KEF LOUDSPEAKERS REPAIR GUIDE

Guide to Repairing KEF Speakers with Falcon Acoustics Parts

Falcon Acoustics, founded by Malcolm Jones, KEF's first Chief Design Engineer, has a deep-rooted connection for over 60 years to classic KEF speaker designs, including those developed for BBC monitors like the LS3/5a. This heritage is why Falcon Acoustics is the international specialist resource for sourcing high-quality replacement parts and upgrades for your vintage KEF speakers.

Why Choose Falcon Acoustics for KEF Repairs?

Due to their shared history and expertise, Falcon Acoustics offers unrivalled knowledge and expertise of KEF loudspeakers, selecting or making components that are often direct replacements or ideal upgrades for original KEF parts, thus ensuring sonic integrity and restoring performance. Falcon Acoustics specializes in components that match or exceed the original specifications of classic designs using KEF drive units.

Common KEF Speaker Issues Falcon Acoustics Parts Can Address

Older KEF speakers although very well engineered inevitably suffer from age-related degradation. Here are some common problems and how Falcon Acoustics can provide solutions:

Aged Crossover Capacitors: Electrolytic capacitors in speaker crossovers degrade over decades, affecting sound clarity, frequency response, and overall balance.
Damaged Drivers: While less common, drivers can be physically damaged, requiring replacement.
Dried Ferrofluid in Tweeters: Many KEF tweeters, such as the T33 used ferrofluid for cooling and damping. This fluid can dry out, causing reduced output, distortion, or even tweeter failure.

Using Falcon Acoustics Parts for Repairs

Replacement Drivers

Falcon Acoustics offers authentic replacements for iconic KEF drivers:

KEF B110 (SP1003) REPLACEMENT and KEF T27 (SP1032) REPLACEMENT: These are critical for models like the LS3/5a and other KEF speakers using these drivers. Falcon Acoustics manufactures these to original specifications.
KEF B139 (SP1044) replacements: For KEF models utilizing this bass driver, Falcon Acoustics manufactures the Falcon B139 to original specifications with improved power handling.
REPLACEMENT DRIVER SETS: For KEF CONCERTO/KEFKIT3 CAMBRIDGE R40, and for KEF based system such as the CAMBRIDGE R50/WEBB TL/CHRIS ROGERS systems and the LINN ISOBARIK.

Repair Process (General): Replacing a driver involves carefully desoldering the old unit, mounting the new Falcon Acoustics driver, and re-soldering the connections. Ensure correct polarity (usually red or blue dots or + sign).

Crossover Components and Assemblies

Crossover networks direct the correct frequencies to each driver. Aged capacitors are a common failure point.

Replacement KEF Capacitor Sets: Falcon Acoustics offers pre-packaged 5% tolerance capacitor sets specifically designed for most KEF models (e.g., KEF Concerto, Chorale, Cadenza, KEF 104, 104aB, Corelli, Calinda, Cantata, 101, 102, 103.2, 104/2, 105.1, 105.2 V1, 105.2 V2, 105.3, 105.4, 107, 107.2 etc.). These sets use high-quality capacitors including specially made Falcon Alcap Low Loss types, which are superior to the original electrolytic capacitors in vintage KEFs. If the set you need isn’t shown, email us, it’s certain we will have the capacitor values needed.
Individual Components: You can also purchase individual high-quality capacitors (Alcap, Solen, ClarityCap), Inductors (iron dust core/ferrite/air core), and Resistors from Falcon Acoustics to rebuild or upgrade your existing KEF crossovers.
Complete Crossover Assemblies: For some models, Falcon Acoustics offers complete, pre-assembled upgraded crossovers all designed by Malcolm Jones (e.g., the No.33Mc Mk2 crossover for KEF Concerto, KefKIt 3, Cambridge R40 and the 33M MK2 Crossover for the Cambridge R50 Webb TL and Chris Rogers TL. Falcon Acoustics also manufactures our famous Gold Badge FL6/23 BBC-spec Crossovers for the Falcon and KEF drivers in the 15ohm LS3/5A.

Repair Process (Crossovers):

Documentation: Before starting, we recommend you take clear photos of the existing crossover and note component values placement and wiring.
Desoldering: Carefully desolder the old capacitors (or other components). Clean off all old solder from the PCB using a solder sucker or solder braid. Where replacing non-polarized film capacitors (e.g. Elcap and Alcap), polarity is not an issue.
Replacement: Solder the new Falcon Acoustics components into place, ensuring good, clean solder joints.
Testing: After reassembly, perform an initial low-volume test before full listening.

Important Considerations and Tips

Model-Specific Information: Always try to find the service manual or schematic for your specific KEF speaker model. This will provide precise component values and wiring diagrams.
Matching Values: When replacing crossover components, it's crucial to match the original capacitance (for capacitors) and inductance (for inductors) values. While voltage ratings for capacitors should meet or exceed the original, generally we supply at 100V rating. 50V rating is used for larger values and some Low Loss types. 150V is no longer made and 100V rating is used instead.
Soldering Skills: Basic soldering skills are necessary for component replacement. If you are not confident, consider consulting an experienced electronics technician. Use a 50W+ soldering iron, it is better to be quick with a higher power soldering iron than to “cook” PCB’s and components trying to heat everything up with a low power Iron (e.g. 25W). KEF PCB’s use older style Low Melting Point solder (185C-215C), not High Melting Point Silver solder. It’s recommended not to mix solder types, it doesn’t work.
Polarity: Non-polarized film capacitors are always used as in loudspeaker crossovers and do not have polarity. This makes everything much simpler to do. Polarized electrolytic capacitors are not used in loudspeaker crossovers and should not be fitted.
Safety First: Always disconnect speakers from your equipment before performing repairs.
Advice. If you’re not sure on something and need advice, email us and we’ll be happy to advise and help.
Testing: After any repair, test the speaker at low volume first to ensure everything is working correctly before applying full power.

By utilizing Falcon Acoustics' specialized drivers, high-quality crossover components, and their deep knowledge of classic British speaker designs, you can effectively restore and even enhance the performance of your beloved KEF speakers.