Realistic manufactures or has manufactured the following equipment (click to expand models list):CD-Players
John Hamm (April 2000): Radio Shack is a LARGE marketer of electronic items. One of their 'brand' names is Realistic. Basically, except for computers and telephone service they only sell their brand items. Technically these speakers should be listed under Realisitc BUT most people will NOT know what the Realistic brand is. IMHO it would be better to continue the Radio Shack ~ Realistic link. The speakers were not sold anywhere else other than Radio Shack and Radio Shack continues to market product(s) under the Realistic brand today. I think these were the only electrostat loudspeakers marketed by Radio Shack.
John Hamm (April 2000): Radio Shack marketed an excellent pair of electrostatic headphones a few years after the Electrostatic IIa speakers. Radio Shack is a LARGE marketer of electronic items. One of their 'brand' names is Realistic. Basically, except for computers and telephone service they only sell their brand items. Technically these speakers should be listed under Realisitc BUT most people will NOT know what the Realistic brand is.
RadioShack Corporation web site (December 2003): Fort Worth, Texas-based (NYSE: RSH) is the nation's most trusted consumer electronics specialty retailer of wireless communications, electronic parts, batteries and accessories as well as other digital technology products and services. With more than 7,000 stores nationwide, it is estimated that 94 percent of all Americans live or work within five minutes of a RadioShack store or dealer. The company's knowledgeable sales associates and brand position, You've Got Questions, We've Got Answers, support RadioShack's mission to demystify technology in every neighborhood in America.
They did also market an excellent pair of electrostatic headphones a few years after the Electrostatic IIa speakers.
Olfoo (January 2005) Words of caution: The early Realistic electrostatic tweeters were NOT push-pull two sided tweeters but one-sided only. At appreciable volume levels the distortion rose sharply. Modern esl tweeters, including even the contemporary Janszens, have two diaphragms equally charged to plus and minus leading to a linear excursion of the constant charge diapragm between them. NOT true with the Electrostat-2 I know, I have one, and I think not true with the Electrostat-3. These tweeters do not have the usual clear clean electrostatic sound IMHO! ( Audio Asylum BOLD EAGLE [..he's very knowledgeable] )
Dave J (February 14, 2005): I feel I must respond to three points made previously by others, all relating to the exclusive use of single-ended ES tweeters by Radio Shack. (Feb05)
These units produce considerable harmonic distortion, as warned of by commentator Olfoo last month, and here is why: ESL's may be biased (polarized) or not. When not biased, a single ended unit produces force on the membrane for each half cycle, essentially rectifying the signal; the resulting sound is doubled in frequency, essentially producing 100% harmonics. When properly biased (above one or the other peak signal voltage), the situation is improved, because now the force attracting the membrane to the stator is proportional to the voltage, though not linearly. This configuration produces distortion for two main reasons:
- The design relies on the tension of the membrane and elasticity of the air to supply most of the restoring force, so the force in one direction is different from that in the other, and
- As the position of the membrane changes, the force for a given voltage changes, meaning the force is nonlinear with voltage. Both conditions cause increasing distortion with increasing signal levels.
- Shack's solution was to use a crossover frequency of 5000 Hz. This was not unreasonble for human listeners, because the frequencies of the harmonics were therefore above the frequency limits of most people's discriminatory sonic capabilities. A dog fond of music, however, may have objected.
Whether the speakers must be plugged in
As should now be clear, polarization is required, but it takes a long time for most of the voltage to decay from the usual polarizing supply circuit (a voltage multiplier). You will only have one chance in maybe several hours to test the effect. Long after pulling the AC, the test would be done by applying an audio signal well above the crossover frequency, placing a microphone that is sensitive at that frequency in front of the tweeter, then applying AC to the bias supply and noting the difference in the SPL. Preferably, wait at least a whole day before trying the test.
If you have been waiting long enough, but using a musical signal and relying on your hearing for measurement, there are at least three factors that may interfere with the test. The ED speaker in your unit probably produces a considerable amount of sound above crossover, so the difference made by the tweeter may be hard to hear using the many sorts of music that have little content above 5000 Hz. The 5000 Hz crossover may be close to one's limits of hearing, which would also affect one's ability to hear the difference. Though the unit will not be loud when there is no bias, the frequency doubling may not sound bad to you.
Possibility of a past relationship between Janszen and Shack
A. A. Janszen and his licensees have never been associated with a product that uses single-ended ESL's. Optimizing and making practical use of the push-pull (dual-ended) configuration in both tweeter and woofer radiators is the embodiment of A. A. Janszen's many ESL innovations of the 1950's. Licensees were required to manufacture an accurate facsimile, and these may be found in many hybrids, but not in those from Radio Shack. Some Shack products were superficially similar, but none were functionally similar. More on push-pull in the Janszen section.
BTW, Olfoo, push-pull radiators, for the most part, have two stators that carry opposite ends of the signal, and one membrane that is biased to a high voltage. Koss made woofers with three stators and two membranes, essentially two push-pull units acoustically in series. There was one exception from BTM that achieved something like push-pull by placing membranes on opposite sides of one stator and relying on acoustic coupling through the trapped air to link the motions.
Forum topics on Realistic
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