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Old 27th September 2013, 07:32 PM   #9501
MiiB is offline MiiB  Denmark
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Agreed, Mikkel calculated 14 bit to be the depth, but as it is relative I am not really sure it matters. Quite sure that current noise will be lower as one can select better resistors with lower noise, and better discrete switches, if a quite high(ish) reference voltage is used, then a N-Jfet could be suitable. Would be low noise, fast and easy to drive.
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Old 27th September 2013, 07:47 PM   #9503
MiiB is offline MiiB  Denmark
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Theres is one Discrete DAC called Sonic illusions see the schematic there (http://www.sonicillusions.co.uk/discrete_dac.htm), What I would change is to have the logic-switches drive discrete switches and not the resistor ladder directly, I am not convinced that the switches in the logic are quiet enough to pass the audio thru. and I would like some separation there. But the idea and concept seems good.

Last edited by MiiB; 27th September 2013 at 08:14 PM.
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Old 28th September 2013, 03:16 AM   #9504
danielwritesbac is offline danielwritesbac  United States
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How on earth????!!! The tennis balls? How are they secured? And why does the speaker not zoom around all over the room? How is it tied down?
Or are the tennis balls used for shock absorbers so the speaker can go bobbing about, with the energy absorbed in the balls so the speaker doesn't scoot around? Surely, concert accurate bass impact makes that thing boogie, right? I'd love to know the details on it. Do tell?
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Old 28th September 2013, 03:17 AM   #9505
Joachim Gerhard is offline Joachim Gerhard  Germany
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It bothered me that the coils needed in power amplifiers as part of the Zobel are often mechanically not very rigid.
So i commissioned Mundorf to make several prototypes.
One is a foil coil and the other 3 are baked copper wire.
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File Type: jpg Zobel mundorf 1.jpg (143.5 KB, 340 views)
File Type: jpg amp coil mu 1.jpg (25.7 KB, 334 views)
File Type: jpg coil amp mu 4.jpg (23.9 KB, 331 views)
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Old 28th September 2013, 03:25 AM   #9506
Joachim Gerhard is offline Joachim Gerhard  Germany
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Daniel, this panel only goes to 120Hz or so. The frequencies under that are handled by active M-Dipole subs.
You also have to consider that the weight of the Enviee wide range membrane ( including coil and everything else ) is only 10gr so there is not much force transferred to the baffles.
The stone base is quite heavy too so this baffle simply sits on the tennis balls without falling over to any side.
I measured vibration with an accelerometer on the baffle and contrary to popular believe, vibration was 20dB less over a wide range of frequencies with the tennis balls in place.
I think what happens is when you place the baffles right on the floor the mechanical energy is not dispersed but steered back in the baffle where it interferes with the vibration there so it gets worse.
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Old 28th September 2013, 03:35 AM   #9507
Joachim Gerhard is offline Joachim Gerhard  Germany
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Here are the subs. They are direct coupled to the front wall via a granite plate so the wall fixes the woofers in place.
Here the baffles are stuffed with the Enviee drivers with wizzer. That version does not need a tweeter. It goes straight up to 25kHz.
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Old 28th September 2013, 03:37 AM   #9508
Joachim Gerhard is offline Joachim Gerhard  Germany
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enviee - the fullrange driver
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Old 28th September 2013, 05:18 AM   #9509
danielwritesbac is offline danielwritesbac  United States
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Speaker driver frequency response chart dips are exactly at ear diaphragm and canal sensitivity peaks. Very clever!
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Old 28th September 2013, 07:08 AM   #9510
keantoken is offline keantoken  United States
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The tennis balls make sense. The same applies to power amps. To get a stable yet precise amp, you've got to know where to put the tennis balls.

PS: Not literally.
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