There are several different types of cable, from 25 pair ATT style, to 16 or 24 pair shielded audio cable, to miscellaneous control cable, all of it has different color codes.  I found the Belden Technical info website to be an excellent source for various color codes.

Doing neat work is best way to keep things in order.  Notice all the wires are labeled.  All the ground conductors have heatshrink, which is required on insulation displacement terminations like 66 blocks, 110 blocks and ICON terminations.

ADC ICON termination block

Once all the work is done, the wire run sheets are updated with changes and additions (there are always changes and additions) which will keep the documentation accurate.

I made up several templates with the wire color code, pair number and cable information on each wire.  This allows the wire man to quickly enter changes to the wire information on the sheet.  At the end of the wiring project, these forms can be saved in several places, printed out and placed in a book or however the engineering manager wants to keep the information.

ATT 25 pair wire sheet .pdf

The excel spread sheet for this is here.

For 16 pair Gepco cable on 66 blocks, click here.

For 16/24 pair Gepco cable on ADC ICON Termination blocks, click here.

I say Gepco cable, any audio cable that is color coded with standard resistor color codes will work with these sheets, or the sheets can be adapted for use with other cables.

66 blocks audio and control for nextgen installation

This is a good installation. The company I work for has several wiremen that are artists and do excellent work. Notice there is adequate room and light to work on the wall.  A dark, cramped area will lead to hurried work, poor workmanship, and mistakes in wiring.

Automation computer on slide out rack with cable management system

All the cables to the rack mount computers are neatly dressed, which allows easier service.

The EBU technical group takes a different approach:

EBU R128 (ed: Loudness Recommendation) is the result of two years of intense work by the audio experts in the EBU PLOUD Group

Aside from the above mentioned EBU R128, there are four technical papers dealing with implementation, meters, distribution and so on.  The body of work is a recommendation not a requirement.  I can’t imagine voluntary implementation of something like this in the US.  Even so, there are advantages to having a single acceptable level of programming audio.  It is interesting reading.

I would establish the basic requirement for a professional sound card is balanced audio in and out, either analog, digital or preferably, both.  Almost all sound cards work on PCI buss architecture, some are available with PCMCIA (laptop) or USB.  For permanent installations, an internal PCI buss card is preferred.

Keeping an apples:apples comparison, this comparison it limited to PCI buss, stereo input/output, analog and digital balanced audio units for general use.  Manufactures of these cards often have other units with a higher number of input/output combinations if that is desired.   There are several cards to choose from:

The first and preferred general all around sound card that I use is the Digigram VX222HR series.   This is a mid price range PCI card, running about $525.00 per copy.

Digigram VX222HR professional sound card

These are the cards preferred by BE Audiovault, ENCO and others. I have found them to be easy to install with copious documentation and driver downloads available on line.  The VX series cards are available in 2, 4, 8, or 12 input/output configurations.  The HR suffix stands for “High Resolution,” which indicates 192 KHz sample rate.  This card is capable of generating baseband composite audio, including RDS and subcarriers, with a program like Breakaway Broadcast.

Quick Specs:

• 2/2 balanced analog and digital AES/EBU I/Os
• Comprehensive set of drivers: driver for the Digigram SDK, as well as low-latency WDM DirectSound, ASIO, and Wave drivers
• 32-bit/66 MHz PCI Master mode, PCI and PCI-X compatible interface
• 24-bit/192 kHz converters
• LTC input and inter-board Sync
• Windows 2003 server, 2008 server, seven, vista, XP (32 and 64 bit)
• Hardware SRC on AES input and separate AES sync input (available on special request)

Next is the Lynx L22-PCI.  This card comes with a rudimentary 16 channel mixer program.  I have found them to be durable and slightly more flexible than the Digigram cards.  They run about $670.00 each.  Again, capable of 192 KHz sample rate on the analog input/outputs.  Like Digigram, Lynx has several other sound cards with multiple input/outputs which are appropriate for broadcast applications.

Lynx L22-PCI professional sound card

Specifications:

• 200kHz sample rate / 100kHz analog bandwidth (Supported with all drivers)
• Two 24-bit balanced analog inputs and outputs
• +4dBu or -10dBV line levels selectable per channel pair
• 24-bit AES3 or S/PDIF I/O with full status and subcode support
• Sample rate conversion on digital input
• Non-audio digital I/O support for Dolby Digital® and HDCD
• 32-channel / 32-bit digital mixer with 16 sub outputs
• Multiple dither algorithms per channel
• Word, 256 Word, 13.5MHz or 27MHz clock sync
• Extremely low-jitter tunable sample clock generator
• Dedicated clock frequency diagnostic hardware
• Multiple-board audio data routing and sync
• Two LStream™ ports support 8 additional I/O channels each
• Compatible with LStream modules for ADAT and AES/EBU standards
• Zero-wait state, 16-channel, scatter-gather DMA engine
• Windows 2000/XP/XPx64/Vista/Vistax64: MME, ASIO 2.0, WDM, DirectSound, Direct Kernel Streaming and GSIF
• Macintosh OSX: CoreAudio (10.4)
• Linux, FreeBSD: OSS
• RoHS Compliant
• Optional LStream Expansion Module LS-ADAT: provides sixteen-channel 24-bit ADAT optical I/O (Internal)
• Optional LStream Expansion Module LS-AES: provides eight-channel 24-bit/96kHz AES/EBU or S/PDIF digital I/O (Internal)

Audio Science makes several different sound cards, which are used in BSI and others in automation systems.  These cards run about $675 each.

