What is the advantage of recording cassettes at higher speed?

[IronWine]

So i got into analog recording in the past few months..i'm slowly learning it while doing my bachelor of sound engineering.

I'm using both the tascam 234L and the akai mg614. Both are amazing pieces of gear.

A question came in my mind while i was testing the sound of my recordings at different speeds (1 7/8, 3 3/4), which i have noticed that has a limited effect on sound "quality" to my ears. I read that it should have an affect on higher freqs and general fidelity.

Considering the fact, or my desire, of eventually realeasing music on cassettes(with a digital pack tho), these realeses would obiously be of normal speed cassettes for normal tape decks...then..what is the purpose of initially record music at double speed? The music will eventually end up at normal speed sometime in the mixing proccess.

If the music is being transfered to digital i would assume that there is an advantage for the higher speed taping. But for the "80'-90' " mindset..times when music was consumed vastly on cassettes, and all-analog recording proccess was somewhat common, what was the notion behind marketing double speed fourtracks? Pure marketing purposes only maybe?

Cheers this forum is a gem for me! And for all analog lovers.

 

[pdmillar]

As the tape speed is doubled, there is a drastic reduction in hiss (part of it is down to the rec/repro EQ that must be used to maintain a decent freq response, and part of it is just the nature of the medium itself), and the amount of available high-frequency headroom is increased. This is very noticeable when trying to record things like cymbals and sibilant vocals at a high level. In addition, the reproduced signal is much "cleaner" - less modulation noise/asperity, because the same signal is physically represented by twice the number of magnetized particles (the best analogy for this would probably be the coarseness of the grain you see on 8mm vs 16mm vs 35mm film - the sound has a higher resolution, but not in the rigidly-quantized digital sense)

EDIT: Try recording/playing back something like a pure 400hz sine osc (with the NR turned off) at 1.875 and then at 3.75 - you'll probably note a difference in the noisy fuzz audible around the tone - this can be pretty upsetting to hear, but on actual music sources, as opposed to sinewaves, it's one of the reasons tape sounds so good

Even if you're going to end up on a medium like a standard stereo cassette, the quality of the master you use for that still makes a pretty big difference - things get nasty fast if you go more than maybe one generation down at 1.875ips, unless you happen to like that kind of sound [I think it's a far less offensive sound than stuff that's been corrected to death in Protools!)

 

[sweetbeats]

Good information there.

Consider too that on a 4-track you might be doing a lot of bouncing/collapsing of tracks during the process and any noise issues and frequency degradation issues will be compounded. The higher tape speed becomes pretty important pretty quickly.

 

[garww]

I didn't mess with 4-track, 4-channel cassettes, but 3 3/4 is from when cassettes needed all the help they could get. Part of that is signal to noise and there also may be some shift of the frequency curve that you can use - one way or the other. If you can get another front end on those, see if that helps

 

[ecc83]

The output voltage of a tape head depends upon the rate of change of flux across the head gap. Thus if you double the tape speed you double the signal voltage, i.e. an extra 6dB. Unfortunately noise increases as well (NSTAAfree lunch!) but, because it is random, not "correlated" the increase is only 3dB. You therefore get a net 3dB improvement in S/N.

Things are a little better than that because the wavelength across the head is halved for any given frequency so HF recording is improved and you need less top end pre emphasis. MOL gets better as well.

As to "why double speed when the end result must be standard speed?" Copying a tape means a compromise between noise and headroom. The better the original, the better the copy.

Dave.

 

[garww]

Part and parcel of the high-speed duplicating service. Tape Project uses the old Half-Speed re-mastering