A Tale of Four Cables (Searching for a TMC-1 to XMon Cable)

The XMon uses a single 15 pin D connector to connect with the monitor controller, the connections includes headphone, unbalanced microphone and digital control and digital metering. We like to supply a suitable cable with the TMC-1 remote so that the customer can immediately connect and use the system. In an ideal world these would all be separate cables with their own connectors but this would make it very untidy at the remote.

Cable 1 - DB15-DB15 overall screen
When we designed the TMC-1 ready made DM15-DM15 cables were available, they were not individually screened but after a resistor change the crosstalk on 5m cables was acceptable. With the 10m extension cable the cross-talk into the headphones from the meter data is annoying.

The supply of the original cable has dried up and we need a new solution. The obvious choice seemed to be to use VGA cables, although not the correct connector these have the advantage that there are 3 screened cables within the cable tha may be used for the unbalanced Headphone and Mic signals.

Cable 2 - Pro Signal VGA cable (cable marking E1199332-T AWM 2919)
Widely available in both Male-Male and Male-Female extension cable format, these cables were specified as having 14 connections + shield, unfortunately when tested there were only 10 connections. The cable still works with X-Mon by leaving out the Midi connections and communicating via RS-422.

Cable 3 - (cable marking AWM Style 2919)
Sourced from our connector supplier this cable has 14 connections - but the grounds of the 3 screened cables are connected in the cable causing a ground loop that resulted in a low frequency noise in the headphone feed.

Cable 4 - (Clever Little Box LPVGA-M/M-5.0M-FP)
The best cable that we have tried so far about 50% more expensive than Cable 2, this cable is blue, more flexible than Cable 2, has 15 connections and nice small 15 way connectors. We tried a 3m cable which it worked well with and without the transformers. The cable is available in lengths of  1,3,5,10, 15 and 20 meters. We plan to stock the 5 meter cable and supply other lengths to order.

We now have the 5m Cables and THEY DO NOT WORK!!!

Daniel had spotted a reference to Icon-Xmon noise issues
http://absolutecad.typepad.com/over_the_wires/tips-tricks/

Reading the article we decided to try using transformers in the audio path using the transformers at one end for ground isolation. For cost and size considerations we used  600ohm telephone transformers . We found a marked improvement in noise levels on all cables, the only worry is the bass performance of such small transformers on the headphone feed.

Conclusion
The next revision of the TMC-1-XMon with have a HD15 VGA connector fitted in place of the DB15 connector and be supplied with a conversion box for the X-Mon connection. The Conversion box will have transformers fitted in the audio path and optional links to swap the digital connections between Midi and RS422. We will supply Cable 4 as an optional extra.

TMC-1 and DAD DX32 Integrating Pro tools, Trinnov MC and Apogee Symphony

A interesting recent TMC-1 installation at Sound Generation mixed a number of different interfaces and demonstrates the insert capabilities of the TMC-1/DAD combination.

The DAD provides the Pro Tools interface and audio routing matrix, the Apogee Symphony provides A2D and D2A conversion. The Trinnov MC is used for room equalisation and bass extension. The Trinnov MC is connected as a speaker inserts and be enabled/disabled by the TMC-1.

Simplified System Block Diagram

The Main and Alt output can be up to 64 channels wide and the Mini output up to 12 channels wide.

Input/output Configuration

First name the input and output Modules  (Module Names) and define channel count

Once the Input and output names are defined the input and output channels are defined by selecting the appropriate module and channel, then a simple mouse click will assign this to the selected input/output

Define the Inserts

Name each insert, select the input and output modules then click on each insert input and output to assign. The channel selection auto-increments.

Define Stereo/2.2 Main Outputs and assign Inserts

Define 5.2 Alt Outputs and assign Inserts

Define Stereo Mini Outputs and Assign Inserts 

Define Main Inputs

The alt input was not defined

Define the Input Pallet

Define Cue Inputs

Define Cue Outputs

Define Talkback and Listenback

Once defined the parameters are sent to the TMC-1 which then defines the routing within the DAD DX32 directly.

