The greatest consumer cassette tape deck ever produced?*

Discussion in 'Audio Hardware' started by Cowboy Kim, Feb 3, 2017.

  1. Classic Car Guy

    Classic Car Guy Forget Scientific & Enjoy the Music

    Location:
    Northwest, USA
    No word yet. Worried....
     
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  2. sunspot42

    sunspot42 Forum Resident

    Location:
    San Francisco
    He hasn't been seen here since late July...
     
  3. perryinva

    perryinva Forum Resident

    Location:
    Richmond, VA, USA
    I guess I don’t know what harbys last post was trying to prove. Was he actually trying to prove that a $360 cassette deck from 1996 can achieve 0.07% ish THD on tape?? Or that, as he said, that say a Nakamichi CR-7 is not a contender because it doesn’t have HXPro, and these amazing numbers prove it? Both are ludicrous. I guess I will have to run out and get me a V662, and see just how great it is compared to a good Nak. I will say it once and let it lie, unlike him, apparently, I have had and still own, many of the top rated non Nakamichi decks, with HXPro, and Dyneq and Actilinear. I own virtually all Nakamichi decks made, and have put hundreds through their paces. There are PLENTY of potential problems with them, that can require more money & time that most will not spend on a “dead” format. The later BPC decks, being newer and simpler are sometimes more reliable. But not one has been close in THD to a good 3 head Nak, regardless of his exercise in A/D manipulation. I measure them all. All the time. No sound card or computer conversions. Plug the deck right in to one of 4 T-100s I own and serviced, and read THD @ 0dB@400Hz directly. After a full service. Per channel. If I ever find a deck that beats a Nak in THD, I will post it and eat crow. But so far, Revox, Tandberg, Sony, NAD and Yamaha, all with HXPro or other have not made the mark. Spectacular (for cassette) sounding decks, all rated very high or at the top. And none of the other techs I know that also service multiple makes, have found one either.

    I will never state that Nakamichi is the be all and end all of cassette decks. I will simply state what I measure and find. There is no doubt that HXPro aids a mediocre deck in sounding & measuring better with a mediocre tape. Absolutely. But to actually think that it is the magic bullet that brings superior non HXPro decks to their knees is completely & utterly false.
     
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  4. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    You wrote, "I’ve recorded THD as low as 0.2% with a Nak. Show me a deck that uses HXPro and can meet what Nakamichi already did."

    I answered.

    Cursed digital technology "manipulation", sensitive enough that I have to move around a 6' RCA to get the lowest loopback reading with 48kHz bandwidth. At -12dBFS:

    [​IMG]

    Your Nakamichi meter-reader has the advantage that it is measuring at 400Hz instead of the 1kHz where distortion is typically taken. Also the advantage that it will just be measuring the third harmonic's level instead of summing all the harmonics like digital analysis. The disadvantage, though, that the 1200Hz discrimination notch is not going to be as selective as digital FFT windowing, letting more noise through to be considered "distortion". One can't make comparisons, even knowing that Nak's 0VU is at 184nWb/M on 70uS instead of 200.
     
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  5. perryinva

    perryinva Forum Resident

    Location:
    Richmond, VA, USA
    But you didn’t. You showed me your version of THD for one deck. Sh0w me a 3 head Nak like a CR-4 or CR-7 calibrated for the same tape, on your same set up and what kind of THD readings it provides and then there can be some discussion. Or it is probably easier for me to buy a comparable JVC. MUCH cheaper to find and compare it on my set up which matches the test typically used in CASSETTE deck THD specifications.
     
  6. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    Four people trying to eBay their Nakamichi CR7A for $1000+, and several sold. Nobody's selling their TD-V662 on eBay, US Audio Mart, Tapeheads forum, or even Canuck Audio Mart. No results on national Craigslist search; only one in eBay's "sold" history - Germany. So doesn't seem easier to buy.

    There's a TD-V661 that just went up, though, silvery face instead of black, amber display, but should have about the same specs. TD-V711 is also nice but the unfortunate amber.

    Closed loop dual capstan, but you have to pull out the felt pad yourself if you think it will make a difference.
     
