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signal to noise ratio
by Doubledashie on 2012-09-17 19:07:20

http://f.cl.ly/items/3X1k213R0l161v0g212u/jam1.mp3

This is just a quick recording using some of my favorite tones from the hd 500

I'm getting a bad signal to noise ratio and also some ugly clipping. I'm not quite sure what's causing it. I'm using cubase 5 and I'm recording directly from my pod hd 500 by usb to my computer. The instruction manual says I should put the master volume at max, but I thought that was for amps or input into a digital audio interface and didn't change the signal to noise ratio via direct usb.

notice the wide panned left rythym guitar hisses alot and the right lead guitar clips and pops constantly at the beginning. And I can't hear anything when all 3 lead guitars are playing at 1:05. I didn't have the volume high when I recorded, and infact, this came out much quieter than I wish I could've gotten it to. The tone is incredible but it always comes with more hissing and humming and other undesireables.

Now, I'll admit, I didn't EQ this properly yet, but I have tried, and I really can't get rid of all of that hissing.

I'm open to any suggestions that could improve the quality of my recordings. Anything at all.

Could this be caused by a bad usb cable?

Do I need to match sample rate in the system I/O of my pod hd 500 with the sample rate of my DAW?

Does Cubase have a clipping problem? (I've actually been worrying about this in particular, because I had less clipping in audacity recordings)

Does the DAW effect clipping at all? (I've been looking all over for an answer to that, haven't been able to find one)

Is this caused by too much reverb?



Re: signal to noise ratio
by ozbadman on 2012-09-17 19:41:06

Hi,

Signal-to-noise in general only refers to the analog stages. If the S/R ratio is really bad, you can get drop-outs on digital connections, but you won't get hiss. The DAW connection is digital, and the internals of the HD are mostly digital, so any S/N problems would be before the HD, or after the final analog output. The noise on your recording is not a S/N problem however.

It sounds very much to me like digital clipping. At some point in your chain the signal level is too high. It is very unlikely it is caused by the reverb. Unfortunately, I don't use DAW so I don't know what control there is there over gains (some kind of record level?), but basically I'd look at all places along the chain, both in the HD and in your computer for where you have control over gain/volume and at some point, you will find the signal level is too high.



Re: signal to noise ratio
by meambobbo on 2012-09-18 07:58:56

for clipping inside or around the pod:

http://foobazaar.com/podhd/toneGuide/tipsAndPitfalls#clipping">http://foobazaar.com/podhd/toneGuide/tipsAndPitfalls#clipping">http://foobazaar.com/podhd/toneGuide/tipsAndPitfalls#clipping

also, note that the Line 6 driver control page for USB has a +18 db checkbox that I believe is defaulted to checked.  This could push the audio into clipping inside your DAW.

I am not sure about the hissing.  If the sample rate didn't match, it would change the pitch of the guitar, not simply degrade the quality.  AFAIK.  Have you plugged headphones directly into the Pod and verified the patch sounds as you want it before it enters your DAW?

As far as pops and crackles, that's almost always associated with not having a large enough buffer size.  Your ASIO driver (I assume this is also on the Line 6 driver control panel) should allow you to adjust the buffer size.  However, larger buffers = more latency, and I think they can also degrade some frequencies.  When you increase the buffer to the point where there's no more crackle, if you find the latency is unbearable, you have to try to use a lower sample rate.

IMO, USB (unless it's USB 3.0 which the Pod HD does not offer) is no good for audio.  It just doesn't have enough bandwidth to reliably transport the data in realtime.  I use firewire.



Re: signal to noise ratio
by CairnsFella on 2012-09-18 19:49:28

Meambobbo. I fully acknowledge that it is not uncommon for people to hold this opinion, however the basic facts are that USB2 provides pleanty of bandwidth for 2 channel applications (and unless you are using very high bit rates etc, enough for multitack applications too).

Yes, real world thoughput of USB 2 is in the mid 30 MBps, but FW 400 is only in the early 40's (and FW 800 a little less than double that).

I researched this in some detail before I purchased a cheap little ... ahem.. err..... behringer interface. I use this currently on a shared port and have had zero issues (on a pretty old spec computer too).

No arguments from me with your assertion that FW is better, but I would have to contest the suggestion that it is inadequate. What is commonly possible, however, is the use of multiple USB devices on a PC could obviously compromise the situation, wheras few people have multiple FW devices, and therefore are less likely to encounter the same problem.



Re: signal to noise ratio
by meambobbo on 2012-09-19 21:45:40

i have not done as much research as you obviously.  i simply speak from experience.  however, when i was using USB for my older Line 6 gear, it was on older computers, with a number of other USB devices present.  It may have been USB 1.2 for all I know.  I always had to allow some latency, or I had issues.

I have super low latency and zero pop/crack issues with my M-Audio Firewire interface using a dedicated Texas Instruments firewire card.  I bet if I used a dedicated USB card on a more modern computer, I couldn't tell the difference, but I need the audio interface for other things anyway, and I am happy with its performance.  Maybe I'll do more research for my next interface.  My newest computer does have USB 3.0 available.




The information above may not be current, and you should direct questions to the current forum or review the manual.