Discussion in 'Audio Hardware' started by Cowboy Kim, Feb 3, 2017.
+5 from the 0 of output rcording.
I would expect you to have the definitive answer to that!
For me, I bring it up to just "tickle" the next LED segment, then back off a touch so there is no tickle. Pretty much what I would do with an analog meter.
I get it all the time.. as you can see even now...
Well that's what i was doing - and found out that's not how they work on my JVCs (as I started to suspect)! The distortion figure I gave for 0dB - actually at +1.8dB. The microprocessor-controlled display ensures you see levels with a peak hold feature if in the red.
In order to answer my own question, got out the oscilloscope (and had to do some math as the voltmeter measures peak-to-peak and not RMS). Compared oscilloscope to my RMS multimeter readings, matching.
The revelation here was how accurate the meters were (except for a strange anomaly between -8 and -10dBs levels) - like instrumentation grade. Clicking the signal generator 0.1dB at a time, one channel would light, then the other with another 0.1dB - and that was because the output was mismatched by 0.1dB indicated. They indicate the correct voltage at 100Hz or 1000Hz.
I have two of the same deck, and for most of the segments, the meters exactly matched between decks.
As soon as the 0VU segment illuminated, the reference voltage level 0f 0VU was achieved (at the probe, 0.2dB under what the manual indicates). The segment went from off to solid with a 0.1dB change (only the -30dB fluttered from noise). They do behave like a "clip" light: if they light up, you are there.
We can also confirm that the dB steps of the levels match the voltage reading when measured exactly when they first light up.
I have one and searched for it for a long time........like over 10 years long. I bought one from a German seller and he did a crappy packing job but it just got a little dent on one of the corners. Not even that noticeable really. It is the silver color and not the black like the picture. It really is a nice deck and a real ‘sleeper’, in that if you looked at it the thing looks like virtually every other deck produced during it’s time period.
If you do happen to find one try to make sure that the heads have low hours, or at least in good condition. The auto-azimuth function (and the auto-bias function) relies on the head block/heads to be in good condition for it to work right. If the heads are worn good luck finding a replacement. The auto-azimuth correction works great and is so fast that you don’t even hear it working. Just don’t use it though to make tapes for others, as I have read that this was a flaw for this deck. Only two heads also so there is no tape monitor function.
Here is a crappy picture of mine. I hope that I haven’t already responded to this thread. If so......sorry .
I know why they are out there. First hand knowledge in fact. I helped a guy last year in going through his friend’s estate, and his friend ran a music publication and radio show for years. So he was constantly reviewing new music. His house was literally crammed full of records, tapes, CD’s, stereo gear, from top to bottom. He had boxes and boxes of these Audiosource tapes......but only these two titles I think. There was also a Kenny Burrell tape on Audiosource and I already had that one previous.
I was able to find stuff in there that I had only heard about.......I was like a kid in a candy store let me tell you, and part of the agreement for helping was that I could have first crack at the stuff. I was not greedy, even though I could had really taken advantage but didn’t. I did get lots of pre-recorded audiophile cassettes that I had only heard about from small labels.
Anyway, those Audiosource tapes are top-rate. He also had tons of Audiosouce vinyl new in cartons. I suspect that he bought out their remaining stock at one point.
There was different deck I was after for a while with an auto azimuth recording feature. When I saw the head in close up.. forget it. I had an 80's akai that ran over 32 years with me. I changed the bleat on that probably 3-4 times and serviced it. Other than that, the head was super shiny and its not even an SA or anything special. I just used a specific tapes and mostly new blank TDK throughout the years..
Wow. That's cool. They are nice, so if you have any other titles spare, I'd love to try some more. Drop me a PM if you're willing.
I don’t have these, but I know that he is still off-loading these on EBay.
Wow that is a real sleeper. I think I like them in black the best. These are so rare now that when they do come up they are insanely priced $$$.
I'm glad to hear it's serving you well. I would love to use one to make digital archives of my prerecorded tapes that were made on other machines.
Perhaps the only decks that rival this one are the Tandbergs out there. Like the TCD 910/911.
