Abbey Roads Brilliance pack anomaly

[digimaton]

using a PC with Nuendo 4 was just running some tests on the Abbey Roads Brilliance VSTs and noticed something that I find problematic.

Essentially, they band limit a channel to approximately 19kHz - if running a project at 44.1 or 48kHz

They appear to behave fine at 96kHz.

I have checked the other Abbey Road releases and they do not behave like this.

does anyone else think this is unusual?

@ 48kHZ RS127, spectrum analyzer showing result of switching bypass on (http://picasaweb.google.com/lh/photo/-nWE5nD1JV6NyEGlzEcxqw?feat=directlink)

@ 48kHZ RS127 bypassed (http://picasaweb.google.com/lh/photo/JIYocxSTl5kgUzLsZGx4pw?feat=directlink)

@ 48kHZ RS127 on (http://picasaweb.google.com/lh/photo/KG8TlTpqft3N70hmthG-3w?feat=directlink)

@ 96kHZ RS127 bypassed (http://picasaweb.google.com/lh/photo/KE2U61KK_5imt7TAejJdtg?feat=directlink)

@ 96kHZ RS127 on (http://picasaweb.google.com/lh/photo/_2u9_M26czZrOL5DS_SnVA?feat=directlink)

threshold of hearing debate aside, I would expect plug-ins coded to operate at 48kHz to cut-off at 24kHz not 19kHz; this also makes no sense in the context of this being an emulation of an analog device.

[kdm]

It could just be their choice for filtering to eliminate harmonic distortion or filter aliasing. Anti-alias filtering normally has to cutoff below 1/2 the sampling frequency, so at 48k, it should be around 22.8K. 44.1k would be 21k (the rule is sample-rate/2.1).

That said, 19k does sound unusual. Could be a bug at 44.1/48k - have you emailed the devs?

[digimaton]

thanks for your input, yes, I had some idea that lower than expected anti-alias filtering might account for this @ 44.1 but not at 48kHz.

Also, I do not see evidence of this type of anti-alias filtering in their other products, have also checked some other VSTs and do not see this anywhere.

I also noticed that the dB scale is completely out of whack, + 10dB on the RS127 is equivalent to + 20dB using Nuendo's stock eq (boosting in the same region), this of course maybe just a design feature.

I didn't email them yet because I was interested in getting some other opinions on this first, in case I am wrong in thinking this is suspect.

The only reason I actually checked these out was to dispel from my mind any hype about VSTs like this, I'm not convinced that will do anything I can't already achieve with other tools.

The whole argument pushed by analog heads is that "the sound" has to do with inaudible harmonics above the threshold of hearing, in fact above the nyquist frequency in the case of 44.1 & 48kHz, so how can a plug-in like this possibly give the character of the real unit? makes no sense to me.

[kdm]

I think devs often play loose with analog concepts to hype their plugins. I've seen other plugins with low pass or high shelf filtering - possibly to minimize some effects of their filtering algorithms at lower bands (e.g. harmonic distortion caused by lower order filters, etc); or that could just be the model of the original hardware. In reality, while analog technically represents the spectrum more smoothly than digital (in theory if not always audibly), it was much more difficult to create an even response across the same frequency range as modern converters (wouldn't be surprised if a lot of this hardware rolled off around 10-15k). Personally, I think a lot of the "inaudible harmonic" claims are non-technical hype, though there is some truth to the difference in effect, if not the actual technical explanations users tend to adopt.

I don't recall much older analog gear having anywhere close to the frequency response of modern digital converters. My old Lexicon delay rolled off at 15k. And that's just a delay. Older EQs probably rolled of around 12-15k, with nothing around 20k, but I'm guessing without seeing actual response curves of that gear.

But, that aside, this could be a bug - it doesn't look right, but maybe that's the model they came up with to emulate the real hardware, or at least what they had to do for 44.1/48k.

[LEX]

Could it be that when they modeled it they put a 48k sound through it, and at 96k they put a 96k sound through it? or some sort of thing like that.

