32 bit recording from 24 bit hardware?

[RawDepth]

The strangest thing! I seem to be able to record to the multitrack in 32 bit depth but, my A/D converters are only capable of 24 bit. How can this be? Does the software interpolate somehow?

I use an RME sound card.
Toslink input, external (44.1/24) A/D converters.
The card came with a combination ASIO and MME driver. (Only I understand C.E.P. is only using the MME part of the driver.)

I read somewhere that MME is limited to 16 bits.

What gives hear? And is my "make believe" 32 bit any better than 16 bit?

[chrisharris]

Originally Posted by RawDepth

What gives hear? And is my "make believe" 32 bit any better than 16 bit?

"32 bit" is a mathematical fiction created (as I understand it) to allow a greater margin of error for math rounding...or something. All I know is, "32 bit" is actually 24 bit audio.

[Rusty K]

Yes and don't forget sample rate. I'm recording at 48K (all my soundcard will do) but Cool Edit/Audition I believe will go up to 96K. My ears are happy with 24bit 48K.

Rusty K

[rpc9943]

32bit is higher than 24bit... It's better than protools. This gives ultimate lossless detail in recordings, so that when you do dither down to 16bit for mixes, it will not be lossy. To see a noteworthy difference between bitrate, try listening to one of your 16bit recordings, or a cd. Then convert it to 8bit. The difference is very obvious. Now imagine what 32bit does more than 16bit! You also might want to note, if you record things 32bit... You can also go past the clipping limit (0 dB) without distortion or loss of data. That is amazing. So you don't even have to worry about volume levels as you record! Of course you'll have to fix it afterwards to burn to cd, but still...

RonC

[lpdeluxe]

as Blue Bear would say, it's bit depth, not bit rate.

[Blue Bear Sound]

Originally Posted by lpdeluxe

as Blue Bear would say, it's bit depth, not bit rate.

Not only that -- our "buddy" Ron here is completely wrong about 32-bit audio.

Someone already pointed out that 32-bit audio IS in actuality 24-bit digital audio - and they were exactly right. The extra byte is for floating point calculations and minimizing round-off error. It isn't 32-bit digital audio - there's no such thing at this point in time.

[apl]

Originally Posted by rpc9943

You can also go past the clipping limit (0 dB) without distortion or loss of data.

I have not heard about this at all. Please explain. Is the extra byte available above 0 dB?

[Blue Bear Sound]

Originally Posted by apl

I have not heard about this at all. Please explain. Is the extra byte available above 0 dB?

Ron was talking gibberish -- I think he needs to brush-up on his digital audio theory....... he's pretty far off-the-mark.

[chrisharris]

Originally Posted by Blue Bear Sound

Ron was talking gibberish -- I think he needs to brush-up on his digital audio theory....... he's pretty far off-the-mark.

He was kidding.

[Blue Bear Sound]

I hope so!

[RawDepth]

Thanks for the eye opener folks. At first glance one would opt to always use 32 bit depth to record. With most of our plugins already working at 32 bit, it only makes sense.

However, I have file size to consider as well. With live mobile recording, I may be faced with recording as many as 24 tracks simultaneously and usually for 3 to 4 hours. Bit depth will surely make a big difference. Won’t it???

I mean, I know HD space is cheap now-a-days. I can devote an entire harddrive to a single session and then shelve it for archiving. But, with live bar recording there are screaming drunks, clanging glasses, buzzing guitars, running air conditioners, cross-talk in mics, and all kinds of problems plaguing the tracks. Do you think anyone will ever say, “Damn, you ruined the whole project by tracking in 16 bit”, ?

What do you think?

[chrisharris]

Originally Posted by RawDepth

What do you think?

You're right about the actual recording. If you were to JUST record a performance on 2 computers (one in 16bit, and one in 32 bit), and then ask the best ears in the world to tell you which is which, only about 50% would get it right - which is the same amount that would get it right through random guessing. I don't think you can HEAR the difference in recording.

