How to do USB audio

A double LP

vinyl

You’re clearly not interested in high fidelity, then :-(

and I plan to do high rez digital transfers from the LP for day-to-day playing
……and back down again.

Its easier to do high rez versions as I can then easily process them down as appropriate depending on what the material is like. However provided it is done with care I find 48k/16 works fine for LPs. Although I may leave it as 48k/24 just because I cannae be bothered to reduce it. :-)

Jim

You’re clearly not interested in high fidelity, then :-(

Mainly interested in the music. In practice I generally find that a good LP¹ comes out fine if I end up with a 48k/16 version. But it is easier to do 24bit recordings and examine the result. One reason for this is that the peak levels on Vinyl vary a great deal. Some discs peak over +15dB(RIAA). Biggest peak I’ve encountered is +18dB(RIAA) on a single (Lady Madonna by the Beatles). So I set the recording level such that +18dB(RIAA) just reaches 0dBFS for the digital recording. Do the recording 48k/24bit. Then usually process down using sox to 16bit having scaled the levels so the peak is about -3dBFs. Given the recorder will do 24bit recording I can’t see why not. Although I vary what I do according to the individual material.

Must confess I’ve never really understood the arguments about LP versus CD. The reality in my experience is that what you get is limited by how much care went into making each specific LP/CD. Sometimes one comes out better, sometimes the other. Little to do with the medium. More to do with care and attention during manufacture. Although I guess you can make an argument for material like pre 1966 pop like the Shadows that the added LP distortion and cutter bending are a part of the sound. The differences are measureable as well as audible.

Jim

¹ The challenge, of course, is if a given LP or CD is a good one. Alas, I have many examples of both that are dreadfully badly made. But also examples of both that are good.

“Foot Tapper” is the most extreme example of compression that I can think of. You can hear the drums being ducked by the guitars.

“Foot Tapper” is the most extreme example of compression that I can think of. You can hear the drums being ducked by the guitars.

What I’ve noticed about that is the degree to which the compression varies from one version to another. Similar for some of the other recordings. And the frequency responses and mixes vary in some cases as well. This was one of the reasons I got the 2LP set as well as the CDs. Curious to see what differences there might be between them. In general, modern re-issues of old ‘pop’ music on CD have more compression applied to them as the suits think “this is what people want”. (sigh)

I did a survey (measurement based) of this a few years ago. One particularly baffling example was a release of a 2CD / 2LP set by Queen. The audio on the CDs was more level compressed than the LPs. It was also clipped and flatted out at 0dBFS. The LPs sounded better. There is of course no real need for this, but that’s the way the music biz operates all to often.

To preserve some vestige of audio credibility though, I should say I didn’t buy the Queen issues. Borrowed them from a mate for the sake of the test measurements. :-)

Jim

Jim.

My ‘and down again…’ comment (which was said jokingly I hope you know) was because you know I’m a vinyl fan and giving up listening to vinyl for a ‘recording’ of vinyl isn’t audiophile in my eyes and now you compound it by processing the recording ‘down’. I’m going to have to take the joke out of the comment :-)

My ‘and down again…’ comment (which was said jokingly I hope you know) was because you know I’m a vinyl fan and giving up listening to vinyl for a ‘recording’ of vinyl isn’t audiophile in my eyes and now you compound it by processing the recording ‘down’. I’m going to have to take the joke out of the comment :-)

In practice I tend to make transfer copies as either 96k/24 or (more often) 48k/24 and then decide if to process the results or not. The key point is that I generally base this on if I can hear any difference when I do between the result and the original LP as played.

As with many “audiophile” debates the key word I’d stress above is the I. Then point out something I’ve been saying for years.

The fact that I can’t reliably detect an audible difference between two items doesn’t mean I’m then certain no-one else could do so. Hence I’m quite happy to accept the possibility that you, or someone else, could tell one of my transfer copies from the original. Although I’d be surprised if they could for a 96k/24 copy correctly played and level matched. But I’m just making transfer copies for my own convenience and as ‘safety’ against the day when an LP or tape is damaged or I lose the ability to play it. e.g. against the time when my V15/III styli finally cease being useable.

