ef37a wrote: Elephone wrote:
cyrano.mac wrote:Ditch the EL3542...
Get something like a UHER if you want to experiment with tape. These have a removable tape carrier. And the heads are available too. New. Not cheap, but hey...
You can pick up a mono UHER for next to nothing. Replace belts. Again, available new. Not even expensive. Clean and lubricate. The chassis and capstan flywheel are built like a tank. And they're all exactly the same. Except for the electronics, but even these are interchangeable.
I'm amazed even the NOS tape carriers show up on evilbay quite often.
Why do they have a dedicated play head that you can use for realtime bouncing and delay?
Are you asking why some tape machines had a third replay head?
If so it was becuse the head construction and winding impedance is not the same for optimum record and replay duties. Replay heads typically had finer gaps and a higher impedance, more turns, giving greater output.
That said, I only recently found out that at least one major tape machine maker (Teac?) used the same head in both positions.
Spot on Dave. A repro head's gap length sets the upper frequency limit, or more correctly the upper wavelength limit, whereas from memory the recorded signal isn't so dependent, tending to appear at the trailing edge of the gap. The record head's coil tends to be lower impedance partly to allow practical record amplifiers which don't need ridiculously high voltage rails to avoid clipping. Whereas a repro head needs the somewhat higher impedance to allow a useably high enough signal to feed a practical preamplifier.
Also repro heads usually needed better magnetic shielding than record heads, even to the point of the front face of the head being shielded. A hinged flap often swung over the head's face when record or play was selected.
The third head also enabled "confidence" monitoring of the just recorded signal to confirm by ear that the recording was up to standard.
The third head also made aligning/calibrating of the tape machine to the tape so much faster than the equivalent 2 head machine, especially when aligning a multitrack machine with its many parameters to adjust.
Tape machines still need to be maintained but more of their use these days is playback of old recordings rather than recording new ones, so it's repro (playback) heads that are the more sought after. I haven't bought a record head for many years.
Yes at higher tape speeds, the same head type can be used for record and playback. One reason is that for audio at say 15ips the standard small gap length play head (say 1 micron) can resolve to well above the audible limit, say to 90 kHz, which for audio is of little benefit. So a wider gap, closer to the ideal record head gap, can be used. Very small gap length comes into its own where very short wavelengths need to be resolved such as slow tape speed formats (cassettes), or anywhere where the highest frequency must be recorded and resolved. I think video tape heads could have a gap length of 0.3 microns. Incredibly small.