In what field do they use analog filters, and for what purpose? Is it ever possible to send plain audio signals through them?
ie,
http://www.analog.com/Wizard/filter/filterUserEntry/
or
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3851133162
As I understand it, many years ago Bob Moog had the realization that you could take standard test modules–oscillators, filters, amplifiers, etc.–and put them together to make a musical instrument.
Similarly, a man named John Chowning had the realization that FM sounds could be controlled to make musically useful sounds. I originally worked with his program on a PDP 10-11 computer that was about four feet square and nine feet high. It took days to design the data for just a few seconds of sound, and then if the data you input had one decimal in the wrong place it wouldn’t work correctly. The computer would take hours to turn the data into sound. Chowning sold the rights to his discovery to Yamaha. The result was the DX-7, which was partly responsible for putting most U.S. synth makers out of business.
Electrical engineering – specifically, signal analysis. It was one of the few EE courses I did well in, thanks to my experience wth synths.
Of course, now that nearly everything’s gone digital, it’s becoming a lost art.
As for filtering audio signals, the filter should be built to handle frequencies in the range of hearing in order for it to have any effect.
Appreciate the info, thanks.
I work in test engineering. Analog filters are used with strain gauges and thermocouples because of their low signal level which has to be amplified about 40dB. Analog filters remove the noise; if you didn’t you would see false fluctuations in the amplified signal.
Analog filters are the building block of EQs; mixing consoles, amplifiers, consumer audio all uses analog filters.
Telecommunications use analog filters for selective reception and processing of signals.
They are also common for rejecting radio interference on audio inputs.
Automotive/aerocraft - your fuel gauge has filters because your fuel sloshing around inside the tank would render an unreliable measure unless you’re sitting still on level ground.
Too many others to list…
Hello,
The telecommunications area of electronics was among the first to use analog filtering as well as oscillators and amplifiers, as MC has pointed out. This is prior to the field’s later merger with the newer field of digital electronics. The roots of the use of these filters are best covered in a basic electronic communications course which includes am/fm wave propogation, etc
The more recent use of these devices in the form that we see on our Moog
and other brand synths was a later adaptation of these devices for audio and high-fidelity applications.
Analog filtering is used less now because since the merger of telecommunications with digital electronics, digital signal processing is used
to model functions that were previously done using discreet ciruits, and this newer method of of doing things brings us cell phones, palm pilots, etc.
Regards,
LWG
Hello,
Although I understand how the DX-7 argument came about, I will submit that U.S. synth manufacturers saw a decline due to their own contradictions
as well as a type of mediocrity that became commonplace in the commercial synth industry.
In my own experience as a music consumer during the late 70’s- early 1980’s, (even before the DX-7’s emergence) the sounds of the analog synth became often overused to the point where these instruments became cliche.
Musically speaking, the human ear does fatigue and by about the mid 1980s, the public had become so tired of hearing this standardized repetoire, that when instruments like the DX7 and Roland D50 appeared,
they offered a sound that was different from what people were being subjected to daily over the radio waves.
Part of this phenomenon was based on the fact that U.S. manufacturers had to make certain compromises in the synths layout and features in order to make the instrument appeal to a mass market. One must remember, among the first polysynths that emerged (CS-80 an OB 4-voice)
the general public didn’t like programming them as they were considered too complicated. The response was to streamline the featuresets as to make the insruments more appealing to a wider market.
This was a two-edged sword, as it made synths easier to use for a wider cross-section of the public however, it tended to standardize the sound of an
instrument that was in theory, supposed to be without limits. Some synth
purists considered this a dumbing-down of the instrument for mass appeal.
Although I don’t necessarilty agree with this, it is something that manufacturers felt they had to do to make the product more commercially appealing.
Even Jim Aikin raised the issue about Sequential’s recycling of the lowpass-
only filter concept on its instruments after the P5.
Arp set out to build a flagship synth in the Quadra, but merely recycled two
existing instruments into the same package.
