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Question about Nakamichi's "Harmonic Time Alignment" technology

Discussion in 'General Audio Discussion' started by thurber, May 17, 2018.

  1. thurber

    thurber AK Subscriber Subscriber

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    I have brought my AV-8 up a lot on this board, so I probably sound like a broken record, but I had a question about HTA. I have not found a dac/amp combo that sounds as good as whatever is built into my Nakamichi AV-8 (within my very limited budget), though it's from after the glory days of Nakamichi (or maybe not?).

    I am thinking about using the AV-8 as a preamp, as it has pre-outs. I haven't gotten a good result yet trying this, but will try a few more times with different amps when I get the chance. I tried running it into a clean-running Adcom GFA-535, and it did not sound as good as the unit itself does alone.

    Here is the actual question: Is the HTA circuitry built into the processing portion of the receiver, or the amp section (or is that not the way to ask the question)? I had figured the former (that it was part of the DAC/DSP portion, and that the amp section was probably pretty simple and straightforward, and separate). The reason it's important to know is because I figure it is part of what's giving me the great sound, and so running it as a preamp doesn't really make sense if it bypasses the HTA.

    I have seen some Nakamichi HTA power amps which makes me think the HTA is built into the amp section, though that surprises me. Obviously this would then be a good choice of a power amp, though they're a little outside my budget at the moment.

    Anyway, curious to know if anyone knows anything, or is wont to speculate. Gracias.
     

     

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  2. JoeESP9

    JoeESP9 ESL's & tubes since 83

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    HTA seems to me like TBS (Total BS).:rolleyes:
     
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  3. DaveVoorhis

    DaveVoorhis Super Member

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    Manufacturers' marketing departments are fond of using fancy terms for negligible tweaks to conventional amplifier circuitry. E.g, "New Class A", "Natural Sound", "Wide Range Linear Circuit", "High Current Amplifier" and almost certainly, "Harmonic Time Alignment". Sometimes there's a distant technical basis for it -- like reduced negative feedback in some circuit, or more negative feedback in another, or whatever -- but mostly it's pure marketese and nothing more than branding.
     
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  4. thurber

    thurber AK Subscriber Subscriber

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    You guys should hear it before you judge (or maybe you have) - it really sounds nice and very unique from any other receiver i've heard. Anyway, my core question is really what circuit it's a part of, if that's possible to know. Reduced feedback IMO would be a highly desirable outcome - best as I can understand HTA actually does not reduce it but claims to make it somewhat uniform.
     
  5. DaveVoorhis

    DaveVoorhis Super Member

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    Many amplifiers sound great without HTA. However...

    An article by Peter Vis at https://www.petervis.com/Amplifiers/nakamichi-av-8/nakamichi-av-8.html states:

    "In the following pages of this multi-page article, you can see that this is a discrete-component power amplifier design, which according to Nakamichi, is far superior than IC power amplifiers. Consequently, the front and centre channels consist of 2SA1943 and 2SA5200 complimentary pair of power transistors manufactured by the Toshiba Corporation, and the rear channels consist of 2SA1962 and 2SC5242 complimentary pair. In addition, discrete transistors on the same circuit board, drive these power transistors, and since this Nakamichi design has to have additional transistors in each channel to provide the HTA functionality, it results in a very large beast of an amplifier with dimensions 430 mm × 140 mm × 370 mm and weight 14 kg." (Emphasis is mine.)
    Note that whilst this appears to suggest the "additional transistors" for HTA are on the same circuit board as the final amplifier circuitry, it could also be interpreted as only meaning that additional transistors are required somewhere for the HTA circuitry and that's why the unit is "a very large beast".

    The article also suggests that HTA is not particularly well-documented:

    "Apart from the Nakamichi designers, very few people actually know what HTA really is in terms of Physics and Electronics. The Brochure literature simply gleans over it stating that this unique approach to amplifier design maintains the correct timing relationship between the signal and its distortion components resulting in exceptional sonic definition, transparency, and the most natural untiring music reproduction."​

    Not much help, I'm afraid, and somewhat typical of manufacturer marketing puffery.
     
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  6. E-Stat

    E-Stat AK Subscriber Subscriber

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    There's info on Wikipedia here on the design.

    It appears "HTA" is just NAK-speak for using minimal corrective feedback consistently across the bandwidth. Good goal, but they could just call it like it is.
     
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  7. thurber

    thurber AK Subscriber Subscriber

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    .
     
    Last edited: May 17, 2018
  8. markn2wae

    markn2wae Mark T N2WAE

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    The "Wikipedia" link above shows someones stereo system "end up" with 1/2 half a cabinet showing? :)

    Mark T.:music:
     

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