As with the other electric horns, their individual sounds can vary. Every snowflake is different, not all alarms make the same sound.
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Except most other electric horns all have the same pitch. Were some SHGs just designed differently from the others? I have never heard two TrueAlerts sound different nor have I heard two Spectras or Genesises.
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Double post but I donāt care.
Apparently electronic horns manufactured in the early 1990s may have different pitch variations but late 1990s horn all have one pitch. Somebody correct me if this is wrong.
I think the volume of the device and the surroundings affect the sound. Destinās SHG was right up next to the microphone, but Charlieās was not.
But why would it only affect some horns and not others? If you were to do the same thing with a standard TrueAlert, there would be no variation. Is it something to do with the fact that it was manufactured in the late 1990s and not the early 1990s?
Hereās another example: Destinās video of a multi-tone TrueAlert sounds different with the two volume settings.
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But I was talking about normal tone alarms. The normal tone TrueAlert has no other pitch change. I think it has to do with what the year the horn was made. Compare the 4 SAE HA2VD videos on YouTube
All of them have different pitches.
Volume has nothing to do with it at all. The SHG has an analog tone generator (at least Iām pretty sure it does), and analog oscillators drift in pitch. Digital tone generators never vary in pitch because itās microcomputer-controlled.
So Simplex 4051, youāre mostly right. It has to do with if the horn is analog or digital, but any horn that has a potentiometer is also subject to pitch changes because not all of them can be turned to the exact same setting.
I donāt remember those Space Age horns having potentiometers, so they could very well be analog.
Destin, Iām curious- how does an analog tone generator work? Does it simply oscillate the frequency with solid state equipment?
So I take that to mean that if an electronic horn has an analog tone generator, the pitches will change from horn to horn then?
Also, were the analog tone generators only used in the early 1990s before being replaced by digital tone generators?
- Just to clarify, this is speculation on my part. Iāve never torn apart any horns to see what kind of tone generator they use or how the pitch is regulated. Iām just making inferences based on what I know about audio and synthesis.
Yes, an analog tone generator uses solid-state analog circuitry. Analog oscillators repeat an electronic signal at a certain frequency, creating a waveform. The higher the frequency, the higher the pitch. Considering that the first electronic horns were developed in the 80ās, I suspect that they use digitally-controlled analog oscillators. This means that a microprocessor is used to regulate the frequency, but the method for tuning analog oscillators is fairly relative and still wonāt achieve the same pitch accuracy as an all-digital tone generator. Long story short, horns with analog tone generators can vary in pitch from device to device.
A digital tone generator basically does the same thing, but instead uses digital signal processing. In the case of modern horns like the SpectrAlert Advance, more complex methods of synthesis such as frequency modulation are used to create rich harmonic variation. Digital tone generators will never change in pitch, unless the horn has a potentiometer that has been adjusted (a wheel on the circuit board that changes the pitch).
During the early days of electronic horns, analog tone generation was probably less expensive than digital, so it would have been more common in the late 80ās/early 90ās. It was also common in voice evac systems until everything went to digital playback. These days, digital tone generation has replaced analog in fire alarm notification, although I donāt know if thatās true for certain chime/strobes. Again, all speculation.
So Destin, in your opinion based on the 4 videos I posted, would the SAE HA24Ds have analog instead of digital? Though finding out when were they first manufactured as that would be a good starting point.
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I think so. I have an HA24D from 1994 that sounds different from all of those videos, so I would imagine that at least a certain part of the tone generation is analog.
Au Contrare. The Edwards 894b-226 is looks like an 892 but it is electromechanical like the 870ās(Adaptahorns).
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Arenāt the electromechanical 800 series like super rare? There is only one video on YouTube that has them.
Iām thinking that pre integrity of 792 is actually electronic, which it is not electromechanical though.
Iām 10 years late but Iām pretty sure most, if not all newer electronic horns use a programmed microcontroller to generate sound. The SHG just uses a simple 555 or 556 timer circuit.
I have a couple I took out a large factory when we did upgrades to their horns. They originally had an Edwards 8500 system, and then we installed a Secutron MR 7900. We are soon to replace that with a VM series panel.
The mechanical horns were labelled by Edwards, and the electronic horns by EST.
Odd branding choice if you ask me. Were the Edwards-labeled ones marked āEdwards GSā specifically? (since it seems like ā100-seriesā Edwards signals were made during that period)
Yes, not on the outside but the interior label had the Edwards GS logo on it. Probably because they bought EST right in the early 90s and was switching more to electronic horns.