Questions about CD/SACD transports and their effects on the music

[Warren M.]

Firstly, I've heard transports connected to players with lesser quality transports, and the results are audible and significant. But I have also heard (and I'm about to own) a JLTi-enhanced Oppo BDP-95, which, to me, sounds better than any CD./SACD separates I've heard, in spite of having what others have described as a pretty ordinary transport.

So... why does the transport matter so much? and if it does matter so much, why DOESN'T it matter in a JLTi-enhanced unit which does NOT have one of the world's great transports??? In other words, what is Joe doing to the Oppo which makes the quality of the transport so much less important, and if he can do that, then why don't the manufacturers of massive transports instead use a cheap transport and do what Joe does for far less cost and, by extension, greater profit for them?

Cheers

Warren

Edited August 26, 2012 by warrenmmmmm

[TD19]

Here is one point of view:

http://www.codebunny.org/audio/cdtransports.html

[Krispy Audio]

Maybe it DOES matter in a JLTi-enhanced unit, but Joe doesn't want to start changing transports?

[Once was an audiophile]

Firstly, I've heard transports connected to players with lesser quality transports, and the results are audible and significant. But I have also heard (and I'm about to own) a JLTi-enhanced Oppo BDP-95, which, to me, sounds better than any CD./SACD separates I've heard, in spite of having what others have described as a pretty ordinary transport.

So... why does the transport matter so much? and if it does matter so much, why DOESN'T it matter in a JLTi-enhanced unit which does NOT have one of the world's great transports??? In other words, what is Joe doing to the Oppo which makes the quality of the transport so much less important, and if he can do that, then why don't the manufacturers of massive transports instead use a cheap transport and do what Joe does for far less cost and, by extension, greater profit for them?

Cheers

Warren

I have owned 3x jlti cd/sacd transports plus a marantz cd50 with terra firma clock which was done in 2008 my terra firma is in the shed collecting spider webs ,average transports nothing special imho i even modded the terra firma clock further but still no cigar i used to think they are great until something else got plugged in with more body,timbre heart and soul less whiteness in the presentation of music..

enjoy your journey

[Gruffnutz]

What transport are you using now Kayak?

[aechmea]

The rotating part in my MSB transport is a computer DVD writer which can be replaced by any old person with a screwdriver. The theory being that after the data is extracted (by re-reading if necessary), the bits are assembled in memory on the 'mother board' and then sent out at the right timing (44.1, 48 etc up to 392) with vanishingly low jitter (according to the blurb).

So it's fair to say that MSB don't care much about the spinning part either, preferring to concentrate on the delivery of bits. I believe PS Audio does a similar thing with their Perfect Wave transport.

[Winter]

Like the Sony Scd1/777es

[kdoot]

Here is one point of view:

http://www.codebunny...transports.html

Interesting. Has he been reading my posts? Because he highlights two of the critical things which do differentiate transports: data accuracy and jitter. But like many others from the IT industry (which is my own field, btw) he projects things which are absolutely true in IT onto CD player and DAC technology where they actually don't apply in quite the same way.

An optical disc reader in a computer will extract the correct data basically always or never (if the drive's busted). It's got sophisticated software controlling it to make sure of that and will go over the disc multiple times until what it gets looks like the right bits. But in a CD transport, the controllers used to be far less sophisticated (cheaper) and usually just did a single pass hoping for the best, with error correction/minimisation algorithms to try and compensate for glitches. So CD read errors used to be a significant source of variation between transports. These days it's less so because the standard of technology has advanced.

Jitter is something that IT guys generally just don't understand. They think we're saying that the data delivery timing is so far out that we end up with a numerical error. That's not it at all.

The jitter factor is definitely something that still differentiates CD transports. How much it matters depends on what (if any) strategies your DAC uses to try and minimise the effect of jitter. Variations in the timing of the conversion of accurate data into analog levels cause changes in the shape of the output wave.

