Headroom on Creamware Cards

cleanbluesky · Post by **cleanbluesky** » Sun Sep 12, 2004 2:31 pm

Hi

I have a Pulsar II and a Audigy Plat Pro (Convinced to buy the Audigy by sales-hype before I found out about pro cards, laugh all you want)
And I was wondering what is the headroom on Creamware cards as it seems to be realy high. So high that my mixer channel-inputs will overload before my analog inputs do... I don't have a great mixer so it would be a good idea not to have to use it to maximise signal level before the CW card.

I would also like it if anyone could suggest a mixer that would be appropriate...

nprime · Post by **nprime** » Sun Sep 12, 2004 4:47 pm

I am a little confused by your question.

Are you saying that your board cannot provide enough gain to overload the Pulsar input? Is your board outputting a -10 or a +4 signal?

If it's -10 then it may not be enough to fully drive the Pulsar input.

R

[ This Message was edited by: nprime on 2004-09-12 17:47 ]

bassdude · Post by **bassdude** » Sun Sep 12, 2004 6:36 pm

On 2004-09-12 15:31, cleanbluesky wrote:
Hi

I have a Pulsar II and a Audigy Plat Pro (Convinced to buy the Audigy by sales-hype before I found out about pro cards, laugh all you want)
..........

Ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha!

Do you have rca or xlr connectors on you pulsar 2? What mixer are you using?

cleanbluesky · Post by **cleanbluesky** » Mon Sep 13, 2004 3:54 am

I have XLR connectors on my Creamware and I am using a Behringer Mixer. I CAN overload the CW inputs using gain from the mixer but my preamp will overload the line-in on the mixer before the mixer will overload the CW inputs (without extra mixer gain)

petal · Post by **petal** » Mon Sep 13, 2004 4:28 am

I'm not sure I understand your problem either, but you do know that a digital mixer (read the cw mixer) will clip at 0 db right? and the level should therefore be set lower than on an analog mixer.

cleanbluesky · Post by **cleanbluesky** » Mon Sep 13, 2004 6:50 am

The reason I would like to be able to overload my CW inputs is that in order to get the best recording as much of the headroom should be utilized as possible without overloading. If I cannot boost my signal to just before the point of overloading then I will not get the best recording. I would rather NOT use my mixer for this as I have seperate preamps and I try to use my mixer as little as possible in order to decrease the amount of 'gain stages', each of which have an effect on the sound.

cleanbluesky · Post by **cleanbluesky** » Mon Sep 13, 2004 6:51 am

On 2004-09-13 05:28, petal wrote:
you do know that a digital mixer will clip at 0 db right?

Do I have it right that 0db is a relative measure of headroom left on the unit? If that is the case then 0db should be different for each unit if they have different levels of headroom

Basic Pitch · Post by **Basic Pitch** » Mon Sep 13, 2004 9:40 am

0bd is max gain for a digital mixer ala SFP, once you exceed that value you then are suseptible to digital clipping. Depending the sound all your sounds do not have to be maxed fully, its all about dynamics in the end, alot of people mistake loud mixes as them being recorded hot, that is not always the case, most of it is in the mastering.

I always try and get a nice hot signal from outboard stuff to besure I dont get alot of noise, but trying to squeeze every last ounce out is not always needed.

Cheers!

nprime · Post by **nprime** » Mon Sep 13, 2004 10:51 am

On 2004-09-13 07:51, cleanbluesky wrote:
On 2004-09-13 05:28, petal wrote:
you do know that a digital mixer will clip at 0 db right?
Do I have it right that 0db is a relative measure of headroom left on the unit? If that is the case then 0db should be different for each unit if they have different levels of headroom

In the analog world 0 dB is referenced to a fixed voltage amount, and does not tell you anything about the amount of headroom available, it varies widely and the better units are said to have more headroom (such as +12dB or +20 dB or whatever.

In the digital world 0 dB is all she wrote. It is the end of the line. Exceed at your peril. So you do not want to push the level so hard that you actually touch 0 dB very often.

Now in practice most manufacturers actually do leave some headroom (3 to 6 dB) because they know that musicians are likely to want to push the limit. So, you must experiment to find out when actual clipping of the signal occurs. If you look at the recorded waveform you will see the wave square off at the top and bottom, that means you have exceeded digital 0dB.

If you have outboard pre-amps they should sound better than your mixing board, use them straight into the Creamware card and see how that works out.

Are you talking about recording with microphones or are we talking about synths, guitar, bass, etc? For the guitar and bass use a quality direct box into a good pre-amp. Honestly I would be surprised if you cannot drive the Creamware card directly from your synth's outputs.

R

[ This Message was edited by: nprime on 2004-09-13 11:52 ]

blazesboylan · Post by **blazesboylan** » Mon Sep 13, 2004 1:00 pm

Gaaaaa! You all are going to make my head explode!