  7. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    I figured a way we can not buy any more tape decks - digital technology. I can share my recordings of 400Hz (precisely 398.4375Hz to align with FFT bins), and you can play them to your meter with a good DAC and see what you get!


    First we can verify your meter. Something Nakamichi doesn't offer (but I do) is calibration tones with distortion, both to see the indicated level, and to see the analog limitations.

    Here's four computer-generated calibration tones (400Hz/-12dBFS/96kHz/24bit), each 15 seconds long: distortion-cal.flac (4MB)

    1. 00s-15s: (L: 0.2% THD, R: 0.5% THD) - 3rd harmonic distortion (not "total" harmonic distortion)
    2. 16s-31s: (L: 0.2% THD, R: 0.5% THD) - 2nd, 3rd, 4th, 5th harmonic distortion (will you measure a correct 0.5%, or just half that?)
    3. 32s-47s: (L: 0.2% THD, R: 0.5% THD) - 3rd harmonic, but I added -50dB lower background noise around it (will you measure 0.5%, or much higher?)
    4. 48s-63s: (0.00000% THD, 0.0000% THD+N, measured with digital loopback) - pure tone

    Here's what the first three look like, with their results:

    [​IMG]


    If you are happy that your meters are happy, then we get to what my deck produces. 0VU indicated at 250nW/m (perhaps not calibrated output with this Metal SR). Recordings were made one channel only (left) on the JVC TD-V662 after bias knob tweaking using the better resolution of computer analysis, then channels copied to stereo results. Dolby C/HX Pro.

    Recording 1: distortion-20db-9.4db.flac (9.5MB, 30s)
    - left: -20dB (-20dBFS playback) -- 0.07% THD
    - right: -9.4dB (I was aiming to find actual 0.2% distortion point, but missed) -- 0.19% THD

    [​IMG]

    Recording 2: distortion-0VU-3.8dB.flac (8.8MB, 30s)
    - left: 0VU/0dB (-20dBFS playback)
    - right: +3.8dB (finding the 3% THD point, perhaps not the way tape manufacturers used 3rd-harmonic-only to specify 3% THD..)

    [​IMG]


    And so we know I didn't use any tricks, like having poor frequency response, bad Dolby tracking, or monkeying with the bias: stereo response sweeps at -0dB, -10dB, -20dB, -30dB (the Sony Metal SR maybe is the source of the 18kHz hump?):

    [​IMG]

    Let me know what you think. Distortion-chasing is somewhat pointless as it is obliterated by unweighted tape noise when doing modern THD+N measurements.
     
    Last edited: Nov 19, 2021
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  8. jusbe

    jusbe Modern Melomaniac

    Location:
    Auckland, NZ.
    I guess you find nice Nakamichis on eBay because there is a known market for them. Less so the JVC. Wouldn't suggest there's causality between the prevalence and quality of the deck at hand. But it's usually not completely uncorrelated.

    Great analysis, Harby. Thank you.

    Will I give up my Nakamichi ZX-7 or Tandberg TCD 440-A any time soon? Nope.
     
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  9. perryinva

    perryinva Forum Resident

    Location:
    Richmond, VA, USA
    I’m not distortion chasing. I am simply trying to find out where your claims of HXPro equipped decks being superior to Nakamichi decks comes from. Now, I don’t understand what happened to your numbers. No one cares about THD @-20dB. It is not even remotely stressing the tape, and any HXPro effect would be quite minor.

    Now you are showing 1.4% THD @0dB, and you say 0dB is at 250nW/m? That is for RTR, all cassettes use 0dB@200nW/m, to set Dolby level@400Hz. 1.4% THD @400Hz @0dB on a Sony SR is poor. We must be talking apples and qumquats, because I apologize, I’m having difficulty understanding your point.

    I will express interest in your FR sweeps. Those are playback of prerecorded sweeps, or record & playback? I don’t understand how the 0db sweep with no NR, can be a rising level to 18kHz like that. No cassette deck I have ever serviced has ever shown that kind of response from -30 through 0dB even with TypeIV. (And Sony SR is not a particularly good TypeIV either). Because the -20dB has such an exaggerated rising response, I will say that bias is incorrectly set; -20dB should be much flatter. That much bias would cause Dolby mistracking. The drop after 18kHz looks like the decks heads inability to deliver at that level.
     