If I were making transfer copies for someone else of their source material I’d do it as 96k/24 or 192k/24 and give that to them. (Unless they specified something else.) Then their choice if that is what they want, or they want to process it in any way they choose.

So for all I know, you might be able to hear a change when I don’t. I can’t say. I’m just doing what suits me.

FWIW I routinely use 24bit because it makes it so much easier to avoid accidentally being caught by peaks clipping. And 96k can be useful on poor discs – e.g. if I need to snip out a repeat-groove section on an ancient disc. or to detect clicks. (That said I almost never bother with de-clicking old discs. Life’s too short.)

Jim

P.S. Although I’ve been writing articles for audio mags, etc, for years I have never done any equipment reviews making any ‘subjective’ comments. The reasons being that I don’t think my ears are particularly ‘golden’, and don’t feel my opinions should be taken as anything more than my opinions. Others can almost certainly hear some things better than me, so I’ll leave it to them. :-)

P.S.2 I have often both heard and measured differences between commercial LP and commercial CD releases of the same material. And often the CD is poorer. But I think this tells you more about the recording companies than it does about either LP or CD. And I find that my own recordings sound pretty much like the source in general, because I avoid clipping or noise and don’t try to fiddle about with the results in the ways recording companies tend to.

Oh well, I guess now I have Dave dissapointed because I take audiophilia too far and Colin who thinks I’m not audiophile enough. :-)

However, Dave, despite your concerns about how many people are interested: Note how many ‘viewings’ this thread has accumulated. Someone must be interested, if only in what the madmen are up to! 8-]

Jim

Oh well, I guess now I have Dave dissapointed because I take audiophilia too far and Colin who thinks I’m not audiophile enough. :-)

Okay – hands up who uses gold plugs?

Your headphone jack – is is 2.5mm, 3.5m, quarter inch, the odd little three-pole round, 2x phono, or 2x BNC?

Do you have different syluses (stylii?) for 33, 45, and 78?

Can anything play 18rpm?
Ever used it?

Do your volume knobs go up to eleven?

If you have volume sliders, which is the loudest position – closest to you or furthest away from you?

I’ve updated the USBAudio archive on my web site http://davehigton.me.uk/Audio

The USBAudio module is new; the !UAPlayer app (which is really only a test bed) has Colin’s improvements to reading the headers of WAV files.

The same page also has the current USBAudio API as an HTML document. Note that I still haven’t assigned the SWI numbers yet, but they are from the official allocation, i.e. the range won’t change but the numbers within that range still might, so access the SWIs by name.

I’m interested in all feedback about the module and its API. Rather less so about the app; I don’t intend it to be a real “product” – I only wrote it as a test bed for developing the module – but if anyone should want to take it and make a proper app out of it, go right ahead. (I would appreciate some credit for originating it if you do.)

Okay – hands up who uses gold plugs?

Erm. The phono plugs I put on leads are usually ‘gold’ in colour. I fear they may not be solid 22ct gold, though. Have I been robbed by Maplin/CPC? ;→

Your headphone jack – is is 2.5mm, 3.5m, quarter inch, the odd little three-pole round, 2x phono, or 2x BNC?

Think they are all 1/4inch or the small size (3.5mm?)

Do you have different syluses (stylii?) for 33, 45, and 78?

Nope. Have three V15/III styli (MR and HE) for most LPs/EPs. Also a couple of M97’s for records that look like rubble scattered fields with added trenches. For 78s I do have a ‘Decca 60’ portable wind-up gramophone with a sock in the horn.

Can anything play 18rpm?
Ever used it?

Yes. Used to use a GL75. Still have one in non-working condition in the shed. :-)

Do your volume knobs go up to eleven?

Only on the iPlayer. :-)

Not sure how high an ‘audiophile’ rating that gives me.

Maybe I’d be better classified in terms of what I tend to listen to and the music I still buy.

I buy about one or two new LPs a year. Although recently I found a local charity shop with a great batch of classical LPs in really amazingly good condition for a couple of quid each, so couldn’t resist an armload or three. Never bought this way before. Some are duds, but many are very good.