A deciBel is a unit of change. It is not a unit of measurement in itself. There are units of measurement that use the decibel scale -- in voltage / sound pressure level / whatever. But dB is NOT A UNIT OF MEASUREMENT.

In the analog audio world there are several units of measurement, including dbm (older units especially rate at dbm with a 600 ohm input / load impedance reference), dbv, and the relatively more recent dbu.

Consumer gear and most keyboards, guitar pedals, etc, output signals at -10 dbv RMS. That means basically that the nominal output level is -10 dbv. You can measure this with a multimeter strapped to hot and cold, or hot and ground. (EDIT: You would do this by sending a sine wave to the output and then reading the AC RMS voltage. The voltage should read 0.316227766 V.)

Pro audio gear output signals at +4 dbu nominal level. Older units output at +4 dbm or +8 dbm RMS, referenced at 600 ohm load impedance.

There are variations, but you're not likely to come across them unless you buy a Mackie mixer (+0 dbu output for many of the outputs) or some esoteric broadcast equipment or DIY gear.

In the digital realm there is also the dbFS (full scale) measurement, which is the clip level for an A-D converter. For example, an A-D converter that accepts +4 dbu nominal levels will clip at 4 dbu or 0 dbFS. A converter that accepts -10 dbv nominal levels will clip at -10 dbv or 0 dbFS.

(In the "air" world there is also db SPL (sound pressure level)... There is also db power for amplifiers... etc...)

Here's an example of a page that discusses the difference between the various units:

http://www.jimprice.com/prosound/db.htm

As Rod stated above, sending the output of a -10 dbv - rated unit into the input of a +4 dbu unit will give you a weak signal.

Often a mixer will have a switch on the back to choose between -10 dbv and +4 dbu output. Some A-D converters (such as the A16 Ultra) also have switches.

If you can't match the levels using your existing gear I would highly recommend adding a line level shifter, which will match between -10 dbv and +4 dbu.

However the other possibility is that you're sending unbalanced signals to balanced inputs. Because of the way unbalanaced and balanced signals work, you will lose 6 db right there. So, for example, if you're sending -10 dbv from your mixer, then the input of your audio card will get -16 dbv. You would then have to crank the mixer by 6 db in order to clip at the audio card input, if the nominal levels are matched.

I hope this makes sense. And please... Stop referring to "db" as absolute units!

Cheers,

Johann

Grumpf!

[ This Message was edited by: blazesboylan on 2004-09-13 14:13 ]

Basic Pitch · Post by **Basic Pitch** » Mon Sep 13, 2004 1:15 pm

^---- Scientific Guy..

[ This Message was edited by: Basic Pitch on 2004-09-13 14:21 ]

blazesboylan · Post by **blazesboylan** » Mon Sep 13, 2004 1:32 pm

sci·en·tif·ic
Pronunciation: "sI-&n-'ti-fik
Function: adjective
Etymology: Medieval Latin scientificus producing knowledge, from Latin scient-, sciens + -i- + -ficus -fic
: of, relating to, or exhibiting the methods or principles of science

nit·pick
Pronunciation: 'nit-"pik
Function: verb
Etymology: back-formation from nit-picking
intransitive senses : to engage in nit-picking
transitive senses : to criticize by nit-picking

nprime · Post by **nprime** » Mon Sep 13, 2004 2:22 pm

You is so smrt!

I was being fast and loose with the terminology.

I think I am correct to reference O dB to voltage in the analog world.

My other use of O dB as a reference to being out of headroom is o.k. isn't it? As in we reference all other levels as -X dB compared to it?

You seem a litle excitable this morning, are you pissed off that Bush is leading in the so-called "polls"?

Go look at porn for a while, that always cheers me up! Try to come up with a unit for "sluttiness".

R

cleanbluesky · Post by **cleanbluesky** » Mon Sep 13, 2004 3:45 pm

On 2004-09-13 14:00, blazesboylan wrote:
I hope this makes sense. And please... Stop referring to "db" as absolute units!

I was referring to dB as an absolute term as I didn't want to get into it...
but thank you for your long and fruitful explanation...

On 2004-09-13 14:00, blazesboylan wrote:

If you can't match the levels using your existing gear I would highly recommend adding a line level shifter, which will match between -10 dbv and +4 dbu.