    Last edited: Nov 21, 2021
  10. perryinva

    perryinva Forum Resident

    Location:
    Richmond, VA, USA
    Also, while the older JVC 700 cassette decks tends to get decent reviews, even casual surfing about the V661 & later V662 have turned up transport issues and aging problems, not atypical for the BPC era of light weight decks. Fragile gears that don’t age well, poor supply & capstan flywheel alignments, and a lack of back tension on the gear driven reel supply hub all contributed to tape path problems, on multiple posts. Unlike the more common Sankyo based DD/slaved dual capstan design, used by many manufacturers, the flywheels on the JVCs are lighter and thinner, and the overall transport, fairly flimsy.
     
  11. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    I just plugged in my deck to see if your THD statement was realistic, and found it was up to -9dB - using true broadband measurement. You didn't say at what frequency or at what level you measured your 0.2%. We have to even look up a model number you mentioned to see it is a Nakamichi distortion meter.

    The JVC service manual is what states the 0dB indicator is 250nW/m (I misremembered 0VU is not 0dB). Other levels are 0VU (160nWb/m) and Dolby standard level (the display bar between them). The JVC calibration tapes are oddly at 1kHz.

    [​IMG]

    The deck's specification for harmonic distortion: Type IV tape, 315Hz, 0 VU: 0.7% @ k3 (third harmonic). I could verify this, but why should I bother.
    Interestingly, at +6dB (-2dBu voltage output), normal tape is spec'd 2% max but chrome/metal is 3%.

    The frequency response measurement shown is a sweep played live through 3-head monitoring, with the power level summed. At 0dB, it was about 40 seconds, but for lower levels I made it shorter by omitting low frequencies, as the tape noise power was also adding to measurement (and maybe still did). Bias could have been set wrong, I've changed the knobs since, but it seems rather that any Dolby engagement at any level adds about 1dB of HF to a record+play. The tape is a Goodwill find that had somebody jamming on their electric guitar that needed to be erased.

    The better response method would be a sweep with a voltage level recorder, but I've found tape an annoyance with this exercise, with high frequency levels bouncing up and down quickly and also differing throughout the tape, makes for a jagged graph, needing many sweeps averaged.

    Best would be tone generator of limited tones and longer level analysis, like below. One must be mindful of self-bias and the goal of measurement when running more than one tone (for example to emulate the deck's calibration where it plays -20dB 1kHz into one channel and 10kHz into the other; with a computer I can match those levels better than the meter and on the same channel).

    [​IMG]

    Bias is "calibrated" with 1kHz and 10kHz independently reproduced at the same level, but 10kHz drops a bit when reproduced simultaneously with others. Understand these levels are bouncing up and down almost 1dB when monitored with fast response, because tapes suck, so an average like above includes the worst with the best. This is my "monkey-with" deck for getting the most out of tapes, while I have another without a screw touched.

    I was going to say that I haven't had one of my tape decks hooked up in two years, but when I look at the head-drop file dates, it's more like six.
     
    Last edited: Nov 22, 2021
  12. MassHysteria

    MassHysteria Music Lover

    Location:
    Minnesota
    Awesome mention of the dark crystal! My favorite movie. Would be awesome to find that nowadays, but I do believe they did a great job with the 4k transfer.
     
  13. BrettyD

    BrettyD Senior Member

    Location:
    New Zealand
    I'm aware my CR-7, being around 30 yrs old, needs regular servicing. Can anybody enlighten me on what becomes "unfixable" when the servicing doesn't occur?
     
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  14. brockgaw

    brockgaw Forum Resident

    Walk this way.
     
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  15. Classic Car Guy

    Classic Car Guy Forget Scientific & Enjoy the Music

    Location:
    Northwest, USA
    You wanna ask @perryinva . He's got so much experience with Nakamichi especially the hi-ends. Pretty sure he can help you in all aspects.

    There you go...:-plnktn-:
     
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  16. Chris Schoen

    Chris Schoen Rock 'n Roll !!!