Audio Science ASI 5020 professional sound card

Specifications:

• 6 stereo streams of playback into 2 stereo outputs
• 4 stereo streams of record from 2 stereo inputs
• PCM format with sample rates to 192kHz
• Balanced stereo analog I/O with levels to +24dBu
• 24bit ADC and DAC with 110dB DNR and 0.0015% THD+N
• SoundGuard™ transient voltage suppression on all I/O
• Short length PCI format (6.6 inches/168mm)
• Up to 4 cards in one system
• Windows 2000, XP and Linux software drivers available.

There are several other cards and card manufactures which do not use balanced audio.  These cards can be used with caution, but it is not recommended in high RF environments like transmitter sites or studios located at transmitter sites.  Appropriate measures for converting audio from balanced to unbalanced must be observed.

Further, there are many ethersound systems coming into the product pipeline which convert audio directly to TCP/IP for routing over an ethernet 802.x based network.  These systems are coming down in price and are being looked at more favorably by broadcast groups.  This is the future of broadcast audio.

It was worse than I imagined, with several unbalanced and balanced feeds improperly interconnected, line level audio going to a microphone level input and so forth.  I explained to the guy about putting line level into a mic level input, something akin to plugging a 120 volt appliance into a 240 volt outlet.  Improperly terminated balanced audio nullifies all of the common mode noise rejection characteristics of the circuit.

In any case, there are several ways to go from balanced to unbalanced without too much difficulty.  The first way is to wire the shield and Lo together on the unbalanced connector.  This works well with older, transformer input/output gear, so long as the unbalanced cables are kept relatively short.

simple balanced to unbalanced audio connection

Most modern professional audio equipment has active balanced input/output interfaces, in which case the above circuit will unbalance the audio and decrease the CMRR (Common Mode Rejection Ratio), increasing the chance of noise, buzz and so on getting into the audio. In this case the CMRR is about 30 dB at 60 Hz.  Also, newer equipment with active balanced input/output, particularly some brands of sound cards will not like to have the Lo side grounded. In a few instances, this can actually damage the equipment.

Of course, one can go out and buy an Henry Match Box or something similar and be done with it.  I have found, however, the active components in such devices can sometimes fail, creating hum, distortion, buzz or no audio at all.  Well designed and manufactured passive components (transformers and resistors) will provide excellent performance with little chance of failure.  There several methods of using transformers to go from balanced to unbalanced or vice versa.

Balanced to unbalanced audio using 1:1 transformer

Using a 600:600 ohm transformer is the most common.  Unbalanced audio impedance of consumer grade electronics can vary anywhere from 270 to 470 ohms or more.  The 10,000 ohm resistor provides constant loading regardless of what the unbalanced impedance.   In this configuration, CMMR (Common-Mode Rejection Ratio) will be 55 dB at 60 Hz, but gradually decreases to about 30 dB for frequencies above 1 KHz.

Balanced to unbalanced audio using a 4:1 transformer

A 600:10,000 ohm transformer will give better performance, as the CMMR will be 120 dB at 60 Hz and 80 dB at 3 KHz, remaining high across the entire audio bandwidth.   The line balancing will be far better into the high impedance load.  This circuit will have about 12dB attenuation, so plan accordingly.

For best results, use high quality transformers like Jensen, UTC, or even WE 111C (although they are huge) can be used.  I have found several places where these transformers can be “scrounged,” DATS cards on the old 7300 series Scientific Atlanta satellite receivers, old modules from PRE consoles, etc.  A simple audio “balun” can be constructed for little cost or effort and sound a whole lot better than doing it the wrong way.

A brief list, there are other types/manufactures that will work also:

Keep all unbalanced cable runs as short as possible.  In stereo circuits, phasing is critically important, so pay attention to how the transformer windings are connected.

Quote:

“Ken said you had a concern about the ruggedness of our consoles as compared to the old PR&E boards. You might not know this, but I was with PR&E before joining Telos. In fact, I designed many of those old PR&E boards. I guess that makes me an old console designer. Ahem.

The Element design is more modern in construction and styling, but it is no less rugged than those old PR&E boards. In fact, you could stand on it if you wish. The top is 1/4 inch machined aluminum plate supported by structural aluminum ribs on the backside. The chassis itself is made of custom extruded aluminum structural pieces, machined aluminum side panels. The flat sheet metal on the bottom is not structural, it’s only a cosmetic cover. You’ll see a lot of folded sheet metal in other consoles because it’s cheap and easy. But it’s not as rugged as the Element approach which is why we chose to go with a more complex and expensive mechanical design.