If you read back, I said I wanted to use my preamps to do all the gain without overloading my mixer. I can overload my CW card very easily using gain on my mixer, but my preamps will overload the inputs to my mixer before I can overload my CW card without mixer gain.
The easy solution to this is to connect my balanced preamp output to the balanced connections at the back of my CW card.
BUT DOING THIS MEANS THAT I HAVE TO F**K AROUND WITH ALL THE WIRES, UNPLUGGING THIS AND PLUGGING IN THAT AND TANGLING ALL THE USB, FIREWIRE KEYBOARD AND MOUSE AND OTHER S**T THAT LIVES BEHIND MY COMPUTER THAT I LIKE TO IGNORE!!!!!!
Ahem. As i was saying, I would like a mixer that I did not have to use gain on...
Maybe it is a guitarist thing, becoming obsessed about gain stages and types of circuitry used for gain but I my preamp is better than my mixer pre and I wanted all the gain (or as much as possible) to come solely from the preamp.
The reason I want this is that in order to master a song properly, full advantage must be taken of headroom. In order to do this properly it is wise to record everything with as little headroom left as possible, to avoid digital multiplying the signal.

nprime · Post by **nprime** » Mon Sep 13, 2004 7:13 pm

as I said earlier, why would you plug a pre-amp into a mixer? that is not right.

Pre-amps should plug directly into the Creamware card. There is no reason to provide any gain at all for the pre-amp, it will output a signal strong enough for the card. to run it through the board destroys the entire concept of an outboard pre-amp.

Does this make sense to you?

Is it really that much trouble togo behind the gear and plug something in? If it is then it's time for some housekeeping!

R

P.S. whining about the mess behind the computer will get you no sympathy here, how about investing in a patch bay?

astroman · Post by **astroman** » Mon Sep 13, 2004 7:15 pm

On 2004-09-13 16:45, cleanbluesky wrote:
... BUT DOING THIS MEANS THAT I HAVE TO F**K AROUND WITH ALL THE WIRES, UNPLUGGING THIS AND PLUGGING IN THAT AND TANGLING ALL THE USB, FIREWIRE KEYBOARD AND MOUSE AND OTHER S**T THAT LIVES BEHIND MY COMPUTER THAT I LIKE TO IGNORE!!!!!!
Ahem. As i was saying, I would like a mixer that I did not have to use gain on...

I once had a small Behringer mixer (DJ-type style) for the same 'convenience' in the signal chain. While it was in fact a handy unit I was rather shocked how much a device with rather 'good' specs (according to the printed doc) could blur the sound - qualitywise is was completely unusable.

I assume that your mixer is a better one, but I'd still suspect the signal gets degraded (unless it is a very high quality one).

I've recently found a simple, yet extremely high quality solution - unfortunately a DIY project from the hifi domain about leveling and switching signals.

The 'standard solution' for your setup (as you probably know) would be an A16ultra or alike converter - if money matters the project mentioned above could be an affordable alternative (if you don't need more simultaneous inputs that your card provides).
The project was introduced in Elektor 4/2004 and usually that stuff appears in kits (sometimes even pre-fabricated) soon after the latest part of the print sequel.
Probably some adaption for symmetric signals required, though - but it's a very interesting design if one wants to keep the original signal as clean as possible.

cheers, Tom

[ This Message was edited by: astroman on 2004-09-13 20:17 ]

Post by **hubird** » Mon Sep 13, 2004 7:22 pm

check out the purchasing forum, 2 A16's to sell...

dehuszar · Post by **dehuszar** » Mon Sep 13, 2004 8:25 pm

Is your Behringer pure analog chain? Even if it is, I don't think it's going to do what you want. If I'm understanding you right, you're trying to get a nice warm analog over-driven sound and are trying to find out what the input limits are on the CWA cards.

If your behringer is in anyway digital, boosting it there will probably cause clipping before it even gets to the CWA card, and even if it's not, I wouldn't trust the Behringer pre's to give you a good sound. If you have an old dual-tape player/recorder with a variable gain, that'd do the job pretty well, or something like that.

Unfortunately, digital boosting just makes sound crap out as opposed to giving you that harmonized crunchy sound.

Either way, if you can get the volume loud enough to color the sound in the way you want, you can still reduce the gain on most of the CWA mixers so you get the coloration but not blow your speakers or overload the channel.

Hopefully that's sort of what you meant...

Sam

nprime · Post by **nprime** » Mon Sep 13, 2004 10:00 pm

You think that's what he means? Then I've been no help at all.
R

dehuszar · Post by **dehuszar** » Mon Sep 13, 2004 10:41 pm

No,I think it was me who mis-understood.

Either way, you can still use the gain adjusters on the CWA mixers to boost the signals from the Behringer so long as the Behringer is not introducting too much noise into the mix.

In fact, the best way to get a clean signal is to keep the Pre's volume super-low and adjust the CWA gain as high as it will go. That way you'll get the least amount of electrical noise coloring the sound on the Behringer end.

Just be REALLY CAREFUL with your volume settings as the gain range is fairly powerful, and you could easily damage your monitors or ears drums.

You've been warned.

Hope that helps,
Sam