A16 Ultra usage

[t_tangent]

I have just set up an A16 Ultra and am having a bit of a problem figuring out how I can hook up a mic to it. I was led to believe that I could just plug in a mic to one of the ins, but it seems I might need a mic pre to get enough signal, as when I tried with the mic I was getting no signal at all. If some kind soul could explain a little about how the A16 is used or how you guys use it, that would be really appreciated. I know this sounds a bit dumb, but I have never had any outboard gear before and just recently started to aquire some, so its a new area for me. But I did manage to get my second hand (new to me) Lexicon MPX1 setup via the spdif and that is working well.

Anyways, thanks again

[hubird]

only line level input, and that's normal.
it's like with a classic (vinyl) pickup, it needs a special input on the amp.
I use a supasmall Mackie 12/02mixer in my studio, it has a few mic inputs

[t_tangent]

Hi Hubird, Thanks for the reply. Yeah I thought that might be the case. I will have to get hold of a preamp or something then I guess.

While on this topic, I was wondering if the following is normal with the A16.

I have the A16 hooked up via firewire cable to my scope z-link card.
In the Scope Samplerate settings my scope card is set to master and when I turn the A16 ultra on the z-link light goes green, but the bottom channel meter lights start flickering green, seems to be a random flickering across all the channels, but only the bottom meter lights. If I link the z-link module inputs to a mixer in the routing window then there is some flickering in the meters, so there is obviously some kind of noise or hum on the A16 inputs. Could this be due the z-link cables as they were not particularly high grade cables. I will try some ADAT cables when I can get some, but any other ideas would be helpful

Thanks

[astroman]

the A16U channels are 'open', so there is of course some noise.
The level display on the mixer will tell you how much. Push the small 'reset margin' button and it will tell you how much.
This is not the 'true' noise level, as the channel needs proper termination, but it's enough to estimate if something is wrong with a cable, ground level, noisy environment, or even the software setup.
If your figures are (almost) equal across all channels and read less than -85 dB everything is ok.

The digital cable does not introduce any noise at all, same applies to the Adat connectors. A malfunction of any of these would rather cause drop outs and sync problems.

cheers, Tom

[voidar]

Whoa, -85dB. The A16U is a noisy ADDA.

In my environment I seem to get around -81dB static. I recently discovered this was a problem when I was trying to do some reamping.
Even using the Flexor Heavy Distortion shaper at 3/4 full tilt, the amplified self-noise level is pretty irritating.

I don't have the best ADAT-fibre, but I am not that long off the -85dB mark. And I guess my environment is pretty noisy. Oslo has severe grounding issues from the start off.

[astroman]

and ?
the best audiophile vinyl on a high-end recordplayer for several thousand Euros will never yield any better than a 65dB SNR
this is about 5 times higher (in level) than your static 'problem'

cheers, Tom

[voidar]

Well, I am just saying it can easily become a problem when using high gain/clipping/compression on a source, like DI guitar.

[garyb]

well, a high gain guitar amp is a noise machine, so....

i think the real problem happens when using 16 bit resolution with low levels and many tracks. the combined noise in such a situation would be worse than an old cassette tape...noise is cumulative.

specs can be misleading. there are many things that go into a good sounding AD/DA and s/n is one of them. i don't think the noise floor is bad on the A16. although it could be lower, it is still very low for real world listening environments. we have become rather spoiled in the spec dept in the digital age, but high spec doesn't necessarily sound bad and lower specs don't necessarily sound bad, as anyone who's ever heard the difference between a really good pressing on a really good turntable can tell you(this was astro's not so subtle reference. ).

ahhh, young people....

[chriskorff]

Does anyone know if the published SNR or the real-world SNR are weighted? I'm guessing the -85dB figure is broadband, since that's how the mixer meters work...

[voidar]

A good high gain amplifier just amplifies what is there to begin with.

Some noise can sound pleasant, and in some way the A16U noise masks the noise I get from going direct into the amp, in a good way. There is some weird RF-noise I pick up now and then.

What we really need is a "thick smokey" dither/noise-shaper plugin, so that you could add pleasant low-level noise to your signal .
Perhaps just mix in some pink noise.

