Clone cassettes: a curious story
While I was in travel for a work, I could take a walk and see some old electronic stores that still survive since the 80s and 90s. Luckily I could find some brand new, SONY sealed cassettes there… but I didn’t figure out what did I really bought until later…
Then I came home with my trophies and took some photographs of them. Luckily I got 3 sealed cassettes, so I thought I could open one of them and do some tests with it. I was very curious about the sound quality of a cassette from the early 70s. My surprise came when I open one and I saw many signs of low quality… how could a brand like SONY make those mistakes?
Suddenly I realized that was not an original SONY cassette, especially when I put it into my K909ES: the quality was horrible. Truly horrible, the worst cassette that I’ve ever tried, by far. Not only the hiss was high, but the output level (MOL) was very (and I mean VERY) low and there were also other issues. Then I remembered that in those years there were clone cassettes, not very easy to find in some places, but yet not that uncommon.
Without knowing it I bought my first clone tapes! Some time later I got a few more used tapes and there came some SONY from that era, so I thought I would be nice to make a comparison between them.
In the photo above there can be seen a few differences between them that I think correspond to the real designs. I mean: the green one (clone) must be probably identical to the original. The real difference between the original one is probably the lack of alignment between the printing plates. If you look closer, you’ll see some misalignment between the red and black ink in some places. But the original one is perfectly aligned.
But things get more interesting when I start to analyze the sound. While the original one (I didn’t open the orange one, I used another already used one) sounds ok (pretty good for such an old tape) the clone sounds more like a piece of magnetic junk. I love cassette designs from early years. The look very opaque with that small window. SONY had some nice designs that I really love, like these ones:
I tried to calibrate the original one and I had to push the Rec Cal a bit (not very much, though) and lower the bias a lot, almost 90º counter clockwise. Then it sounded pretty good. It had not a very high resolution and not a very low noise cassette, but it still was OK.
But when trying to calibrate the clone, I had to push the Rec Cal level to the maximum and… it still was way low! Then I had to under bias it as much as to the lower possible setting. I never remember to had to underbias to the minimum and set the rec cal to the maximum. That clearly indicates that:
- Having to set the Rec Cal to the max means that tape sensitivity is very low. As a general rule of thumb, the best tapes are the ones that matches the input and output signal level, thus needing no record calibration correction.
- To under bias as low as that means that the tape is a very very basic ferric. In fact, the less needing bias tape I’ve ever seen. As a general rule of thumb, the more bias a tape need, the better it is.
I decided to take some measurements with the oscilloscope both to the clone and to the original one, in my K909ES. Here’s the response at -20dB, which usually gets very flat with almost all tapes:
As a reference, here’s the response of the original cassette with same conditions:
As you can see, the original one is pretty flat until almost 18 kHz while the clone starts to fall off at 3 kHz for up to 4 dB until 18 kHz. And that’s with the minimum bias!
Then if I compare the difference between the 0dB level and the background noise, it can be seen this:
And the difference between the maximum and minimum level is only 32 dB! As a reference, a good chrome tape has about 58 dB, which is 250 times lower!
The original SONY tape had this measure:
Where we can see 35 dB, which is two times the dynamic range and also the background hiss is half the level of the clone. I haven’t measured the distortion of both them but there’s a big difference for sure and I can clearly hear it. Finally, here are some sound samples. I have used a Maxell XL-IIS recorded in my SONY K909ES using the original release CD as source, encoded with dbx. I recorded onto the clone tape both without NR and with dbx, calibrating to my best (as previously described).
As you will hear, there’s a very low frequency level oscillation (around 10 seconds/cicle) that makes the music go high and low for about 4-5 dB! I have never heard something like that, but there it is… As a reference, there’s the same recording made on the original one.
Source (from CD with dbx)
Final note: after only 10 minutes recording, this is how the rollers on my K909ES looked like. I had cleaned them before putting it and, obviously, immediately after seeing this…