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#1
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Is AKAI "High Com" Noise Reduction the same as DBX?
Can anyone tell me about the AKAI High()Com Noise Reduction
used in AKAI Cassette Decks like the GX-F37? How did it compare to dolby B, C and DBX? I heard Nakamichi also used High()Com Noise Reduction. Is it the same noise reduction? Did Nakamichi or AKAI make it? |
#2
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HighCom was designed by Telefunken in the late 1970s as the simplified,
consumer counterpart to their "Telcom c4" professional noise reduction system. Telefunken and Aiwa sold outboard noise reduction processors using the HighCom system in its original form, and Telefunken also sold separate modules and ICs for this system. Nakamichi derived their own version which used the Telefunken ICs but divided the audio frequency range into two parts and used separate HighCom processors in each half. Recordings made with the Nakamichi version of HighCom are not compatible with the others. The system is considerably more powerful (reduces noise and print-through more effectively) than Dolby "B". If I recall correctly it is also somewhat more powerful than Dolby "C". Like those two systems it uses a recorded set-up tone which is used to set the gain in playback for more accurate tracking. While the system is more tolerant of playback gain errors than Dolby B or C, dbx is more tolerant than either of them, and numerically it does reduce noise more than the others--but dbx is highly problematic, or rather it tends to expose severe problems in the underlying media (tape modulation noise, for example). One could even say that it reduces noise too much for its own good. I was never able to use it for classical recording. And I used HighCom only once, unfortunately under odd conditions which prevented it from being calibrated properly, so I hesitate to give an opinion about it. --best regards |
#3
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On 23 Jun 2005 20:16:44 -0700, "David Satz" wrote:
HighCom was designed by Telefunken in the late 1970s as the simplified, consumer counterpart to their "Telcom c4" professional noise reduction system. Telefunken and Aiwa sold outboard noise reduction processors using the HighCom system in its original form, and Telefunken also sold separate modules and ICs for this system. Nakamichi derived their own version which used the Telefunken ICs but divided the audio frequency range into two parts and used separate HighCom processors in each half. Recordings made with the Nakamichi version of HighCom are not compatible with the others. The system is considerably more powerful (reduces noise and print-through more effectively) than Dolby "B". If I recall correctly it is also somewhat more powerful than Dolby "C". Like those two systems it uses a recorded set-up tone which is used to set the gain in playback for more accurate tracking. While the system is more tolerant of playback gain errors than Dolby B or C, dbx is more tolerant than either of them, and numerically it does reduce noise more than the others--but dbx is highly problematic, or rather it tends to expose severe problems in the underlying media (tape modulation noise, for example). One could even say that it reduces noise too much for its own good. I was never able to use it for classical recording. And I used HighCom only once, unfortunately under odd conditions which prevented it from being calibrated properly, so I hesitate to give an opinion about it. --best regards -- I still have an Telefunken Studio 1M portable HiFi set (tuner, cassette recorder and amplifier all-in one with detachable 3-way speaker boxes, ca. 35 W/channel). It has the HighCom too. But I used it only once when I dubbed a tape on which I recorded two friend musicians at a beach restaurant patio to a cassette. It was long ago, in 1983 and I still have that cassette. I recorded the tape with 2 Uher dynamic microphones connected to an Uher Royal magnetophone {a better term than a tape recorder}, at 19 cm/s, 7 1/2 inch/s. The cassette is still very listenable today, although it's HighCom processed. At the Telefunken set, you have a switch which has, besides the High Com on, also a position for reproducing Dolby recorded tapes which uses a part of the HighCom to roughly match the Dolby B so when I today reproduce that particular cassette, I use Dolby B. Here I've found a Japanese page about servicing and obviously a total recapping of an Nakamichi High Com II where it can be seen 4 High Com ICs. This is what David said, the two frequency bands were processed separately and there must have been good results of such an approach but yes, they are incopatible to all but Nakamichi -- a drawback. This is what I can conclude of the images as ofcourse I can't do much with Japanese. http://www.kantama.com/annex/highcomII/highcomII.htm Edi Zubovic, Crikvenica, Croatia |
#4
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ACH wrote:
Can anyone tell me about the AKAI High()Com Noise Reduction used in AKAI Cassette Decks like the GX-F37? I think it's basically the consumer version of Telcom C4. How did it compare to dolby B, C and DBX? I never used it, and I never even used Telcom C4 to be honest. I heard Nakamichi also used High()Com Noise Reduction. Is it the same noise reduction? It should be the same, although given the vagueries of cassette alignment, it may be just like Dolby where no two machines ever have quite the same NR. Did Nakamichi or AKAI make it? Neither one, it was licensed from Telefunken. -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
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David Satz wrote:
Nakamichi derived their own version which used the Telefunken ICs but divided the audio frequency range into two parts and used separate HighCom processors in each half. Recordings made with the Nakamichi version of HighCom are not compatible with the others. I thought the Nak version was the standard way to implement the "home version" of C4, ie. that it was always a two-way compander. The system is considerably more powerful (reduces noise and print-through more effectively) than Dolby "B". Oh yes, it gives ferric casette tape the same dynamic range as 38 cm/s halftrack stereo. I recorded the LiveAid concert with HC2 and recently made it into mp3's, quite acceptable. I probably have the service manual somewhere, got it prior to replacing opamps in one of the two HCII's I have. When watching the adjustment tone on the meters it is quite obvious that casette tape dropouts do get exaggerated, I did make some radio recordings on 9.5 cm/s reel to reel using HCII, seems to be a better setup. Fairly precise tracking is required for a natural sound, and this includes internal adjustment of the unit, something that is "fairly easy" to do with a few standard lab instruments and the service manual. Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
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