Step 11: Electrical connections There will be electrical connections to be made next, these vary between manufacturer’s typically the tinsel/braid needs to be soldered to the chassis connectors and if your re-cone kit was of type C,D or E then there could be voice coil wires to be soldered to the tinsel/braid where it is fitted to the cone. At this stage it is best to only solder connections which will lie under the dust-cap. When soldering especially near the voice coil take care that nothing falls into coil.
Step 12; Dust-cap fitting When the glue is dry, carefully remove the shims from the coil. Check the gap for and debris as this is your last chance, once the dust-cap is on it’s too late.
Step 13; Dust-cap fitting Fold a piece of masking tape into a 'T shape, and stick to the dust cap to form a handle to hold the cap by. Place the cap centrally on the cone, and use a very soft pencil to draw a faint line around it to act as a guide for gluing. NB DO not push the pencil onto the cone, it is less than 0.5mm thick, and made of paper !
Step 14; Dust-cap fitting If the dust-cap has a foot where it glues to the cone then the glue is best applied to the foot then fitted to the speaker. Apply an even bead of a glue to the dust-cap foot using a small paintbrush, stick or spatula, and place the cap on the cone using your pencil guide to get it central. Use just enough glue to squeeze 1-2mm out from the foot all round. Leave to dry until the glue has cured. A small weight may be used to ensure the dust-cap sits firmly onto the cone.
It the dust-cap does not have a foot then it is best to put the dust-cap in place, hold it down with a small weight and then apply a bead of glue. Apply an even bead of a glue half on the dust-cap and half on the cone. The amount of glue required increases with coil diameter/power handling and reduces with increasing frequency range. So subs maybe 6mm wide bead, mid/highs 2mm wide. You can use the old software as a guide to the amount of glue required. Leave to dry until the glue has cured.
Remove the masking tape once the glue has cured
Step 15: Final electrical connections If the tinsel/braid wires come from a moving part (typically single suspension units and some double suspension units the wires come off the back of the cone) then the ‘loop’ of tinsel is critical. It is best to put the tinsel/braid in place setting a loop such that the wires cannot touch each other and secure without soldering. Next try moving the cone back and forth (carefully so as not to damage anything) and observe if the wires pull tight at full excursion, if they do the loop is too short. Note this needs to be done with the glues cured. Once a suitable loop length has been set then the connections can be soldered.
Step 16: Testing
Appendix 1 Shims
If the shims are not supplied or seem too tight then use card or similar, these need to be the same thickness all round the gap, they may be made up of different thickness bits but each ‘set’ must be the same thickness otherwise the coil will be off center. The aim is to have as few gaps between the shims as possible however sometimes removing 1 set and re-spacing the rest is the only way to get a good fit. What you don’t want are big gaps between the shims as this will lead to an out of round coil. The coil needs to be a snug fit over the shims, too loose leads to off centre coils, too tight and you risk deforming the coil when fitting it.
Appendix 2 Setting the coil height
For type E above you will need to set the height of the coil in the gap, the aim here is for the coil to be positioned such that the amount of coil above the top/front plate is the same as below. This is not easy as you can’t see the bottom side, the way to proceed is a combination of matching the old parts you removed (IE distance from bottom of suspension to start of coil winds) and measuring the thickness of the top/front plate thickness (at the centre if the plate is not the same thickness all the way across) and setting the coil equally about this thickness. If you know the mathematical Xmax (coil wind length-front plate thickness)/2 then this is the amount of coil which needs to be set above the front plate. Note not all manufacturers use mathematical Xmax in their datasheets, often however they do state the front plate thickness and the wind length of the coil. Once you have worked out the position for the coil, fit it in the gap with the shims holding it in place and mark the coil on the inside with the correct height (line level with the top of the centre pole). Fit the suspension over the coil and lower it into the magnet gap, adjust the coil within the suspension to align the height (using the mark you made earlier to ensure correct setting) Glue the coil to suspension and allow to cure.
Appendix 3 Stripping out double suspension units
Some speakers are dual or double suspension, in this case there will be some sort of spacer ring holding the suspensions apart, this will be part of your re-cone kit and so the old spacer needs to be removed from the chassis. Often these spacer rings are glued to the chassis, a wood chisel may be put at the joint with the chassis and tapped gently with a hammer to separate them. If it is bolted in then you have been lucky, simply un-bolt it. If you damage the chassis land when removing the spacer it will need to be filled and filed flat so that the new coil suspension assembly sits in place flat.
Appendix 4 If the gasket supplied is of the strip type
If the front gasket is of the strip type then don’t fit it at the same time as the cone surround is glued in. instead use a soft, blunt ended (piece of wood shaped like a scraper) to rub the surround into the glue. This should be done every few minutes and with gradually increasing pressure until the glue has grabbed the surround. At the same time the suspension should be rubbed into it’s glue, you will probably find your fingers best for this. Make sure when rubbing down:
A: You don’t sink or tilt the assembly
B: You don’t rub through or otherwise damage the surround
Appendix 5 Separate cone and suspension assemblies
For re-cone kit types types C,D and E as detailed above the coil/suspension assembly should be fitted first and so only apply the suspension to chassis glue (no glue if it is a bolted in assembly)
A: Check the lead out braids are facing the chassis connectors.
B: Check the shims feel even all round and not tighter one side than the other, if they are gently try pushing the coil into the gap and letting it ‘bounce back, making sure it ends up only slightly ‘dished’ not excessively sunk or ease the assembly over to even the feel of the shims.
Allow the glue to grab,
With double suspension assemblies especially bolted in types it is well worth running the unit at low power to check it is not rubbing. If it rubs try loosening the bolts and tightening them in a different order, or in extreme cases opening the holes in the double suspension assembly up a bit with a drill. Bolts should always be tightened working opposites never working around in a circle.
Apply a suitable glue evenly around the surround land. This should come to the inside edge of the rim, but be a thin coat so it doesn't squeeze out under the surround. Note which way the cone has to align for the tinsel/braid wires to align with the chassis connectors.
Lower the cone surround over the coil, ensuring that if there are coil wires sticking up to be soldered to the tinsel wires in the cone that they are on the inside of the cone neck not out of site underneath. It is important to lower the cone as level as possible, if it is tilted then glue may pick up on the rear of the moving part of the surround, this will cause at best edge ticks and at worst reduce the life of the speaker
A: Check the cone tinsel/braid wires align evenly with the chassis connectors
Now return to step 9