Clocking Issues ( Master, Slaves, AES or AUTO)

AndrewKirkland

Inspired
Hello I am currently using an AXE FX 2 via AES into my Metric Halo ULN-2 interface. I am a bit confused about the proper way to clock both systems.

This bit on the support wiki confused me.
  • SPDIF/AES IN: uses the recovered clock for all input sources. A valid 48 kHz data stream must be present at the AES or SPDIF input. If a valid stream is not detected the unit will fall back to the internal clock and display "NO INPUT CLOCK!". The SPDIF/AES select must be set to the appropriate value, i.e. if the data stream is input to the XLR jack then SPDIF/AES SELECT must be set to AES.
So on the halo I can use digital in (44.1/48 kHZ) or internal. If I use digital in I set the axe fx word clock to auto and it works fine.

However it also works when I use the metric halo's clock set to internal ( sample rate 48khz) and then the AXE world clock will work set on AES/SPDIF or AUTO. A brief message when I go to AES/SPDIF comes up and says "No Input Clock". When this message appears does this mean it is just setting the axe fx back to auto even if it stays selected on that area? Does it go away because it takes time to detect the new clock selection and I am on AES clock selection after it is detected? This is what mainly confused me.



The halo says for AES I should clock using dig in (44.1/48khz) however I would then need to set the axe fx to auto, as when I set it to AES and have the metric set to digital in there is an ungodly screeching noise. If someone could shed light on this issue, I would be extremely grateful. Thanks for your time and I hope every has a nice Thanksgiving.

So if axe is set to auto, and halo is set to dig in, does that mean the axe is the master clocking source?

And if the axe is set to aes/spdif or even auto, yet I have the metric halo set to internal, does this mean the axe fx is the slave?
 
A brief message when I go to AES/SPDIF comes up and says "No Input Clock"... Does it go away because it takes time to detect the new clock selection and I am on AES clock selection after it is detected?

Yes, it's locked to AES once the message disappears.

So if axe is set to auto, and halo is set to dig in, does that mean the axe is the master clocking source?

Yes

And if the axe is set to aes/spdif or even auto, yet I have the metric halo set to internal, does this mean the axe fx is the slave?

Yes when it's set to AES/SPDIF. When set to auto there's no synchronization and each device uses its own clock (not recommended).
 
@Bakerman Thanks so much for the response! It is very confusing when that message appears and disappears. It should be stated on the wiki. I think both the axe and halo when using their own clocks sync pretty well because I have the sample rate on the halo matching the axe. ( But I definitely understand why this is not recommended for use)

One last question should the Axe be the slave, or should it be the master? Or does it really matter? I noticed it sounds so similar. Slightly higher frequency response with the Axe as the Master in my configuration. When the AXE fx was the slave a little less high frequency response, but this actually sounded warmer in a way. I guess it comes down to what is the better clocking source. Both are quality products, however the Halo is solely an interface.
 
@Bakerman once again I cannot thank you enough for providing clear answers to my long/drawn out questions. Now to just be super OCD and see what clocking configurations works best with each guitar's pickups. Also what sounds in the axe fx or gear in my fx loop responds best lol.
 
Click n isn't an eq option...
You have one unit sending one unit receiving digital data.
So... Recording from Axe to MH axe will be master, MH will be slave.
 
Click N? Do you mean clocking? I am not saying it is an eq option, I just noticed an extremely subtle frequency response when changing the configuration as described in the previous posts. If you could provide a more descriptive explanation that'd be helpful! I understand the AXE FX is transmitting data, and the MH is receiving. But I am able to clock off either source. Once again, if you are extremely knowledgeable about this, I would be interested in learning from you! So do not take offense if I am completely wrong conceptually. I am here to gain wisdom from others.

So from the last part of what you said, is it is not possible for the HALO to be the master when recording with the axe fx? What is occurring when I switch clock settings on the halo/axe then? ( the way described previously at the first post in this thread)
 
One last question should the Axe be the slave, or should it be the master? Or does it really matter?

