Comment

Comment by Richelle Thompson on September 25, 2012 at 9:27am

Thanks Erich and Richard - some good thoughts and great resources.

Cheers,

~R

Comment by Erich Friend on September 24, 2012 at 10:09am

The key to clarity in block diagrams is in minimizing the number of places that wires (lines) cross each-other, and in keeping most of the signal flow consistently from left to right. Labeling inputs and outputs in a consistent manner so that it is always clear whether you mean mic, line, video, data, etc., is helpful if you ever have to rebuild the system or rely on someone else to troubleshoot it.

If there is space, or you can show a graphic representation of each connection, then using symbols or text abbreviations for each connector type (XLR, TRS, RCA, RJ45, screw, etc.) can help to define the connections better.

Try not to constrain yourself to thinking in terms of 8 1/2 x 11 paper. Make each block as big as is necessary to read it, 3/32" tall text, minimum, being a good goal to strive towards in the finished document. Large format printers are available at most office supply or document reproduction services, so if you need 24x36 or 30x42 paper to make the print, so be it. If your drawing exceeds 30x42 size, then you may have to consider segmenting it horizontally or vertically to fit on each sheet. If you do this, it helps to plot all the segments at the same scale so that your can abut them later and clearly see the signal flow from sheet-to-sheet.

If a certain item needs more detail, just provide a supplementary 'break-out' drawing to do that.

Adding wire tags that show the type of cable and/or it's ID number can me helpful, too. A consistent system of enumeration can really help in troubleshooting. I use a system where Mic cables all start with 'M', Line with 'L', Video with 'V', Speaker with 'S', Intercom with 'IC', Modulated Radio/TV signals with 'RF", and Data / Control with 'D'. The cable numbers then start with 101 for the first segment, then as they advance through any signal processing, switches, or relays they advance by 100 to the next level (101 becomes 201, becomes 301, etc.). If a cable is spliced or splits at a terminal block, then the number stays the same and gets a suffix -A, -B, -C. etc. A typical wire tag might be: M202A or S301B.

Understand that a wiring diagram need only show a line per signal path, where a schematic diagram may show the individual conductors in a cable (red +, black -, Shield, etc.). A large Wiring Diagram can become too busy if schematic level connection information is included at each interface point. This is a good place for break-out diagrams to show typical wiring for each connector type.

Another graphic that can help on wiring diagrams is to use a heavy line type to show a perimeter around all the items at a particular physical location. This helps one see the range of cables that interconnect between various equipment sites like the Stage Manager's Console, Amplifier Rack(s), Aux Rack(s) at the mix position, and other major junction boxes that house connector panels.

If you have individual inlet or outlet plates, showing the symbol that is used on the floor plan adjacent to the connector symbol can help to correlate the physical plan to the electronic schematic.

The USITT standard documents referred to by Richard Ingraham are a very good source of examples.

Comment by Richard B. Ingraham on September 24, 2012 at 8:10am

I would urge anyone that hasn't done so, to read the USITT Student Drafting Guidelines about system block diagrams. It is well thought out and does a resonable job of showing what information is really important to be put on the block diagram and what information is much more effective on a hook up or excel sheet like document showing what plugs into what.

http://ww4.usitt.org/commissions/sound/Sound_Comm_Graphics_Project_...

Typically I show only the basic signal flow on the block diagram and the details about what cable run is what and what function each connection serves is all in the hook up. Sometimes I use Excel for simple projects but on larger projects, paticularly when there are shop orders and rentals involved I will use Stage Research's ShowBuilder software for the hook up part of the paperwork.

Because I don't have regular access to a large format printer, I often break my signal diagrams down into smaller pieces so they will print neatly and clearly onto standard 8.5 x 11 sheets of paper or sometimes legal size paper.

There are several examples on my web site.

http://www.rbicompaudio.20m.com/past_projects.html

Hope some find that useful.