- This topic has 4 replies, 3 voices, and was last updated March 12, 2014 at 1:36 pm by Raoul Duke.
March 10, 2014 at 7:04 pm #1057102Raoul DukeParticipant
Does anyone know where to find that sort of telephone sample in this track?March 10, 2014 at 9:55 pm #1277709General LightingModerator
it is produced by a device known as a “dub siren”.
This is (as its name suggests) often connected to dub/reggae sound systems via an echo unit.
it is traditionally built from analogue electronic components and sounds like a 1980s telephone as analogue telephone circuits signal ringing by sending around 100V AC at 25 Hz (EU) or 20 Hz (US/CN etc) down the phone line.
It originally rang an electromechanical bell but as smaller components became more affordable and convenient circuits phones were redesigned to use this signal to modulate another higher pitched tone from an oscillator circuit. A dub siren works in exactly the same way but unlike these telephones where you can sometimes adjust the pitch of the ringing oscillator (but its always 25/20 Hz signal from the line) you can vary the frequency of the “ring” signal, if its made lower frequency it would sound more like an emergency vehicle siren, and higher frequency would be like a warbling “space alien” type sound (at least to my age group).
Coincidentally a lot of sound system engineers also had day jobs in telecoms (many still do)- in the 80s/90s there was still custom built kit for big clients so many companies had test and development areas and it wasn’t that difficult to build such things as the basic circuit for a dub siren at work, especially as it was a fairly common request from clients to have an noisy device that was louder than a normal phone, or was triggered if “prompt alarm” conditions activated on the internal telephone exchange (these mean that something has gone wrong and many folk will soon not be able to make any phone calls, so it is best investigated) and it was still affordable for a junior tech to make this (today you can get a very loud siren for a few quid from China)
I’ve seen a few traditional dub sirens on sale for way inflated prices compared to what the components actually cost but there are a few circuits on line. I found a link to one circuit below (using 555 timers feeding an op amp), it is fairly simple but if you don’t want to go to all that trouble building one I’m sure there must be loads of VST plugins for them… (or maybe Daftfader has encountered such a plugin or the same sound could be made with other VSTs)March 10, 2014 at 10:18 pm #1277711cheeseweaselParticipant
Nice! Might even have a stab at that myself.March 11, 2014 at 8:12 pm #1277712Raoul DukeParticipant
Cool, thanks! :weee:March 12, 2014 at 1:36 pm #1277710General LightingModerator
@cheeseweasel 561569 wrote:
Nice! Might even have a stab at that myself.
if you do, I’d suggest resisting any temptation to substitute the 741 for more modern, cheaper alternatives.
It is surprisingly expensive in a DIL-8 package, it seems to cost the same as it did in 1986 in spite of all other similar components (even from the same TI plant in Malaysia) being heavily reduced in price.
Even then in 1986 it was thought of as “noisy” for audio circuits but as it is the circuit is deliberately generating two rough square or triangle waves and modulating them at what may be beyond distortion level, all this noise would be part of the sound – just like the 303 (which made use of transistors that the Japanese had over the years rejected for hi fi audio use and even cheaper transistor radios because of the distortion and feedback they made)
- You must be logged in to reply to this topic.