16 foot wide, or tall?
Sufficient ITD, IID, or a combination of both.
Within a soundfield, alteration of one portion of the music with respect to another in one channel...For example, an 11 band eq with 16Khz interchannel differences can shift vocal sibilance with respect to the fundamental frequencies. An out of body ssssss...so to speak.
I seek to establish sufficiently capable testing of a driver to determine the velocity modulated variance of Ls/Rs, to determine the level of effect lower frequencies can impose on higher frequencies within one VC given music.
jn
Since it is well known for a long time that a non-linearity enclosed in a feedback loop creates new harmonics even from the simplest mathematical treatment, I don't see how this issue could be approached in a way that has nothing to do with previous results.
Ah! One of the things Douglas found is that the shape of the initial increase of harmonic levels with increasing feedback, and the subsequent decrease when feedback continues to be increased, is very much dependent on the initial non-linearity of the forward path. (Howzzat for a short, succinct sentence?).
That may be somewhat intuitive of course but the upshot is that a small improvement in forward path linearity even to the detriment of the available feedback factor can greatly decrease this 'Feedback InterModulation'. At least that it how I read it.
But I'd like to hear how others look at this. It's somewhere around page 80 in his book.
jan
not the "linearize 1st" chestnut - again
To add to the conversation you really have to spell out how this “linearize 1st” can be done – otherwise the phrase is just empty noise
Cherry summed up the options to linearize a circuit as
increasing bias vs operating range (using less of the nonlinear transfer curve)
distortion cancellation as in diff pair or Class A complementary outputs
or negative feedback (in all of its forms)
yes you can choose devices - from a very restricted set of families of characteristics
tune bias conditions subject to power budget, implementation limits
use complements/diff pairs/symmetric circuits for even order cancellation
but these options are actually of limited use, are quickly exhausted - seldom give better than 20-30 dB "linearizion"
but feedback works for many orders of magnitude linearizion
so the real question in amplifier design is where to apply feedback, as local, nested, multiloop, global... for what result and at what cost in attaining circuit performance goals
To add to the conversation you really have to spell out how this “linearize 1st” can be done – otherwise the phrase is just empty noise
Cherry summed up the options to linearize a circuit as
increasing bias vs operating range (using less of the nonlinear transfer curve)
distortion cancellation as in diff pair or Class A complementary outputs
or negative feedback (in all of its forms)
yes you can choose devices - from a very restricted set of families of characteristics
tune bias conditions subject to power budget, implementation limits
use complements/diff pairs/symmetric circuits for even order cancellation
but these options are actually of limited use, are quickly exhausted - seldom give better than 20-30 dB "linearizion"
but feedback works for many orders of magnitude linearizion
so the real question in amplifier design is where to apply feedback, as local, nested, multiloop, global... for what result and at what cost in attaining circuit performance goals
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This is an analog input amplifier, not relevant to a digital to the output amp. Zetex was bought by Diodes inc. who only have modest products suitable for mobile speakers and speaker docks in the lineup. I think the high end variant landed at CSR who pitched me at CES but it doesn't seem to be a real product to use yet. There are many competitors trying to do a digital to the speaker solution with some feedback trick. First out of the gate was Freescale I think. This is a realm where .1% THD is considered perfection and power ratings are at 10% THD.
Suppose you have the option of increasing the VAS gain (sorry Mike) so you have more feedback return, but it does increase the VAS distortion. That increased VAS distortion is then decreased again by the increased feedback return ratio.
But where is the optimum?
As an example, if I decrease VAS gain by 10dB and this decreases its distortion also by 10dB, as well as increasing the feedback ratio by 10dB, it seems that there's no net change.
But if you figure in the feedback IM you may actually have made progress towards better closed loop linearity.
jan
Should of course be as well as decreasing the feedback ratio by 10dB....
So we are just going to have to make fun of Jan for the day.
That is so funny. so true too.
-RNM
Makes me wonder, does Santa Jan send you greetings on December 24 with : Ho Ho Ho ? (Mare Xmas)
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