Error?! [Actually, maybe not...]

[Anonymous]

SteveR750:Craig M.:
SteveR750:The whole point of PC music is realising error free ('bit perfect') source data. I am not convinced iTunes delivers that, and if it does, do you know it is? Similarly, if it is not, do you know, other than your ears. That, or as JD says your CD37 is doing a better job than itunes....

he is using a mac, itunes is bit perfect on a mac.

really?

bit perfect out of itunes maybe, but out of the s/pdif driver? At the optical in on the DAC? And anyway, itunes uses error correction when ripping, so 20% of your data is not what was on the disc to start with!

The optical out on the mac is good and, depending on the DAC, can produce better results than USB. Came across some tests on this in an american hifi magazine. The spdif driver isn't going to have an impact on file size, that's not how they work.

 

[the record spot]

Been following this with some interest; I'm not too surprised that the rDAC might not be as good as the CD37. It's a £1300 CD player after all and yes, I get all the talk about "giant killers" when it comes to products in hifi (Ebay in particular's awash with them), but unless there's something wrong with the product, I'd have a chat with the dealer and/or Arcam for their view and also consider taking it back. I was going to suggest a DAC that's a tad over your £500 budget but which I've seen appearing for less of late on the odd occasion; the Stello DA100 Signature which is around the £700 mark.

The write-ups are good and Hi Fi World rated it with its partnering transport a couple of years back - in fact, they recommended I buy one when I'd written in to them when I still had my old Mimik. There's a few reviews on the web, so check them out. And I'm not just plugging products that feature the word "Signature" in the name...would probably contact Arcam in the first instance however.

One last thing, if you bought online, as opposed to in person, you should be able to return the DAC within 7 days if it's not panning out to be a match made in heaven. Or Cambridge!

 

[ID.]

You mentioned volume increasing with sound check off, but I seem to recall someone mentioning that to get bit perfect, etc. from iTunes you should have ITunes' volume turned up to full and then do any volume adjustment from your amp. Not sure what the effect is, but running iTunes on PC into my fubar IV it made a noticeable difference.

Whether you believe in it or not is another matter, but I've read several people's reviews online where they said it needed a lot of burn in time (100-200hrs...)

 

[Singslinger]

I'd agree with the need to properly burn-in equipment, even DACs.

However, if you're still unhappy with the sound, then for your budget I'd suggest the Musical Fidelity M1 DAC. I can't comment on the Arcam or Rega DACs because I haven't heard them, but I found the M1 to be a significant upgrade on my Cambridge Audio DacMagic.

 

[ID.]

Either way, good to hear of your experience. I was considering an rDac as a way of bringing the Arcam sound to my system and streaming simply, but I think I may be disappointed with the performance compared to my current DAC, and as I live in a country without an Arcam dealer, trialling one or buying with the option of returning isn't possible, so rules it out for me.

I've said it before, but rather than the the rDac in the solo range I really want a DAC in the FMJ range...

 

[Anonymous]

As i said earlier in the thread..

I would recommend having a listen to the MF M1 dac its on par with the rega apollo cd player and sounds very good but its £399.99

I did demo the arcam Rdac and it was a bit of a

and no where near as good as the Musical fidelity M1 dac IMO.

If it were me i would wait for the rega dac and see what thats like, i think it will be the product to beat in 2011 and may well be worth the extra outlay.

I would'nt wait around for any burn in, just get it back to the dealer and get it changed otherwise you may be stuck with it...

 

[crusaderlord]

I will take a stand for the rDac alongside WHF and HFC high rated reviews.

I have the rDac and at £300 it is excellent kit so hopefully everyone wont just write it off. I have directly compared it to Musical Fidelity V-Dac and it won hands down and the MF M1 is 33% more expensive to consider.

The rDac has the same chips as the CD37 so whilst it shouldnt be miles apart from the rDac you have to take into account the price different which may mean better components here and there plus i think multiple chips in the CD37.

My rDac holds up really well v the CD36 - the CD is better but not by too much. It could be that the CD37 is just a level above the rDac, the price would expect it and it certainly keeps getting high ratings in some mags. I think i may have to give it a try one day and see.

Finally what dacs do show up is the source material, a poor recording or compressed file from your PC is clearly evident so a direct Mac v CD comparison is often going to be down to source, connections, cables etc maybe more than the dac.

 

[Anonymous]

sorry but the rdac is no way near on par with the MF M1 dac, it was completly outclassed in every way, and as for brightness the arcam was the one with a touch of brightness not the other way round.

I suggest people go and listen to the 2 dacs mentioned and hear the difference for themselves, its not a little difference its a big difference.

 

[John Duncan]

6th.replicant:Can't find an equaliser in iTunes, where in Prefs does it hide?

On my Mac it's under 'Window/Equalizer'. My win laptop is upstairs, will check shortly.

Sound check is doing digital volume normalisation and should absolutely be turned off.

