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Lou
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 Posted: Sun Jul 03, 2011 7:24 pm Post subject: Audio Quality, USB, Cables or S/PDIF |
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Has anyone tested the three options and what have you decided on?
USB sounds pretty good. Just picked up a good pair of cables to check out, haven't tried s/pdif yet..
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Bruce Lychee
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| Posted: Sun Jul 03, 2011 10:47 pm Post subject: Re: Audio Quality, USB, Cables or S/PDIF |
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| Lou wrote: | Has anyone tested the three options and what have you decided on?
USB sounds pretty good. Just picked up a good pair of cables to check out, haven't tried s/pdif yet.. |
If you are using USB or SPDIF isn't your result going to depend on the DAC and output stages of your receiving device?
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Lou
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| Posted: Mon Jul 04, 2011 12:12 am Post subject: |
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I think so, not sure? .. Right now I'm USB out putting to Ensemble.. (Aggregate)
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Bruce Lychee
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| Posted: Mon Jul 04, 2011 12:27 am Post subject: |
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| Lou wrote: | | I think so, not sure? .. Right now I'm USB out putting to Ensemble.. (Aggregate) |
I was pointing out that USB and SPDIF carry digital signals that need to be converted on the receiving end. You will end up hearing the DAC and output stage of the receiving devices. If you use the analog outs on the KRONOS you will hear the DAC and output of the KRONOS, so comparing the three is really just comparing the KRONOS v. your other device.
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Lou
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| Posted: Mon Jul 04, 2011 12:45 am Post subject: |
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| Bruce Lychee wrote: | | Lou wrote: | | I think so, not sure? .. Right now I'm USB out putting to Ensemble.. (Aggregate) |
If you use the analog outs on the KRONOS you will hear the DAC and output of the KRONOS, so comparing the three is really just comparing the KRONOS v. your other device. |
Confused here? If you use the analog outs (Kronos) going thru my Ensemble, then you would be hearing the Ensemble DAC, right?
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Bruce Lychee
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| Posted: Mon Jul 04, 2011 12:59 am Post subject: |
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| Lou wrote: | | Bruce Lychee wrote: | | Lou wrote: | | I think so, not sure? .. Right now I'm USB out putting to Ensemble.. (Aggregate) |
If you use the analog outs on the KRONOS you will hear the DAC and output of the KRONOS, so comparing the three is really just comparing the KRONOS v. your other device. |
Confused here? If you use the analog outs (Kronos) going thru my Ensemble, then you would be hearing the Ensemble DAC, right? |
Yes. Actually ADC conversion then DAC. You might hear some difference because it will go through the KRONOS DAC too, but make sure you make sure all levels are equal if you really want to test that out. If you are going through your Ensemble in all cases, I would just go USB or SPDIF and avoid multiple conversions.
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Last edited by Bruce Lychee on Mon Jul 04, 2011 1:05 am; edited 2 times in total |
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burningbusch
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Joined: 30 Jan 2005
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Location: Seattle
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| Posted: Mon Jul 04, 2011 1:01 am Post subject: |
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I use S/PDIF with my Protools TDM setup and it works flawlessly. It's great that you can lock the Kronos to an external clock. I use USB for MIBI.
Busch. |
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shap
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Joined: 09 Apr 2011
Posts: 194
Location: US northwest
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| Posted: Mon Jul 04, 2011 1:17 am Post subject: |
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| Bruce Lychee wrote: | | I was pointing out that USB and SPDIF carry digital signals that need to be converted on the receiving end. You will end up hearing the DAC and output stage of the receiving devices. If you use the analog outs on the KRONOS you will hear the DAC and output of the KRONOS, so comparing the three is really just comparing the KRONOS v. your other device. |
If I'm understanding Lou's question and your answer correctly, then I think you have that backwards.
I think Lou is assuming that he is proceeding through some form of PC, perhaps with a DAW. If that's the case, then he's going to run an output-side DAC in all cases. This will be the DAC on whatever channel his PC is using to drive his monitors. Since the monitors are analog devices, there is no way to remove the final DAC stage from the processing. The remaining questions all have to do with what happens between the synth and the PC.
If the audio from the synth to the PC goes out the analog mains on the synth, it goes through a DAC there. It then gets re-converted to digital by an ADC as the signal enters the in-coming audio interface on the PC. Each of those stages loses a bit of fidelity and introduces some amount of conversion noise. The analog cable itself can also contribute to signal degradation.
If the audio from the synth to the PC instead goes over a digital carrier of some form (USB, S/PDIF, FireWire, others), then the outgoing DAC on the synth and the in-coming ADC on the PC are eliminated. Digital encoding also (in practice) eliminates corruption in the cable. While there are significant differences between USB1 and USB2 cables, fancier cables don't really help. The cable either meets the high-speed USB spec or it doesn't, and that's all you need to know. I suspect the same is true for coaxial S/PDIF.
