I've found those IIR-coefficients and the corresponding Transfer Function.
Does a Linux command line programm exist where I can pass this function, the coefficients and which then computes my soundstream in realtime (more or less)? I take it that the ubiquitiuos bruteFIR can only convolve FIR-filters? Sorry if these questions seem dumb, seems this area of signal processing is above me.
Rüdiger
Yes, SoX. Windows and Linux versions both GPL. Don't knock the DOS comandline, things work very well once you ge the syntax right. If you are adventuresome MinGW is a gcc compiler for Windows and you can make your own Unix style pipes/filters that work just fine with Sox from the DOS commandline. You must set stdin and stdout to binary manually on Windows (that will save an hour of wasted time). 🙂
I wrote an inverse RIAA tone generator piped it to Sox did and RIAA IIR and piped that to play. Plays fine in real time with computaional latency up front of course.
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Uh-oh. I could see the forest for the trees not.
Sox has the command 'biquad b0 b1 b2 a0 a1 a2'
That'll keep me going. Thanks!
Rüdiger
Sox has the command 'biquad b0 b1 b2 a0 a1 a2'
That'll keep me going. Thanks!
Rüdiger
ok, it seems as if as if the sox manual is wrong. it states
'sox ... biquad b0 b1 b2 a0 a1 a2'
If I instead write
'sox ... biquad a0 a1 a2 b0 b1 b2'
all seems well (from listening only, so far)
Rüdiger
'sox ... biquad b0 b1 b2 a0 a1 a2'
If I instead write
'sox ... biquad a0 a1 a2 b0 b1 b2'
all seems well (from listening only, so far)
Rüdiger
I think a0 is by convention normalized to 1 so the second looks right. The source has the convention for a vs. b in SoX.
Any update on your experiences, Dave? I've got Pure Vinyl, my daughter's Mac, the Yamaha interface, and a big hard drive. I'm ready to go, but I'm looking for suggestions for recording/archiving the albums, in an environment where I'm currently limited to 16/44.1 by the DAC, but will at some point move to 24/96.
I've mailed with (one of) the maker(s), and they clarify this in the manual for people like me... 🙄
Meanwhile, I can really recommend using sox for riaa playback along with a decent prepre and a reasonable adc/dac. Using sox with command line linux keeps the diy spirit as well.
Rüdiger
I use apple lossless and rip with iTunes, Max or download from a site like HD tracks. Store to an external hard drive following the recs in the pM manual. I try to use Max to rip, but it can be difficult to pull tagging data well. I use it to convert other formats to apple lossless, too. Now pM will read Flac, so probably best to go with that. More versatile. I think you need to use Max or something similar if you have higher bit rate CDs than redbook, iTunes only sees 16/44. pM will down convert to your dac, so no worries there. Rip the biterate of your source.
Time, lifetime, taxes, death. It certainly is easier to rip a CD than a record. With over 3K records it seems unlikely that they will all ever again come under the needle. Still it is nice to finally feel that at least those already in digital format don't really have to be retransferred.
Thanks. I'm actually all set on ripping CDs, using dB Poweramp on a Windows platform. My interest in Pure Vinyl is to record and archive vinyl, in FLAC, now that that is supported, and using the resulting files as part of the music library for a Squeezebox system.
I've more or less decided, unless someone has some experience to suggest that my plan is unworkable, to record at 24/176.4, archive that on an external drive, and then batch downconvert to 16/44.1 for storage on the existing internal drive and playback on the existing Meridian (561) processor. Then upgrade the Meridian to one capable of 24/96, downconvert the vinyl files to 24/88.2, and play those. All of this on a SB Touch via coax to the Meridian.
Yup, a couple of posts back I mentioned that I have a Mac, a firewire interface, and the software. The Mac, however, belongs to my daughter, and will not be part of the system for playback.
I rip vinyl the old fashioned way ... turntable, cartridge, RIAA preamp, A/DD/A, computer.
For software I use Amadeus (and now Amadeus Pro, although you don't need multitrack for ripping vinyl) at 24/96, keeping levels well below digital clipping (-3dB FS is a nice target, when in doubt go lower. You've got 8 bits to play with). If necessary, ClickRepair by Brian Davies. Normalize to -13dB RMS, but if I get a any clipped samples I go to -1 dB Peak FS instead. Then master with dither down to 16/44.1 with Amadeus/Pro and load into iTunes. You always have the undithered 24/96 to listen to anytime as well.