Gain and Calibration

There are several points to consider in configuring, the TMC-1, the global settings are made in the TMC-1 Advanced Setup menu, the input and output trims are only available when in calibration mode

Insert and Gain Control

SPL display:

85spl represents Unity Gain when all trims are set to 0dB

Input trim: -10 to +20dB in 1dB steps

In digital systems normally there is usually no need to control the inputs but it is sometimes necessary (see a previous blog on how 10dB gain is used with the Dolby RMU to compensate for the 10dB loss.)

Output Trim: +/-4dB in 0.5dB steps

Each individual output has a gain trim

Digital Headroom: 0 to 10dB in 2dB steps

This is a global setting  on all outputs allowing equalisers to be placed in the chain.

 Insert Makeup Gain: 0 to 10dB in 2dB steps

This is a global setting for all inserts to compensate for any loss.

Where analog output cards are used in the AX 32

Analog O/P for 0dBFS: +6, +12, +18 and +24dB

This is a global setting for all Analog outputs

Installing a TMC-1 and PD-1 in the S6 in the Jigsaw24 7.1.4 demo room

Yesterday I was at Jigsaw24's new facility in Golden Square with Andy Brooks and Ian Duncan installing the TMC-1 and PD-1 into their S6 console for "Mix with the Pro's"( 15th of October). This was the first install of a TMC-1 in the S6 and it fitted first time! We fitted the TMC-1 in front of the PD-1, the choice is yours.

 

We had a few problems, I discovered a keyboard scan issue on the TMC1-S6 which is fixed with a few minor tweaks today in the s/w posted today. We had a silly connection problem at the end which wasted at least an hour but apart from that it was a simple install.

If you are in London on the 15th of October Daniel and I will be showing the TMC-1-Penta, you can find out more about "Mix with the Pro's" here.

Atmos, 7.1, 5. and Digital Signal to Noise

Pinewood emailed last week and asked if I would visit at the same time as the Dolby engineer and set up Theatre 6 for four standards:-  Atmos Performance, Atmos Home, 7.1 and 5.1

The front speakers were not a problem but I was concerned that the different level settings for the surrounds would reduce the digital signal to noise. The problem was caused by the gain range required to configure the surround  speakers for the different formats and speaker combinations.

The Formats

Theatre 6 has two left, two right, two left rear and two right rear surround speakers
Atmos performance uses all the surround speakers as individual point sources.
Atmos Home uses only one left, one right, one left back and one right back as individual point sources.
7.1 uses the surround speakers in pairs
5.1 combines the left side with left rear and combines Right side with right rear to make four left surround and four right surround speakers.

Setup Procedure:

1) Set up the room for Atmos performance and Atmos Home by adjusting the individual +/- 4dB trims provided by the TMC-1.
2) Set up the room for 7.1 using the global 7.1 surround trim in the TMC-1 to reduce the surround level
3) Set up the room for 5.1 using the global 5.1 surround trim in the TMC-1 to reduce the surround level.

The problem:

After calibration there eas approximately 10dB of attenuation on the surrounds for the 5.1 setup. 10dB, almost 2 bits of resolution lost, but this is not the only loss, consider the following.

1) The levels are set for 85dB SPL
2) The RMU has an insertion loss  of 10dB to allow for digital equalisation
3) Set to 5.1, on the surround channels there is a further 10dB insertion loss
4) Reduce the monitoring level to the Dolby Home level of 79dB SPL which adds a further 6dB insertion loss
5) Speaker trim range is  (+/-4dB) in the worst case there can be a further 4dB insertion loss.

The worst case insertion loss is 30dB or 5 bits, this would reduce a 16 bit signal to 11 bits. This is the case with the surround speakers in pairs, consider the possible insertion loss in a bigger studio where the surround speakers are in sets of 3, 4 or more.

The Solution:

The 10dB insertion loss in the Dolby unit is unavoidable and is required for any digital equaliser,  we have to accept this. (I would have limited the boost to a maximum of 6dB and reduced the insertion loss to 6dB but this is a design choice).

The DAD AX32/NTP Penta 720 also provides analogue gain control. I tested this for the gain control but the four 6dB relay steps cause unacceptable glitches in the audio. When used for  the speaker trims, Calibration Level adjust and surround trim the relay switching is no longer a problem!