Whether it's digital or analog, you always want to keep a minimum one foot gap between low voltage and house voltage cables to prevent voltage cross-talk. When household voltage gets picked up (through cross-talk) on low-voltage lines, you'll certainly get corruption (at a minimum), but you may also exceed the voltage range tolerances on the receiving circuitry. If you've heard 60Hz hum on an analog cable, the most like sources are (a) voltage cross-talk from a power cable that is running alongside the analog cable, or (b) lack of a common ground plane across the devices. Shielded cable makes essentially no difference w.r.t. high-voltage cross talk.
There is no possibility of cross-talk between household power cables and optical cables.
Lou: Any of this helping, or did I misunderstand the question?
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Motif XF8, Kronos-88 (ordered), V-Synth GT, DT-Extreme eDrums
PC Core i7-920/24GB/3TB (2x)
Motu 2408mk3 + 24I/O
Sonar Producer, everything EastWest
Brian Moore iGuitar+Roland GI-20, Composite Acoustics 6, 12 string guitars, Multiple Ovations from when they were still worth it
Presonus Eureka (2x), TC Helicon VoiceOne
ADAM A7's and JBL 4328Ps, each for its purpose
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Bruce Lychee
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| Posted: Mon Jul 04, 2011 1:31 am Post subject: |
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I'm not sure how I had it backwards. I just didn't realize he was trying to go analog to the Ensemble, but pointed out in my follow up that if he was trying to do that he was going to go through three conversions. If he goes analog out to the Ensemble it's going to go through a DAC, ADC and DAC again. If he goes from USB or SPDIF it will go through a DAC and that's it.
If there is a difference in the output stage of the Kronos, it might show up since it goes through that DAC first. Again, just make sure you level everything if you want to test that.
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Lou
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| Posted: Mon Jul 04, 2011 1:51 am Post subject: |
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| shap wrote: |
Lou: Any of this helping, or did I misunderstand the question? |
Yes Shap, it's helping. Pretty much I gather is that eliminating the analog out of Kronos and going some form of digital out, will eliminate the need for DAC on the synth and ADC to the computer.
I think that right? So, stay USB or s/pdif. I was thinking that the Ensemble has better conversion than Kronos and didn't know which way to go..
What confuses me is that if I go S/PDIF, that goes from Kronos directly to the Ensemble in.
Where as the USB goes from Kronos directly to computer, but as it is now, I have an aggregate of Kronos USB and Ensemble, thus my confusion? Can you understand why I am confused here.. thanks.
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Bruce Lychee
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| Posted: Mon Jul 04, 2011 2:19 am Post subject: |
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If the USB goes to the computer, then to the ensemble, it will not be affected. You will end up with a DAC conversion at the Ensemble. I'm assuming that's how you have it set up.
Don't use your analog outs on the Kronos if you are going to the Ensemble. It won't make sense.
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Lou
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| Posted: Mon Jul 04, 2011 2:30 am Post subject: |
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Yep, that's how it is. Thanks Bruce.
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shap
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| Posted: Mon Jul 04, 2011 5:39 am Post subject: |
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| Bruce Lychee wrote: | | I'm not sure how I had it backwards. |
What caught my attention was your statement that the S/PDIF signal was converted on the receiving end. Strictly speaking, no conversion is done on the receiving end of the a digital connection. The conversion is done at the final output channel, and is entirely unrelated to the portion of the path covered by the S/PDIF connection.
I suspect I was just reading your statement too literally.
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Motif XF8, Kronos-88 (ordered), V-Synth GT, DT-Extreme eDrums
PC Core i7-920/24GB/3TB (2x)
Motu 2408mk3 + 24I/O
Sonar Producer, everything EastWest
Brian Moore iGuitar+Roland GI-20, Composite Acoustics 6, 12 string guitars, Multiple Ovations from when they were still worth it
Presonus Eureka (2x), TC Helicon VoiceOne
ADAM A7's and JBL 4328Ps, each for its purpose
Border Collies + Misc. Squeaky Toys |
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shap
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Posts: 194
Location: US northwest
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| Posted: Mon Jul 04, 2011 6:06 am Post subject: |
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| Lou wrote: | | Pretty much I gather is that eliminating the analog out of Kronos and going some form of digital out, will eliminate the need for DAC on the synth and ADC to the computer. |
Exactly. More generally: even the very best conversion involves some introduction of error and noise, so any place you have the option to move your sound around in digital form at the desired sample frequency, that's preferable in abstract. This is not particular to the KRONOS in any way.
For context: when people say that the converters on the KRONOS are good, well, they are, but everything in life is relative. There are boxes out there that only do conversion that cost as much as the KRONOS in its entirely, and in many cases those converters are more accurate. Avoiding conversion altogether is still going to be better than the really expensive boxes.
