Patchbay – II

Connections

Below, an example of how they are connected the various instrumentations and how they are written the various notes on patchbay (fig.1)

Fig. 1 (typical situation from the recording studio, as mpe.berklee.edu)

studiol3_patchbay da mpe.berklee.edu.jpg

n.b. Before starting to physically wrap any audio instrumentation and / or write the various notes on Patchbay strips, it is recommended to create a schema similar to that in slot 1, defining already wiring paths so you can see if everything is possible to connect it according to your need, if you need to buy more patchbay or just one with fewer channels than the one designed, and do not get into any wiring during the wiring phase that can cause confusion and have to do the job again. The diagram drawn up will then be used as a reference (guideline) during the wiring phase to ensure that everything is properly connected, especially if wiring work is left to other technicians. It is also important to always keep this schema in hand so that if one day you decide to make changes, maintenance or for any reason disconnecting a connection, this helps to know the position of each connection, also because the wiring phase occurs at the back of Patchbay where the wiring notes are generally not written.

As can be seen from Figure 1 this kind of situation offers several Patchbays, usually when there are more Patchbays it is useful to identify them with letters (not numbers as there are already the channel numbers of the patchbay), example A and B are Out and In the first Patchbay, C and D are Out and In of the second Patchbay and so on.

Considering the example in figure 1 in the first Patchbay connect in the A all the signals that arrive from the Stage Box or direct from the microphones and D.I. Box or any line to be connected to an audio mixer, outboard processor or multi-track recorder. In B we connect all microphone inputs of the Audio Mixer. The first will be Full Normal Patchbay so as not having to use example Bantam to create bridges and directing each audio signal at its input.

For the second Patchbay will connect in the C the returns the multitrack recorder and in the D the monitor inputs of the audio mixer (in this case is a mixer inline audio in which the return of the recorded signal arrives on different inputs with respect to the microphone pre-amplifiers, used as inputs listening and mixing of the recorded signal), (we will see in subsequent audio mixer arguments and their types of operation). Even this will be a Full Normal Patchbay.

The third Patchbay will have in E the Send of the Insert of the audio mixer and in the F the Return of the Insert of the audio mixer, with Patchbay Full Normal or Normal in order to interrupt the signal flow only when it is necessary to withdraw to bring towards external Outboard or send to the input of the mixer audio an external signal pre-amplified or line level, and then without going through the pre-amplifier of the audio mixer.

The fourth Patchbay will have in the G the Direct Out, outputs analog or digital depending on the audio mixer used (outputs used for sending pre-amplified signal to external inputs such as multi-track recorders, which can sometimes also be pre or post processors as equalizers and internal dynamics of the audio mixer or even pre or post fader for a possible control of the output signal using the faders), in the H the multi-track recorder inputs, with Full Normal Patchbay so that the signal arrives directly to the multitrack recorder without use of outside decks.

These are the main connections, with other Patchbay such as those in Figure 6 is then possible to connect any other device, precisely from external outboard processors, for aux and main outputs of the audio mixer, cd player, and everything from which you want to withdraw or send an audio signal, appropriately considering the right to use Patchbay.

On the Neutrik site you can find a program that helps in compiling the patchbay data sheet, with schemes and the ability to write all the notes at will, save as a digital file or print it on paper. In this case it is specific to Neutrik’s Patchbay but it can still be used for all Patchbays that follow the number of Neutrik Patchbay channels.

Here is the link:

Patchbay Neutrik

 

Digital Patchbay

The analog Patchbay as mentioned are used and serve exclusively to manage the routing of the signal in the analog domain (mono – stereo – unbalanced – balanced) or in the digital domain for standards such as AES3 which presents 3 conductors for the stereo signal transport.

Digital Patchbay instead are used to manage the routing of signals in the digital domain, dall’AES3 to Madi, ADAT, AES50, DANTE and all digital protocols for audio environment.

A Digital Patchbay may take the form of physical hardware in a rack or software.

 

Physical Hardware

Unlike analogue, the Digital Patchbay are univocal for the reference standard, so if you are handling MADI protocol signals you will need to purchase a Digital Patchbay often called a Digital Router that manages the MADI protocol (figure 2) (figs 3 – 4).

