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Bridge mode and damping factor

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Sonic the hedge View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic the hedge Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2020 at 11:17pm
Not wishing to contradict myself (again!) but something else came to mind regarding back EMF and amplifier DF figure.

Certain well known Class D manufacturers claim that their amplifiers can recycle the back EMF from drivers, into the amplifier's PSU, recharging the caps. 

If, as some would suggest, the back EMF from drivers is most all dissipated by the VC as heat, such recycling claims by amplifier manufacturers would seem to be pure marketing horsesh1t. Which is of course possible.

However, there is still this issue, around cabinet/driver resonance, and effect on impedance curve.

Originally posted by Sonic the hedge Sonic the hedge wrote:

...driver impedance is not equal to DC resistance, nor is it constant across the frequency spectrum and most especially around any resonant peak(s) in the driver loaded in a particular cabinet, the exact region(s) where effective damping is most important (Just IMHO, as I have said before sound is subjective!).

So perhaps, there is something in it. 

The maximum back EMF, seen by the amplifier, occurs at exactly the point(s) where the driver/cabinet impedance curve drops to a minimum. The exact same point(s) that an amplifier headroom boost, from recycled back EMF, will be most useful, in preventing clipping (due to lower impedance/increased output). In which case, these class D manufacturers may be on to something quite ingenious.

That would also mean, that perhaps relatively higher amplifier DF figure can be quite important, but only if the amplifier has plenty spare current available too

e.g. class A/B or G/H amplifier in bridge mode, loaded and leveled to provide 1.5x - 2x headroom. Of course the class D still does it more efficiently, but the result is the same.

I'll get my coat LOL





Edited by Sonic the hedge - 22 May 2020 at 10:42am
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singingfish View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote singingfish Quote  Post ReplyReply Direct Link To This Post Posted: 31 May 2020 at 3:22pm
I may be wrong..
but here goes.

Is it correct that two or four matched drivers in an enclosure actually damp 'each other' electrically and by air pressure damping?
If true, his would mean that ganging up drivers would present an easier load for the amp to drive/control, wouldn't it

That was always my assumption anyway.

very interesting thread.

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Sonic the hedge View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic the hedge Quote  Post ReplyReply Direct Link To This Post Posted: 01 August 2020 at 3:31pm
Originally posted by Sonic the hedge Sonic the hedge wrote:

Originally posted by csg csg wrote:

According to the audiologist i see ( in ear molds etc, but is medically qualified and very well known in his field) the most dangerous frequency range for causing hearing damage is bass/ sub, this having by far and away the greatest amplitude and energy which causes the physical damage to the nerve hairs . Its particularly dangerous as we are naturally insensitive to this range so we don’t get the natural warnings that we would from screeching mid/ high frequencies

Interesting, I have also read/been told that loud sounds produce a denseification reaction in the middle ear, which is fast enough to protect the ears from lower frequencies, but not higher ones. I guess the two things are not mutually exclusive.

Discovered this on my travels, which is what I was referring to


Lower bass frequencies trigger a contraction effect in the ear, which protects it from damage at high levels. High frequencies are too fast to trigger the reaction, but the reaction produced by lower frequencies reduces the pressure across the spectrum.

Essentially it's like having a compressor in the ear, that is sidechained only to the lower frequencies. This is consistent with my experience that mid/top heavy systems causes most ear ringing afterwords, whereas very bottom heavy systems can produce no ringing at all, even when very loud.

I guess this has evolved in humans because the very loudest sounds that occur naturally (thunder, earthquakes etc) tend to have low frequencies.


Edited by Sonic the hedge - 01 August 2020 at 3:56pm
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