It used to be that USB over audio ran into real problems if the path went through a hub or competing high-load devices (e.g. a hard disk) were actively in use on the same USB bus. Significant improvements were introduced in the USB 2.0 Audio Class definition, so I don't know if this kind of thing is still an issue for most users. From the OS perspective, I can imagine rare error scenarios that are unlikely to go well, but I don't know if these are actually seen in the wild.
My sense is that USB2 more commonly runs into issues when you have multiple converters and you want low latency. More precisely, the PC ASIO driver runs into issues - the problem isn't USB2 per se. The ASIO spec only supports one audio interface driver at a time. The Ensemble is one interface. If you use USB-Audio, the KRONOS becomes an interface too, and that one needs a different driver from the Ensemble interface. And ASIO doesn't support more than one driver. At that point you're forced off of ASIO or forced into ASIO4ALL, which doesn't always work reliably.
Because of the ASIO issue, it's pretty unusual to see larger setups using USB Audio to individual devices; by bringing everything in and out through (say) the Ensemble you only need one ASIO driver, and then you don't hit that issue. Starting in Win7, there are newer driver technologies that do support multiple interfaces, but not all interfaces come with the appropriate drivers, so again it's a hassle.
Eventually you may want more inputs than you can get on a single converter interface box. At that point you hit clock synchronization issues and bussing issues in both USB2 and FireWire, and it becomes (at least in my opinion) a lot easier to move to a PCI-Audio solution (which is how I ended up there).
| Lou wrote: | | What confuses me is that if I go S/PDIF, that goes from Kronos directly to the Ensemble in. Where as the USB goes from Kronos directly to computer, but as it is now, I have an aggregate of Kronos USB and Ensemble, thus my confusion? Can you understand why I am confused here. thanks. |
I think I got that.
Since the Ensemble has S/PDIF inputs, you have three options:
1. [Very Unusual] It is possible to use the Ensemble as a zero-latency mixer. In that case you would take S/PDIF from the KRONOS into the ensemble, hook up a pair of analog outs on the ensemble to your monitors, and then use the Ensemble mixer control software to direct the various signals. This is approximately what I'm doing with the 828mk3 in my current multi-mixer setup.
While there are some use-cases for this mode (e.g. to provide individualized mixes to individual in-ear monitors), it's not a configuration that you see in the wild very often, because most of those use-cases arise involve more outputs than the cheaper converter boxes supply. You'll sometimes see this mode used to support headphones in a vocal booth in a smaller setup.
2. KRONOS S/PDIF->Ensemble S/PDIF input -> DAW on PC -> Ensemble analog outs -> Monitors. Non-zero, but low, latency.
This would work, but most users don't do it this way, because they tend to be running MIDI over USB to the workstation anyway, and once the USB is connected you might as well use it for the audio as well. What seems to happen is that people get forced into this path when they find that ASIO4ALL doesn't work for them.
3. KRONOS USB {MIDI+Audio} -> DAW on PC -> Ensemble analog outs -> Monitors. Non-zero, but low, latency.
This will work fine, except for the ASIO problem. If the Windows WDM drivers work for you, then this should be okay.
Personally, I'd go with option [2], because then you won't be fighting the limits of ASIO. But if [3] is working for you, I don't see any reason to switch.
_________________
Motif XF8, Kronos-88 (ordered), V-Synth GT, DT-Extreme eDrums
PC Core i7-920/24GB/3TB (2x)
Motu 2408mk3 + 24I/O
Sonar Producer, everything EastWest
Brian Moore iGuitar+Roland GI-20, Composite Acoustics 6, 12 string guitars, Multiple Ovations from when they were still worth it
Presonus Eureka (2x), TC Helicon VoiceOne
ADAM A7's and JBL 4328Ps, each for its purpose
Border Collies + Misc. Squeaky Toys |
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Bruce Lychee
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Joined: 16 Jun 2011
Posts: 856
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| Posted: Mon Jul 04, 2011 6:35 am Post subject: |
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| shap wrote: | | Bruce Lychee wrote: | | I'm not sure how I had it backwards. |
What caught my attention was your statement that the S/PDIF signal was converted on the receiving end. Strictly speaking, no conversion is done on the receiving end of the a digital connection. The conversion is done at the final output channel, and is entirely unrelated to the portion of the path covered by the S/PDIF connection.
I suspect I was just reading your statement too literally. |
I was just trying to keep things simple for OP and point out that the conversion can happen in the Kronos if he goes analog out or in the device receiving the digital signal if he goes USB or SPDIF. The SPDIF cable obviously only carries the signal and the DAC and it's output stages are going to get that sound in a form that can come out of your speakers. Most importantly, I just wanted to make it clear to OP not to use analog outs of the Kronos in his setup because going through multiple conversions makes little sense.
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Vintage Vibe 64 |
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