Latency with Carbon and Focusrite Clarett+ Octopre?

[gp23]

Hey ya'll,

I have a Carbon that I'm setting up, along with the Focusrite clarett+ octopre to connect via ADAT. That's the plan at least.

I've been considering expanding with another Carbon Pre, in place of the Focusrite, so I can have 16 channels of DSP (0 latency).

My question is this:

Will not having 8 DSP on the focusrite cause latency when tracking 16 channels at one time (while the Carbon is armed with DSP)?

That's my only concern. That 8 channels will be slightly off, causing a sort of slap back feel.

Figured I'd find this out before making any changes.

Thanks for the info!

[Darryl Ramm]

Will not having 8 DSP on the focusrite cause latency when tracking 16 channels at one time (while the Carbon is armed with DSP)?

What DSP are you talking about? There is no DSP on the Focusrite or a Carbon-Pre.

You keep posting separate but related posts here. Why can you just keep your related questions in one thread and at least try to avoid folks repeating stuff.

A Carbon-Pre is likely be a better choice for audio quality and integration reasons, but if you read the documentation for the Carbon Pre you would see it has no DSP onboard and relies on the DSP in the Carbon.

And DSP has nothing to do with ADC conversion to ADAT latency differences in the Carbon Pre and any other brand of ADAT box, but those are likely a small number of samples, and worse case correctable. Presumably a Carbon-Pre matches a Carbon conversion/input latency at all sample rates. But heck something to measure.

We've tried suggesting you read the documentation and that seems not to be helping. At this stage I'd suggest you just wait on getting your hand on the actual boxes and playing with them and stuff should make more sense. Please wait and do that before making any more purchase decisions.

[gp23]

Hey Darryl Ramm....
This is a community forum. Where people help each other out.
Not everyone is privy to the heavy audio terms and tech specs.
Even after reading docs.

There's no need for schooling here. It's unnecessary.

Try being kind. It'll take you more places.

Thanks

[Darryl Ramm]

You need to work out how to learn what you need. *This* clearly is not working. And yes it's a open forum, you are free to ask questions and folks are free to express their opinion. Again my suggestion, which you are free to ignore, is just stop posting these questions now, get you hands on the actual gear and once things are clear then ask questions you need help with.

[gp23]

Darryl, it' hard to get to the valuable info you provide, when you lead in with criticism. I puts off a tone of arrogance and belittling.

Is that how you're wanting to come across (that's a real question)?

Also, I'm sorry, do you work for Avid...am I missing something, or do you monitor for the forum? If so, man are you're a doing this brand a disservice.

Customer service is "service", not ridicule.

Chill out with the schooling...don't care for it, and I'm betting nobody else does either.

[Darryl Ramm]

Keep it up. You've been given help and it just gets stupid with one question after the other you keep at it. Are you like this in real life? Unable to work out anything for yourself? You seem to be struggling to understand the difference between an ADC and a DSP. Etc. You invent problems that don't exist because you have not looked at stuff like read the data sheet to the Carbon-Pre and seen what it actually does, e.g. it does not have DSP. Look that's all OK, nobody needs to understand all the guts of this to use one of these boxes, just stop worrying about all this stuff and get your hands on a box and use it.

[gp23]

Thanks for exactly proving my point.

[LDS]

All of the I/O in the Carbon share the 8 DSP chips, so you will still have access to low latency hybrid monitoring across anything connected to ADAT. Just toggle the thunderbolt icon on your ADAT channels.

It is highly likely that the focusrite will have slightly different AD/DA latency to the Carbon, but I doubt it will be substantial enough to cause any kind of slap back. It will be closer to phasing as a result of microphone placement. You will naturally deal with it when throwing up mics and making adjustments to get it sounding good, but if you are super concerned about it just ensure you aren’t splitting instruments between the two devices - like having half the drum kit on the Carbon and the other half on the Focusrite. Any use of physical measurements to get microphones aligned (like overheads to snare) will only work when they run through a signal chain with the same latency, so keep ‘‘em on the same interface.

[dominicperry]

I can't find specs for converter latency for the Carbons - I can't even find which chips it uses. Likewise I can't find details on the Focusrite, but I didn't look for long.
RME publish specs for latency conversion for their devices, and modern A/D and D/A are really short.

For example..(all from the manual)
RME Babyface (not really high end)
At 48KHz, AD 0.10 ms DA 0.15ms
Roughly half that at 96KHz

So, if you assume that modern interfaces at that price point are similar, +/- 100%, then you have a trivial amount of difference to compensate. EDIT: The following is not true - see LDS's post below. [Not worth worrying about. You won't hear it and you will struggle to measure it].

Dominic

[LDS]

Originally Posted by dominicperry

I can't find specs for converter latency for the Carbons - I can't even find which chips it uses. Likewise I can't find details on the Focusrite, but I didn't look for long.
RME publish specs for latency conversion for their devices, and modern A/D and D/A are really short.

For example..(all from the manual)
RME Babyface (not really high end)
At 48KHz, AD 0.10 ms DA 0.15ms
Roughly half that at 96KHz

So, if you assume that modern interfaces at that price point are similar, +/- 100%, then you have a trivial amount of difference to compensate. Not worth worrying about. You won't hear it and you will struggle to measure it.

Dominic

That is only really true from a does-the-talent-hear-any-latency perspective. From an audio engineering perspective, 0.15ms is clearly audible and measurable. It is the equivalent of pushing a microphone 5cm out of position, which can ruin a nice phase coherent multi-microphone recording by introducing audible phasing at 6kHz and up.

RME AD/DA latency is some of the best in the business. Lynx is still exceptionally quick at 25 samples but it still equals 0.56ms at 44.1kHz, and when put side by side the RME you have quoted, it equates to a 15cm difference in microphone placement and potential phasing from around 2kHz and up.

Avid HD I/Os are around 50 samples AD/DA from memory. Metric Halo ULN8 MKIII is closer to 100 samples. Based on the RTL differences between AES and AD/DA loops, the MTRX II is around 70 samples. The Octapre and Carbon might have very similar AD/DA latency, or they could be 50+ samples off. 50 samples doesn't sound like a whole lot in terms of audible latency, but it is audible phasing from 800Hz and up.