Sample Rate Questions

[jesussaddle]

A few newbie questions. I have a newer Quad PC, which seems pretty fast, 6 gigs of ram, an RME fireface 400 (up-to-date drivers) and Reaper 64 bit. I get enormous static and glitches when I use large VSTs with Fireface set to 192k. I have not figured out how to do this without using the DDS screen in the Fireface settings, which is odd to me, since you need to activate the DDS to select any variation in sample rate - there should be a way to change sample rates with DDS disabled (okay, I know this is a Fireface question, not a Reaper question, so ignore it). Also, I'm a bit confused by the Project Settings/Prefs in Reaper, "request sample rate" for example, and also the project sample rate setting.

1) Does one or both of these selections supposedly cause the soundcard (Fireface 400) to adjust, or does this vary depending on soundcards? If the rate is adjusting I cannot tell because when I go back into the ASIO settings screen it still shows whatever I had originally set; boy it would be nice if there was (is?) a feedback screen somewhere to indicate the current rate.

Anyway, 2) is it possible to have a project set to a sample rate above 48K with a couple of larger VSTs like Arturia Arp2600, BFD2, Omnisphere, etc, and not experience horrendous static and glitches? And do a lot of people use the stem-rendering technique to avoid this, and is this better than simply importing the rendered wave into the project as new media, and just deleting or muting the VSTs?

And 3) if one renders initially to a high sample rate like 192k, and then does a final render to 44.1k shouldn't some quality improvement still wind up sticking in the resulting CD? I definitely hear the difference within the Reaper environment with 192k, so shouldn't at least some of this translate to the 44.1 render onto CD?

4) Also, is there are way to render a higher sample rate onto DVD?

Those are my annoying newbie questions, if anyone knows.

[jesussaddle]

I've tested the Fireface Settings and found now that they do actually respond to the project settings with the Prefs set to the right value. And so this frees me up to turn off DDS (RME's way to allow real-time sample rate changes - and the only way in the units settings program to go up to higher values than around 48k!). Having DDS activated may have been the cause for some of the overall static when playing VSTs in the project since with it off the results seem better.

Also, to solve the noisy rendering issue at higher sample rates, I've gone ahead and stuck with the high buffer (1024) in my Fireface 400, and doubled the media buffer to 2400, and turned on "anticipate FX processing". I began to get good results rendering the Arturia VST (CS-80V) at 96k, and that was a good sign since I think that one is pretty hoggish. At 192k when I stem rendered the track it sounded a bit brighter and more lifelike overall, but had a good bit of "sporadic static" here and there in the recording. I was looking for a trick to getting this to sound clear - maybe in the project settings having to do with render. I'm set set to render to 24 bit PCM, Full Speed Offline. I changed the resample setting from 192 to 512. That did the trick. The audio rendered at 192k is now clear, no static, and sounds excellent. But it did get noticeably less loud - about 20 percent I think. I wonder why the fireface does that?

(Not that I really need 192k on most things, but its a nice experiment, and good to have on certain things. Most people seem convinced that 192k is a load of garbage, but I'm not most people, and what convinces me is mostly just the fact that there are interactions, call them psychoacoustics, that get chopped off easily below about 300k. Just consider a square wave or sawtooth wave at about 10K. 44.1 doesn't allow for the number of samples that are needed to preserve the shape of the square or triangle, which is then going to interact with other shapes in the audio wave environment, be it your ear, a speaker cone, a room, whatever. So the motion resulting from those shapes can't interact and produce as "living" a signal. Just my opinion, gotten from talking to a family of violin players.

[Diogenes]

The current audio settings are shown in the upper right hand corner of the Reaper main window...



Just in case you haven't noticed...

FWIW, my card will do up to 192k sampling. I never use it. After much testing, I decided I couldn't tell enough difference between 24/44.1 or 24/48 versus 24/96 or higher to justify the massive load such high sample rates put on the computer. YMMV...

D

[cerberus]

try writing 64 bit files. otherwise, imo your monitoring may be inadequate.

jeff dinces