[digimaton]

for the sake of casting even more uncertainty on all of this consider the following, a claim made by Rupert Neve, taken from the foreword of Moylan's Art of Recording:

"In 1977, Geoff Emmerick, who, with George Martin, recorded The
Beatles at Abbey Road and later at Air Studios, London, showed me that
he could hear a difference between two identical channels on a recently
delivered new console. After some hours of listening with him, I agreed
that I could hear a subtle difference. When we measured I found that out
of 48 channels, three had been incorrectly terminated and displayed a rise
of 3 dB at 54 kHz. The limit of hearing for most humans does not extend
beyond 20 kHz and this small resonance, whilst obviously an oversight in
the factory, would not normally have been regarded as important.
One of the significant features of this episode was that Geoff was
deeply “unhappy,” even “distressed” at what he was hearing or perceiving.
Since then I have seen much more evidence that the range beyond 20
kHz is part of human awareness. Newly introduced designs which
transmit frequencies to beyond 100 kHz (with low distortion and noise),
surprisingly, sound warmer, sweeter, and fuller."

Personally, I remain sceptical, but I'm neither an expert engineer or an expert listener, I have seen it suggested elsewhere (in a more 'scientific' context) that 64kHz sample rates are the highest we need to do the job well, with 96&192 being recording industry contrivances that stem from the earlier 48kHz standard, but if what Neve is saying above is true, maybe 192kHz isn't such a bad idea?

Were Neve &Emmerick listening to sine tones while testing the desk? because if it was recorded material there is then another question about the frequency response of the microphones, and all of the equipment in the signal path, it suggests they would all have to have been capable of dealing (accurately) with frequencies of up to at least 54kHz.

Of course the most cynical way to explain it is that Neve sells consoles, so it's in his interest to proliferate stories like this.

[LEX]

for the sake of casting even more uncertainty on all of this consider the following, a claim made by Rupert Neve, taken from the foreword of Moylan's Art of Recording:

"In 1977, Geoff Emmerick, who, with George Martin, recorded The
Beatles at Abbey Road and later at Air Studios, London, showed me that
he could hear a difference between two identical channels on a recently
delivered new console. After some hours of listening with him, I agreed
that I could hear a subtle difference. When we measured I found that out
of 48 channels, three had been incorrectly terminated and displayed a rise
of 3 dB at 54 kHz. The limit of hearing for most humans does not extend
beyond 20 kHz and this small resonance, whilst obviously an oversight in
the factory, would not normally have been regarded as important.
One of the significant features of this episode was that Geoff was
deeply “unhappy,” even “distressed” at what he was hearing or perceiving.
Since then I have seen much more evidence that the range beyond 20
kHz is part of human awareness. Newly introduced designs which
transmit frequencies to beyond 100 kHz (with low distortion and noise),
surprisingly, sound warmer, sweeter, and fuller."

Personally, I remain sceptical, but I'm neither an expert engineer or an expert listener, I have seen it suggested elsewhere (in a more 'scientific' context) that 64kHz sample rates are the highest we need to do the job well, with 96&192 being recording industry contrivances that stem from the earlier 48kHz standard, but if what Neve is saying above is true, maybe 192kHz isn't such a bad idea?

Were Neve &Emmerick listening to sine tones while testing the desk? because if it was recorded material there is then another question about the frequency response of the microphones, and all of the equipment in the signal path, it suggests they would all have to have been capable of dealing (accurately) with frequencies of up to at least 54kHz.

Of course the most cynical way to explain it is that Neve sells consoles, so it's in his interest to proliferate stories like this.

I'll call Geoff and ask him. Though he may still be in the UK. Not the greatest at returning calls right away, but eventually does.

LEX

[digimaton]

I was just having a look across the web, to see where else the Emerick story turns up, and it's on quite a few forums, anyway found one good response:

"First, the reason for extended response into the 100Khz high frequency
spectrum of much equipment is certainly not that humans can hear that
high, but more likely because that allows flat response in the audible
range.

And second, it's indeed possible to have the result of a 50Khz frequency
modulate with other -audible- frequencies in a recording (or performance),
resulting in intermod frequencies, but the -lowest- one would be in the
30Khz range, again, pretty danged inaudible to humans. Maybe dogs?

These intermod products -could- result in some small amount of non-
linearity, but that's not terribly likely, and not terribly audible,
either."

so judging by that, though I have no idea what level of expertise this person has, 64kHz would seem to be a sensible upper limit for sampling.


also found this here (http://www.poonshead.com/articles.html), originally from Audio Technology Magazine, 2000.