I’ve bought a small number of 96k/24 downloads this year as an experiment. Not yet convinced this makes much sense. Particularly given that they take foreeevvvveeeerrrr to download. Spend five hours getting the equivalent of 3 CDs worth a few days ago. Real PITA. Oh well, the Britten War Requiem does sound pretty good this way. But I doubt I’ll buy many more such files unless we finally get something closer to real broadband speed here. Wish they’d sell 96k/24 flac on DVDs with a leaflet of notes. Some of us simply don’t have a connection that makes high rez downloads feasible.

Happily buy CDs. Most recent being the ‘Decca Sound Analogue Years’ 52CD set. Many of these sound really wonderful. They seems to have been systematically retransferring them recently. (The previous box ‘Decca Sound’ is also good.) Also various individual issues and other boxes like one of Dave Brubeck albums, one of Louis Armstrong’s early work, etc. The bulk of the CDs I buy are classical/jazz and – by avoiding much of EMI – often sound fine to me.

The recent EMI SACD/CD remasterings I got a while ago are also good. Better than the previous CD versions. But the CD layers sound better on these than the older CDs. So another example of what mattered was the care and skill applied, not the medium per se. Love a lot of EMI’s recordings. Always hated the way they often foulded up making the actual LPs and CDs!

If you have volume sliders, which is the loudest position – closest to you or furthest away from you?

Only slider volume I use is on the iplayer. There 11 is on the right. :-)

And yes, the engineers confirmed, it is a Spinal Tap joke. ;→

Jim

Just tried the Arcam rDAC. This failed to work. Wouldn’t work with Colin’s modules. Nor with Dave’s module/player.

Dave’s player gave “Unknown descriptor at line 1580”

When I clicked on a wav file the TaskWindow opened with Colin’s player gave

I’ve modified Colin’s player so it prints out a time elapsed after each 10 secs of play. If I leave it, this duly appears. And I can hear a ‘click’ as playing starts. On one occasion I heard the first half-second or so of music, then silence. So it thinks it is playing out the audio, but I get silence. Tried various formats to check. No change.

Is this simply that the modules don’t recognise the setup needed for the rDAC? I’;d thought this worked on the Iyonix, but can’t recall for sure.

And the orginal (Class 1) DAC Magic was OK with both sets of modules and players yesterday.

Jim

We’ll have to start the debugging process this evening.

Jim.

You may as well try the latest version of USBModule.zip – the recorder will now record at the correct frequency on Rob Andrews’ record player – can you tell me.

1) Is the Arcam RDAC failing in USB 1 mode?

2) Does it have a USB2 mode?

3) If both are true does it work in USB 2 mode?

4) If in USB 1 mode does it work plugged directly into your ArminiX?

If you are in USB1 mode you want as few hubs as possible between your device and the motherboard. Unfortunately they are hard to avoid on an ArminiX as the board has a hub built in (as do all the boards that have been ported) but you also have another hub inside the box which is what you plug in to.

Edit. I should add that my DACMagic XS doesn’t work in Class 1 mode when plugged into a USB 2 hub. I have to use it in Class 2 mode for it to work over a hub. It doesn’t even get as far as being recognised by the computer.

I’ll try the new modules later today or tomorrow (may be occupied with something else this afternoon). Quick question: Can I use the new modules with the previous version of your player? If so it will save me having to re-edit to get it to print out duration and elapsed time. These make it much easier to note how things are proceeding.

1) Is the Arcam RDAC failing in USB 1 mode?

Yes. So far as I know it is Class 1 only.

4) If in USB 1 mode does it work plugged directly into your ArminiX?

I was trying it plugged directly into a front socket. When I try again I can also check the rear sockets. FWIW for other uses the rear sockets are more ‘fussy’ than the front ones. If I have my keyboard + mouse connected to the rear the machine stiffs at startup and never boots. This started happening with the 5.20 upgrade for whatever reason. Took a couple of days of experimenting to find that shifting them to the front cleared the problem!

