Horus/Hapi FAQ

This is the historical repository of Merging related FAQs, known issues, tips & tricks.
The current Knowledge base is now located at https://confluence.merging.com/display/PUBLICDOC/
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This is the historical repository of Merging related FAQs, known issues, tips & tricks.
The current Knowledge base is now located at https://confluence.merging.com/display/PUBLICDOC/
Ricardo Ryan
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Horus/Hapi FAQ

Postby Ricardo Ryan » Fri Jun 08, 2012 11:35

Horus FAQ (This list is subject to updates)

Horus users will find documentation and download information here.

HORUS Modules


Can the MIC Pre-Amps gains be controlled by using remote protocols HUI/Eucon/OASIS?
Right now, the MIC Pre-Amps' remote is accessible from the Horus Web Page. That is true for any connection (even Pyramix). Remote control over Oasis/Eucon/HUI etc will be integrated later.

Is the MIC Pre-Amp in the Horus/Hapi able to handle the DPA 130V MIC systems?
No, Horus supports 48V MICs.

Are the AD modules available in Line Level only (without the MIC Pre-amplifier)?
No they are available in Mic or Line (switchable). All Analog Input modules are all switchable (on a per-channel base) between Mic and Line. It is not an option but a feature.

Does Horus/Hapi have an AD circuits that differ from the Sphynx II ones? Will I get different sound if I will put the Sphynx II to Horus the digital input and compare?
Yes. Horus has an entirely re-designed Analog as well as AD conversion circuitry. In terms of "sound quality", Mic/Line and AD will be quite close between the two generations of products (all specs within 1-2 dB of THD+N and noise specs, with Horus being typically better.

What happens if a MIC signal is split passively to Horus and a Mixer and both generate 48V? Will it blow up?
No. The Horus MIC input is designed so that if an external source also provides 48V to the input with the 48V supply of the Horus activated, it will not blowup.

Could we have 48 MIC Pre-Amps channels in one Horus (6 AD modules)?
Yes, but you will need to have the proper power supply configuration

Does the Horus/Hapi AD8 Mic Preamp provide a direct PreAmp output without latency, with parallel recording output for the monitoring operation ? Is there any possibility for this option ?
Merging's AD8D, AD8DP, AKD8D and AKD8DP modules do provide a discrete, Analogue-only Direct Outputs for each Mic-Preamplifer without latency.

Is there a difference in audible quality between the Mic and Line input settings of the HORUS AD8 / AD8P cards?
We would not expect that a user would normally experience any audible shift in quality between Line and Mic modes. There are some minor changes in the Frequency response, depending on the gain settings of each, which can be measured. But, those will occur in frequency bands either above 100kHz or below 10Hz, thus way outside the audible range.
As an addendum to this point, since the Line input must be attenuated to cope with signals coming in at levels above +13dBu, which is what is presented to the AD converter for 0dBFS, this adaptation process uses resistive division, which will in turn slightly higher the noise floor in Line mode due to the thermal resistor noise. Thus, if you can be assured that the Line level signal presented to the analogue inputs will not exceed +13dBu, there is then a very slight advantage in setting the input to Mic mode instead. Similarly we would not recommend to engage the PAD in Mic mode, if not required, for the very same reason.

I was surprised to see that analogue out from the Horus comes back on analogue input less 6dB. Why?
Merging made sure that nobody can overdrive its Line inputs (capable of accepting up to + 24 dBu for 0 dBFS) nor overdrive their existing Analogue equipment when connected to Horus Line Outs (+ 18 dBu for 0 dBFS) with Default ex-factory settings.
It's however extremely simple to either increase the sensitivity of your Horus Line Inputs (from +24 dBu to +18 dBu) by setting a Line Input Gain of 6 dB on all your Line inputs) or alternatively increase by 6 dB your Horus Line Outputs (from +18 dBu to +24 dBu) by changing the Dip switch settings on the Line Output cards (refer to the Horus User Manual). Either way you will then be able to enjoy an almost 1/1 level correspondence after applying one of the above described change.


Does Horus have a DA circuit that differs from the Sphynx-2? Will I get different sound if I will put Sphynx II to Horus digital input and try to compare?
Yes. Horus has entirely re-designed Analog as well as DA conversion circuitry. In terms of "sound quality", Line Out specs will be vastly superior with the Horus.