And while I also liked some of the older Moogs, for example, the Memory, I think that a more flexible filter arrangement (like the one presently on the Voyager) would have significantly expanded the sound palette, all issues of reliability aside.
I would recommend an article from the September 1992 issue of Keyboard magazine written by Bob Moog himself titled, “Who’s Not Supporting Whom?”
Even Dr. Moog seemed to disagree with the notion that the Japanese synth firms were to blame for the the decline of the U.S. synth.
Problems with unreliable, poorly conceived products, combined with bad management on the part of some major players in the industry lead to
this decline in the U.S. analog synth companies. (E-MU and to a degree, Oberheim did survive this early decline, only to later be acquired by other firms).
Regards,
LWG
LWG, that’s why I said the DX-7 was PARTLY responsible for the decline of U.S. synth companies. There were many causes, including poor hardward design, copycat modules (2-3 oscillators, 1-2 EGs, 1 Filter [LP or multimode], and a few other various ones), bad financial control, etc. But when the P5 was selling for $4,000 list with 5-part polyphony and the DX-7 came out for half that price, 16-part polyphony, and voices that sounded far more like traditional instruments than any of the analogs, the DX-7 was, IMO, the straw that broke the U.S. synth camel’s back.
My P5 was stolen, and I received only $2,000 from the insurance. The DX-7 was brand new and had strings, horns, bells, pianos, and unique sounds unlike anything available from Moog, ARP, Sequential, EMu, and any of the smaller companies. And, as I wrote above, I was already familiar with Chowning’s FM, so programming it was familiar to me. It was the obvious choice and I’m happy I made it. I eventually purchased an SY-77 which, IMO, along with its SY-99 sibling, are possibly the most original and best-sounding and most capable poly synths ever.
YMMV
Don, no doubt, this is true. Most of those instruments were beyond my means when they were new, and I only got to drool over them.
Also, the SY-77 and SY-99 are killer synths. They give you the sample playback, FM, filters, and fx in the same bundle.
Haven’t used either of them myself, but I’ve heard them used extensively by Chick Corea on his Elektric Band’s release “Behind the Mask”.
I like the timbral versatility of the fm systems as I have a Yamaha FS1
module I use for those sounds. Roland’s JX series got some of these sounds using am. It would be interesting to see someone develop an fm instrument where the audio path can be kept in the analog domain.
Regards,
LWG
… It would be interesting to see someone develop an fm instrument where the audio path can be kept in the analog domain.
but detunning of FM operators will change the sound more then the average difference in beatings of a substractiv synth. And to do something like the DX7 analog it would take way more then a single PCB. 16 voices of 6 ops each. Plus plenty of envelopes and a variable array to change the op structure. This would cost more then average synths, even if done monphonic only. And I wonder, if the difference in sound is worth the efford for an FM synth.
Hello,
Qwave, it is true that vcos may present a problem where this is concerned
however, signal generators used for mathematical operations that fm requires can have a digitally-controlled current source (dco). Dcos have added pitch stability yet the audio is still analog. Roland used them for a
limited form of am on their JX-8P and JX-10 synths.
Although an analog equivalent of 6-op fm would require a large number of osc, env, and filters, it would have to be implemented using an approach
similar to that Alesis deployed in the Andromeda.
4-op fm would probably not be as much of a problem.
To my own ears there is a significant difference between fm done in the analog domain and the fm derived from first-generation digital technology.
If you modulate the filter (or another osc) on the Voyager or any other analog that allows this, you discover that the timbres produced by taking
a simple wave and building your tone by generating sidebands, are more
complex and richer than the three basic waves that form the staple of most analog oscs.
The fm waves also can contain specified harmonic as well as non-harmonic partials without using a noise source or rm.
You are on point if you’re saying that companies now wouldn’t be willing to invest in the idea of an ubersynth for a market thats not there.
With the advent of home recording and sequencing, the synth market is mainly geared toward workstation type sampler/synths. Thats where the bread and butter seems to be.
Regards,
LWG