DQ-20 skrev:
Om man bultar baslådan i golvet, golvet är tillräckligt tungt, låda styv och signalen lågpassfiltrerad så finns ju sannolikt inga resonanser i det aktiva området och lådan beter sig som den vägde 10 ton eller så. Och det är väl bra.
/DQ-20
Behöver verkligen högtalarelådan bultas fast för att bete sig som att den vägde 10 ton, eller bara litet mera än den gjorde utan bultning ?
Räcker det inte med fyra rejäla spikes ordentligt nedkörda igolvet, för att uppnå något liknande ? ( det borde bli väldigt svårt att flytta högtalaren med kraft av elementens kraft/ motkraft till lådan, om lådan står stabilt förankrad med kraftiga spikes nedkörda i golvet ).
Lådan borde inte flytta sig alls då, det blir ju kraftiga repor på golvet om den kunde det. Inte ens en tiondels millimeter.
Johan Atkinson kallar det för " mekanisk jordning" , just för att öka massafördelningen låda/ element med hjälp av spikes.
Har han fel även här ?
"It was the impecunious English, therefore, who first got into loudspeaker tweaks. In particular, they heavily investigated the relationship between the speaker and the stand, and the stand and the floor (though the Mod Squad's Steve McCormack pretty quickly got into the act with his effective Tiptoes, which in turn spawned a flood of imitators). I remember putting on a series of single-blind listening tests at the very first Heathrow Penta Show, where show visitors could audition a pair of Spendor loudspeakers either on stands that rested on the rug, or with the same stands spiked through the rug to the concrete floor below. The difference was not subtle; listeners overwhelmingly chose the spiked speaker stands as sounding superior. Even a couple of engineers from the BBC (an organization not normally regarded as being tweaky) confessed that they heard the spikes improving the sound of the Spendors.
The late Raymond Cooke of KEF, who was a subject in those 1982 listening tests, offered a typical dose of Yorkshire common sense by pointing out that when hi-fi got going in earnest in the 1950s, loudspeakers featured such massive construction as sand-filled cabinet walls. They also often sat directly on uncarpeted floors—the thought that they might not have a secure enough foundation wouldn't have crossed their owners' minds. Since that time, speakers have become flimsier and rugs thicker, allowing the cabinet to move in reaction to the woofer's motion.
This is a practical illustration of Newton's Third Law of Motion: to every action there is an equal but opposite reaction. If a typical 10" woofer cone/voice-coil assembly with a moving mass of 50 grams moves 25mm peak-peak, a cabinet with a mass of 5kg sitting on a friction-free surface will move 250µm: a quarter of a millimeter! Any friction from the support will reduce the cabinet motion, but even if it does by a factor of 100, the resultant 2.5µm cabinet motion is still of the order of that of the tweeter diaphragm's and will frequency-modulate its output. Spiking the speaker or its stand to the floor beneath the rug gives the system a much better mechanical "ground," reducing its reactive motion to the benefit of its sound. "
- John Atkinson.
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