Fig. 2 products_madi_router_3b

Fig. 3 SSL-MADI-X8_lrg

Fig. 4 SSL-MADI-X8-rear_lrg.jpg

In some cases, it is possible to buy a standard digital converter (example from MADI to DANTE) and then interpose a Digital Patchbay DANTE and manage the routing under another protocol. But it is always advisable to introduce less signal conversion also possible in the same domain, so if there is Digital Patchbay useful for our purpose it is good to use only that one.

Digital Patchbay routing is often handled by a cable-connected remote device (usually USB or CAT5-6) or hardware wi-fi, as it may be a PC with installed management software, from which you can decide the path of the internal audio signal to Patchbay.

Some Patchbay like the one in figure 2 also provide the management of the routing hardware directly.

The digital Patchbay on external hardware as opposed to analogue ones, they always need an external power supply.

The number of channels and portable type of connection depends on the type of digital Patchnbay and constructive model and the standard used, it is therefore necessary to inquire about the technical characteristics prior to purchase.

Even an Interface Audio (fig. 5) to send signals to recording and reproduction of computer software can be considered a digital Patchbay, because then within the software it is possible to control all the routing of the signals at its input and output.

Fig. 5 avid_hd_io_front_1

Even a Stage Box – Digital Splitter (fig. 6) can be considered a digital Patchbay being connected to the digital audio mixer that has the software to manage the signal routing In / Out or even through external software for the remote control of the routing of digital audio mixer.

Fig. 6 S16_P0AJA_Top-Front_XXL
Also router Switches for Network Connections (Figure 7) or other formats that are analog or digital hardware with remote control over software or on-board machines can be considered Patchbay for managing audio signal routing.

Fig. 7 71pWTJNSiTL._SL1500_.jpg
The routing of each standard and Patchbay device used may be different in its functionality and management so even in this it is necessary to know well the equipment available.

 

Synchronization

A digital Patchbay often also has BNC IN / OUT connectors for synchronizing (fig. 8) so you can receive the sync clock for sampling the audio signal at the input or because the external clock clock is better and more stable or why the internal Patchbay does not work properly causes wear over time. Or to send the same Patchbay Clock to other devices for the same reasons.

Fig. 8 Cattura

n.b. Some types of Digital Patchbay also include an AES11 or SMPTE input (in addition to the Word Clock), an alternative used in the broadcast to synchronize audio and video as a protocol that determines synchronous pulses divided by frame / second mainly, or other forms defined by the ” user, such as Sample, Bar, etc.).

n.b. We’ll see in detail Word-Clock and AES11 when we talk about syncing in digital audio.

 

Software

Patchbay software is used exclusively to manage the routing, DAW (figure 9) digital processor and digital mixers (figure 10), external audio interfaces (figure 11).

Fig. 9 6.png

Fig. 10 x32 s16 p16.PNG

Fig. 11 soundgrid-studio-application.jpg

Any software can have different graphics and management so it is good to know in detail its function.

 

Use

The Digital Patchbay as mentioned are used for the management of the audio signal transfer in the digital domain, but sometimes it may occur also in the form of A / D converters (fig. 12) (fig. 13) with routing functions (such as may also be the Stage Box – Digital Splitter).

Fig. 12 ssl_alpha_link_mx_4-16_front.jpg

Fig. 13 analog to madi optical back (2).jpg

With the A / D converter, it is possible to enter the analog domain and fetch a digital domain output in the form of the protocol used. Some devices also offer the opposite solution to enter and exit in the analog domain and enter and exit in digital domain, so that they have full routing management.

Most of the time, especially if they are converters in a single unit like the one in figure 11 and figure 12, having regard to the small size hardware, its cost, and the ability to bring in a multi-channel or a little more digital connections (for example, the MADI standard allows to bring 64 – 72 channels on a single conductor), it is preferred to use analog inputs and outputs D-Sub, and multi-channel connectors and not as individual connections via XLR or jack that would take much more space and allowing for a number of channels much more limited analog I / O.

Generally, the use of Patchbay in Live audio environment can be (fig. 14).

Fig. 14 2016-03-02_13-40-41.jpg

Lines and microphone signals from D.I. boxes arrive at Digital Stage Box (if analog will be necessary to introduce an A / D router patch to send then the digital signal mixer digital audio), from the Digital Stage Box is taken signal on a digital level according to its own standards and sent to a digital mixer stage which follows the same standard audio (if different standards will be necessary to introduce digital protocol conversion interface).