Telos Axia console cross section, Courtesy of Axia Audio / TLS corp

One very visible difference between Element and a PR&E consoles is the use of lexan on the front panels (PR&E would use aluminum or steel on the top panel). This might seem less rugged, but it is actually chosen because it is a more durable surface than painted and silkscreened metal. It is more scratch resistant and it is rear-printed so that the markings never wear out. Silkscreens would wear off under heavy use — particularly next to faders and monitor controls — and look horrible over time. These lexan panels will look just as good after 15 years as they do now.

But lexan for all of its durability has its own limitations. The edges can crack under abuse. This is why you see many older Wheatstone consoles (they have used lexan overlays for many years) with cracks and tears at the very edges of the plastic. This is particularly troublesome in the fader slot. A frayed edge on a faders slot can cut your fingers. That is mighty unpleasant! So when we decided to use lexan, we wanted to have all the benefits and none of the drawbacks.

So we designed a machined recess on each channel allows the lexan insert to have its outside edges protected by the aluminum. More obvious is the bezels around each button and even the fader slot. Look carefully and you will notice that all of the control bezels edges are above the lexan. The edges of the lexan are not exposed and therefore not prone to cracking, chipping or splintering.

Axia Audio console control surface, Courtesy of Axia Audio / TLS corp

In this drawing, you can see the panel without the lexan. The machined pocket to protect the outer edges of the lexan, plus the raised edges of the button and fader bezels to protect the edges around the holes. These button guards are also designed to prevent accidental actuation of the buttons. And while the guards are designed to protect accidental actuation, they never hinder deliberate activation. Notice the guards at the sides of the ON/OFF buttons and not on the top and bottom. Even operators with long fingernails will have no problems with these controls. The small round keys are engaged with a light touch of the fleshy pad of the fingertip.

Yes, I think we built great consoles at PR&E. But Axia was a fresh start, a chance to raise the bar even higher, by retaining many of PR&E’s better attributes and improving upon some of the weaker areas. DIPswitch configuration has been replaced with the convenience of the web browser. Spill-prone motherboards and electronics have been eliminated from the control surface. Unreliable monitor pots have been replaced with optical rotary encoders rated for 5,000,000 rotations.

And you asked about the faders. This is a particularly important component in a broadcast console. PR&E used Penny & Giles faders for many years. We used their Series-4000 faders in the X-Class consoles (BMXIII, AMX, ABX and STX). This was their top-of-the-line fader at the time and performed beautifully… for a year or two. Then our clients started experiencing field failures at a very high rate. We worked with P&G on a return/rework/replace program that took years to clean up. Our clients were disappointed and we spent a fortune making things right. It was that experience that caused us to begin searching for alternatives.

The market for high-end faders is quite small. There are tons of consoles out there for live sound, home recording, etc., but these products are sensitive to costs and generally use very cheap faders. There just aren’t enough high-end recording consoles or broadcast consoles being built to attract a lot of fader vendors. After a lengthy search, I disqualified all but two fader companies: P&G and a Japanese firm by the name of Tokyo Ko-on Denpa (TKD). I assigned one of our engineers to create a set of environmental and life-cycle tests to see if the TKD faders could keep up with the P&G faders. We were all shocked by the results.

Out of 100 of each type tested in various environmental conditions and physically cycled for the accelerated equivalent of 10 years of heavy use, we had only one TKD fader failure, compared to more than half of the P&G Series 4000 faders! We defined “failure” as any deterioration to specifications or any discontinuities. All the failed units had discontinuities (audio dropouts). We were able to clean the failed TKD fader and it passed the retest. About half of the failed P&G units were cleaned and passed the retest. So in the end, the practical results were TKD 100% good and P&G 75% good. Not what I expected at all.

We then designed a TKD fader into the Radiomixer. We watched the customer support logs carefully for problems. Out of the first 1,000 console channels shipped, we saw one TKD fader failure during the first year. Warranty replacement of course. The failure rate did not increase with use as you would normally expect. We were seeing consoles with 3 or 4 or 5 years of heavy use with no fader problems at all. I have heard of 20 year old Radiomixers with original faders still working great.

One particularly elegant feature of the TKD fader used in Element is a side loaded wiper arm. This prevents liquids or other foreign matter from spilling into the fader slot and directly into the fader element. This feature alone is probably responsible for extending the useful life of the faders by a considerable amount. Of course, these can be disassembled and cleaned just like a professional fader from P&G, they just don’t need it so often.

Axia Audio TKD faders, courtesy of Axia Audio / TLS Corp

Some have the misconception that if a fader is not P&G, it must be cheap. Actually, these are very expensive faders, about the same cost as P&G. But they are so well made, I think they’re worth every dollar. I know there are still some folks out there who remember P&G’s glory days when they made bullet-proof faders. I remember fondly those days as well. But in my experience, the TKD fader is superior to the equivalent P&G fader. We feel so confident, that we warrant all Axia consoles for 5 years, including all components….”

End Quote

That is a great explanation of what goes into one of these consoles right from the designer.  The pictures are courtesy of Axia Audio / Telos Corporation and special thanks to Mike for taking time out to give us a glimpse into the mind of a console manufacture.