What is the possibility to playback through the Horus DA converters in single ended as well as in balanced modes?
The Horus Line Out circuitry is fully symmetrical, but non-floating. So driving asymmetrical (single-ended) loads is easy and possible and should be wired in such a way to just use one of the symmetric outputs (either Hot or Cold) and Ground. It is not recommended to short the other (unused) output to Ground . This will also reduce the output signal level by 6 dBus compared to the full differential swing of the symmetric output, which is usually too high for usual single-ended loads. Further reduction of the level might be further required to avoid clipping the single-ended receiving side.
(for details, refer to the Horus User Manual)

What happens with the Horus, if a sound engineer accidentally turns on his Phantom Power on the mixer which is connected to the Horus Output?
The Horus is protected against such a case. It is not recommended but the Horus DA output supports 48V, if driven through 6.8 kOhms resistors, as typically used in Phantom power designs.

HORUS Network Accessories and Features

On one RAVENNA network, is it possible to have one Horus running at 44.1kHz for example and the other one at 96kHz and use them both for different DAWs or in turn?
Yes. RAVENNA allows for concurrent multiple Sampling rates on the same network.
Note: While RAVENNA does indeed provide the possibility to simultaneously convey signals at different sampling rates over the same network, Horus is however designed to operate at a given sample rate and will only accept RAVENNA streams that are presented to it at the proper matching sampling rate. This said if, during this summer, we find out there is some FPGA real-estate left, Merging may add a few channels of real-time SRC in the architecture of the internal Horus router to provide such capability on a limited number of audio channels.

Is the Merging NIC card (NET-MSC-GBEX1) temporary and why do you need this special card?
The MassCore Ethernet PCIe Network card is required for performance issues. MassCore has a dedicated driver for this (and only this) NIC. It took several months of engineering to write such a low-level driver for a specific NIC and we certainly cannot afford to repeat this exercise with the tens (if not way more) of different Ethernet chips that exist on the market.
This said, RAVENNA (and Horus) will also work well without the need to use this specific card, when operating with an ASIO/CoreAudio driver that we are also currently developing in parallel for RAVENNA/Horus. More details in a near future.

Do I have to pull out the Mykerinos Hardware (PCI MB2) before I install the "Masscore Single port Gigabit Desktop Adapter"?
No, but be aware that in RAVENNA/MassCore only the MassCore PCIe Ethernet card will be enabled, users cannot use their Mykerinos card simultaneously. You must keep the Mykerinos card in your system if your keys are on it and if you want to switch back to Mykerinos/MassCore.

What parameters does the network need to be compatible with RAVENNA? Does it need to support some Layer 2 or 3 or Jumbo packets for example?
The Network must be Layer 3 compliant and must be a Gigabit network. For additional information please consult the following page and related ones under: http://ravenna.alcnetworx.com/technology/open-technology-standards/based-on-standards.html

What network equipment does Merging specify for use with the RAVENNA network? Do I need to buy insanely expensive switches etc?
The types of switches and equipment you purchase relates to the size and complexity of the RAVENNA network. The switch that Merging currently recommends is the Dell PowerConnect 2816. Note that the Switch needs to be configured prior to usage. More details in the Merging RAVENNAGuide.

For a list of network requirements, please see the RAVENNA webpage relating to this: http://ravenna.alcnetworx.com/technology/technology-overview.html

Does the RAVENNAPCIe card NET-MSC-GBEX1 have a secondary port (like the Horus unit) or will I need to buy two such cards for redundancy?
You will need to buy and install two such cards for fully redundant link operation. More details in the near future.

Is RAVENNA secondary (redundancy) port on the back of Horus a standard or an optional feature?
Second RJ-45 port on the Horus is standard. More details in a near future.

How would the latency be affected if HORUS (in RAVENNA mode) is connected via a 54mbps wireless network, assuming you have the whole bandwidth available for the HORUS application alone, with a physical distance of 50m?
RAVENNA is not designed to transmit audio on Networks without minimum QoS requirements. Typically for now we do not recommend using RAVENNA over Wireless. However control data has no problem operating over Wireless.

Do I need to use the Merging Ethernet card (NET-MSC-GBEX1)? I want to use my Laptop to run Pyramix with Horus!
It is important to realize that the MassCore Ethernet PCIe Network card will only be required when using MassCore. An ASIO (PC) and CoreAudio (MAC) driver will be provided, allowing the use of Horus with standard PC/MAC Ethernet ports (on laptops as well!).
The NET-MSC-GBEX1 board manufactured by Intel has its firmware reprogrammed by Merging for RAVENNA/MassCore acceleration, so this card must absolutely be supplied by Merging!
Users that are eager to run MassCore on a laptop will need to use a PCI Express Expansion System (i.e. Magma) in order to fit the Merging Ethernet PCIe card NET-MSC-GBEX1. Note that Merging does not certify any PCI Express Expansion System.