IIRC I tried the Original DAC Magic on a front socket. That worked OK. Although I have the (Class 2) Pro on the rear via an external hub which also is for the printer, etc, (usually not switched on).

Jim

Ok, decided to try the new modules immediately. Alas, no success.

Front socket. Usually no sound at all. But sometimes a short burst of the music for a fraction of a second intiailly.

Rear socket. As above. But with the addition of random clicks from/during bootup and continuing until I try playing a file. Which makes me feel that I am “streaming silence” so far as the rDAC is concerned. Also after the first try, any following attempts to play a file generated an escape report after the initial startup details. Escape 63 for example.

So if anything the front sockets seem to be ‘not as bad’ as the rear. As per the odd behaviour in some other ways. (I suspect the keyboard/mouse problem is because I’m using an ancient left-handed keyboard via a PS2-USB1 adaptor

Jim

I looked at the APIs and specs, and all seems OK to me.

I would be very happy, at a point, to be able to use an USB module to play sound, especially since 1/ it does not work very well on Panda and 2/ Raspberry does not have a good stereo output.

The only real problem is that I have no clue (and don’t really wan’t to read 22 pages of messages) of wich USB audio device (low cost, low power and low size) is adapted to your project.

So… perhaps the problem is here: most people don’t have a RISC OS computer, and people who have one don’t know wich peripheral to use.

:)

For example, does this peripheral could works?
http://www.ldlc.com/fiche/PB00072349.html
(sorry, it’s in french).

I haven’t seen the Terratec Aureon Dual USB before, so I have no experience of it. However, all but one of the low cost USB audio devices I have works, so your chances are high.

The text on the page you linked to suggests it has SP/DIF too, but I can’t see from the picture where the SP/DIF (or TOSLINK) connector is.

I have a USB audio interface that claims to have 8 channels out (although it only provides connectors for 6 of them), 2 channels in, and TOSLINK in and out, and the module works with it. The device defaults to analogue in and out, which is probably what you want.

David.

The device you pointed out would definitely work on an Iyonix and it wouldn’t matter where you plugged it in – I know that seems an odd thing to say but it seems beagle/pandaboards may have problems with devices plugged into hubs. It is the type of device I’m trying to get to work properly on panda/beagleboards – a USB 1 Class 1 audio device and the most common. Jims more expensive devices work without problems on an ArminiX in USB 2 Class 2 Audio mode.

If you just want to try something out or join in with testing this works well for me and its very cheap – though you will have forgotten you sent for it by the time it comes from hong kong :-). As far as USB is concerned it works the same way as the device you pointed out.

USB for a Raspberry pi requires changes to a different controller driver so getting the device to work with a pi is further in the future.

I should also back-pedal a little. The cheap devices tend to work, but only give one or two sample rates, e.g. 48000 or 48000 and 44100. You seem to have to spend rather more to get a wider range of sample rates.

The Release 2 devices aimed at audiophiles are more likely to support even higher rates, but perhaps not lower rates.

It depends on what you want.

Arguably the most versatile device I have access to is a Logitech headset, which supports any sample rate from 8000 to 48000 at both microphone and headset. The next most versatile is an old Griffin iMic (visibly different from the current model) which support any sample rate from 4990 to 48010 at the output, and 12 different rates in total at the input.

Jim: can you fetch ModuleTest1.zip from my web site, please, run the BASIC programme from inside it in a task window, and email me the results, please. We’ll take it from there. It will, unfortunately, require a bit of to and fro before we find and fix what’s wrong.

Thanks Collin for the information. I think I’ll put an USB audio key in my next buying list :)

Jim: can you fetch ModuleTest1.zip from my web site, please

I will do. However we were out shopping this morning and will be busy again shortly. So it will be end of this afternoon. I assume you want the test run with the rDAC connected?

Jim

The Release 2 devices aimed at audiophiles are more likely to support even higher rates, but perhaps not lower rates.

FWIW all the ‘audiophile’ Class 2 ones I’ve tried support 44.1k/48k as well as higher rates. In practice they are almost certain to work 88.2/96 and probably also 176.4/192.

Have no experience with the inexpensive general items so can’t comment on them.

Jim