tell you to apply the thread locker to the screws, but if you do this the stuff will just get wiped off as you pass the screw through the mounting gasket on the speaker. Instead, apply the thread locker to the T-Nuts. I used a cotton swab that I pulled most of the cotton off of so it would fit easily into the T-Nut. Use enough thread locker to fill two or three threads. Put the thread locker in at least 2 of the T-Nuts. I did all 4. Do one speaker opening at a time so the thread locker doesn’t set-up and make it hard to start the screws by hand.
10. Now, carefully position the new speaker over the opening, lining up at least one of the screw holes to get started. Put the lockwashers on the screws first, followed by the fender washers.
11. Install the first screw by hand, being careful not to cross-thread the screw. Leave the screw loose so you can move the speaker as you lineup and install the remaining screws. Once you have all the screws installed, tighten them by hand in the order shown in the picture. DO NOT over tighten them, tighten them securely with a hand screwdriver. Tighten each screw a little at a time, making 2 -3 passes until they are all tight.
Repeat steps 9 - 11 and install the remaining speakers.
12. Stand the cabinet upright and wipe off any excess thread locker that has run out of the T-Nuts. You can also cover the T-Nuts with some black tape so they will not be noticeable through the grill cloth. Re-install the speaker grill.
13. Now it’s time to re-connect the wiring. If your speakers have standard solder terminals, simply reconnect the original wires exactly as they were removed. You can re-solder them (recommened) or use push on terminals, the choice is yours, just make sure that you provide a secure connection and MAINTAIN POLARITY (ie. positive to positive, negative to negative).
The Eminence Delta Pro 12A’s I am installing have binding post terminals so I had to come up with a secure alternative to soldering.
14. Using some good quality 16ga speaker wire, cut a 12 to 15 inch length pigtail for each speaker. Strip a good 2 inches of insulation off of one end of the pigtail.
15. Slip a 1 inch length of heat shrink tubing down over one end of the stripped wire. Pass the wire through the hole in the binding post, stopping about 3/8” from the insulation. Bend the inserted wire back towards itself forming a loop as shown.
16. Wrap the end of the wire on to itself forming a sort of noose. Wrap tightly 3-4 times. Tighten the binding post firmly BY HAND. Don’t use pliers, you will cut through the wire for sure.
17. Slide the heat shrink up to the binding post and carefully apply heat to secure the wire.
18. Repeat steps 15-17 for the second terminal.
19. Slip a 1 inch length of heat shrink tubing onto the pigtail to keep the wires together. Stop a couple of inches from the binding posts. Apply heat to secure.
20. Repeat steps 15 – 19 for the remaining speakers.
21. The cab is wired with a pair of speakers in parallel, then the two pairs in series. Connect the right pair in parallel then connect the pair to one set of black/white wires from the jackplate. WATCH THE POLARITY! Use solder and some heat shrink tubing for the most reliable connection. DO NOT JUST TWIST THE WIRES TOGETHER AND TAPE THEM. Repeat for the left pair.
22. I chose to gather the wiring together and secure it to the soundpost with a cable tie. The last thing you want is for the wires to rattle around inside the cabinet or rub against the speaker cone. Just make sure the wires are long enough for the jackplate to pass through the back of the cabinet when it is back on.
23. Place the jackplate on the soundpost. Re-install the back of the cabinet being careful not to over tighten the screws. Reach through the jackplate hole and pull the jackplate through. Install the jackplate to the back of the cabinet.
24. Plug in your amp and enjoy your new speakers. Start with low volume playing for ten minutes or so before you crank it up for the first time.
Dom
