Thursday, March 23, 2006

Le DX-7 est arrivé

Isaac is starting to take keyboard lessons and wants to learn to play synthesizer. We have been considering options for some kind of a keyboard with full-sized keys he could use at home. I was looking into cheapo home keyboards, low-end digital pianos, and a used Yamaha KX-88 MIDI controller keyboard. Advantage of the KX-88: it is built like a tank, it has weighted keys with realistic action. Disadvantages: it weighs 75 lbs.; it doesn't produce any sound (I'd need to find a sound module, like an Alesis NanoPiano); and some of the key expressiveness you could get with the nice tactile key mechanism would be unavoidably lost in translation to MIDI.

After looking at a KX-88 available locally for $300 and scouting tone modules on eBay, and scratching my head for a while, I finally decided to bid on an original Yamaha DX-7. I lost the auction, but apparently the high bidder didn't come through, so I got a second chance offer, and yesterday a humongous box arrived, filled with packing peanuts, bubble wrap, and the DX-7 in a nice padded soft case, along with two ROM cartridges and original manuals, all for about $250 including shipping.

The DX-7 was one of the most popular synthesizers sold in the 1980s and had its debut in 1983. I first used one around 1986, in college. The College of Wooster's music teacher, Dr. Brian Dykstra, gave a concert on the DX-7, which I attended. My friend Jim Batman was a piano player and also interested in the synthesizer, so he got permission from Dr. Dykstra to go in after hours and play around with the DX-7. Jim had the keyboard chops and I had the geek chops, so one night we took a casette deck and spent the entire night in the music studio. We would listen to sounds and I would work on modifying them until we had something cool, and then Jim would improvise a composition and we'd record it. I got a crash course in programming the DX-7, and Jim got to record some neat compositions. Of course, like most of the truly useful and fun things I did in college, it had nothing to do with my classes and involved staying up all night and ruining my concentration the next day. I still have the tape and will get it online sometime when I am able.

The DX-7 is a quirky brown beast, extremely well-built and nearly indestructible. It does not have realistic piano action, but the keys are full-sized, solidly built, velocity-sensitive, and springy. It uses FM synthesis, also known as subtractive synthesis. It produces some kinds of sounds that are very realistic and rich-sounding, and some that are really mediocre or poor. In general, it was extremely good at producing sounds with a lot of high harmonics and metallic ring modulation. I'm not sure just why this is the case, but basically instruments with metal mouthpieces, strings, reeds, pipes, or bells can be quite nicely rendered by the DX-7, and most other kinds of instruments can't be. It probably has a lot to do with the generation of even and odd harmonics.

The DX-7 had several electric piano presets that, despite sounding somewhat artificial, had very rich, pretty bell-like overtones; other synthesizers of the time could not produce electric piano sounds that were anywhere near as nice-sounding, so the DX-7 sounds became extremely popular: synthmania: DX-7 electric piano sample

The Rhodes electric piano simulation has what I would call a surreal gloss or saccharine sound which made it fit very well with highly-polished (some would say over-produced) '80s ballads. You can hear that sound here, used on a Whitney Houston track: synthmania: Greatest Love of All excerpt

The DX-7 harpsicord (another of the metallic sounds at which the DX-7 excelled) is almost supernaturally realistic: synthmania: DX-7 harpsichord sample

The DX-7 does great chimes including this tubular bell simulation: synthmania: DX-7 tubular bells

There is a nice clavinet that reminds me of Stevie Wonder: synthmania: DX-7 clavinet sample

The strings are less realistic, tending to sound less "fat" than analog synth strings, and its replicas of wind instruments like flute are not very good, although it does generate a number of very fine organ sounds (reproducing metal pipes or reeds): synthmania: DX-7 organ sample

On one of the cartridges is a harmonica sound (again, a metal reed instrument), and although not all that realistic, it was charming and homey enough to make it into a popular Tina Turner track, where it makes a good counterpoint to the somewhat sad lyrics synthmania: What's Love Got to Do With It excerpt

The "fat" analog sound of the Prophet 5 and ARP is not really possible on the DX-7, although some DX-7 percussive and metallic synthetic bass sounds became popular and got a lot of play in dance music (I believe New Order may have used a DX-7): synthmania: DX-7 bass sample New Order also used some hollow, spooky human voice sounds, which I think also came from a DX-7, although I could not find a good example.

Programming for FM synthesizers is trickier than programming a traditional analog synthesizer. The oscillators interact in unintuitive and unpredictable ways. You don't have filters in the usual synthesizer sense; you can't just grab a knob and twist it to change the frequency envelope as you play. All the parameters are available via menus and there is a single data-entry slider. A lot of trial-and-error is involved.

It is relatively easy to start with an existing patch and modify it to make it sound more interesting. That was how I got most of the sounds I used for the tape. Starting from scratch building up sine waves with operators will usually give you something that sounds weird and metallic and hollow and not very "pretty," and it is not very clear how to get closer to "pretty" except by accident. Thus, the DX-7 also has a kind of second life in gothic and harsh rock music like Nine Inch Nails, especially when some of these metallic sounds are fed through effects like distortion and ring modulators to fatten up their harmonic content and make them more suitable for lead or bass lines.

I'm recommending to Isaac that he stick with playing his exercises and not worry at first what all those operators and modulators mean. We're putting away the programming manual for now. If he wants to learn to program it, though, I won't discourage him, and I'll happily show him what I know, which is not that much, and let him dig into it. It will certainly teach him the virtues of patience. If he likes the DX-7, there are lots more interesting synthesizers available on eBay, so he can start saving his allowance.

The DX-7 is long out of production but FM synthesis still has many fans and there are plug-in versions (FM-7) and rack versions (the FS1R), so the great sounds and the quirky FM synthesis techniques live on. Vive le DX-7!

2 comments:

Simon Lowes said...

i think the DX7 doesn't have filters because it's not subtractive...i might be wrong, but subtractive synthesis is where you start with a wave and filter out selected frequencies to get different sounds.

i was going to mention the FM7, but i see you've already tried it!

thanks for the info, good post.

Paul R. Potts said...

It looks like Synthmania rearranged their directory structure, so all my audio clip links were broken. I have fixed them. If anyone stumbles across a broken link, please let me know.