- 100v line is most commonly used in distributed audio systems.
- The main advantage they give the user is the ability to put multiple speakers on the line, something which traditional low impedance amplifiers will not tolerate.
- 100v line is also good over long runs in say a large factory for example./ 200-300 metre runs are no problem. This is because the voltage loss over long runs of cable is negligible with 100v compared to low impedance amplifiers.
But I’ve heard 100v line sounds bad!
- Its not the use of 100v line itself that effects the sound, it’s the quality of the amplifiers & speakers that are used. If a factory needs 100 speakers to give even coverage, then the factory isn’t going to fork out on 50prs of Dali’s or B&W’s. They will buy $40 horn speakers with
limited frequency response. People hear this & just assume that it’s the use of 100v line equipment that has effected the sound quality.
- So don’t be afraid to recommend 100v line amps & higher quality 100v line speakers (such as TOA’s F1 000 & F2000) when a cafe or pub for example, wants a better sounding system that still involves multiple speakers & long runs of cable with possible use of paging mics etc.
Good Practice & how to calculate which amp & speakers I might need
- Lets say a customer wants to put 8 x 15w horn speakers into a warehouse
- 8 x 15 = 120. The customer will of course want to spend as little as possible & think “OK … 8 x 15 = 120, I need a 120w amp.
- Good practice is to allow some headroom on your amplifier. In the same manner that it is not advisable to redline a cars engine & simply leave it there. It is not a good idea to only buy the minimum amount of watts.
- Allowing 3db of headroom means we must double the wattage, so if a customer is buying 120w total of speakers he SHOULD buy a 240w amplifier.
- This means that if something happens like a paging microphone is dropped or someone turns the gain up on one of the channels, the amplifier has something left to give …. It has Headroom.
- If it’s a 120w amp & its flat out supplying 15w to 8 speakers & somebody drops the mic …. It has nothing left to give & may blow up altogether or blow a fuse.
- Either way, this warehouse now has no emergency evacuation system in place because they did the job on the cheap. Potentially lives are now at risk to save a few bucks.
Tapping a speaker?
- A speakers sensitivity (often referred to as efficiency) varies from speaker to speaker depending on type. A horn speaker for example, may produce 100db at a distance of 1 metre when fed 1w.
- To be able to limit or vary the amount of decibels a speaker will produce, most 100v line speakers can be ‘tapped’ at various settings eg: 15w, 10w & 5w.
- This function means you can set different tappings in various places of a business depending on the environment.
- As an example, the warehouse needs the speakers to perform quite loudly to cut through the noise from a machine running nearby, the forklift driving past &the trucks waiting to be unloaded. The foremans office is somewhat sheltered from this so the speaker in there doesn’t need to go as loud & the admin office upstairs is quiter again so needs the speakers to be even less loud again.
- By making use of tappings on the exact same speaker we could tap the speakers in the Warehouse at 15w (maximum), the speaker in the foremans office at 10w & the speakers in the office upstairs at 5w. Thus achieving different levels of loudness in each different part of the business as appropriate.
Reliability is Key
- TOA amplifiers & speakers have a well deserved reputation for their reliability. They also sound very good compared to most other brands on the market.
- TOA soak & torture test every design for 6 months & even up to a year before they release them onto the market. This means that all the little bugs have been ironed outs & lots of “what ifs” are now known about what will happen in stressful situations.
- Our return rate is less than 0.5% on TOA products. DOA’s are very few & far between & most of what we see is end user or installer faults.