Gli strumenti del Tweaking: lo stetoscopio

Medical equipment for HiFi tweakings

a.k.a: there's a method in our madness

Now you can stop laughing, thanks :-)
The instrument I'm going to introduce you is as serious and useful as it can be so don't laugh, there's a method in our madness.

The problem

I've always told you that trying to dampen the vibrations of any HiFi component could make it sound better. This is normally true for CD players, turntables and loudspeakers.
I've also show you some interesting and easy way to do this but what I have not explained yet is a scientific method to apply these damping materials.
Yes, of course you can knock on the loudspeaker cabinet or tick the metal top cover of your CD player but in order to act professionally and scientifically (?) you need a far more precise method.
This is especially important when trying to improve complicated mechanical systems with moving parts and electric motors, such as CD players and turntables.
Obviously enough, you can use your EAR to test-listen the results but sometimes you may need to reduce the number of trials (and subsequent errors).

The solution

A stethoscope!
Yes, Virginia, a stethoscope, the medical instrument your doctor uses to auscultate your lungs and heart. A stethoscope, since it has to reveal every tiny noise inside the human body, is very sensitive and can detect any vibration inside every kind of apparatus.
It is very easy to use but maybe it is better to give:

Some advice on how to use it

Since the stethoscope is a very sensitive and accurate instrument you should use it with extreme care: move the sensor gently and smoothly over the surface you're investigating: a hit on the sensor becomes a thunder into your ears.
It should be even better to use a soft cloth cap to protect the sensor from accidental hits.
In order to detect the most resonant areas of your HiFi components just place the sensor over the cabinet and then gently knock on the opposite side. For example, if you're investigating the top cover, gently knock on the bottom cover.
Acting this way you'll be able to apply the damping material and listen to the damping effect in real time. When not in use, do as the doctors do: place the earphones around your neck, just to avoid that an accidental hit can destroy your golden blessed ears.
The secret for a correct use is: smooth movements and silence all around. It is better to use the stethoscope while there's nobody home, and with some reason.
First of all you'll have a silent background that will make revealing vibrations easier plus you'll avoid to be considered tragically insane if some of your relatives (or your relevant S.O.) sees you while auscultating your CD player :-) Believe me, they may laugh out very LOUD :-)
Well, to be honest, the very first time you'll find yourself laughing out loud...all alone. Don't worry, it's still normal ;-)

Does it work?

OK, we've seen it works well for laughing out loudly, does it work well for our insane purpose?
You bet! You just need some experience to get the better results but after some trial and error you'll be able to detect any vibration inside every HiFi component.
It is insanely effective when the patient is a turntable: you may know that the needle of a pick-up is so sensitive that can detect (and then reproduce, amplified) every little vibration near it while playing a record. These unwanted noises may include the electric motor vibrations, the subchassis resonancies, the belt friction, the transformer vibrations and so on.
It is very HARD to detect these noises simply by ear, unless you have a built-in spectrum analyser somewhere inside your body ;-), so the stethoscope can help you. You can be sure that if a noise is there inside the turntable you'll be able to detect it, my dear Watson.
The same applies, even if less relevantly, to CD players. This instrument has helped me a lot improving and tweaking several HiFi components I own, a Garrard Zero 100 SB being one of these (an article on the tweakings made is on the way, please be patient).

Availability and costs

A stethoscope is easily available at any medical instruments store or chemist's shop (drugstore?). Its price is variable but for our audiophile purposes even the cheapest one will work just fine (few dollars, here in Italy, dunno abroad).
If you can't find one please don't ask me...ask your family doctor instead. It should be better to have a *friend* in the field, so to avoid to be considered, once again, desperately and dangerously insane :-)

Conclusions

This instrument, easy to find, cheap and extremely effective, can help you seeking and destroying any unwanted vibration into each HiFi component of your system.
Some of you ask for a more *scientific* approach to HiFi, I hope you consider this... scientific enough :-)