It is a good machine but I am not going to lie to myself just because I own one. It does have very good specs but besides having the MAAC function, which is it’s real draw, it sounds indistinguishable from any of the nice HK decks in the “CD” range of cassette decks. It does have a nice ‘bright’ sound like the Harman Kardon’s, so it suits me just fine.
Those Harman Kardon’s are the real sleepers I have to say. Even the lowly CD191 can blow away decks that cost three times as much. Those decks never got the respect that they deserved.
I use to have a CD401 that I bought used and it was a great sounding deck. I sold it. Presently I still have a CD191 and it just needs belts and probably needs maintenance. I'm a bit hesitant to work on it because when I saw the construction of the inside, it was not really as solid as the nakamichi. Besides the metals frames are thinner, it wasn't anodized to benefit the protection of rust in long term. There were so many spots inside that rust and excessive oxides were building up. lets just say out of 20 nakamichi that I opened and worked on, I saw 1 that was beginning to build up but it was evidently neglected. If you guys have a formula how to maintain those HK deck from getting this early signs of cancer, share it.. Thanks,,,
You can get those HK decks for probably the same as a good overhaul of yours would cost. I never had any problem with them, but yes the lower range was a bit lighter and not as robust feeling as the others. Still, for what they are they are marvelous. I saw one on Craigslist a day or two ago, I think it was the CD391 or 401 for something like under $200. Could always even haggle the price down.
Very true and very good point. Its just what I saw and I'm not really familiar with the HK much but I do know any these decks HK or Naks are good in certain purpose and its all a matter of personal preference. Pretty much I have Nakamichi backup decks and parts that's probably why I didn't touch the other one much.
Okay so much for that. Time to go back to work again. Man cant believe not much people working during the holidays. But we all gotta do what we gotta do. Anyways it pays for the bills and at the same time I have time to talk to you guys while I'm on standby.
Take it easy.....
I would assume that would be obvious, but it does show how little the subsequent harmonics add. Going from 0.19 to 0.18% is hardly significant. Snd any deck will show great numbers at -10dB from Dolby level. That’s like quoting a cars miles per gallon while coasting downhill in 6th gear.
Dolby level THD is important because the tape is already not becoming artificially saturated by Dolby boosted HFs, and the tape is approaching its saturation curve. A +1.8dB zero will guve significantly higher THD readings since most tapes quality is speced at 3% distortion. A deck can easily already be at 1.5% THD @ +1.8dB. No one would use a decks meters to measure level at, since they are easily manipulated to read whatever you want. Many decks digital meters segments at 0db still have as much as 4dB threshold from first illumination to start of the next segment. That is why better decks have a zoom high resolution mode where each segment then becomes more like 0.2dB per segment at 0dB during calibration.
Classic Car Guy works at the Chum Bucket?? LOL.
Since when my boss left last saturday for a long holiday, all of a sudden it became a ghost town at my job... I couldn't even take off now even I put a vacation in advance way ahead than most employees...
I found my deck meters to be extremely accurate. With measurements of the line out (line out being connected directly to the meter amp and CPU with no adjustment possible) made by either the peak-to-peak voltmeter of my Tektronix oscilloscope, or the true RMS of my multimeter, any of the three segments that represent calibration levels go from off to fully illuminated with a 0.1dB step in signal generator, to achieve the expected voltage output on the line out jacks, at either 100Hz, 400Hz, or 1000Hz (didn't measure higher to find the frequency response of meters). The difference between .312 and .316 volts.
The manipulation possible is in not reading the meters correctly - misreading as I initially did to come up with my record calibration reference level. One might envision the digital segments of a meter as an analog to a needle VU meter, where you'd "fill up" the bar just until the next segment is all-but illuminated. Instead, the 0dB bar illuminates the moment 0dB output is achieved. An error would be to turn up the volume the 1.9dB more you can while still just 0dB is illuminated.
A zoom-in would certainly be useful, as it reduces the chance of misinterpretation. I wonder if other semi-auto "bias calibration" modes for decks with record bias and level knobs do indeed provide this zoom on the display for you. (next thing to find out for myself...)