Benchmark do a good setup guide for itunes here, though how up to date it is I don't know...

 

[John Duncan]

6th.replicant:I guess so, but the rDAC and CD37 have the same Wolfson WM8741s. Umm??

In which case, the audio output stage of the rDAC isn't as good as the CD37's...

 

[John Duncan]

Update - on Windows it's under 'View/Show Equalizer'.

But to be fair, if it degrades the output of your CD player as well, then there's not much you can do. And the review says "Some system-matching is required to avoid the bass becoming bothersome"...

 

[the record spot]

Indeed - if all things were equal between the CD37 and the rDAC, there wouldn't be other things to consider beyond the DAC, however, that extra £1k suggests there's a bit more to consider than the digital conversion happening. As for whether the MF M1 is "better" or the rDAC is "worse"/"brighter" is going to be dependant on the partnering equipment so it's not as straight a conclusion to come to IMO.

 

[Anonymous]

The rDac gets good reviews. I read somewhere that suggested that it was a good match to the MF M3 cd player.

I can't comment on the comparison to the MF M1 as I've never listened to the rDac, I got the M1 on Friday and was told it would benefit from 100 hours of burn in, which is good news, because it sounded pretty darn good straight out of the box when I compared it to my Oppo BDP-83SE

 

[SteveR750]

sam68:
Hi 6th.

As far as my limited knowledge allows, error correction means that, in the case of any missing or incomplete information (caused by surface scratches etc.), that section of the disc is then re-read until a complete (digital) picture is obtained which can then be transferred as a track to the hard drive.

Steve, with the 20% difference, are you referring to the compression applied by the ALAC algorithm, or errors in the error correction function?

Cheers, Sam

I am talking about the individual sectors of data on the disc, nothing to do with the compression process.

Error correction on when ripping doies the same interpolation that a trasnport will do when playing the disc - the very thing you don't want. the whole point of EAC and similar accurate rippers is that they check and re-read the disc until there are no errors. This is not the same as error correction! As far as I understand with iTunes (and WMP) is they will happily rip through tracks that have fatal errors (in my collection of circa 350 dics, I have two discs that have a track that cannot be read by the drive in my PC, and I have tried several times to rip it with J Rivers. WMP sails through it.....)

 

[Anonymous]

You can turn off error correction in itunes. It's under preferences>advanced>import settings.

 

[SteveR750]

Grottyash:SteveR750:Craig M.:
SteveR750:The whole point of PC music is realising error free ('bit perfect') source data. I am not convinced iTunes delivers that, and if it does, do you know it is? Similarly, if it is not, do you know, other than your ears. That, or as JD says your CD37 is doing a better job than itunes....

he is using a mac, itunes is bit perfect on a mac.

really?

bit perfect out of itunes maybe, but out of the s/pdif driver? At the optical in on the DAC? And anyway, itunes uses error correction when ripping, so 20% of your data is not what was on the disc to start with!

The optical out on the mac is good and, depending on the DAC, can produce better results than USB. Came across some tests on this in an american hifi magazine. The spdif driver isn't going to have an impact on file size, that's not how they work.

It's nothing to do with file size. Google transmission jitter and s/pdif.

This is a useful website with plenty of general practical info on most topics of digital audio

http://www.thewelltemperedcomputer.com/Intro/SQ/USB_SPDIF.htm

However, from what I have found, the general concensus of web expert opinion seems to be that s/pdif is not great, better than unmodified USB perhaps, but not the optimum way of moving digital data for audio streaming...

 

[Craig M.]

yes, the optical output from itunes is bit perfect on a mac - it's been proven. pcs can shift digital data all over the place without corrupting it in anyway, if they couldn't, they wouldn't work.

error correction is just that - correction. read about it, as long as it is performed during the rip, and any errors aren't so bad they are concealed, then an error corrected rip will be bit perfect when compared to the original disc.

 

[SteveR750]

Craig M.:
yes, the optical output from itunes is bit perfect on a mac - it's been proven. pcs can shift digital data all over the place without corrupting it in anyway, if they couldn't, they wouldn't work.

error correction is just that - correction. read about it, as long as it is performed during the rip, and any errors aren't so bad they are concealed, then an error corrected rip will be bit perfect when compared to the original disc.

That's not logical Mr Spock...

Otherwise a CD transport made of chocolate would sound great even with all that error correction taking place! Error correction when streaming or ripping is just that - the data is interpolated (guessed) to fill the missing blanks, and cannot be bit perfect. However, using a ripper that verifies the data accuracy, such as EAC do not correct for errors, they simply re-read until the data is correct or give up totally. Using an accurate will give you bit perfect rips. From then on the playback starts to mess things up. Apple don't have an exclusive way of using the optical driver - teh whole pint of WASAPI in W7 means you can bypass all of windows audio engine and resampling, so efffectively connects the media player directly and exclusively to the optical driver.