Hot tip: monitor with headphones. Why make the 'table dance with speakers if you don't have to? You will definitely like the bottom end you get ... better than actually playing an LP, and at least on my planet, it sounds pretty fine 'actually playing an LP'.
There are lots of decent audio recording apps for Mac OS ... if you have an old box with a good PCI soundcard you can use ProTools Free (yep, it's free) in OS9.
For software I use Amadeus (and now Amadeus Pro, although you don't need multitrack for ripping vinyl) at 24/96, keeping levels well below digital clipping (-3dB FS is a nice target, when in doubt go lower. You've got 8 bits to play with). If necessary, ClickRepair by Brian Davies. Normalize to -13dB RMS, but if I get a any clipped samples I go to -1 dB Peak FS instead. Then master with dither down to 16/44.1 with Amadeus/Pro and load into iTunes. You always have the undithered 24/96 to listen to anytime as well.
Hot tip: monitor with headphones. Why make the 'table dance with speakers if you don't have to? You will definitely like the bottom end you get ... better than actually playing an LP, and at least on my planet, it sounds pretty fine 'actually playing an LP'.
There are lots of decent audio recording apps for Mac OS ... if you have an old box with a good PCI soundcard you can use ProTools Free (yep, it's free) in OS9.
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Good tip about headphone monitoring. Why down-sample to 16/44.1 if you are sourcing from a computer? This would only be required if you were burning a CD. One of the advantages of Pure Vinyl is its ability to change the sample rate as needed so why not just play the high res file.
It was a file size issue on one hand (limited storage space, and no real-time lossless compression available), and the ability to play the 16/44 file on an iPod in my vehicle(s) on the other ( I don't have any lossy compressed audio anywhere, and my iPod has never had an mp3 on the drive). I started doing this around 2004, when a 250GB hard drive was top dollar and top capacity.
In 2005 I did a project where I tore down the 3gen iPod, removed the 1.8 drive, and hooked it up via 2 IDE adapter cables to a 250GB 3.5" HD with everything mounted in a console I built in my truck. Pulled the battery while I was at it ... they run fine via the FW cable hooked up to a 12V source with no battery. It was controlled by a remote mounted on the dash.
I do, of course, still have the higher rez original files. I figured at the time that hirez playback was just a matter of time.
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Glad to hear that you still have the hi res files. I still have a 44 MB removable hard disk that at $100 a pop could store a record on 10 disks for a grand, but With 2 TB, even in an external case going for $89 these days, and Thunder around the corner there really is no reason at home not to use Pure Vinyl to enjoy 24 / 192 or whatever, as it changes the sample rate on the fly. I don't even bother with Apple Lossless or Flac leaving the files as uncompressed AIFF. I will have to test to see how much time it takes to decompress as Pure Vinyl will decompress during the load into RAM and then playback from memory. It can also up-sample 16 / 44.1 in real time with very good fidelity.
I can't comment on much of your plan as I'm not very familiar with Meridian products but I will give you some advice regarding your workflow.
Do the downconversion to 24/88.2 and 16/44 at the same time, and save the 88.2's with the 176 originals. It will not add significantly to your workflow or time per file ... mere minutes really ... but will save you many, many hours later.
Many hours.
Few people do this, and it will require a bit of research and listening tests on your part, but I find that a good implementation of dither to the 16 bit down-conversion makes for a much better Redbook-quality file. Any app that can do the kind of audio recording and processing you're doing now should be able to load some Audio Unit or VST plugins; free ones are available suitable for the job, and plugins can be implemented in batch processing.
Also, since you're creating original tracks from your own recordings, there is no particular reason why you can't avoid the Redbook standard altogether and do 192, 96 and 48 Khz files. If there is some limitation in your current playback system that demands 44.1 instead of 48, that won't work, but otherwise I see no rationale for it, and it will offer genuine sound quality advantages in light of your future plans.
And now, to try to atone for my sins and get this somewhat back on topic, I have a question for the PureMusic users.
I realize I can download a demo and play around myself, but 20 years with computers that I depend on to do real work has taught me a few lessons, and one is don't download demos, because they're like the houseguest who never leaves, and cookie crumbs will mysteriously show up on the kitchen countertop for the rest of your days, causing domestic mayhem. So, I avoid them broadly speaking.
Do those of you who've sprung for the app find that it offers benefits to people who don't have modern-quality DACs and adequately hi-end systems to playback on? For example, would I hear improvements on, say, a Macbook Pro with Ultimate Ears via the Mac's headphone out?
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