XO using MOTU 828mk3 hybrid

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi,

I am new to digital crossover and want to use MOTU 828MK3 for my 3 ways TAD+Horn project.

I want to know:
1. Can 828MK3 use for active crossover?
2. Does it need to run with a PC/MAC? or it can be alone?
3. Any software needs to make 828MK3 as a crossover?
4. Can it accept digital input such as CD, CAS, I2S?
5. Can it output digital signal that can be used by individual DAC?

Thanks
Gary
 
XO using MOTU 828mk3 hybrid: yes works

Hi

I am actually using the Motu828mk3Hybrid as crossover.
I use analog in and SPDIF in.

Out I use analog (to 8 amps at the moment, will be 20 in the future with addition RME Fireface UFX)

I use it with Win7, running VST host (Plogue Bidule) and using a lot of different VST plugin.

I run various filters the most advanced is using "acourate" www.acourate.de" for FIR filter design. To run you need a convolver VST.

How it works:
Sound is coming in (analog or SPDIF) to Motu, is converted to digital, runs over USB to computer.
There, into VST host, through VST plugins.
Runs back over USB to Motu.
After that to DAC and to analog out of Motu. Here it goes to analog poweramps and to the chassis.

And its loud and clear!!
You can do whatever trick you ever wanted to try.
Cross talk cancellation, ambisonic etc. etc.

Digital crossover (or at least active crossover) is by far superior to these "very high quaility" passive crossovers.
 
Hi pschelbert,

Thanks for your detail information. It is very useful for me to make the decision to purchase this machine or not.

Regarding to your "...Runs back over USB to Motu. After that to DAC and to analog...",

- Can it be use Firewire connection to channel in and out signals between PC and 828MK2?
- "to DAC", does it mean I can connect external DACs to 828MK2 using digital outputs? how many DACs that it can support? I need 3 DACs for High/Mid/Low amps.
- you mentioned to use RME Fireface UFX to expand the outputs, does it mean you will use external DACs?

Thx
Gary
 
xover with Motu

Hi Gary

yes you can use firewire if you prefer, both MOTU and RME have USB and Firewire I used only USB though)

Yes with both you can use external DAC (however why do you want to spend again moneay as the DAC in the MOTU or RME are already in there and paid...

Both have two ADAT=2x8 channels=16 channels. The limit is more the analog outputs with Motu as far as I remember you can route 10 channels to analog (enough for a 4-way stereo system which needs 8 channels, so 10 DACs). With RME you can have 12 channels analog out (menas 12 DACs).

RME expand.
As I need 20 channels analog out (to go to the amps) I need both interfaces. I use the internal ADC and DAC (thats what I paid for), no need for any external DAC.
The Motu has good DACs and the RME has superduper DACs, so no need to have anything more. Imagine this system needs 20 DACs, if you buy them separate its a fortune..

I will use the RME to output 12 channels analog (maximum it can do) and the remaining 8 channels go through Motu

Peter



regarding to your "...Runs back over USB to Motu. After that to DAC and to analog...",

- Can it be use Firewire connection to channel in and out signals between PC and 828MK2?
- "to DAC", does it mean I can connect external DACs to 828MK2 using digital outputs? how many DACs that it can support? I need 3 DACs for High/Mid/Low amps.
- you mentioned to use RME Fireface UFX to expand the outputs, does it mean you will use external DACs?

Thx
Gary
 
hi gary and peter,

im actually looking for more info on using MOTU in active system also.

if using PC/MAC as source, will it be any difference between the SPDIF and the playback thru Firewire?

as i understand if the playback thru firewire it will be in digital domain, is this correct?

cheers
henry
 
Motu XO

Hi

Firewire: here you have the choice to use USB or Firewire. Both are digital, its just another standard, there should be no difference else than bugs...in implementations
This is to transfer signals to and from computer (for DAW software running in the computer)

SPDIF is for in and ouptut of digital signals coming from CD, DVD, Receiver etc. and going to digital inputs of amps etc.

ADAT is the same as SPDIF but for 8 channels (semipro)

Peter
 
Hi

I am actually using the Motu828mk3Hybrid as crossover.
I use analog in and SPDIF in.

Out I use analog (to 8 amps at the moment, will be 20 in the future with addition RME Fireface UFX)

I use it with Win7, running VST host (Plogue Bidule) and using a lot of different VST plugin.

I run various filters the most advanced is using "acourate" www.acourate.de" for FIR filter design. To run you need a convolver VST.

How it works:
Sound is coming in (analog or SPDIF) to Motu, is converted to digital, runs over USB to computer.
There, into VST host, through VST plugins.
Runs back over USB to Motu.
After that to DAC and to analog out of Motu. Here it goes to analog poweramps and to the chassis.

And its loud and clear!!
You can do whatever trick you ever wanted to try.
Cross talk cancellation, ambisonic etc. etc.

Digital crossover (or at least active crossover) is by far superior to these "very high quaility" passive crossovers.

what is the latency of all this signal path?
 
Motu828 x-over

Latency is quiet a lot.

However if you process all parallel you will not notice in HIFI.
In video thats another thing (I am using it only in HIFI).

1) Latency is first due to AD, DA and internal processing of audio interface (Motu or others). This is not much 18-256 samples
2) it depends much also on what VST plugins you are using. For IIR filters its not much. For FIR filter (convolver it may be huge, depending on filter size, can be up to 1s).
 
Motu828 xover

not there is no way to have less latency. A certain FIR filter length has always a certain number of tabs. This defines the delay. Its just mathematics. No hardware can turn the time back. The Hardware therefore does not play a role (just medicre differences) in delay.

The easiest to deal with delay, if you delay all other singals as well. Then you do not notice the delay. There is actually no other solution.
To minimize delay use IIR filters not very steep ones.
 
Motu828 xover

Hi

the TRS out on the back are all balanced. Now if you connect a mono TRS you will get unbalanced, right to connect to cinch

If you use balanced TRS connectors, the they are balanced, go for example to XR inputs of amp.

The only stereo TRS are in front (Main, headphone), they are unbalanced ans stereo (one TRS Stereo for Left and right)

If you have the choice go balanced.

Peter
 
TRS Stereo (balanced) XLR

here for example a cable.
pro snake 17582/3,0 SW Audio Cable - Thomann UK Cyberstore

Thomann has a whole bunch of cables (I could not find pinouts though, may be they are somewhere).
I have almost all my cables from Thomann, it just works, choose the right connectors on both ends (be careful also male, female must be correct).

in the manual of my RME Fireface UFX on page 97 (english version) you see the wiring of TRS balanced and XLR.

They are standardized, you should find it also on the net

Peter
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.