Asynchronous Sample Rate Conversion seeks to get around this by re-mapping the incoming jittery data stream onto a new data stream that will be converted with a much more stable clock. But the less stable the incoming data stream, the greater the error in the re-mapped signal (it can't be perfect) and so even sophisticated DACs can show some difference between transports due to jitter.

More recently we've also started being concerned about other kinds of noise being propagated down the digital interconnect cable, including USB, and the side-effects those energies could have on the stability of the D-to-A process if not mitigated. That's something I feel is more an issue for computer-based transports than older-style CD spinners.

[Once was an audiophile]

What transport are you using now Kayak?

marantz cd/94 modded with a zenelectro clock running off a car battery :lol: using a (OCXO crystal)

[Gordon Macfarlane]

I know that from my point of view dedicated transports do make a difference however whether is is necessary to use something like the Phillips CDM1 mechanism inside the transport is something I am no longer so sure off.

A number of manufacturers (Meridian and Audio gd) sell or sold transports that either use cd rom drives or cheapo Sony dvd mechanisms. So , the mechanism may be cheap and cheerful but these products have sophisticated data buffering and reclocking circuits and unlike the cd mechanisms wich only read the data once before handing it off to the digital output circuits the Audio-gd and Meridian products read and re-read the data.

Oppinions vary as to which method produces the better digital singnal

[Addicted to music]

I know that from my point of view dedicated transports do make a difference however whether is is necessary to use something like the Phillips CDM1 mechanism inside the transport is something I am no longer so sure off.

A number of manufacturers (Meridian and Audio gd) sell or sold transports that either use cd rom drives or cheapo Sony dvd mechanisms. So , the mechanism may be cheap and cheerful but these products have sophisticated data buffering and reclocking circuits and unlike the cd mechanisms wich only read the data once before handing it off to the digital output circuits the Audio-gd and Meridian products read and re-read the data.

Oppinions vary as to which method produces the better digital singnal

I know that from my point of view dedicated transports do make a difference however whether is is necessary to use something like the Phillips CDM1 mechanism inside the transport is something I am no longer so sure off.

A number of manufacturers (Meridian and Audio gd) sell or sold transports that either use cd rom drives or cheapo Sony dvd mechanisms. So , the mechanism may be cheap and cheerful but these products have sophisticated data buffering and reclocking circuits and unlike the cd mechanisms wich only read the data once before handing it off to the digital output circuits the Audio-gd and Meridian products read and re-read the data.

Oppinions vary as to which method produces the better digital singnal

You find that all the Sony BDPs and Samsung BDPs will do this, you can here the unit take off spinning. I am beginning to think that its filling the buffer or the disc is hard to read. The latest Sony BDPs are a real improvement where the laser will just about read any disc unless it is really badly damage like from your local library.

[techspurt]

So... why does the transport matter so much?

Transports matter in three ways - 1) correct data, 2) correct timing, and 3) noise.

1) is a given or the drive is broken - go get a new one if its corrupting the data. Some very cheap CD players do corrupt the data because they implement a digital volume control on their SPDIF out. Avoid such unless the digital volume feature is attractive. Transports that claim they need multiple re-reads to get the data correct are broken; don't spend money on features like massive RAM buffers.

2) is generally overplayed in marketing materials. Bottom line is SPDIF introduces jitter by its very nature so no matter how perfect the transport, some jitter will always be introduced by the mere fact of using SPDIF. So do not pay extra for a very low jitter transport - unless it has (say) I2S over LVDS output.

3) is generally underplayed but IME the biggest influence on the sound. DACs should reject noise but designers seem unaware of the issue by and large.

[LHC]

3) is generally underplayed but IME the biggest influence on the sound. DACs should reject noise but designers seem unaware of the issue by and large.

What do you mean by 'noise' in the digital domain? It is just 1s and 0s, so how does noise differ to error? Perhaps you are referring to noise in the recording process.