When setup correctly the maximum extra digital insertion loss is 6dB so that when combined with the RMU gives a maximum 16dB insertion loss in any condition over the required range, a worthwhile improvement.

Update: originally I referred to "digital resolution" Florian Camerer pointed out that reducing the bit count does not reduce the resolution but reduces the Signal to Noise or dynamic range. 




   

IBC-2015 Hall 7, stand F06

This year we will be featuring the TMC-1 multichannel monitor controller, described by one customer as "The large console monitor controller without the large console". New this year are the interface to the NTP DAD/Penta digital interfaces to make a fully digital monitor controller r and the S6 drop in module plus a host of new software features.  Colin Broad (the designer) is on the stand to demonstrate the new features and explain how the TMC-1 can be used will all monitoring formats including a full Atmos and or Auro system.

You can see a photo of the TMC-1-S6 on my post of the 17th of July, below is a description of the two major upgrades to the TMC-1 Penta that will be released at the IBC.

Input Pallet
The TMC-1-Penta has 6 inputs, Main and Alt which can both be up to 64 channels wide, I/P1 - I/P4 which can be up to 8 channels wide. I/P1-I/P4 can now be assigned to any input from a pallet of 16 inputs. Each input on the pallet can be a different format, the monitor output is set to the correct format when the input is selected. If the Main and Alternate inputs have a maximum of 8 channels the main and alternate inputs  may also be selected from the pallet.

Note. You can program the input names for all inputs and outputs.
  
Analog Input Control
The DAD AX24 or NTP Penta 720 can be fitted with analog input card(s) with 8 inputs. The TMC-1 now has a MicLine page that allows you to meter the digital levels, control the Gain, select Mic/Line Input, Mute On/Off, phase reverse and  Phantom On/Off. When selected to Mic/Line inputs the meters display the digital input level and the PFL (Pre Fade Listen) key switches the monitoring to the selected input.

There are a number of other small improvements in the user interface, this should be the last major upgrade to the TMC-1 Penta this year. It has taken longer than I expected to make these upgrades, every time I was close to finishing I found more to do! 

I am on holiday next week and will post Beta test versions of this software for both the XMon and Penta versions when I return. It will be necessary to update the Penta Configuration software which inludes the new Pallet and Bass Management systems. You may even have to read the updated manual.

I have started on two more projects, one of which I should have finished for the AES in New York but more about that in my next post!

TMC-1 Penta 7.1.4 Case Study

The TMC1-Penta provides a framework to build your own monitor system, to design your
system you will need to specify the input/output data and the speaker groups as follows

1)  Map out the speakers

2)  Map out the Input and Output connections

Note the +10dB gain on the Dolby Return to remove any Level differences
between monitoring direct or through the RMU

3) Label modules in TMC1-Penta program and set Maximum channel count if not defined. As
an option you can add the Offset for each input

4) Label Speakers and assign channels

Note: The surround channels are checked in the corresponding Surround Column. This
allows the speakers to be assigned to the correct source when 7.1 or 5.1 are selected. To
use the LFE as a bass extension to the surround channels check the appropriate output in
the LFE column.

5) Assign Input name and channels for RMU 7.1.4 Outputs. Every surround speaker is
individually assigned

6) Assign Input name and channels for direct 5.1 and 7.1 outputs from Pro Tools,

Note. Only the main surround inputs are defined the 7.1 switch can the enable the extra surround speakers. Alternatively you can assign the extra surround speakers for 7.1 so that they are always used. 

S6 panel for TMC-1

The TMC-1 has joined the PD-1 by being available in a Avid S6 Module, the PD-1 is in a S6 Fader size module, the TMC-1 in a S6 knob size module.

Connecting the TMC-1 GP inputs to the S6 GP Outputs you can connect the S6 talkback controls to the TMC-1 and enable auto-talkback  alternatively the TMC-1-Penta will emulate a XMon for control from the S6 or D-Command.

TMC-1-Penta-S6 (Click on image to enlarge)
I kept the controls at the bottom of the panel for two reasons

• To keep them as close as possible to the operator
• To allow space for the connectors at the rear