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Noisy Ds!

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Noisy Ds!

Postby ef37a » Fri Apr 24, 2020 1:35 pm

No, not a typo!

I was a little sad to read Phil Ward's review of the Kali Audio IN-8 where he rather 'excused' the audible self noise? I am of the opinion that monitors should be completely silent at the listening position even near fields and in quiet surroundings (there will always be some hiss if Mk1 lug is applied to tweeter) . Of course, very low cost speakers might be excused a bit of hiss but I do not consider close to £700 budget. In any case, it is not that hard or expensive to make power amplifiers with extremely low noise levels, even ones delivering several hundred watts which necessarily have more gain than the 50-100W fare.

But, to the title! The world of monitors has gone Class D! Now, I have only THE most rudimentary knowledge of these amplifiers but could it be that they are inherently noisier than good class B designs? Does Phil know this, if true and so makes allowances?

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Re: Noisy Ds!

Postby James Perrett » Fri Apr 24, 2020 1:54 pm

ef37a wrote:But, to the title! The world of monitors has gone Class D! Now, I have only THE most rudimentary knowledge of these amplifiers but could it be that they are inherently noisier than good class B designs? Does Phil know this, if true and so makes allowances?

There's no reason why a class D amplifier should be noisier than a non switching design. The noise is usually introduced in the earlier stages of the amplifier where signal levels are low - the input stage of the Quad 405 is a good example where people often modify it to be less sensitive and hence give lower noise.

The Hypex class D amplifiers powering my main monitors are certainly quieter than the Quad 405 powering my secondary monitors but neither are noisy enough to be audible at the mix position and I have a pretty quiet studio.
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Re: Noisy Ds!

Postby Hugh Robjohns » Fri Apr 24, 2020 5:26 pm

ef37a wrote:I was a little sad to read Phil Ward's review of the Kali Audio IN-8 where he rather 'excused' the audible self noise? I am of the opinion that monitors should be completely silent at the listening position even near fields and in quiet surroundings

I completely agree with you that active speakers should not generate a level of electronic hiss that is audible at the listening position in a quiet room. I'm not sure it's fair to say Phil 'excused it' though -- had that been his intention he could simply not have mentioned it at all. As it was, not only did he mention it in the text -- albeit with typical British politeness -- he also listed it as a Con. That doesn't feel like excusing it to me.

At the end of the day, a reviewer's job is to draw the potential purchaser' attention to the product's various strengths and weaknesses, not to lambast manufacturers -- a route that would actually be very counterproductive!

I'm certain this wouldn't have applied to Phil's review set up, but I have come across punter's situations where the audible hiss was actually due to very poor gain structuring across the monitoring chain, rather than in the speaker itself.

When I'm testing active speakers, I use a shorting plug on the input so that I'm just hearing the contribution of the speaker itself, and not any driving equipment or spurious pickup from the connecting cables.

The world of monitors has gone Class D! Now, I have only THE most rudimentary knowledge of these amplifiers but could it be that they are inherently noisier than good class B designs?

No. There are good and bad Class-D designs, of course, but the vast majority are pretty good these days and some are quite exceptional.There is no inherent noise problem that I'm aware of and I can't recall having any noise issues at all with class-D amps in any speakers I've used or reviewed.
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Re: Noisy Ds!

Postby ef37a » Fri Apr 24, 2020 6:56 pm

Thank you Hugh. Yes maybe I was a bit harsh on Phil but I did put excuse in ' '

The problem of noisy monitors was quite a common one a couple of years ago on forums and it is particularly galling to me that there really is no need for the noise? I think it was probably you that said a while ago that many active monitors have too much gain?

This whole situation of course comes down to the fact that there is no real standard for AI output ref 0dB fs in the 'prosumer' world and I suppose monitor mnfctrs try to make their products universal?

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