[astroman]

...specs can be misleading. there are many things that go into a good sounding AD/DA and s/n is one of them. i don't think the noise floor is bad on the A16. although it could be lower, it is still very low for real world listening environments. we have become rather spoiled in the spec dept in the digital age, but high spec doesn't necessarily sound bad and lower specs don't necessarily sound bad, as anyone who's ever heard the difference between a really good pressing on a really good turntable can tell you(this was astro's not so subtle reference. )...

I'd rather extend that first sentence to specs are made misleading
recently someone advertized an M-Audio Audiobuddy preamp on eBay with measured(!) specs - they really wrote 'measured'
wtf - I have that piece of crap and it showed (empty) on the Scope mixer with a noise level no better than -70 dB, though specs told 100dB or so. A 0.000x THD figure but a blurred signal...
Btw M-Audio completely changed the printed specs on their website and in the manual of the thingy... they don't give numbers anymore

dB is a relative unit, so it only gives conparable results if the scale is known and applicable.
following excerpt is from wiki Sampling (signal processing)

...CD quality audio is recorded at 16-bit. In practice, not many consumer stereos can produce more than about 90 dB of dynamic range, although some can exceed 100 dB. Thermal noise limits the true number of bits that can be used in quantization. Very few analog to digital converters have signal to noise ratios (SNR) above 120 dB, which make useless the need of greater than 20 bit for the quantization process. In 24 bit converters, the 4 LSB has useless random values with no information...

to me it often seems they just take the theoretical maximum figure and then add a most optimistic final bit deviation in spec sheets.

Gary, I really love to hunt for good pressings (when time and cash allows) - but that would at least require a person actually can listen.
My hint was even more profane, as it referred to the plain vinyl surface without any signal recorded.
This surface has a certain roughness that will never allow any lower than about 65dB SNR

cheers, Tom

[Neutron]

feed the output to an input, then those directly to asio in/out and use the RMAA on it. then you will know the overall S/N of your system. ill try it tonight with my A16u as well.

http://audio.rightmark.org/index_new.shtml

[chriskorff]

I have that piece of crap and it showed (empty) on the Scope mixer with a noise level no better than -70 dB, though specs told 100dB or so.

The discrepancies you describe probably have the same cause as with the A16U — that is, mixer meters display broadband level, and the 100dB figure is, most probably, 100dB A-weighted, meaning that noise in the more audible part of the spectrum (the mid-range frequencies to which our ears are most sensitive) is given more 'weight' (they basicallly try and 'push' the noise away from the frequencies that we are most sensitive to, a bit like noise-shaped dithering). This is why the meter reading is, in fact, fairly useless in telling you how much noise you hear from a piece of equipment, because it doesn't take into account the fact that a lot of the noise is in the non-critical bands (the more, the better, obviously).

As long as the 'published' or 'measured' noise figure is given a weighting (A, C...), it does at least tell you something (if only slightly) useful, in terms of comparing noise figures — especially if you assume that all manufacturers do their damndest to test their gear in the best possible conditions, and that their figures are likely to be better than in the real world!

[katano]

Hi,

As I wrote about two years ago, I still love my tfpro 16x in addition to my A16Ultra... If you don't need that many channels at once (i.e. recording drums), go for a decent mono or dualmono/stereo channelstrip or preamp

http://www.soundonsound.com/sos/feb04/a ... /tfpro.htm



Cheers
Roman

[astroman]

...The discrepancies you describe probably have the same cause as with the A16U — that is, mixer meters display broadband level, and the 100dB figure is, most probably, 100dB A-weighted, ...

I don't think so, because I never met any gear where the a-level deviated for about 30dB
more likely they just looked up the specs in the opamp datasheets... as mentioned M-Audio removed those figures completely from their website. The seller on eBay isn't very likely to be sued, as noone would seriously expect this performance from a $80 dual channel thing anyway.
I once bought such an Audio-Buddy because of an example clip on a mag CD, which really did sound quite good in comparison to the other participants of the 'test'.
Real world turned out to be a different game, tho - sometimes you have to pay a little bit for education...

cheers, Tom