Step by step speaker swap

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domct203

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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.
jackplate.jpg


2. Now remove the back of the cabinet. Next, remove the 9 grill screws (circled in red) and remove the front grill.
grillscrews.jpg


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.
origV30b.jpg



5. Stand the cabinet upright and remove the original speaker bolts. They will unscrew out of the baffle.
removescrew.jpg


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.
hardware.jpg

hardware2.jpg

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
drilled_out.jpg


This is what I removed from the T-Nut to clear the speaker cut-out. Do this BEFORE you install the T-Nuts.
tnut2.jpg


Here are all the T-nuts installed
nuts_in.jpg


8. Now lay the cabinet back down on the floor and unpack your new speakers.
unpack1.jpg
unpack2.jpg


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!
loctite.jpg


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.
loctite2.jpg


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.
hardware3.jpg


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.
install1.jpg


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.
tapeover.jpg


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.
posts.jpg


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.
pigtail2.jpg


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.
wire1.jpg


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.
wire2.jpg


17. Slide the heat shrink up to the binding post and carefully apply heat to secure the wire.
wire3.jpg


18. Repeat steps 15-17 for the second terminal.
wire4.jpg


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.
wire5.jpg


20. Repeat steps 15 – 19 for the remaining speakers.
wire6.jpg


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.
wire7b.jpg
wire7.jpg


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.
wire8.jpg


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
 
I've only had one practice with them but first impressions are that they are much smoother than the V30's and they are not even broken in yet. They also seem alot tighter and punchier in the low end.

I don't have one for comparison but they are supposed to be very similar to an EVM12L at half the price. They were described to me as a poor man's EVM.

Dom
 
domct203 said:
I don't have one for comparison but they are supposed to be very similar to an EVM12L at half the price. They were described to me as a poor man's EVM.

I've heard them compared against each other, and the EMV12L has a more pronounced high end than the Delta Pro. They sounded quite similar other than that.

Nice instructional post, by the way! The heat shrink solution is a good idea.
 
I know this is an older post, but how did you take the grill cloth off without damaging the tolex / cloth?
 
dmcguitar said:
I know this is an older post, but how did you take the grill cloth off without damaging the tolex / cloth?

The entire front grill frame/cloth/piping comes off. See Step#2 in the first post. It's a snug fit so take your time. I grabbed the Mesa badge plate and gently pulled the frame out. If the grill frame is stubbern remove the speakers and gently push it out.

Dom
 
Nice step by step instructions. One question, I know the Delta pro speakers only come in 8ohm (i dont know what comes in a 4x12 recto cab but a 2x12 has 16ohm speakers) so has you Ohm load changed?

I thought about trying the deltas in my 2x12 but am unsure if i want to change the ohm load on the cab to 4ohm wired in parallel(i guess it really doesn't matter since i would only be using 1 cab anyways)

I have the delta in a 1x12 widebody ported cab i made but im not sure how i feel about it at band volumes
 
The Recto 4X12 had 8 ohm V30's to begin with so the cabinet load stayed the same at 8 ohms.

I love this cabinet now at band volumes. It stays nice and tight and punchy at loud volumes now. With the V30's the cabinet would get too loose and mushy at loud volumes.

Dom
 
Im half tempted to order another Delta Pro and put both in my 2x12 to see what it sounds like
 
Im half tempted to order another Delta Pro and put both in my 2x12 to see what it sounds like
 
Well our drummer was a no-show for practice last night so I had a chance to really crank up the Delta Pro loaded Recto 4X12 to see how it sounds.

I ran the Roadster at 100 watts in ch 4 Modern, ch master at around 10:00. With a little EQ an Gain tweaks along the way I had that sucker up to 3:00 on the output with NO farting out or mushy bottom.

Man is that a loud amp! I think it took an hour for me to stop smiling!

I don't recommend anyone to do this for longer than a couple of minutes, it really was that loud.

Dom
 
So those screws that hold the grille the heads are facing the back correct?

This could be the post that I have been waiting for

Thanks!!!
 
I know this is an old post but does anyone else have experience with these speakers? Do they cut through a mix like a v30? Would they be good with a v30 in an x pattern?
 
I'm seriously considering this same swap. Anyone have experience with these speakers? I know the post is old but are you still happy with them?
 
I ended up mixing 2 V30's with them in my bottom cab, and kept my V30/C90 mix in my top cab.

The Delta Pro's are just a little too relaxed on the top end for me. Mixed with a mid/treble strong speaker like the V30 works great for me with the Roadster. A full quad of them was just too dark for my rig.

Dom
 
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