Leslie Cabinets or speakers can be a very important part of old and new organs. Older ones that date back to the beginnings of the Leslie speaker will now need servicing or overhauling in order to ensure their continued reliable operation.
Valves and Amplification
Many of the Leslie cabinets incorporate their own amplification system and if your cabinet dates back to the 1970’s or earlier, then it will likely be a valve amplifier. Valve amplifiers are somewhat more dangerous than more modern solid state amplifiers due to the high voltages of over 250V DC and the high temperatures generated by heating the thermionic valves. The high voltages and the extra heat takes its toll on many components on the amplifiers which can leave the you with a noisy amplifier, loud hum, popping and crackling or no sound at all.
The good news here, is that all the valves used in the Leslie cabinets are still available today. New old stock (NOS) and newly manufactured valves are available and depending on your requirements I can fit new valves of the correct rating and ensure the amplifier is biased correctly for them.
Capacitors, if they have not yet been changed, should be changed as a priority as after 30 or more years of service in a hot environment (in close proximity to valves), they are on borrowed time and the amplifier would benefit greatly from new, better made capacitors.
Even the types or resistors used in these amplifiers can cause problems at this stage and so it is important that these are checked and replaced if they are no longer within their value range. This can also have a very negative impact on performance resulting in damaged valves or poor performance.
The Cabinet
Leslie cabinets use moving parts in order to create the effect they are known for. Because of this, all the moving parts require regular maintenance. This ranges from routine oiling based on usage up to checking belt tension, overall performance and motor servicing.
The motors used in these cabinets are fairly maintenance free but do require periodic oiling to keep them running freely. Over time, they will require a service which involves stripping the motor or dual motor assembly and checking for wear and tear, then reassembly. This often includes a number of small checks on the motor bearings and drive shafts too.
If routine maintenance is not carried out, the motors can stall or fail to start which might not be immediately obvious. When this happens, the motor will overheat causing irreversible damage. Preventative service is always better than trying to source a new set of motors.
Servicing
I am able to rebuild the motor assemblies and carry out repairs on the motors, drive shafts and rubber tires. Very often servicing the motors will cure any strange problems such as stalling, running slow or overheating.
Full lubrication and servicing of the drums and rotating horns is also possible. This involves careful cleaning of some of the parts, stripping down and re-lubricating after checking for excessive wear.
In the cases of the large woofers, repairs to cones and voice coils are sometimes possible and range from repairing a tear, to fitting new cones, surrounds or voice coils. It is unlikely that the speakers are blown as they were originally matched with the valve amplifier to compliment each other but they can be damaged in some circumstances.
The Valve amplifier will often need servicing due to the excessive heat generated by the valves. I usually replace these like for like and in some places, replace with uprated capacitors capable of withstanding the higher temperatures with ease. Valves can be checked and replaced if required. Resistors are also checked to make sure they are within specification and replaced if needed.
A full restoration can be performed if you wish depending on your requirements.