There are many varied trades in the audio world and in previous blog posts we have explored a few. Today we will talk about speaker re-coning. All audio professionals will eventually be faced with the problem of a defective speaker but not all of them know that it is possible to simply replace the membrane while conserving most of the original parts. I had the chance to learn more about this type of work with Frédéric Lanteigne who, on top of having his own re-coning business also repairs other types of audio electronic devices and teaches electronic basics at Musitechnic. Last time, we covered re-coning and some basic repairs. This time, we will see the other types of modifications that one can make to a speaker, the tools that are needed for re-coning, as well as some useful tips from Frédéric.
Other types of modifications
Even if most of the requests are for the replacement of defective parts, replacing the membrane (or cone as it is also called) can allow a modification of the characteristics or specifications of a speaker (impedance, frequency response). It is possible for a speaker to produce more of the lower or medium frequencies with a change of cone, “surround” or “dust cap”, for example. For outdoor use, the membrane can also be waterproofed. It is also possible to increase the impedance (going from 4 ohms to 8 ohms for example). When you need a speaker to tolerate power better, installing a coil that dissipates heat better can help. There are different ways to reduce the heat of a speaker. Some use types of liquid (like ferrofluid for example) between the coil and the magnet gap. When you replace the moving coil, because you want to dissipate heat or because the coil is burned, you also have to replace the membrane because it is physically attached to the coil. The opposite is also true: if you touch the cone, you touch the moving coil. Frédéric does not get a lot of requests for this type of modification, most requests are for repairs. Sometimes, clients working in sound for live shows may request a second spider be added for more durability.
The necessary tools used for re-coning
The tools Frédéric uses most often are a utility knife and an exacto knife. The parts’ dimensions are measured to the nanometer with an electronic caliper. When the speaker is taken apart, he uses a Dremel drill to rid the surfaces of any residue glue, especially on the basket. Obviously, for all assembly work, he uses a variety of latex glues and epoxy. Also, some speaker manufacturers sell the glues they recommend for their products. A soldering iron is used to connect the speaker to the leads ??? that will receive the audio signal. Finally, in order to test the speakers, he uses an NTI Minirator MR2, as well as Visual Analyzer (free software for PC) that goes through the computer’s internal sound card then to a Bryston amplifier and to the speaker being tested.
Last piece of advice
I don’t know to what extent the ease of reconing is a factor for you in choosing a loudspeaker, but among the speaker manufacturers , Nexo and JBL stick out as being the brands that Frédéric enjoys working with the most. He lists a combination of factors: the ease in reconing, an excellent service, as well as the quality of the parts. Other brands are too expensive or simply ship the parts loosely in an envelope which increases the risk of making a mistake. Another thing worth mentioning, when you need to recone a speaker in a stereo system, it is advised to proceed with reconing of the second speaker as well in order to respect the molecular integrity between both speakers. Same thing when it comes to refoaming: you refoam on, you refoam the other too. The last thing you want is for one of the speakers of a pair of monitors to sound brighter than the other for example. I hope you do not have to use this advice too often!
Questions or suggestions: k.blondy@musietchnic.net
