LS101

B&W drivers refoam rubber in grey and black for all models.

Tannoy HPD series 15" dual concentric drivers refoam. Genuine surround foams made in England.

Speaker modifications. Recently i was assigned to a modifications job on a pair of OJAS bookshelfs. Very interesting for me, at least something unfamiliar and off the mainstream brands.
A quick search in the company profile says that they are from New York, more like an audio boutique concept.
The stock speaker comes standard with a single 8" coaxial unit each in a squarish reflex box made with some sort of nice plywood. Inside the enclosure, the labels on the back of the magnet reveals the driver sources from JBL. Apparently the driver and crossover components were originally designed for in-ceiling applications. The concept of turning ceiling speakers into hifi isn't new. Mind you, if you don't already know. Many of the early Altec lansing duplexes have made it in to audiophiles man's caves, and are still very much appreciated now.
My work here is about converting the coaxial unit, moving out the compression tweeter to the top with a dedicated waveguard.The kits come as an optional product available from the company's website.
Accordingly to the source, the modification is to "offer better coupling of the driver and air in the room".

Note that this is not a product review here but rather about how different configurations affect the sound differently.

I received the speakers a day before and it was scheduled to be returned in the following day. I started with playing some music to ensure everything is working properly and at the same time, to familiarise myself with the sound for comparison after the mod. I enjoyed the wide open presentation in the original state and also the imaging department where coaxial a.k.a point source usually fares very well.
The modifications proceeded smoothly and completed later in the day. A second round of testing and listening was done. My impression was "loud and forward", very soon I realised that the initial L-pad levels was set to the max. It was evident that the added waveguards have boosted the upper frequencies by some degrees. Tuning the levels down to about halfway smoothen things out considerably. The hint of forwadness in the upper mid is still noticeable. A typical character with horn loading tweeters. Less obvious however, when I moved further away from the speakers as per suggestion in the product literature.
I must say, the end product sounded a lot larger than life with greater dynamic and air.
On the other hand, the stock coaxial configuration communicates music in a more intimate manner and warmth particularly suitable for near field listening.
As always, there is compromise in every designs, engineers usually decide with the best balance. For the individual however, it is important to know what you are looking for.

Some of the recent crossovers recap and upgrades. Replacements of capacitors may not possibly turn a Rm1k speakers sound like a Rm10k speakers! But, it will definitely restore your old speakers to play like how they intended to play (perhaps slightly better) when they rolled out from the factory.

Sony APM square type foam surrounds refoam is now available at LS101.

Broken magnets. One of the reasons in tweeters loosing outputs (faint and distorted sound) is due to the degradation of magnets.
Modern Neodymium magnets are superior in many ways compared to the traditional counterparts like the ferite and alnico.
Ferite can normally last forever and the alnico type may loss its magnetism overtime. The neodymium on the other hand, i have personally encountered quite a number of corrosion issues (powdering).
I believe that the cause of degradation has to do with the quality of materials used and the process of making the magnets.
The corrosion usually starts with the breaking down of the protective nickel plated layer. The exposed magnetic powder then slowly make its way into the gaps to the point that it jammed the voice coil.
Attached herewith pictures of tweeters with neodymium magnets that have turned into powder.

Woofer without spider but ferrofluid filled to work as lubricant to keep the voice coil centered. This type of design is common in tweeters and also in some mini 1" or 2" fullrange drivers mainly used in portable speakers.
Extremely rare in this case is a midbass unit produced by NEAR speakers from the early 90s. The concept of using ferrofluid was a big thing back in the days but I personally think this combination in a woofer is impractical with no real benefit in sound quality.

Speakers with front mounted magnets. Yes, it is a new norm in car speakers design. The objective is to save space so that the speakers can be squeezed into the tight space between the door card without hitting the window glass. In a traditional speaker, the magnet makes up about 1/3 of the total depth of the driver. It means, the depth of the driver can be greatly reduced by putting the magnet in the front, clever.
The driver in the picture is Mark Levinson model M2.

But, how do they work? Yup they work pretty much the same as the normal driver do, except that the voice coil and magnet is reversed mounted in front of the cone.

In case you are wondering about the sound, I personally prefer the old fashion way of doing it. It is more of a compromise between sound quality and space availability.

The craziest repair and modifications in speaker drivers! Repair with cardboards, waterproof bitumen tapes, paper spider, painted woofer cones etc. Some modifications are just irreversible!

Do not drop! handle your speakers with care! Structural damages are beyond repair. The main structure holding the cone and the magnet together in a speaker driver is called the basket. Baskets materials varies from plastics, stamped steel, cast aluminium, magnesium etc. Some are better in acoustics control, some have better strength and durability while others are just cheaper to produce. I have seen some basket designs that are just too flimsy to withstand the slightest drop. Especially the ones with heavy magnets are the recipe for disaster.