Is there any distance limitation for RAVENNA mode use? In some cases, I may have to be more than 100m distance from stage.
100 Meters is the GbE (Gigabit Ethernet) maximum distance specifiation. For longer distances we recommend either inserting Gigabit Ethernet switches at regular distances less than 100 meters, using them as repeaters or better Copper to Optical (Ethernet to Fiber) adapters at each end (can be used with optical fibers up to roughly 600 meters or 2000 feet on a single hop.). A good reference starting point where this is all explained briefly is:http://techin.oureverydaylife.com/difference-between-normal-ethernet-cables-fiber-optic-2401.html
Customers should refer to the specs of the manufacturers of the CAT5e or CAT6 cables that they deployed or plan to use, as Merging only support those cables.
Note that Merging has certified the TP-Link MC200 (NET-TPL-MC200 on pricelist)

Is it possible to use one Horus for a few DAWs inside the RAVENNA network?
Yes, RAVENNA allows sharing of common sources between all devices on a Network.

Can RAVENNA and OASIS run on the same physical network?

I/O Configurations and Features

I saw two headphone jacks at the front of the Horus. Are those of the same sonic quality as the converters on the DA-module card?
The two headphone Jacks use a different D/A, so they are not exactly of the same level of quality as the Line Out themselves but still quite decent.

Can the headphone jacks be used without installing any DA-module card?

It is possible to divide the Horus channels between different DAWs?
And control them separately?
With respect to control, the answer is also yes when controlling different portions (channel groups) of a Horus. However when several controlling devices (web pages, control surfaces, etc.) want to address the same channels, some rules will have to be established in terms of access priority and authorization as is typical with any properly managed Network architecture.

For example, can a 24 AD/DA version have the 24ADs being recorded on two computers/DAW’s at the same time and in addition route them directly out to the MADI-stream as well simultaneously (To FOH)?
… And at the same time record 64-channels from the MADI-stream (FOH) to the computers/DAWs
YES! Although the possible track count being recorded will depend on the DAW’s ability to record lots of tracks. (We know that Pyramix can do it though)
… While sending to 12 channels Horus D/A from computer 1 and 12 D/A from computer 2?
Yes but note that the Horus modules can be routed (at the moment) in blocks of 8 channels. So you could route 8 channels from DAW1 and 16 from DAW 2 etc.

So, the AD/DAs and other I/O modules need to be configured in groups of 8? Or can you route individual channels (Like common talkback/listen)?
We have decided for the moment to simplify the routing capabilities (Analog - AES - MADI - RAVENNA) by groups of 8 consecutive channels, except for the Headphone monitoring that is just a stereo signal.

How are Gain, Phase, Phantom Power etc. controllable via RAVENNA from within Pyramix?
For the final Pyramix v8 the gain will be controllable from within the Pyramix mixer.
Wondering if those functions are available through the OASIS protocol?
They are in the process of being implemented in the OASIS protocol.

Can you route, for example AES and AD/DA (I/O) straight to MADI via DSP while they at the same time go to RAVENNA
Yes. Any input can go to any combination of outputs.
How Can I set it all? Do I have to do it on the front panel of the Horus unit?
No. Each Horus unit can be configured and controlled by web page access which can be viewed and manipulated using almost any standard web browser (Chrome recommended/Internet Explorer does NOT work)

Latency: It’s to my understanding that the Horus has sub-millisecond latency, but do you have an exact number?
I am afraid we may be confusing several functionalities here. In terms of A/D to MADI or MADI to D/A converter, Horus has just a few samples of latency (well under a millisecond) so that should not be a problem.
The main issue about latency is actually not with the converter itself but with the driver to/from the application. So the latencies noticed will vary greatly between the MassCore and the ASIO based usage of the Horus.

So then, what is the Latency of a Horus being used with RAVENNA and MassCore?
The Latency from live in to live out of a Horus being used with our MassCore engine can go as low as 1.33ms (currently at 5.3ms for Pyramix v8 Beta cycle)

What is the latency of the Horus if used with the RAVENNA ASIO/CoreAudio Driver?
As ASIO and CoreAudio are “host-based” processes, the latency when using the Horus with these drivers will increase substantially. This will be similar for any ASIO / CoreAudio solution as it is essentially due to the non-deterministic behavior of the application running under Windows or MAC.
… And what If simply wanting to use it as an AD/DA and take the converted analogue signal out of the MADI or AES outputs?
Then we go back to the original statement, “Horus has just a few samples of latency (so well under a millisecond)”.

What is the maximum channel count for RAVENNA/Horus @1fs? How about at DSD sample rates?
We've deployed RAVENNA under MassCore with an equivalent capacity of 384 x 24-bit channels equivalent at 1 FS (ie 44.1 or 48 kHz) and this bi-directionally. That corresponds to 48 channels at DXD or 384 kHz rates. Refer to our recommended RAVENNA configurations http://www.merging.com/pages/pcconfig

Can the RAVENNA ASIO driver work on any Gigabit port like the built in of a Mac Pro or PC?
Yes. It is only our own MassCore implementation that will require a dedicated Gigabit adapter card for the best performance.

