![]() ![]() But to put things into perspective, you may not notice this issue if you are concentrating on the music. If you're listening to sustained piano notes or decaying bell sounds, you may hear flutter at the high-speed switch setting and wow at the low-speed switch setting, regardless of whether the capstan adapter is used. If you are a listener who is particularly sensitive to speed instability, the wow & flutter of the M-8 and X-150D may bother you, hence the 7-out-of-10 rating. In practice, what this would mean is that if you were to listen at very loud volumes, the M-8 and X-150D's recordings would have more noticeable hiss during quiet passages in music. It is the difference in the high-end playback equalization electronics and the tapes of different eras that account for the difference in signal-to-noise ratio specs. ![]() The boosted high-end is well-documented in a technical article in one of the major American audio magazines. I have to emphasize here that this has nothing to do with whether NAB equalization was used (it is). If you play a recording from these decks on a deck of a later era, including the Tandberg 3500X or the Akai GX-747 (or its dbx variant), the high-end will sound somewhat muffled in comparison. Both these machines are factory biased for a lower bias Scotch 150 and Scotch 111 (very similar), which were good for its time but is lacking in high-end headroom so the machines (like others of its era) include an exciter via a capacitor to boost the high-end (at least at 3-3/4IPS and 1-7/8IPS). Where the M-8 and X-150D differ from the rest is in its inherent playback equalization due to the era that these two decks originated from. These are qualities that are shared by the Tandberg 3500X, which also has the Cross-Field head design but the Tandberg is a 3-head monitoring deck (not counting the fourth Cross-Field head) so it has a slight edge in frequency response performance. The 1-7/8 IPS is good for the open-reel format but it's high-end is definitely audibly rolled-off. Presumably, this is due to the Cross-Field head design. The lower of the two speeds audibly retain nearly all the extended high-end of sources that are demanding on the high-treble. Although the M-8 has a built-in tube amplifier and speakers instead of the transistor deck (speakerless) design of the X-150D, both machines are capable of subjectively wide and flat frequency response at 3-3/4 IPS and 7-1/2 IPS. The sound quality of the M-8 and the X-150D are quite similar. Having owned Akai M-8, GX-747dbx (still have this one) and Tandberg 3500X open-reel decks, I believe those are good references to compare to the X-150D despite the differences in era between the last two and the X-150D. ![]() Semiconductors: 11 x silicon transistors, 2 x diodes, 2 x rectifiers Heads: 1 x record/playback, 1 x erase, 1 x biasįrequency response: 30Hz to 23kHz (7 1⁄ 2 ips) Track system: 4-track, 2-channel, stereo/monaural system ![]() This allows the recorded signal to remain on the tape with high fidelity. These two heads are located in different positions, as determined inter-relatively, so that the magnetic field of the bias will not affect the signal recorded on the tape, even when sufficient bias is applied. In the cross-field system, the signal current is applied to the recording head while the bias current is applied to the bias head. This phenomenon is particularly noticeable at high frequencies. That is, the wide magnetic field of the bias current affects the recorded signal, resulting in weakening or even erasing the signal. However, the bias current providing such an advantage also has an undesirable character. It is well known that the purpose of bias current is to record, at high sensitivity, a signal applied on the tape, with little distortion and minimizing noise generation. In the typical recording system, the signal current and the bias current are combined together and applied to the recording head. What is superior about cross-field recording? How does it differ from typical recording methods as far as construction is concerned? Using this cross-field head, Akai model X-150D provides a surprising recording performance of 30-23,000 cps at a tape speed of 7-1/2 ips, 30-18,000 cps at 3-3/4 ips and 30 to 9,000 cps at 1-7/8 ips. The cross-field head created a sensation in the tape recorder market by making possible a wide range recording never before heard on any conventional tape recorder. ![]()
0 Comments
Leave a Reply. |