Misleading information. I stumbled upon this tweeter removed from an old speaker cabinet. The label reads a frequency response from 4hz to 22,000hz all from a 1" hard dome tweeter! If it was true, it must be some sort of an ultra subwoofer + fullrange + super tweeter all in one.
The point here is, the published specifications by manufacturers may be inaccurate either by mistakes or deliberately to mislead.
In the context of loudspeaker sound quality, excellent specs on the paper does not necessarily mean excellent sound to your ears.

One of the smallest manually wind voice coils measuring 13mm diameter for a vintage tweeter recone job. In the background is a 100mm diameter full aluminium voice coil.

Edge would voice coils (flat wire) vs normal round wire voice coils. Flat wire windings have the advantage of lighter and shorter core compare to the regular round wire that leave gabs in between. Attached pictures show the flat and round aluminium wires for comparison.
Aluminium edge would voice coils are only found in very high performance speakers as they are more expensive to make.

Magnet sweating? Removed from a pair of old speakers suffered from rusty steel plates with shiftted magnets. I have been observing this particular pair of magnets for almost a week now. Tried placing them in different locations including in open air and enclosed carton boxes. A thin layer of liquid similar to the condensation effects on a cold water glass is developed on its surface every overnight. I never had experience with magnets attracting moisture. Not sure if this is normal or something triggered a chemical reaction on them.

One of the most commonly asked question is if old crossovers need to be recapped? The answer is Yes and No.
My advice is "No" when you are absolutely happy with the current sounds, you have no reasons to alter the way it sounds right?
Otherwise, "Yes" are for speakers that are already in their teenage years or older. Capacitors degrade in time!
Capacitance value drift in ageing caps depending on the types and quality of caps used in the crossovers. Electrolytic bipolar caps are generally less durable than polyester (MPT) and polypropylene (MKP) are usually preferred for better sounding as well as durability.
My most recent recapping in a vintage Trio speakers with bipolar caps have drifted between 25% - 60% it's original values. A 4.7uf cap reads 7.44uf and a 10uf reads 14.38uf means a lot in terms of the crossover frequency point!
In this case, the speakers sound brighter and harder in the middle high regions due to the overlapping frequencies. The lower crossing point also puts the tweeter coils in danger when it gets too hot.

Vintage Diatone P610b fullrange speakers. Made in Japan in the 60s, alnico magnet.
One of the best fullrange speakers ever made in Japan. Incredibly sweet vocals with decent bass and trebles.
This pair of drivers are in fair condition considering its age, cabinets are custom made new.
Yours for Rm 1,380/=

Repaired one of the thinnest drivers in the world. The 6 pieces of the flat drivers from the Harmon Kardon Sabre soundbar is 45mm diameter each with only about 5-6mm depth making it one of the thinnest drivers I have ever worked with. The drivers have minimal components consist of a neodymium magnet, a relatively big voice coil and a foam surround holding the cone in position only. There are no space for the spider to work, meaning if the surround foam is gone, the sound will be gone too.

The Yamaha NS10MC is one of the two horizontally configured version other than the Studio in the entire 10m series. They are exactly the same as the Studio with the added "C" literally means "ceiling" with the provision of bolts to accept mounting brackets.
This pair in good physical and working conditions at Rm 1,900 Sold

Kent Engineering and Foundry (KEF) dual concentric drivers of different eras came in for repairs. The overall design concept has not changed too much but the materials have evolved in time.

Fostex 4" fullrange FE103 in back loaded horn bookshelf size enclosure. Made in the late 80s in Japan, Real wood veneers. Great for near field listening in small space.
Dimensions approx 8" W x 9" D x 18" H.
Cabinets in great shape and working perfectly.
Rm 1,280/pair
Self collection at USJ14 or shipping at buyer's cost.
Functional test for serious buyer only.

Technics honeycomb coaxial from the reference SB RX series speakers. One of the rare gem models built by the Japanese giant to rival the Tannoy HPD back in the days. You can tell these guys are really serious with the massive magnet structure on the heavily cast aluminium basket. (I put a normal 8" driver for comparison)
The tweeter is cleverly mounted on the center pole design with a foam surround not only to keep the dust away but also work as an air seal.
Behind the honeycomb is the 75mm bass voice coil that are as big as the dynaudios.

Over engineered woofer from the Epos es14. It was a surprise discovery for me to dig up a double spider system in this es14 midbass unit. I have seen this kind of configurations in some high powered subwoofers but not anything smaller. The spider plays its part along with the surrounds to ensure a linear movement of the cone when current is connected to the voice coil.
The driver runs on an underhung motor system with a hefty magnet. The thick squarish cast aluminium basket with an integrated phase plug is a piece engineering art by itself.

