When you had finished to test and tune a DIY device, and before to screw the cover, it is a good practice to hit all circuit boards, with some non conductive tool while you look at a sinusoidal signal. A good way to verify all your weldings at a glance. Do the same for your wirings. As SY said, the vibrations will be hundred time higher than any acoustical or mechanical vibrations in normal use.
Marce, yes, you're right about SMD litics. A good practice is to secure them with some varnish or glue once welded.
Marce, yes, you're right about SMD litics. A good practice is to secure them with some varnish or glue once welded.
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Sure, in practice 20 kg mass on valve springs gives a pretty low (and benign) resonance frequency.
Icing on the cake might be filling the springs with cured silicone or other substance....maybe Crazy Putty.
Dan.
Gorilla Snot...
Dan.
Just be wary of yellow contact glue that breaks down with heat and time, becomes corrosive, conductive and eats pcb tracks.
Dan.
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On the contrary, transports, and specially optical devices like CDs are very sensitive to vibrations. I have two experiences on this.
First, in my car, i used, long time ago, a portable CD player. Isolated with a support mounted on springs (damped with foam) at low resonance frequency in all directions: perfect, even during very aggressive drive or paved roads.
I use an old Marantz CD player in my hifi system. I had dumped with lead all the mechanical parts of the transport, until everything sound deaf. Including the motors and the tray. With great benefit. The all transport part itself was mounted on floating silicone suspension.
First, in my car, i used, long time ago, a portable CD player. Isolated with a support mounted on springs (damped with foam) at low resonance frequency in all directions: perfect, even during very aggressive drive or paved roads.
I use an old Marantz CD player in my hifi system. I had dumped with lead all the mechanical parts of the transport, until everything sound deaf. Including the motors and the tray. With great benefit. The all transport part itself was mounted on floating silicone suspension.
Hitting The Note...
If the acoustic feedback excites a high Q mechanical resonance, the modulation might be more than we might reasonably expect !
Dan.
Maybe not so....acoustic induced vibration can be pretty high amplitude in a high SPL situation.
If the acoustic feedback excites a high Q mechanical resonance, the modulation might be more than we might reasonably expect !
Dan.
Nope, not even close. Here's a way to demonstrate it: mount an accelerometer on your amp/pre/DAC. Play music while recording the output of the accelerometer. Now tap on different places on the amp/pre/DAC. Look at the accelerometer output.
For this purpose, you can either use a MEMs device or a cheap PVDF film sensor.
Once you've convinced yourself that the tapping is a much more rigorous test, you now have a cheap way of tracking down your construction errors!
Right.
Thats all the difference if you hit a guitar chord (or body, or a snare drum), or if you look for sustain or Larsen with high spl. It is, indeed, not a matter of level, its a matter of acceleration.
The mechanical excitation will produce a huge higher peak and it is not frequency dependent.
Same way a fast rising edge square wave will excite any resonance peak in the bandwidth of an amp.
Max, you can believe-us, it is experienced.
Duration is not a matter, and you can hit in the 3 dimensions if you fear, while it is not necessary.
Keep-it simple.
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If you are convinced your hardware is vibration proof, try moving it to the next room except the speakers and listen.
Having the stuff between the speakers really messes with the acoustics of the room but we must have the shrine.
I used to do a demo- pair of Quads in a room pretty clear of stuff with damped walls and a carpet. Put a record album on the floor between the speakers (lowest output angle for Quads) and everyone heard the significant change to the sound, not a good change either.
Having the stuff between the speakers really messes with the acoustics of the room but we must have the shrine.
I used to do a demo- pair of Quads in a room pretty clear of stuff with damped walls and a carpet. Put a record album on the floor between the speakers (lowest output angle for Quads) and everyone heard the significant change to the sound, not a good change either.
A turntable is a microphone !!!!! Designed to transform any mechanical vibration in signal !!!!
We are talking of electronic devices. *Except transports*. Were-we not clear enough ?
Even a CD player can be sensible to vibrations, because they change the relative position of the lens and the record, and so can create errors due to unfocus or unexpected move of the head out of the groove. Of course hundred times less than a PU head. Just reading's errors, no creation of signal ! Hit your turntable, you hear-it loud. Hit your CD Player, no sound, but you can see errors correction changes, jump of frames, or event music can stop.
Hit your USB key, your SSD, your preamp, your DAC, your power amp : nothing.
It is SOOO simple to understand.
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But John said "(very expensive)." The Momentums are only $350, a bit more than $1,000 less than the HD-800's. So if not the HD-800's, maybe the 700's.
Or maybe John considers $350 to be "very expensive" for a headphone.
By the way, I've a pair of HD-800's here and find them to be a bit on the "extra crispy" side at the top end. Though maybe that's because I'm used to my LCD-2's.
se
Or maybe John considers $350 to be "very expensive" for a headphone.
If so, I'm with John. I spent a couple of days with an array of hideously expensive headphones, and while they were very nice, at the end of the day, they were... headphones.
If you want to show how 'essential' are special feet or astonishingly rigid chassis then the best way to do this is to ensure that your circuit contains a follower which is oscillating at some VHF frequency. RF oscillators are always very sensitive to movement.
This technique works best if you don't realise that your circuit contains such an oscillator, so don't check for it. The best way to avoid checking for it is to remain ignorant of RF so you don't know how to check for it and don't even think you ought to.
This technique works best if you don't realise that your circuit contains such an oscillator, so don't check for it. The best way to avoid checking for it is to remain ignorant of RF so you don't know how to check for it and don't even think you ought to.
Right, and i have pontificated at it. If your preamp or amp is oscillating, it is a *failure*.
Fix the electronic, not the chassis.
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