Leslie wrote:

link explains a lot!

Very good thread Leslie, I dont doubt that you are very handy with your fingers, we have seen what you can do several times, but for me, not shimming is like working in the dark, you just dont know if the cone is centered. Consider that 0.1 Mm is 2-3 human hairs ( one of mine is 0.04 Mm. ) I have very fine hair.😂

Hello all,

Leslie contacted us and we answered some of his questions, then we read the comments above, there's a few things we would like to add.

Fist of all, pls realise that refoaming is an exciting experience for most people. We are not used to repairing anything ourselves (anymore) and shimming makes it more exciting. Because many of the speakers mentioned above have pretty big tolerances we recommend the 'cloth peg' method for beginners because it works well enough, especially because only about 5% of the centering is done by the foam ring, the gasket does most of the job - this is a simple law of science because the gasket is so muct closer to the coil.

But, if you shim, pls use the right tools and do it in the right environment. The manual linked under 'link explains a lot!' talks about paper shims. According to my experience these are either to big (thick), to soft (thin) and might tear leaving debris between the coil and the magnet. Professional re-cone kits (that's when you replace everything, coil, cone, spider, wires, dust-cap) will be provided with shims made of foto film. This is what we recommend if you want to shim. It's thin, extremely strong, and can be used many times.

Then there's the problem of dust and debris if you shim. Speakers are equipped with a dust-cap to protect them from (the name says so....) dust. In the factory the department that puts all the parts together to become a speaker has to be a dust free (or low dust) environment. Imagine people shiiming their woofer on a dusty table in their garage...... If you shim, do so in a nice an clean environment.

The manual ' explains a lot!' show you how to cut a dust-cap and re-use it. of course, in many cases (guess from experience: 50%) this is the case, but in the same amount of cases the cap will be damaged and has to be replaced. Because the cap effects the sound and finding an exact copy is very hard we recommend to be careful in removing the cap. Don't forget the cap is probably made of paper and 20-30 years old as well....

Still my S80's sounds great without shimming!

And next time when I have my RL140's I 'll try to use the shimming method!

GoodHifi wrote:

Hello all,

Leslie contacted us and we answered some of his questions, then we read the comments above, there's a few things we would like to add.

Fist of all, pls realise that refoaming is an exciting experience for most people. We are not used to repairing anything ourselves (anymore) and shimming makes it more exciting. Because many of the speakers mentioned above have pretty big tolerances we recommend the 'cloth peg' method for beginners because it works well enough, especially because only about 5% of the centering is done by the foam ring, the gasket does most of the job - this is a simple law of science because the gasket is so muct closer to the coil.

But, if you shim, pls use the right tools and do it in the right environment. The manual linked under 'link explains a lot!' talks about paper shims. According to my experience these are either to big (thick), to soft (thin) and might tear leaving debris between the coil and the magnet. Professional re-cone kits (that's when you replace everything, coil, cone, spider, wires, dust-cap) will be provided with shims made of foto film. This is what we recommend if you want to shim. It's thin, extremely strong, and can be used many times.

Then there's the problem of dust and debris if you shim. Speakers are equipped with a dust-cap to protect them from (the name says so....) dust. In the factory the department that puts all the parts together to become a speaker has to be a dust free (or low dust) environment. Imagine people shiiming their woofer on a dusty table in their garage...... If you shim, do so in a nice an clean environment.

The manual ' explains a lot!' show you how to cut a dust-cap and re-use it. of course, in many cases (guess from experience: 50%) this is the case, but in the same amount of cases the cap will be damaged and has to be replaced. Because the cap effects the sound and finding an exact copy is very hard we recommend to be careful in removing the cap. Don't forget the cap is probably made of paper and 20-30 years old as well....

And finally, like Lesly mentioned, there's woofers out there that simply can not be shimmed because the cone and cap are made out of one piece. The most common kind our customers have are the Dynaudio 9" and 11" woofers. These are really nice woofers - worth a repair, but can not be shimmed. We wonder if the 'shimming refoamers' will throw these away 😎.

This are just our 2 cents, based on our experience with our customers,

Kind regards,

 

Itching fingers......

We do not question the statement that many 'badly refoamed woofers' are offered at professional repair places at a regular base, but from our experience (having over 20.000 satisfied customers worldwide we consider DIY....) many, many, many times people can do it using the çloth peg method'.

About the 'original' replacement woofers, we just want to tell you this might seem a nice solution, but please ask the date of production before buying! If the units are old (> 10 years) but have been shelved the foam ring will still be effected, although less than in a living room environment, but you have to refoam soon, guaranteed!!! Another issue with these replacement woofer is that the design flaws (like the dried out 'cracking' rubber rings in the Beolab series are not resolved - you will suffer from the same problem soon! Sometimes replacing the ring is the only option.

Then the bad-sized rings - true. Be careful what you buy. Look on the internet and find a trusfull seller, or a seller you trust. One thing to check might be how often the seller sells. If the seller had his foam rings produced in 2003 and is selling those now...... If you get what I mean. Fresly pressed foam ring have a longer lifespan than rings that have been shelved for years....

The discussion also seems to turn into an A versus B discussion. If you have the confidence to shim, you have the tools to shim, you can do so. But if you don't, you will still be able to refoam a speaker. It's no rocket science!

Fianlly, for those who have no experience, before you refoam that precious woofer, maybe practice on a cheap woofer you can get from a second hand shop for a scatch. But be careful, after having a succes you want to do it again!!!!

Kind regards,

Good Hifi

Great job Leslie! Your S80 look very nice. 🙂

For my MC-120.2s I chose the Martin option. Of course he did a great job for not that much outlay.

He uses shims.

I have repaired many woofers in the past but for those I wanted a professional touch to the job because these speakers would be my main ones, and I wanted to keep them mint.

Yes, it is quite possible a job to do, but then there is always the glue problem. Martin has special tools I believe to get the foams perfectly round and centered, and commercially available glue is not ideal from my experience.

Good Hifi have indeed a good feedback, but I think their—your!—video tutorial should be of better quality! 😕

Good Hifi wrote:

The discussion also seems to turn into an A versus B discussion. If you have the confidence to shim, you have the tools to shim, you can do so. But if you don't, you will still be able to refoam a speaker. It's no rocket science!

My two cents, as we say in the States.

First, a summary of my limited experience.

For the six eight inch woofers I have refoamed, I cut off the dust cap, used shims, used a new (slightly larger) dust cap.  100% success rate so far.

For the two CX50s I refoamed, I did not shim, did not use a battery, did essentially nothing to center the foam to the basket except "use feel."  This method worked fine, but I wouldn't recommend it, nor would I even try to describe it to someone who wanted to use the method.

Conclusion:  my limited experience puts me square in the shimming camp, but I do know other methods can and do work.

And for the record, I have used

Thanks Rich! Certainly is a beauty like your Avatar🙂