It shouldn't really matter. I think a difference in freq. response is unlikely. That doesn't really make sense and you could test with a high freq. synth tone.

I keep the Axe set to SPDIF clock for convenience when connected to computer/interface. That allows keeping the interface set to internal clock the whole time.

Click n isn't an eq option...
You have one unit sending one unit receiving digital data.
So... Recording from Axe to MH axe will be master, MH will be slave.

The Axe II can slave to an external clock while recording, if desired. The word clock parameter (added a few years ago) makes this possible.
 
It shouldn't really matter. I think a difference in freq. response is unlikely. That doesn't really make sense and you could test with a high freq. synth tone.

I keep the Axe set to SPDIF clock for convenience when connected to computer/interface. That allows keeping the interface set to internal clock the whole time.



The Axe II can slave to an external clock while recording, if desired. The word clock parameter (added a few years ago) makes this possible.
Since we were talking about AES and digi in on the MH...its not bi directional.
So while I'm aware that the Axe can receive clock. I'm guessing that the MH only receives?

On the Motu and UAD interfaces you have the option to up sample on the input so I leave each at their own click and go that way.

That said rather than using the digi I/o I found that running them as an aggregate device and using the Axe as an external.plugin gets me a lot more milage.
See my post in the re-amp sticky for that. Assuming you're on a Mac.
 
If you hear a difference in frequency response that means the clock frequency is different. The Axe-Fx will lock onto a 44.1 kHz clock but all the filters and IRs will be off by about 10% since they assume 48 kHz.
 
Thanks for the info, that would seem to make sense. Although I have the sample rate on the MH set to 48 kHZ so I am still a little lost. I think I will just use the dig in clock, and set the axe to auto to be the master in the system. It is an extremely subtle difference and maybe I only perceived a change in frequency because of the way I played a reference back. (Hard to be 100% the same unless you just run a piece of recorded audio through/a synth with a set velocity)
 
The fractal forum always is a wealth of knowledge and I appreciate how helpful the community is. This product has truly changed my life for the better! It is a marvel of engineering/design.
 
Since we were talking about AES and digi in on the MH...its not bi directional.
So while I'm aware that the Axe can receive clock. I'm guessing that the MH only receives?

The bidirectional part happens by adding a second cable from MH AES out to Axe AES in.

It sounds like the OP did this, based on the thread so far. The Axe would keep flashing "no input clock" if there was no clock source while word clock parameter = SPDIF/AES.
 
In general, a digital audio system can have any number of Slaves, but it must have exactly one Master. We always set the Master to Internal clock, and we always set Slaves to External clock.

If we have a bidirectional connection between the Metric Halo and the AxeFx, then we can set either one to be the Master, and the other to be the Slave.

If we have a unidirectional connection from the AxeFx to the Metric Halo, then the AxeFx must be the Master, and the Metric Halo must be the Slave.

The Auto setting tells the AxeFx to determine automatically whether it should be Master or Slave. If we understand how clocking works, then we don't need Auto.

There is one exception to the single-Master rule: IF the Metric Halo input has a sample rate converter, then both devices can be Masters. A sample rate converter is a piece of hardware that translates a digital audio stream from one clock to another.
 
The metric halo has a sample rate converter in addition to being able to select the main sample rate. That is such a thorough explanation, thanks so much. I did have aes in and outs between the halo and the axe fx. So two aes cables in the system.
 
The bidirectional part happens by adding a second cable from MH AES out to Axe AES in.

It sounds like the OP did this, based on the thread so far. The Axe would keep flashing "no input clock" if there was no clock source while word clock parameter = SPDIF/AES.
Spdif is bi directional...AES/EBU isn't and requires two cables.
 
It only flashes for a second or two than disappears so if there was only one cable it'd stay flashing until you switched back to auto
 
Spdif is bi directional...AES/EBU isn't and requires two cables.

SPDIF isn't bidirectional w/ 1 cable. Either way I'm not sure how that's relevant. The OP seems to be using 2 AES cables, making either device a possible clock source (while using analog main input on Axe).
 
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