Delay Systems for Guitar
With all the different kinds of guitar delay units on the market, there is considerable misunderstanding of the ways delay is generated and the pros and cons of each type of unit. In this article, we'll try to make the murky waters a little more clear. I'm going to go at the three basic types of delay in the order they were historically invented.
TAPE DELAY: Delay is accomplished by recording to a tape and playing it back. Fuss-free operation is accomplished by recording to a short, endless loop of tape. Delay length is increased by moving the playback head away from the record head (Echoplex) or changing the tape speed (Roland Space Echo). Regeneration or repeats are caused by feeding back some of the playback signal back to the record head to be re-recorded. Analog tape is a lossy format and the circuits and tape-handling systems used in tape echoes generally haven't been audiophile in nature. As a result, quality naturally degrades with each pass through the tape system. A well-tuned tape delay doesn't degrade the signal much on the first delay but it goes downhill smoothly from there. This reproduces pretty well the way echo occurs in nature (more on that in digital delay). A poorly maintained unit degrades the signal on the first repeat and it goes down very quickly from there. So, what's the verdict on tape echo?
Ups?
1. A well-maintained unit yields a very nice sounding echo - probably the most desirable echo sound in the guitar market. Because of Mike Battle's excellent Echoplex preamp designs, some of these units made your guitar sound fuller just by passing the signal through the unit, even in bypass. You lost a little high-end but you didn't care. It just sounded great.
2. The decay curve on the Echolpex is different from any other device I've tried and imparts a certain interactive "feel" to your performance with it that I haven't found elsewhere.
3. The Fulltone Tube Echo is a brand-new version with a 20-year tape supply estimated. It is well-reviewed but apparently has a slightly different sound.
Downs?
1. This is an electromechanical device, subject to entropy. It is essentially a portable, special-use tape recorder. Like a car, it is failing from the moment it is born. It requires maintenance to stay in peak performance and many modern players have no idea how to do that maintenance. Tape delay units eventually exhibit mechanical component failure and must be repaired.
2. This device is a dying technology. Many of the original units are between thirty and fifty years old. Parts and qualified service people are becoming scarce. Unless they are rebuilt, many of the existing units are on their way to no longer being road-worthy. Of course, the Fulltone Tube Tape Echo is a newly-built variant.
3. All, including the modern Fulltone, rely on magnetic audio tape. As magnetic audio tape has gone out of vogue in both professional and consumer realms, the manufacturers have died. There are now very few manufacturers making very little tape, and tape doesn't keep well on the shelf. Supplies are dwindling and existing stock is degrading.
4. The units are bulky and are both physically and electronically noisy. Joe Walsh and Tom Scholz were complaining about the electronic noise in the mid-1970s.
5. Because of their complexity and desirability, these units are becoming expensive. A used unit in only fair shape starts around $800 from a dealer and the Fulltone units are $300 more than that. EBay features units for considerably less.
6. Tape echo units have no tap tempo feature.
Now, don't get me wrong: I love the Echoplex, enough to have recently bought one. For ten years I missed the one I sold more than any other single piece of guitar gear. I eventually found a gorgeous, barely-used one and replaced it. As a recording engineer, I was and am able to keep mine in excellent shape but they might not be for technically un-savvy players. I'm considering buying a non-functional "hangar queen" from which to pick parts as needed. But, here is a big take-away: These days most of the new delays are trying to sound, wait for it... just like an Echoplex.
ANALOG DELAY: Delay is accomplished by running the signal through a series of analog delay paths called "bucket brigades." Each adds delay, noise, distortion, and bandwidth reduction. Longer delay requires stacking more delay stages. As a result, the longer the delay selected, the lower the quality of the delayed signal. Repeats are generated by recycling the output into the input, as on the tape delay. A short delay on an analog delay can sound very much like a tape delay. On a long delay, the first delayed sound begins dull, distorted, and noisy and the quality goes down sharply from there on repeats. This was this first shot at replacing tape delay with a more roadworthy medium. Ups? Cheap, reliable, compact, and easy to power. Short delays have the warmth of a tape delay. Downs? Limited delay length. Long delays are a dirty wreck. The Japanese firms that manufacturered the bucket-bragade delay chips have ceased production and the new crop from China are noisier and lower-fidelity.
DIGITAL DELAY: Delay is created by recording the sound into a solid state digital memory and spitting it back out at a later time as requested by a timing circuit. The recording plays back crystal clear. Typically, repeats are generated by mixing some of the output to the input, as with the others, but there is comparatively little bandwidth limitation and noise build-up in successive repeats. An infinite repeat can be generated by ceasing recording and endlessly playing back the sampled sound. Ups? Quietness, reliability and stability. Indefinite, crystal clean repeats, tap tempo! Downs?
1. With repeats, that pure sound is unnatural. Echo doesn't occur that way in the real world. Instead, in the real world, a sound travels through air loosing high-end and low-end, bounces off multiple and irregular surfaces causing distortion, and then comes back through the air, losing even more high-end and low-end. Any repeats continue the degradation process. In order to duplicate this, many higher-end digital delay manufacturers give you the choice of optional processing in the recycling circuits. This processing reduces bandwidth and adds distortion and delay to make things sound more natural. However, that engineering adds cost and required processing power.
2. Poor analog to digital and digital to analog conversion within a pedal can make the digital recording sound harsh. Each repetion can add harshness. For years, both guitar and studio equipment manufacturers chortled to themselves that effects simply didn't need high-quality signal A-to-D and D-to-A because the effects themselves were low-bandwidth, low-quality signals. Surprise! Engineers and guitarist could feel the difference through their bleeding ears. To keep things sounding smooth, designers have begun using audiophile-quality 24-bit D-to-A and A-to-D converters such as the Burr-Brown units. Yahoo! The golden eared guitarists have joined the golden-eared audiophiles. However, increasing quality adds cost and demands more line power.
Funny Little Thing Called Taste: Do understand that taste is a big factor in this whole issue: Some folks prefer to build their sound around clean repeats. For instance, the '80s was a period of clean repeats as guitarists emulated recording studios in their use of digital delay. If clean repeats work for you, you'll love existing digital delays as-is. However, if you like long, warm delay such as those from a tape delay system and you bailed out of your Echoplex a while back for the convenience of digital, you may have found yourself in an ugly purgatory for several years. In the interim, many guitarists had added multiple types of delay onto their boards to satisfy multiple needs.
Where Do We Go From Here? Digital delay for guitar is just emerging from its infancy. For years, all you could get was the clear crystalline repeats. Then, at the request of users, makers started adding optional recycling processing to degrade the signal and give a more natural repeat. Next makers began addressing the bypass issue. Once they dealt with that, they began addressing the A-to-D and D-to-A issue. Now we are looking at the first units to dial in all the factors to come up with a complete, flexible package. We are just now beginning to see the units like the T-Rex Replica and Empress Superdelay that approach the sonic ballpark of the Echoplex. The Empress even allows you to store eight presets of your favorite settings. And it even sounds something like an Echoplex...
UPDATE Inspired by my research for this page, I started researching Echoplexes and looking for one on EBay. See the results, HERE .
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