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Show Synthesist with Utopia Top LA. Studio Keyboardist - > OSCAR PETERSON A Up FromCK's Advisory-Board -;r .v ,.-.¦.'• ¦;':<¦;¦' and more... LETTERS Send to: Contemporary Keyboard, 20605 Lazaneo, Cupertino, CA 95014. I think Craig Anderton should have the courtesy to use high-quality op amps in his designs for your readers. 4558, 4136 op amps are pure junk for any audio use. Radio Shack carries LF353N, which is a direct replacement for 4558, and TL084BCP, which is a quad bifet nput op amp at 13voit/usec. slew rate. Com-o\ex waveforms cannot be reproduced without noise and distortion by slow op amps (741-type), and it is a disservice to have someone go through the work of building some circuit and never know how good it might sound when high-quality op amps are either the same price or sometimes cheaper. The reason so much gear sounds like junk nowadays is because of that damn 4558 op amp, and i don't think anyone with care would use them. George Rigney Downey, CA [Mr. Anderton replies: George, I'm glad you've found out that many bifet amps will substitute directly for bipolar types when a high slew rate is required, but you could have learned this sooner had you read my July '79 CK column, where I recommended that people replace their 741s with TL071s if they wanted improved performance. In fact, I specif ically try to use industry standard pinouts - and stress the use of sockets - to allow for easy upgrading as new parts are introduced. However, to assume that slew rate is the only op amp parameter that really matters is a simplistic approach to a complex problem. Specifying an op amp involves tradeoffs between cost, availability, ease of use, ability to withstand abuse, thermal stability, current consumption, type of compensation required, and many other factors. Since industry has not yet invented the perfect op amp, I choose what I feel is best for a given circuit, with an admitted bias towards devices that yield the lowest overall noise. You are entitled to your opinion concerning the performance of the 4136, but if you run some noise performance tests comparing the 4136 and the LF353 at low source impedances, you just might change your mind about the 4136 being "junk." On the other hand, I am well aware that bifets can do things that bipolars can't, which is why I have specified them from time to lime in the past and will continue to do so in the future - when they are the right part for the job. I'd like to correct three other misconceptions. It is incorrect to place the 4136 in the same class as a 4558 (the 4136 has much less noise); it is incorrect to say that "high quality" op amps are the same price or cheaper than general purpose op amps (the LF353 is $1.89 in Radio Shack's current catalog, more than double the price of their 4558 and 39c higher than the typical price for a 4136 quad op amp); and it is incorrect to assume that if a piece of equipment is truly a piece of junk, then it will magically cure itself if you replace the ICs with high slew parts - you will simply have a piece of junk with the capacity for improved high frequency response and possibly lower noise. If your real complaint is about 4558s in equipment, don't write me - readers of my columns already know about substituting op amps. Instead I would urge you and other readers interested in substituting op amps to be willing to pay a few more dollars and ask manufacturers for effects that include sockets for the ICs. That way, if you don't like the sound of 4558s - or LF353s, for that matter - you can pull out the stock /C and substitute the pin-compatible replacement of your choice. I hope this gives you a clearer insight into how I go about specifying the op amps used in my projects.) Regarding the three responses in your March '80 issue to my letter about Oscar Peterson [see CK, Feb. '80], it looks like I struck a nerve, and the truth really hurts. I agree with Mr. Radd that a player only needs sufficient technique to express his or her ideas; I was only saying that Oscar's ideas bore me. If it's speedy fingers you like, there is much of that in the service of the modern polytonal sounds these days; I refer you to Richard Beirach, Denny Zeitlin, Don Pullen, Joanne Brackeen, or Warren Bernhardt. Also, I'm happy to report to Mr. Bryant that I will be releasing my first double album on my own label in the near future, so you will indeed then hear what you've been missing. I even plan to show Keith Jarrett a few things. The album wili include a 6000-word essay on the horizontal/vertical evolution, so Mr. Kincaid will know that these terms are not my "jargon." Oscar's wide acclaim is due to the fact that he is a fine representative of pre-modern jazz, a dazzling pianist, and a living encyclopedia of old jazz styles, with a huge repertoire in his head, but I was simply saying that early jazz bores me. I am not drawn to diatonic music. Jazz is polytonally consonant, in contrast to European music, which became monotonally dissonant. Understand that even when jazz is horizontal it is really vertical, and conversely, when European classical music is vertical it is really horizontal. There is much yet to be explored in vertical composition, but you'll have to wait for my album to really understand what's going on in American music. Paul Ellingson Salt Lake City, 0T It seems to me that many critics still view synthesizer music on a traditional "just the notes, ma'am" basis, an attitude that leads them to dismiss certain compositions as "extremely simple" or "relentlessly trivial." As a synthesist myself, I judge the virtuosity of other synthesizer players not just by the notes they play, bu in terms of their ability to make one single note beautiful. If beauty can be heard in the individual timbres of each note, then very simple melodies can often come across as very beautiful melodies. When we hear beauty in simplicity, how can we dismiss that simplicity as trivial? Zon Vern Pyles Morgantown, WV 4 rONTFMPORARY KEYBOARD/iUNE 1980 |