    Location:
    Maryland, U.S.A.
    Once they developed good tape formula (TDK-SAX, Maxell XLIIS) there really was no need for any kind of "noise reduction"
    because the better tape formula meant there was so little tape noise, it was not worth dicking around with Dolby "type whatever"...
    AND, you could confidently play the (non-Dolby futzed) tape in any other tape deck. Two good reasons right there...
    Dolby never did anything to improve my listening experience. One thing I always did though: spend the cheddar for top quality
    tape. If the music is worth it, then get the best tape available, and set your record levels as high as you can, short of distortion.
     
  17. Classic Car Guy

    Classic Car Guy Forget Scientific & Enjoy the Music

    Location:
    Northwest, USA
    I'm gonna have to insert this posting for those cassette deck guys newsflash.
    I just got this one today and I have no idea when it came or how long is it on my other mail box. For it might be in moist. Anyways trying to thaw/dry it naturally so I can do a trial demo. This is NAC's (National Audio Company) latest 799 Studio Master type II cobalt cassette tape that is replacing the old version of their type chrome version for environmental reasons. I am very excited to try this new tape possibly in 2 days from now till I feel like its dry enough. I have very strong faith with them since I been using their old type I cassette and been very happy throughout the years.
    I don't wanna excite myself too much for I was looking at the texture and that's a lot of spool for a 60 minute tape so we'll see,,

    [​IMG][​IMG]
    [​IMG]

    [​IMG]

    2021 799 Studio Master 60 Minute Type II Cobalt Packaged Cassettes
    799 Studio Master 60 minute tapes, imprinted and packaged in boxes of 10.

    • NAC’s highest quality mastering cassette
    • Smooth-running cassette housing
    • Imprinted tape and traditional J-card
    • Clear Norelco-style box
    • Individually cello-wrapped with tear strip
    • Packed in protective 10-pack box
    • 10-pack box shrink-wrapped to prevent contamination.
    Requires recording equipment with a high bias setting.
    SKU: C799-C060PB
    Categories: Audio Cassette Tapes, C756 Cobalt Cassettes Type II

    Featuring genuine high bias cobalt mastering tape. For the most demanding recording applications, Studio Master sets the gold standard in Type II performance. Cobalt oxide combines outstanding output and low distortion providing unmatched musical clarity. This high bias tape delivers up to 4db more output than earlier Type II tapes without saturation or distortion.
    Specification is for +2 db over biasing at 6.3 kHz. 20 db below reference level.
    Record Equalization — For optimum performance, record equalization should be set after biasing as the oxide in this tape responds somewhat differently due to its high performance characteristics. Sold in Cartons of 10.
    The length of the tape refers to the full recordable time on both sides of the tape. A C-60 cassette has 30 minutes of recording time on each side.
    Note: National Audio’s Cobalt Type II tape, manufactured in Springfield, MO, has replaced chrome in our packaged 799 Studio Master cassettes because chrome tape can no longer be made because of environmental reasons.
     
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  18. jusbe

    jusbe Modern Melomaniac

    Location:
    Auckland, NZ.
    You're in Aotearoa, like me. You have one of the few decks that GennLab in Wellington will look at. He won't mess with lower end decks but he services high end stuff.

    Given his good standing in the international Tapeheads community, I'd highly recommend calling Gennady for a chat about what to do with you excellent deck.

    Aroha.
     
  19. sunspot42

    sunspot42 Forum Resident

    Location:
    San Francisco
    This depends on the kind of music you're listening to. For rock, maybe. For classical and a lot of jazz? Even metal tape still has audible hiss in most decks, until you reach ear-bleed priced 3-head decks from the likes of Nakamichi.
     
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  20. Chris Schoen

    Chris Schoen Rock 'n Roll !!!

    Location:
    Maryland, U.S.A.
    I have a Denon 3-head (late 80's DRS-810) and it makes nice recordings. I use it for AAA vinyl that I wish to listen
    to (AAAA?) without flipping sides. Luckily, I bought a few cases of good tape 15 years ago, and use it judiciously.
     
