24-bit and 48/96Hz - what's the difference?

[Scotsman]

In my research for a front-end incorporating preamps, phantom power and a/d conversion, I've come across numerous products.

One of these is Mindprint's Di-Port, which just happens to be the most readily availalbe and affordable for my needs. I've already posted about that though so I shan't repeat myself and annoy everybody.

The point of this question relates to the bits and hertz. The Di-Port is capable of 24-bits and 96 Hz. My SB Live soundcard is only capable of 16-bits and, as alfalfa kindly pointed out, this would lead to truncation -- which presumably means something like 8-bits will simply be lopped off. It doesn't sound good.

Alfalfa has been a big help in pointing out the C-Media CMI8738 chip which is available on several budget soundcards. I found a fairly good list of cards with this chip here. The documentation for this chip states that this chip supports professional digital audio interface such as 24-bit SPDIF IN (0.5V ~ 5V) and OUT (44.1K and 48K format).

So it seems that I could transfer the converted 24-bit digital data from the Di-Port digitally to the PC without the truncation that would occur with a 16-bit soundcard, but I'm not sure what the 96/48 Hz thing is all about. Could someone explain in simple terms what it means, and whether it would make any real difference to any music I would record.

And in the board's opinion, would the Di-Port and a soundcard incorporating the CMI8738 chip be a good solution for someone with minimum recording requirements?

Thanks
Jock <after days online, just *beginning* to understand...>

 

[christiaan]

We're talking about sample rates here. And it's not in Hz but in kHz. An audio cd for instance is 16/44.1 which means 44100 samples of 16 bits per second to describe the soundwave. Obviously higher is better, especially for higher frequencies.
FYI: The Di-Port does not support 96kHz, just 44.1 and 48 which I think is just fine for most home recordists.

 

[alfalfa]

44.1/48/96khz refers to the sample rate. 16/24 is the bit depth.

If you are recording with the goal of producing a CD then you will be fine at 44.1 khz (which is the CD standard). Theoretically recording at a higher sample rate (eg 96khz) is higher quality but you end up downsampling to 44.1 for transfer to CD and I doubt most home recording setups will allow you to notice any difference. I do all my recordings at 24bit 44.1 then dither the final 2track mix to 16 bit before burning to CD.

Do a search on sample rates for more info.

Your DIport / cmedia combination should work well. For others that may not be aware the cmedia chipset is the same as that used by the M-Audio DIO 2448 (and can use the M-Audio drivers for asio etc). You could always continue to use your soundblaster but you would be limited to using 48khz (one of the restrictions of the live digital i/o) and you have the truncation issue. You could record at 48 and resample your final 2track mix to 44.1 before burning a CD.

An alternative is to get a basic pro soundcard like an Echo Mia, M-Audio Audiophile, Terratec 6Fire or EWX24/96 and combine that with a basic mixer from behringer/mackie/soundcraft or a dedicated preamp. Lets see what others have to say.

 

[Track Rat]

Here's my take on sampling rates. The rule is the highest frequency that can be reproduced is half of the sampling frequecy; 44.1k=22KHz, 48k=24KHz etc. Obviously this is a good thing. BUT, resampling can undo all the good of the higher sampling rate. I'm refering to artifacts that can be introduced in the resampling process not to mention the storage/processing hit on your work station having to deal with twice as much data. Longer word length (bit depth) on the other hand has the most bang for your buck. Tracking and mixing at 24 bits/44.1k and dithering the final two track master to 16 bits is the way I prefer to work.

 

[Scotsman]

An alternative is to get a basic pro soundcard like an Echo Mia, M-Audio Audiophile, Terratec 6Fire or EWX24/96 and combine that with a basic mixer from behringer/mackie/soundcraft or a dedicated preamp

Thanks for the info so far; it really is a steep learning curve.

The Terratec EWX 24/96 card is still affordable; would that be any better a card to go with the Di-Port than one with the C-Media chip? I guess that if the Di-Port only samples at 48KHz, a 96KHz card would be overkill.