I think that if you are going to be making very few edits to files, then the difference between 16 and 32 bit is marginal. However, the more edits you make (i.e., compress the whole file, EQ the whole file, limit the whole file, re-EQ the whole file, etc), the more important it becomes. I probably cannot explain this very well, b/c all I'm basing it on is my own ears...but my experience has been that the more you do to a file "in the box," the more important the bitrate becomes in CEP/AA.

[Rusty K]

If you are going to the trouble of recording 24 tracks separately then it would seem that you would likely do some editing....otherwise just do a stereo mix 16bit. You better have a "humpin" CPU though.

Rusty K

[RawDepth]

Originally Posted by Rusty K

You better have a "humpin" CPU though.

Rusty K

Yes, it is indeed one bad-ass rig. Each and every component hand picked for ultra high end performance and stability. From the Golden Dragon dual channel memory all the way down to the Raptor 10,000 rpm HD. Even the power supply is high end.

It eats Dells and Gateways for breakfast.

[Rusty K]

Raw,

Would you mind giving some more detail about your rig. Is is custom built from top to bottom or a brand name with picked options?

I just wanted to know for my next computer upgrade.

Rusty K

[RawDepth]

The whole recording rig is not complete just yet. I am still waiting on two A/D converter cards for the front end gear. It is about 90% complete though.

As far as the computer, I built it myself. For years my hobby has been building and repairing computers. My two sons and I have become deeply drawn into building “hotrod” computers just to out-do each other. Just like in drag racing, we have studied and experimented with tons of high performance parts and pushed most of them to their limits. Between the three of us, we have probably blown enough money on computer parts to put them both through college. And all in the name of just having fun. I am also a veteran musician and sound engineer.

When it came time to build my music rig, I focused mostly on what I’ve learned about stability. Having a system that crashes and/or misbehaves while clients are sitting there has got to be embarrassing as well as bad for business. Being mobile means that it must also be tough and withstand somewhat harsh conditions. It won’t always be sitting in a nice clean air conditioned studio. I’ll take it to bars and rehearsal rooms to make live demos for local bands.

Recording a high number of tracks means I need speed and power too. Laptops are most portable but lack performance because of the way they are designed. Laptop CPUs, memory, and drives are all designed to be lighter, run on lower power, and create less heat. This translates into a lot less muscle and speed when compared to desktops with the same ratings.

I used a full size rack mount PC case. When complete, my whole rig will be contained in two rack mount road cases complete with wheels and handles. It will accommodate any type of input signal and be comprised of power conditioners, isolated mic splitters, 24 hardware mic pres with inserted dynamics, and two recording machines, one for 2 track and one for 24 track.

I took my time and carefully thought out each component. I tried to determine what areas I could skimp in and what areas I could not. I finally settled on the following components:

Epox 8RDA3+ mobo with 400fsb and nForce2 chipset
AMD 3200+/400mhz “Barton” core
1GB Geil Golden Dragon dual channel DDR433 (no heat sinks needed)
WD360GD 10,000rpm Raptor w/8mb cache
WD800JB 7200rpm w/8mb cache
Liteon DVD+/-RW
The award winning PC Power and Cooling, Silencer 360 ATX
All silent cooling fans and HD coolers, less than 20dB.

It is turning out to be one sweet rig. I may consider selling recording rigs like this as a complete package deal some day. I could make them a lot cheaper by reducing them to 16 or even 8 channels.

What do you think?

[Rusty K]

RawDepth,

Cool very cool. I may never need to record 24 tracks at one time so your rig might be more than necessary for me, but I think it would sell if it's as good as you say. I like your approach (obviously from an experienced musician/tech perspective).

Excuse my technical ignorance, but would one just roll it up and plug mics into it or would a mixer be in between?

Could you give a "ball park" figure for the total cost to me.

Thanks,
Rusty K

[RawDepth]

No mixer needed. One can just plug mics into it and record independently of the house mix. It will split the mic lines either at the stage or at the FOH (front of house) position. I could also just use inserts cables to get signal from the house mixer straight into a patchbay if I needed to. A snake can be used to get the rig away from the ambient room noise, like to another room or perhaps to a truck. I am considering experimenting with digital snakes pretty soon too.

I have about $4800 into it now. That is paying retail for everything. I imagine that I could build them for less if I started a dealership.