[techspurt]

The noise I'm referring to here is common-mode noise. That's noise carried equally on the inner and outer conductors of the coax used to convey SPDIF. Its commonly introduced by SMPSUs but isn't limited to these. It differs from errors because it doesn't result in any bit errors unless the noise is huge - its impact is on the analog circuitry in the DAC, not the digital.

[LHC]

The noise I'm referring to here is common-mode noise. That's noise carried equally on the inner and outer conductors of the coax used to convey SPDIF. Its commonly introduced by SMPSUs but isn't limited to these. It differs from errors because it doesn't result in any bit errors unless the noise is huge - its impact is on the analog circuitry in the DAC, not the digital.

Hi Techspurt. Thank you for your answer. Does this common-mode noise also affect optical SPDIF/Toslink? The cabling is different.

[techspurt]

No, it can't affect Toslink - for the simple reason that Toslink isn't a cable, its optical fibre. Hence its non-conductive and gives perfect isolation. However Toslink transmitters and receivers are heavily bandwidth limited so distort SPDIF signals much more than coaxial (wired) connections. The end result is more jitter even though zero CM noise.

[mattjtaylor2809]

What are people actually using as a CD Transport?

I guess more & more are using thier old CD or even DVD burners & the into an external DAC? This was what I was doinf until my Marantx CDR started introducimg more & more clicks, ticks & crackles & pop's into the music that I removed it.

I've simply replaced it with a Philips CD player / media surver & using as a transport to my Burson DAC via coax.

I have started to look at dediacted Transports & read up on the little Dot & the MF CDT.

Cheers

Matt

[Milo]

Hi, Matt, there's still a few dedicated transports being made: Stello, Cyrus, MF, Heed, Audio GD, and of course Esoteric. There are probably others, but that's all I can think of off the top of my head.

I certainly believe a good transport makes a difference; all though the march of technology in DACs has meant that jitter management is much improved from the early days of CD. My view is that the role of buffers in transports now days, i.e. 'memory players', makes a difference when compared with older transports.

[Gordon Macfarlane]

Here is another transport to consider : http://shop2.hifidiy.net/index.php?main_page=product_info&cPath=10_21&products_id=104.

[mattjtaylor2809]

thanks Ozcall & Milo.

[Milo]

MSB is another dedicated transport in production also.

[Monkeyboi]

I'm using a Sony SCD-XA5400ES SACD/CD player. In transport mode I use external decoding via HDMI using Sony's H.A.T.S. (High quality digital Audio Transmission System) which synchronises the transport and the data stream to the clock in the external DAC as well as controlling the data flow. To my old cloth ears it sounds better in this mode than external decoding via SPDIF. H.A.T.S. supports both DSD and LPCM signals, but to get the advantage of H.A.T.S., the DAC or receiver must support this system.

Cheers,

Alan R.

[Currawong]

Some useful reading, the first more related to USB transports, but none-the-less relevant:

http://www.head-fi.org/t/493152/low-jitter-usb-dan-lavry-michael-goodman-adaptive-asynchronous

Technical, but fascinating:

http://lampizator.eu/LAMPIZATOR/TRANSPORT/CD_transport_DIY.html

[Gruffnutz]

I'm using either a heavily modified Pioneer PD9700 stable platter player (re-clocked, data buffer, spdif and AES/EBU outputs) or a slot load Pioneer dvd-rom drive with an external controller and ttl to spdif converter.

Both good transports. And cheap.

[Decky]

Firstly Oppo transport is one of the better spinners found in commercial disk players today. What matters more is clock information sharing between DAC and transport rather than just the shear mechanical quality of the mechanisms. Finally, Joe's mods (at least the one that I used a while ago) created rather dark and veiled sound that was rich and "tube-like" in presentation but it lack fine detail level information. This is maybe not the best thing to have if you want to assess the quality of the transport itself.