Both the Digital Stage Box that any A / D converter router patch can have internal routing control operations (albeit minimal), eg. to vary the sampling and world clock of the digital signal, or to handle input and output lines of more devices connected in a bridge.

The routing of the signal that arrives at the digital audio mixer is controlled by the digital Patchbay on internal software to audio mixer itself or through external software, for eg. manage the address of the input and output channels (eg. In 1 of the Stage Box must arrive in the In 1 of the audio mixer, the 2 in the 2 and so forth, but may also be sent to the input 8 or 9 of the audio mixer, etc …, or divide the digital signals for groups and Stage Box, eg. from channel 1 to channel 8 using the signals of 1 to 8 of the first Stage Box and those from 9 to 16 those from 1 to 8 of the second Stage Box, etc …).

Even the routing of the digital signal that reaches the FOH console is always controlled by the internal software Patchbay of the audio mixer or via external software.

In case of recording it is possible to send as seen in the article Splitter and Adders – II, a copy of the digital signal directly from the Stage Box (if it has one) or directly from the audio mixer (such as direct out or through an audio interface) that can be the FOH mixer or a stage mixer, all the while with digital connection whether via audio interface it is connected directly to the computer for direct recording with DAW available (the internal software for recording, such as Pro Tools), whether through direct out then you will have to connect the signal to an external audio interface, which is then interfaced with the DAW on the computer).If the analog signal is sent it will be necessary to introduce an A / D converter that follows the protocol necessary to send the digital signal to the input of a digital audio interface connected to the DAW on the computer, or connect the analog audio signal directly to a DAW A / D which in addition to convert the analog signal to digital also has the task of transferring the signal to the recording software (DAW) on a computer.

n.b. If the signal is pre-amplified by a Digital Stage Box or by pre-amplifiers in an audio mixer or external outboard, is always better to send the signal digitally to the audio digitally connected to the DAW for recording, if the signal is analog send the pre-amplified signal (line level) to an A / D converter that is not also pre-amplifier, and from this to send the signal to the audio interface connected to the DAW on the computer.

If the digital signal is sent from a digital audio mixer, its routing is managed by Patchbay of internal software mixer and can be managed using recording software routing channels In / Out internal to the recording software.

If the digital signal is sent directly from the Digital Stage Box usually the signal routing is controlled exclusively by the Patchbay of the DAW software on the computer used for recording.

n.b. Generally, the signal sent directly from the always digital Stage Box post-gain so that by adjusting the pre-amplification from Stage Box is possible to manage the signal levels sent to the recording but not its routing.

Generally, the of Patchbay in audio Studio environment can be (fig. 15).

Fig. 15 2016-03-02_14-29-57.jpg

The input of the microphone signals and D.I. box can take place directly at the input of the pre-amplifiers A / D of the digital audio mixer or through a Digital Stage Box positioned in recording room, their routing is always as also seen before Patchbay controlled by internal software of the mixer or via software outside with sometimes minimal possibility of routing audio from the Stage Box itself.

The routing of digital signal In / Out audio sent from audio mixer to the audio interface for recording, is run by Patchbay always on internal software in the audio mixer, and recording DAW software on the computer it is possible through her Patchbay manage the routing of the In / Out of the software itself, a bit as seen in the above example.

On the use of analogue outboard you will need to use the analog Aux In and Out or Insert, if provided in the digital audio mixer or if used and if provided in the Digital Stage Box.

If you prefer to use A / D converters (for example, they are connected to analogue outboard) and / or external digital outboard, these must be connected using digital connections of the digital audio mixer if planned or audio interface for recording forever if provided. The routing which is managed by the internal software Patchbay of the digital audio mixer with any minimum routing controls also from the A/D converter used.

Further to the greater transparency offered by the digital router than the analog one, and the fact that it does not have to wrap each time the patch to handle routing (by doing it through remote software) there is also the fact that it can store scenes and routing settings, so you can resume it at will, while in analog patchbay, you always need manual wiring.

Other digital Patchbays offer the option of accepting and managing analog signal routing, generally on a D-Sub multiconnet, managing AES3 digital signal routing, generally always on D-SUB or XLR, and other digital protocols such as MADI and DANTE BNC and / or Fiber Optic and / or Ethernet (fig. 16), provide for the possibility of linking more Patchbay (usually the same manufacturer) to obtain a wider and more complex management system, which can be controlled remotely via software. Or proprietary connections for their audio interfaces (figure 17), such as the DigiLink or DigiLink mini connections to connect the Patchbay Digital to the PCI audio interfaces that provide this type of connection and interfacing and remotely controlling, for example, Patchbay with one DAW on PC.

