Contractor FAQ and FMS
You're probably all familiar with the acronym FAQ for Frequently Asked Questions, but maybe less familiar with the acronym FMS, which is Frequently Made Statements. We'll include both on this page so we can discuss them together.
This page is all about the business of contracting, and working with and within the specification. We will cover a variety of issues that come up again and again in conversations on-site.
Shop drawings are part of the required work in the specification, and they have three very valuable purposes.
Most times that we hear this statement in turns out that it was in the spec, and we can tell the contractor the section number of the spec too. We strongly recommend that two different people read a spec document before replying to a tender. An administrative person should read through the document section by section, initialing each section as they go, and hilighting any item that they may have a question about so that we can clarify all issues before the tender closes. The technical person should read through the entire document section by section, also initialing each section and noting any questions. Do not assume that all the "boiler plate" is the same for each project, many projects have unique items that are identified in the spec document. Some of these issues will affect the cost of the project, and they should be included in the costing of the job.
It's important to understand that a spec document is not an instruction manual, it specifies the pertinent and critical aspects of the system in adequate detail that the project can be installed properly. As much information as there is in a spec document, we don't specify the fundamental aspects of systems installation such as; how to solder, how to drill holes, how to strip wire, how to bolt equipment in a rack, how to use an oscilliscope, how to use a digitial multimeter, how to measure noise and distortion etc. In short there is a certain basic and fundamental level of knowledge required to be in the systems contracting business, and we assume that any contractor bidding on a project must have at least that level of knowledge.
Where there is no specific instruction, the assumed direction is to implement the installation using the highest industry standard of technique in all aspects of the installation. This means that every installation, whether it's worth $5,000 or $500,000 should have the same calibre of workmanship, the only difference should be the amount of labour and workmanship that was required.
Testing has two major benefits, by testing every signal path for level, bandwidth and distortion, the contractor can identify signal paths that may have problems such as restricted bandwidth, or excess distortion when used at their rated capability, and these problems may not be immediately obvious in a casual listening test. In other words, by testing the entire installation, the contractor can tell when the installation is finished, and at that time can request a substantial completion inspection.
The second important benefit of testing is that it gives a reference point for the performance of the system so that the owner knows that when they take delivery of the system, it is functioning as specified. Testing also eliminates the problems related to subjective interpretation of what good quality sound is, as long as it measures to spec, there can be no question about whether it sounds good enough, it either performs correctly or it doesn't.
No one said life is fair. Being in a technical business requires a certain committment to the technical requirements of the industry, which means owning enough test and measurement equipment to support the installation work. Seat of the pants installation may be fine for backyard mechanics, but this is supposed to be a bit more professional than that.
If you don't own the equipment to meet the spec, how are you testing and measuring the installation work you're doing now? If all else fails you should be forming an alliance with a bench tech that owns his own equipment to do the system testing, although there is no substitute for owning the gear and knowing how to use it. A contractor will learn a great deal by doing test and measurement, and that's a good thing!
As we said before, we expect a certain amount of basic technical understanding by the systems contractor before they win the contract. It helps if the contractor has some experience with computer modeling software, but speaker aiming is simple geometery, so it can be understood without the aid of computers as well.
Where installation of the loudspeaker requires something greater than mounting in a ceiling tile, or pointing it at the audience seating, we will specify the X, Y, Z coordinates of the loudspeakers, and then indicate the azimuth, pitch and rotation of each component. The relationship between loudspeakers in a cluster is very important, so it is critical that it be right and not just close.
This whole cluster thing seems to be confusing for some systems contractors, but it is really quite simple. X and Y are always horizontal coordinates referenced to some point of origin. That origin will be identified in the spec section containing the table of locations and aiming information, as will the X/Y axis orientation. Z is always the vertical height from a reference point, usually the floor below the loudspeaker. If four speakers have the same X/Y coordinates and different Z coordinates, the speakers are stacked vertically. If they have the same Z coordinate and different X/Y coordinates they are arrayed horizontally.
Azimuth is the aiming angle in the X/Y plane, left and right if you like, away from the axis of the cluster. Pitch is the up/down aiming angle, and rotation refers to the front face of the loudspeaker, and its rotation around the centre of the front face (clockwise or counterclockwise).
It's really not that complicated. As we mentioned before, the purpose of shop drawings is to sort out the issues that the systems contractor does not understand to avoid building or installing things the wrong way. If something does not make sense, then ask a question before it is built or installed. And then send a shop drawing so that we can tell you if the proposed arrangement is acceptable. We will mark up a shop drawing, but we won't do your shop drawings for you.
In all cases we will specify loudspeakers to point at listeners, if you find that you're pointing speakers off in strange directions when you're following aiming instructions, then you have a translation of axis problem, we don't specify wacky things, and you should request clarification before continuing, it will save you having to do things twice.
A printable version of this page is available here.
Mc Squared System Design Group, Inc
323 - 901 West 3rd Street
North Vancouver, BC V7P 3P9
Phone 604 - 986 - 8181