What are the Specifications for the ASIO/CoreAudio Driver? What can I achieve with it?
This ASIO driver is expected to allow up to 64 bidirectional I/O channels of 24-bit (at 1FS). It will of course not allow ultra-low latency operation as with MassCore implementation but for many applications, this will be fine.

Can I use the ASIO or CoreAudio Driver with DAW Applications other than Merging’s Pyramix and Ovation? Like for instance AVID Protools or Steinberg Nuendo etc?
Yes! These drivers were specifically designed to make sure that regardless of the tools you use you will be able to incorporate Horus into your workflow!

Is the ASIO driver going to allow a DAW to sit on a RAVENNA network as a standard node? I mean, if I had 2 DAWs using the ASIO driver, could I connect them both to one Horus to do parallel recording?
Yes you can record a Horus stream from several ASIO driver.


What about the Horus fan, surely that means the box makes too much ambient sound ?
There will be a fan, capable of turning itself on gradually whenever the internally sensed temperature exceeds pre-set limits. We do not want our customers to have their Horus audio characteristics degrade or even fail above certain temperature!

Fortunately, Merging has spent enormous time carefully engineering each and every component of Horus to be drawing as little power as technologically possible these days, without compromising the sound at any time.
We therefore expect our users to enjoy their Horus as an essentially "fan-less" device since the fan will in many (if not most circumstances) never switch on. So the fact that we still planned a fan is to be more seen as an "emergency" fan that:
a) will only turn on when absolutely required (for instance in situations of high ambient temperature, with many phantom-powered connected microphones drawing a lot of aggregate power)
b) even when turned on, we are engineering it in such a way that the fan will be essentially inaudible.

Designing a 2 U unit which offers, in such a compact space, up to 4 MADI ports, 24 channels of AES I/O and 24 channels of MIC preamplifiers along with ultra high-quality A/D and up to 24 channel of D/A conversion, not even mentioning RAVENNA, a backlit TFT touchscreen and an optional Redundant Power supply with no decent "heat-control" would just have been ludicrous. As a matter of fact, we expect a fully loaded Horus to still not consume more than 50-Watt to maximum of 60-Watt total.

In a configuration where HORUS is a stagebox connected to a PC running Pyramix, can I use Pyramix native or do I need a Mykerinos card?
Starting with Pyramix V8, there is no need for a Mykerinos card.
RAVENNA can be connected either:
a) Via our own PCIe x1 Network RAVENNA/MassCore accelerator card NET-MSC-GBEX1 for Pyramix MassCore operation (available in Pyramix V8 Beta today). Allows a maximum of channels with lowest latency
b) Standard computer GbE NIC in ASIO or Core Audio for Pyramix Native and/or other third-party applications (expected ot become available over the summer). Will probably allow up to 64 channels at 1 FS (32 channels at 2FS, 16 channels at 4FS) with moderate latencies, as usual with existing Native audio applications.

Does Horus have a DSP mixer or any other way of controlling/setting up low-latency monitoring?
This is not yet on our list of priorities to implement. At initial release of Horus we'll just provide a low latency router, which may be used for direct monitoring in certain circumstances.

How does Horus process DSD to and from Pyramix over RAVENNA?
Internally, the Horus actually processes and moves the DSD signal in a 352.8kHz / 32bit stream. It is not converted to actual PCM, rather the raw DSD data is just transported in this manner.
• A DSD64 stream actually only uses 8 bits of the possible 32bits.
• A DSD128 stream uses 16bits
• A DSD256 stream uses all 32bits.
• The DXD (352.8kHz PCM stream) uses the 24bits
All of these DSD stream types are actually multiples of 352.8, itself being a multiple of 44.1 kHz.
Therefore, for the Horus mainboard there’s no real difference between all these 4 formats. That’s only the AD and DA that are configured automatically and transparently according to the streams they are receiving audio from or sending audio to.
In fact as far as only playback or DA is concerned, you can set your Horus unit to DSD or DXD, that’ll make no difference. It’s only the way the Pyramix projects are configured that will define if audio is sent directly as DSD (when using DSD projects) or converted to DXD (when using DXD projects)

Horus/Hapi AES Cables
The AES ports connect the AES-EBU I/O using DB25 D-SUB connections (Tascam Digital). This means that AES cables that came with your Mykerinos cables are not compatible with the Horus/Hapi. You can order those cable directly from our sales partners.

The Merging Team