  21. perryinva

    perryinva Forum Resident

    Location:
    Richmond, VA, USA
    Gennady is excellent, and the only Nak tech I know in New Zealand. We have communicated a few times, and he is selective of the decks he services, as am I. He makes good calibration tapes, too. There is really nothing that will be unfixable if the deck is not serviced, that servicing will prevent. All Sankyo based transport models basically suffer from the same things: if tire driven, the tire is thin & small and hardens & slips sooner rather than later. All have the propensity for dead spot motors in the mode motor and reel motor. The best preventive for this is to use the deck regularly, at least 2-3 times a week. Once they dead spot, the motors have to be replaced, which means transport removal and obtaining the correct repairs motors which can be difficult. All need belt replacements eventually, especially the back tension belt, the original of which gets gooey and makes a mess if let go too long. Bad back tension eats tapes.

    Of course, the bearings should be lubricated regularly (every few years) to prevent wallowing and wear.

    All my THD measurements mentioned in this thread have already been referenced as 400Hz as shown on multiple Nakamichi T-100 audio analyzers. I own 4, all calibrated and used regularly when I service gear. I also own a Magura Distortion Analyzer that is both 400 & 1000Hz based, but it always agrees with my T-100s and is huge in comparison so it is on a shelf in mu garage. Absolute values in distortion are of little value. What is important is the comparison of different gear, or repaired gear before & after, on the same analyzer.
     
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  22. perryinva

    perryinva Forum Resident

    Location:
    Richmond, VA, USA
    Perhaps I should also mention that THD on a T-100 is specifically just 3rd harmonic level as relative to the primary frequency (400Hz in this case), which, during the cassette era, was the normally used standard when expressing THD for any tape. In fact, for a long time in the 70’s & ‘80’s, I assumed THD stood for Third Harmonic Distortion. Today THD can be a more complex combination of many odd harmonics.
     
  23. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    ...and therefore those who digitally measure 0.19% THD on their cassette deck at -9.4dB will discover even lower distortion reported when all but the fundamental and 3rd harmonic is removed from the same signal (to replicate the notch filter of an analog distortion meter):

    [​IMG]

    Even harmonics will also be measured. Odd harmonics are of more interest: the product of dynamic waveform compression such as from mismatch of head record signal and tape hysteresis (up to a square wave, which is synthesized of all odd harmonics in equal amounts).
     
    Last edited: Dec 3, 2021
  24. Classic Car Guy

    Classic Car Guy Forget Scientific & Enjoy the Music

    Location:
    Northwest, USA
    Hi,
    Follow-up on the 2021 Type II NAC Studio Master tape.
    I was able to put it on the recorder 2 days ago to run the 1 hour album. It got cut off on the third song. I forgot and even mentioned to another member that my BX-300 shut down a few days ago. So I'm gonna pull out the other BX-300 tonight and record it again. But so far on the playback of the 3 songs easily sounds better than my old NAC recordings. But in all fairness the tape on the left side is recent copy of a "Type I" only which sounds the same from my very first one I recorded in the same NAC tape close to 10 years ago.
    Anyways I just did a quick video on the just using an iphone. What I can say is this tape "sounds" way better than the type I collection I made. Of course besides the New NAC type II, I'm gonna try recording another Type II which is a Fuji DR II and compare it side by side. But as you can hear in the video even its maxed out to 5db, its very clear with a bit of warmth and excellent bass dynamics. But after the recording, the true test is yet to come and how long will the quality last after so many playbacks.
    PS. Very curious about the spool thickness. The other one is a 90 minutes comparing to the new NAC.



    [​IMG]
     
    Last edited: Dec 5, 2021
  25. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    Since this is the only thread tape lovers might be looking at, a question not worthy of a new thread..

    With digital level meters, do you consider 0dB to be when the 0dB segment has just barely lit enough to become solid, or when you turn up the level perhaps 2dB more to just be tickling the next segment? The latter is how I "calibrated" my testing output, but it seems that could be too hot.

    Wonder if any service manuals address this. With a digital "clip" light, at least you have an absolute answer. Otherwise, perhaps some experimentation would be required to see how other segments of different dB intervals respond in comparison.
     

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