Rupert Neve on 24bit 96kHz :"Well, the number of bits is OK, but the sampling rate isn't. It has to go to twice that. We have to do 192kHz because we need a reliable audio frequency range, free of distortion and noise, up to about 75kHz 3 . I can't prove that, but there's a lot of evidence from a lot of people who have done a lot of listening, and we think that if we could get a really good pass band, up to about 75kHz, we would lose absolutely nothing from the state of the art as we know it. Sampling at 96kHz would give you barely a 50kHz pass band, which is not quite enough - the resolution in the time domain is still not quite what it should be. We can go upwards from a 96kHz sampling rate, and every few kHz you add is going to make it a bit better."

just spotted another suggestion, that Emerick was not hearing the 54kHz frequency itself, but was instead hearing the result of the harmonic distortion but within the audible range, due to inter-modulation or phase effects.

There is a long discussion (http://www.gearslutz.com/board/high-end/128405-hearing-above-20khz-analog-consoles.html) on this hearing above 20kHz thing above over on GearSlutz.

[Andrew J]

also found this here (http://www.poonshead.com/articles.html), originally from Audio Technology Magazine, 2000.

I happen to have a copy of the full interview notes for that article. PM me with your email address if you'd like a copy.

[digimaton]

thanks for the offer, but is that not everything from the interviews on the website linked? is there some more stuff included?

I think it's quiet clear that some instruments do produce significant amounts of ultrasonic information, and at levels loud enough to influence our experience of one sound or another, maybe we don't necessarily hear it, but we "sense" it some how (though I imagine that is limited to specialists), so if it's missing, we notice.

But this implies that all equipment used in recording and playback will have to have a linear response up to at least 100kHz, which is simply not practical for most of us.

So going back to the original question, why the hell are the Abbey Road Brilliance VSTs band limited to 19kHz at 48kHz?? :eusa_wall:

[Michael Tibes]

I think devs often play loose with analog concepts to hype their plugins. I've seen other plugins with low pass or high shelf filtering - possibly to minimize some effects of their filtering algorithms at lower bands (e.g. harmonic distortion caused by lower order filters, etc); or that could just be the model of the original hardware. In reality, while analog technically represents the spectrum more smoothly than digital (in theory if not always audibly), it was much more difficult to create an even response across the same frequency range as modern converters (wouldn't be surprised if a lot of this hardware rolled off around 10-15k). Personally, I think a lot of the "inaudible harmonic" claims are non-technical hype, though there is some truth to the difference in effect, if not the actual technical explanations users tend to adopt.

I don't recall much older analog gear having anywhere close to the frequency response of modern digital converters. My old Lexicon delay rolled off at 15k. And that's just a delay. Older EQs probably rolled of around 12-15k, with nothing around 20k, but I'm guessing without seeing actual response curves of that gear.

But, that aside, this could be a bug - it doesn't look right, but maybe that's the model they came up with to emulate the real hardware, or at least what they had to do for 44.1/48k.

I have never measured analog studio gear which had a frequency response inferior to an A/D at 44,1/48kHz in the top end. The micpres / EQs and compressors I know are normally +/-1dB flat if they're trafo balanced, the transformers are the weakest link in the frequency response. Even tape goes beyond 20k with a good deck and alignment, though the frequency response will be slightly more bumpy. A V72, a design of the early 50s, goes from 20Hz to 20kHz within a dB if you take out the locut filter. A TG 12413 is flat up to 20kHz, then falling gently (at least the one I just built, that's without transformers).
Your lexicon delay falling at 15k might be because it's digital? And what EQs do you mean that have 'nothing' at 20k? Starting to roll off at 12-15k and being gone at 20k is a really steep filtering which normally needs quite some effort to design. Even the german broadcast equipment designers which seemed very scared of the 18k pilot tone didn't add such filters. Nevertheless I sure don't know every device, so maybe there are some designs which had a steep rolloff?

Michael

[Andrew J]

thanks for the offer, but is that not everything from the interviews on the website linked? is there some more stuff included?

Actually, it looks like that website has most of it.