Yamaha NS10mT, a "turbo" charged version of the standard NS10m? Produced in the 90s when audio companies jumped on the bandwagon in offering home theater products in the new A/V market. With no exceptions, the NS10m came out with the "T" version to target Theater applications. To qualify for A/V applications, the NS10mT was redesigned to be ported to address the limited bass extension of the predecessor models. The 2 way configuration and the dimensions of the front baffle remained the same but a much deeper cabinet. A new tweeter was also adopted for greater clarity in the high region. As a result, they can cover a much bigger bandwidth with a claimed frequency response of 45hz to 30khz.
The NS10mT is overall a more enjoyable speakers than its predecessors as far as hi-fi is concerned.
If you are looking for studio sound in hi-fi, they will fit nicely.

Focal / JmLab is well known for its inverted dome tweeters. If you not already know, this French company doesn't just sell complete speakers, they also do OEM for raw drivers. Besides the speakers marketed under their own brand, their drivers have made their way in to some of the world’s most highly regarded speakers like the WilsonAudio Grand Slamm, Chario, Acustik Lab, KRK, just to name a few. They also made some of the best car speakers using the similar inverted dome tweeters. Don’t be surprised if your favorite speakers have one of those JmLabs drivers in them.

Most of their woofers have extremely durable rubber surrounds but the tweeters from the early models have foam surrounds which have rather limited service lifespans. Unlike a woofer where the spider will still hold the cone in place after the foams had deteriorated, the tweeter’s inverted dome (diaphragms) in this tweeter design will only be held back by the tiny lead wires once the foams are gone. Not only will it not work properly, a regular dusting or a gust of wind will send the diaphragms flying.

Refoam is now available for the JmLab / Focal tweeters at LS101.

Most of the older speaker drivers have voice coil former (bobbins) made of paper. It was the choice of material for the ease of use and the availability from the earliest moving coil transducers. Aluminum, Kapton and some other materials with higher resistant to heat were introduced later and quickly adopted by speaker manufacturers.
Although paper formers are now less popular but is not all forgotten for the fact that they are much lighter and more natural sounding. Some modern day manufacturer continue to use paper as an option for their high sensitivity low power designs e.g fullrange.

If you start wondering at this point if your speakers have paper voice coil formers, high chances of yes if your speakers were produced before 90s.

Just to name a few of the highly regarded speakers running on paper voice coil formers: LS3/5a (B110), Yamaha NS1000, JBL 43** and 44** series studio monitors etc.

Rare Fostex FE103 Sigma 4" full range speakers in a compact bass reflex configuration. Good balance of bass and smooth frequency from 68hz to 20khz. Will work with a wide range of tube, solid-state or class D amplifiers from 5w up. Easy to drive 16 ohm with high sensitivity at 92db.
Drivers are from the 1960s used, recently reformed, boxes are custom made new. Comes with covers, fully assembled plug and play. Dimensions 180mm W x 280mm H x 240mm D.
Very lmited pairs while stocks last.
Rm880/pair fixed.
Self collection at USJ or by courier at buyer's cost.

Miniature back loaded horn Fostex 100K (FE103) 4" fullrange speakers.
Designed to work with small amplifier for desktop placement.
Drivers are made in the 70s with signs of use and some small creases, recently reformed with new foams, working perfectly. Boxes are perfect in beautiful real wood veneers.
Box dimension 4.5"W x 11.5"H x 8"D
Rm-Sold

This speaker is by far has the most number of surrounds I have ever installed in one driver. It has a total of 4 pieces with 2 from the front and 2 from the back. It was a long throw passive radiator from a little car subwoofer system.

Hazardous Beryllium!
The beryllium dome drivers are known for the superior sound quality that usually found only in the big tickets audiophile speakers. This topic however, is not about the sound but a note to the owners in case you didn't know.
Beryllium is a highly toxic material, it may cause lung cancer or chronic disease if exposed. However, you don't have to be overly worried, they are safe to use as long as they are not broken. Manufacturers have taken extra care to protect the domes with covers and wire mesh to keep harms at bay.
Do Not Attempt to remove the protective covers for whatever reasons and disposed off properly if it is broken.

As a tech support, I will make sure I am in proper PPE before I put my hands on those. I have repaired some from the Yamaha, Focal, Scanspeak etc.

All and all, you don't have to stop playing or not to consider buying a speaker with beryllium drivers after reading this. Despite the hazardous material disadvantage, Beryllium produce exceptional brilliant high frequencies that others just can't come close.
I have a pair of the Yamaha NS2000 sitting in my room for over a decade of which I never get tired of.

Attached herewith a statement (last picture) from Scanspeak for your perusal.

Some of the recent repairs on Thiel speakers from various models. Their drivers are usually proprietary design and built in-house in a rather unconventional approach.