 

[Craig M.]

i say again - read how error correction works, it is not guesswork. benchmark media, a pro audio company with a very well regarded range of products and no b.s., say that any competent cd transport can output a bit perfect audio stream. they stress that competent does not mean expensive.

on an apple, you don't need wasapi etc., because it doesn't resample the audio like windows k-mixer does.

 

[SteveR750]

Fair enough, but if any transport can output bit perfect data, why do some manufacturers spend so much money on beefing up the transport to eliminate errors? How many mis read bits is acceptable, and when does it become an audible problem? My ears are telling me that my PC source is much better sonically, yet the DACmagic is unlikely to be a better DAC than the one in the Cyrus CD6SE, so something is working differently to generate such a different sound.....

 

[Anonymous]

That was my understanding of the error correction process: the disc is read and re-read in mulitple passes to correct any errors, not to add information that doesn't exist. If there are any "bad sectors" on a cd then, put simply, the ripping process won't work. These are, after all zeroes and ones we're talking about

(waits for the inevitable to hit the fan)

 

[Anonymous]

Steve, part of the "beefing up" process includes re-clocking to reduce jitter as well as improving the transport, but this is still reading the information in real time - maybe oversampling in the process, but with ripping, the computer can make as many passes as it takes until all the information is present and correct before commiting the information to the hdd. This could be why ripping with error correction turned on is an interminable process (I can vouch for that first-hand, as I'm re-ripping everything into ALAC as I type this - 400 plus albums = funtime). There is no sound output until you access the file to play it. This is the reason some find the output from computer-based systems sounds superior.

I should state I am in neither camp.

 

[crusaderlord]

the record spot:Indeed - if all things were equal between the CD37 and the rDAC, there wouldn't be other things to consider beyond the DAC, however, that extra £1k suggests there's a bit more to consider than the digital conversion happening. As for whether the MF M1 is "better" or the rDAC is "worse"/"brighter" is going to be dependant on the partnering equipment so it's not as straight a conclusion to come to IMO.

i agree it must be a factor of what equipment you used it with. Hence WHF are always saying that balancing equipment is as, if not more, important than picking the best rated individual items.

 

[SteveR750]

sam68:
Steve, part of the "beefing up" process includes re-clocking to reduce jitter as well as improving the transport, but this is still reading the information in real time - maybe oversampling in the process, but with ripping, the computer can make as many passes as it takes until all the information is present and correct before commiting the information to the hdd. This could be why ripping with error correction turned on is an interminable process (I can vouch for that first-hand, as I'm re-ripping everything into ALAC as I type this - 400 plus albums = funtime). There is no sound output until you access the file to play it. This is the reason some find the output from computer-based systems sounds superior.

I should state I am in neither camp.

As I understand it re-clocking is a process that takes place in a remote DAC, because of the difficulty of synchronising a master clock over s/pdif or USB for that matter...The transport will have its own clock which determines its own sampling rate. The challenge is to get the remote DAC to sample at exactly the same time interval as the output data, but the output device clock data is also subject to transmission errors, hence the need to use Phase Locked Loops etc to establish it. Ideally the master clock is controlling the DAC sample rate and is also controlling the output rate of the transport, but this is not easy to achieve. In a integratd CDP the master clock runs both processes, ad in theory is inherently more accurate, but then electrical intereference, power supplies, vibration all start to have an effect. Like many things, the reality is often a compromise of the ideal science.

The Cyrus servo evolution transport is all about mechanical accuracy of the laser tracking and reading the data accurately at first pass (so the Cyrus chappie explained to me when I spoke to them last year). Of course it will have a half decent clock to make the sampling rate is consistent. When you are ripping data to a file then the clock speed is irrelevant, its simply reading and copying chunks of data, there is no sampling and streaming taking place, hence any old transport will suffice for ripping, so long s it can eventually get the data off the disc.

What is intriguing is that J River offers a WASAPI Event style mode, where the DAC pulls data from the source, rather than it being pushed. In which case, and depending on buffer size, suggests that it is less dependant if at all on the clock in the PC optical driver. I am now out of my depth of understanding of how this works, though trying to find the answer from their interactive forum....

 

[shooter]

SteveR750:
As I understand it re-clocking is a process that takes place in a remote DAC, because of the difficulty of synchronising a master clock over s/pdif or USB for that matter...The transport will have its own clock which determines its own sampling rate. The challenge is to get the remote DAC to sample at exactly the same time interval as the output data, but the output device clock data is also subject to transmission errors, hence the need to use Phase Locked Loops etc to establish it. Ideally the master clock is controlling the DAC sample rate and is also controlling the output rate of the transport, but this is not easy to achieve. In a integratd CDP the master clock runs both processes, ad in theory is inherently more accurate, but then electrical intereference, power supplies, vibration all start to have an effect. Like many things, the reality is often a compromise of the ideal science.

Check this out. EDITED BY MODS - House Rules

Explains how master clocks and DAC's are implemented and the cheapest ways to do it.