Fig. 16 Cattura     Fig. 17 Cattura

From any digital audio signal has been mentioned so far, it has been referred to the PCM (which we will see when we talk about digital audio), some Digital Patchbays allow to manage in addition to the type of digital audio signal PCM and DSD (figure 18).

Fig. 18 Cattura.PNG

In the choice of use, you always have to consider the signal domain to be brought to the input and handle the output, in any case with the analog Patchbay you can generally split a split for each input, while in digital you can copy an input signal to all audio outputs (then have for an input signal also 32 to 64 and more, equal outputs). So, the digital system certainly offers greater versatility in transparency and above all that you are not limited by the physical channel position as seen in this topic.

 

Structure of the Patchbay / Digital Router

A digital Patchbay in its characteristics may submit entries type 2×2, 8×8, 16×16, 32×32, 64×64, 128×128, 256×256 and beyond, this identifies the number of channels manageable by patchbay, the first value identifies the inputs the second the outputs.

Generally, the number of inputs equals that of outputs, but not always, such as in digital audio mixer and stage box the number of inputs is often higher than that of outputs, eg. 16×8, 32×8, 32×16.

As for the A/D converters and D/A also patchbay having to manage digital signal may be synchronous or asynchronous.

Synchronous Patchbay

The synchronous Patchbay are those more qualitative but allow users to connect and obtain a signal flow only if every tool used and connected works at the same sampling frequency.

Asynchronous Patchbay

Asynchronous Patchbay are the most expensive but less qualitative as they have a more complex circuit but have the advantage of allowing simultaneous flow of multiple sampling frequencies (for proper operation, however, the output and input devices will need to be same sampling frequency, eg if a digital stage box works at 96 kHz, the digital input of an audio mixer should be 96 kHz), Patchbay only makes it possible to stream multiple samplings simultaneously.

So, the best solution is always to have synchronous audio patchbay to which instruments that work at the same sampling frequency of the patchbay are connected (example if the patchbay is set to work at 48 kHz it is important that all instrumentation be 48 kHz if it does not lose the clock and does not circulate the signal).

However, if you have equipment that work with different sampling then it may be useful to use an asynchronous Patchbay so you can handle regardless example sampling equipment at 48 kHz and 96 kHz.

The synchronous Patchbay unlike those asynchronous often allow to change the routing of the digital audio signal without interruption, while asynchronous to how they are structured recalculate the type of sample to be transferred to the desired output and therefore pose a brief interruption.

The best digital patchbay that are synchronous or asynchronous must be completely transparent to the passage of the audio signal, a bit like for said analog ones and should therefore not interfere with the addition of artifacts in the sampling and quantization. Some, however, have the possibility via remote software or internal settings patchbay to the use of DSP or Sample Rate Converter for processing the signal before its transfer, this can lead to the addition of artifacts on the signal and the not complete transparency.

The patchbay asynchronous in the case of complex situations and instability and / or disorders of the electric current to lose power more easily than the clock synchronous.

For all of these factors just seen in live situations it is crucial if you need to use synchronous patchbay, for recording and mastering studio environments can be helpful to use a mixture of synchronous patchbay and asynchronous depending on the type of equipment available.

There are also Patchbay modules capable of receiving and transmitting synchronous and asynchronous modes simultaneously for the resolution of numerous and complex issues at the expense of a higher investment.

Generally, they consist of several separate ASRC / SRC converters and conversion modules, and in some you can only select whether to use SRC or ASRC.

 

Some manufacturers of Patchbay or Professional Audio Routers:

  • ART 
  • AVID
  • Audiovero
  • Behringer
  • Cranesong
  • Crookwood
  • Dangerous Music
  • DBX
  • DirectOut
  • Friendchip
  • Ghielmetti
  • Kramer
  • Millenium
  • Motu
  • Neutrik
  • Optocore
  • ProCo
  • RME
  • Samson
  • Sonifex
  • SPL
  • SSL
  • Switchcraft
  • Tascam
  • Tegeler
  • Z-system

 

Some Videos:

 

More on Patchbay:

Patchbay – I ( Analog Patchbay )

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