The Harmon/Kardon a few pages back, a very early Dolby HX Pro deck, is one of the first and only I've seen with user-adjustable Dolby levels or an offer for the consumer to acquire a calibration tape. 1996 deck - there's no direct Dolby calibration even in the service manual (with an all-in-one IC that could be as precise as laser-trimming), only adjustment of ancillary levels that may affect its operation.
BTW, did re-measure 0VU THD: Spec: 0.7% 3H, measured: 0.59% metal. JVC TD-V711 improves the spec to 0.5%, but it's calibration levels also differ by 0.5dB (just as one has to dig very deep to find a Nakamichi 200nW/m cal tape is actually 183nW/m.) Notable is beyond that, Dolby noise reduction also is THD reduction for a large frequency range.
It would be great for capturing prerecorded tapes with a weird azimuth. One of the benefits I've heard of owning a deck like yours, is it fine tunes each tape to the perfect playback azimuth, revealing higher frequencies that most all other tape decks would miss. At least that was the selling point. It's nice to talk to an owner.
Yes the MAAC system works great. Every dedicated cassette user will know the frustration of playing old cassettes made on various decks, that sound like crap on their current deck. I made a quick video last night but didn’t know if it came out that well, so I didn’t post it. Here is another one showing the ‘MAAC’ in operation, and the one that I did. Mine is the second one.
After not using it for many a year I need to figure out how to get in there to clean the heads. It has this door that doesn’t allow clearance to the heads. I believe the last time the heads were cleaned is when it was serviced last. I am afraid to use my Allsop system as the little pads move back and forth and don’t want to damage the heads. And I can’t find a user manual.......anywhere!
Your search terms: "long clean room swab ESD". Like Texwipe TX761D. More expensive swabs can be pre-saturated with 91% IPA.
Most decks have a door cover that slides up and off. Examine with the door open to see how it separates and clips in place.
The deck has not just an on-the-fly playback azimuth adjustment of different tech than Nakamichi (which seems like it must have willingness to continually have small errors to operate), but also has CPU bias calibration. No thinking about it azimuth seems like exactly what you'd want if you aren't a perfectionist trying to transcribe the last 1% off a tape. It also calibrates two high-frequency EQs to add to the recording to tune up the sound, a peculiar arrangement -- when a good deck can record flat through those 7kHz and 15kHz frequencies.
Discussion here, with only one sayer of nay that it doesn't produce tapes that play well on other decks: Non-Nakamichi PB Auto-Azimuth Schemes? - Tapeheads Tape, Audio and Music Forums
Wow. That is a huge difference when you have it turned off.
One thing I know about these special R/P heads is how very fragile they are. I've talked with several owners who broke the piezo element by pushing the head too hard. Very gentle strokes.
I'm not sure if this diagram would help you. From the service manual.
Something that's a bit poignant, demonstrated when evaluating REW software for measuring tape decks (which it can barely be cajoled into doing correctly, because of the record-to-play head delay and lack of control over the sweeps and impulse window used) - the ratio of harmonics depends on how hard you are mashing the tape levels into compressive distortion.
0.6% - the H3 and THD almost overlap:
0.04% - 2nd and 3rd contribute in nearly equal amounts:
The "source" loopback distortion floor from the deck instead is mostly 2nd harmonic.
Thanks for posting this. Boy, that seems like a lot of work just to clean the heads. I am wondering if just removing that little facade panel thing on the front and then the 1 & 2 screw will allow me access to the heads? There seems to be another piece involved......I believe that in normal use when door is closed it is pressed up in the back of the cassette compartment behind the take up reels. Not sure. But that is what is blocking access to the heads when the door is open as it moves in conjunction with the door.
I did look at it and noticed that you can’t lift up and remove the door cover manually like you can with some decks. My Yamaha deck has this ‘feature.’ Good thing that I didn’t yank on it before giving it a once over or I could had damaged it. I might just buy one of those cleaning tapes and find one that is not abrasive. I probably have a few or more around already.
Thanks again for posting this.
Hey, another Portland taper! I am from the area and grew up in NE PDX. I am currently in the burbs now after 50 years of “city” life. Of course Portland is more like a large town.........hence the quotes .
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