Jock

 

[alfalfa]

If you get the terratec you will have to factor in the cost of getting a mixer or preamp. The terratec has no preamps or headphone amp like the diport. And despite the fact that it can record at 96khz (which you will likely never use), the terratecs converters are probably slightly worse than the diport at 44.1/48.

If you can get the diport for a decent price it is a good all in one option for now. You can always use a diport with a terratec later to get 4 simultaneous inputs if you need to expand.

EDIT: ok i just reread your post. Did you mean to get a diport and an ewx2496? If so then yes an ewx2496 is better than a cmedia card. I only recommended the cmedia card because I was assuming you didnt want to spend much more after getting the diport. However if you were getting the terratec then you would question whether the diport is the best companion to it or a mixer or a dedicated pre. The diport/terratec combo will give you 4ins and outs if you need more than 2 i/o.

 

[Scotsman]

Did you mean to get a diport and an ewx2496? If so then yes an ewx2496 is better than a cmedia card. I only recommended the cmedia card because I was assuming you didnt want to spend much more after getting the diport.

I did mean the Di-Port with the Terratec card, and I did want to keep the cost down which is why the cmedia card seemed such a good option. However I've heard from someone with a cmedia card who said that the chip can't handle a 24-Bit 48 kHz input without downconverting/resampling (in digital loopback it can, but that's useless, unless converting from optical to coax). He said that the card gave average to very poor test results and the drivers were buggy, and then went on to say that the Terratec would be a better long-term investment. Since the Terratec is a more popular card, I should be able to pick one up on ebay for not much more than a new cmedia card would cost. Makes sense, don't you think?

However if you were getting the terratec then you would question whether the diport is the best companion to it or a mixer or a dedicated pre. The diport/terratec combo will give you 4ins and outs if you need more than 2 i/o.

I've looked into various options (mixers, dedicated pres, Aardvark, SM Audio Pro) and it seems that the Di-Port is a good solution as it has decent pres and carries out the AD conversion externally. It's also affordable and available, so I'm tending towards that now. I think it would make quite a good partnership with the Terratec card and, as you say, would provide another line-level input if I needed it.

BTW, the Terratec card uses the same DAC as on the Delta 44 & Delta 66 cards.

Thanks once again for the input.

Jock

 

[alfalfa]

The cmedia card does not resample (unlike soundblasters). I am not sure why your friend says that because many people have used it with no resampling. No resampling (along with the 24bit digital i/o) is one of the major pluses of the cmedia chipset over other budget consumer cards.

The cmedia card is definitely a budget option and not as good as a pro audio card (I use an Echo Mia which is a great card in that price range). If you can afford a pro audio card or get one cheap second hand then get it. Unfortunately here in Australia a new EWX24/96 costs 10 times what a cmedia cards costs (Aus$40 vs 400) so second hand it would be at least 5 times the cost.

However the cmedia cards do work for bit perfect digital i/o. I am not sure what measurements your friend refers to (perhaps analog measurements but I am only referring to the digital capabilities). Driver wise Cmedia I agree is not optimised for pro audio but you also have the option of using the m-audio drivers (though there wont be any maudio updates). I am not saying it is as good as a proper pro card but it is definitely useable and at an unbelievably low price (though those trust cards seem overpriced, double what cmedia cards cost in Aus, Asia and the US and the same price as the hercules muse and terratec aureon fun which are name brand cmedia implementations - at that price I would go with the muse or aureon fun).

I was aware the terratec uses the same converters as the delta 44. The diport converters are slightly better and measure better than both the terratec and maudio cards (you can compare the sound on sound measurements). Whether you notice any difference is a separate issue (the difference will be subtle). All will be a big improvement on your sblive. Dont get hung up on internal vs external conversion. The soundcard with the best measured sound quality (lynx2) uses internal converters.

The Diport and the EWX24/96 is a good combination and will serve you well. Have fun!