Cassette and RTR Recording Speeds

As attractive as 3 3/4 ips on cassette might seem, the deck selection is thin, no compatibility with other 'normal' machines, double tape cost, more trips to the machine to turn it over, and equalization is designed for 1 7/8ips. The quality gains for the faster speed are not as dramatic as one might think.

As others have suggested-use R2R for better quality, if that's what you are after.

1tumbleweed said:

15 ips is a fairly uncommon speed for R2R. It can be beneficial when doing live recording, but for copying from another source 7.5 is usually sufficient.

As for cassette, more or less the same thing applies. 1-7/8 is nearly universal for cassette, with Philips by and large controlling the format and refusing to allow faster speeds. The Tascam is one of the few exceptions. Again, it depends what you're recording - but faster almost always is better (but eats up twice as much tape).

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3 3/4 Ips faster speed on Cassette Decks is or was not that uncommon!Marantz SD Series had it as well as other Brands :thmbsp:

oldvinyldude said:

As attractive as 3 3/4 ips on cassette might seem, the deck selection is thin, no compatibility with other 'normal' machines, double tape cost, more trips to the machine to turn it over, and equalization is designed for 1 7/8ips. The quality gains for the faster speed are not as dramatic as one might think.

As others have suggested-use R2R for better quality, if that's what you are after.

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Not that dramatic is almost right but better even if slightly,is more accurate!Marantz did it I was told because they didn't want Dolby/DBX so they came up with a faster Speed hoping for some improvement on Tape Hiss and to be better sounding.HK had it also and a few others and as far as not many other Decks having it,who cares if I wanted it that's all that counted because quite frankly I had regular Speed 1 7/8 Ips Decks also as well as R2R

BOUXY said:

3 3/4 Ips faster speed on Cassette Decks is or was not that uncommon!Marantz SD Series had it as well as other Brands :thmbsp:

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A grand total of four; Dual, Tascam/Teac, BIC, Marantz. Pretty minor in the larger scheme of things.

Happy trails,
Larry B.

Chip Chester said:

When I needed to make staggered-track edits, add a 1/8" sliver to correct timing, or shave oxide to alter attacks, I was happy to be at 15ips. :thmbsp:
Chip

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I'm sure, but these are sophisticated techniques, met in musical production(and feature films too, but then it was not done on 1/4" anyway). If you need to do this sort of things, there is no doubt that 38 cm/s is a big help. For usual editing 19 cm/s is quite good enough and was used extensively in the good old days of analogue radio production, even for sophisticated post jobs.

oldvinyldude said:

and equalization is designed for 1 7/8ips. The quality gains for the faster speed are not as dramatic as one might think.

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EQ have more to do with the sound rather than some silly noise reduction. Anyways, faster speeds do increase resistance to dropouts, therefore protecting the tape from defects.

Not that I understand the technology very deeply, I know, by heart, that not only EQ but the three main allignments for tape formulation is influenced by tape speed.

• Equalization
• Bias
• Record Level

If you can change speed on a deck, you should also be able to adjust these allignments seperate for each speed, seperate for each channel and, apart from bias, also seperate for recording and for playback.

Ultralyd said:

Not that I understand the technology very deeply, I know, by heart, that not only EQ but the three main allignments for tape formulation is influenced by tape speed.

• Equalization
• Bias
• Record Level

If you can change speed on a deck, you should also be able to adjust these allignments seperate for each speed, seperate for each channel and, apart from bias, also seperate for recording and for playback.

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This is absoultely correct for Eq. and bias. The recording level OTOH is the same at all speeds in a given standard, ie. 0dB = 320nWb/m for CCIR, 185 for NAB, 257 for Revox, etc., so it is not normally useful to have a separate adjustment for each speed, and many decks don't have it. The reason for having one is that internal specificities of the machine can yield different gains for each speed seting - the difference is not large as a general rule, in the order of 1 dB, but some manufacturers prefer to give you full caibration capabilities to perfectly match the standard.

BOUXY said:

Not that dramatic is almost right but better even if slightly,is more accurate!Marantz did it I was told because they didn't want Dolby/DBX so they came up with a faster Speed hoping for some improvement on Tape Hiss and to be better sounding.HK had it also and a few others and as far as not many other Decks having it,who cares if I wanted it that's all that counted because quite frankly I had regular Speed 1 7/8 Ips Decks also as well as R2R

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For whatever reason, cassette at 3.75ips sounds like R2R at 7.5ips. Not only does hiss go down by 3-5dB, the frequency response extends to higher than the audible (at least by me) spectrum. And that's with any type of cassette, even low end Fe.

At high speed, combined with dbx and recording at moderate levels (e.g. peaks of -3dB) you get a frequency response and dynamic range that in most cases is better than the source.

Talk about compatibility (a 3.75ips cassette with dbx isn't perhaps popular outside my own house) and that's another story.

jlb2 said:

This is absoultely correct for Eq. and bias. The recording level OTOH is the same at all speeds in a given standard, ie. 0dB = 320nWb/m for CCIR, 185 for NAB, 257 for Revox, etc., so it is not normally useful to have a separate adjustment for each speed, and many decks don't have it. The reason for having one is that internal specificities of the machine can yield different gains for each speed seting - the difference is not large as a general rule, in the order of 1 dB, but some manufacturers prefer to give you full caibration capabilities to perfectly match the standard.

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As I said, I have not the deep understanding of the techniques behind this.

However, I do understand, from doing a billion allignments on my pro open reel decks, that record level and Bias continiously influence on each other and in fact has to set "as a ping-pong pair".
As such, it's fully understandable to see Record Level for each speed when Bias, in nature has to be set at each speed.

It is true that the bias level has a small influence on the level at 1 kHz. In fact a long outdated bias setting technique used on consumer decks used 400 Hz or 1 kHz instead of 10 kHz, for some reason I never figured out. That was remarkably unreliable since the main effect was not at the frequency used for the setting. Anyway, the current technique of setting bias at 10 kHz does not yield imbalance between channels at 1 kHz. It might possibly happen if the recording levels are grossly misadjusted in the first place, but not if you do things right.

OTOH it is not true that the recording level has a noticeable influence on the bias adjustment. Unless, of course, it is really, really way off adjustment - but then you would notice it immediately. It is good practice to check your adjustments to make sure you haven't missed anything, but it is nothing to do with an interdependence between bias and recording level adjustment, and especially not with an effect of the speed.

jlb2 said:

If you say so The main correction is that 7.5 is not a "consumer speed": many more professionals have used it than 15 ips. On the whole, not having 7.5 on a professional deck would be a major problem, since it would prevent you from playing virtually all the film and broadcast archives.

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With modern decks and tapes, using 7.5ips is of sufficient quality as well as better tape economy than 15ips. Later archivists used 7.5ips because of reasonable audio and saving of tapes.

Lapis said:

With modern decks and tapes, using 7.5ips is of sufficient quality as well as better tape economy than 15ips. Later archivists used 7.5ips because of reasonable audio and saving of tapes.

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It completely depends on what you want to archive, and what the copy is intended for.

Archivists always strive to keep the originals anyway, and keep them in controlled storage conditions to avoid degradation. For these, there is no question of choice: the format is the production format, the archivist must be able to play these tapes with their original speed, equalization and track layout.

Dub copies are made on a medium that is at least as good as the original to avoid quality loss, so it can be used to make consultation copies without having to play the original again - now it's all digital for quite a number of reasons, but back when it was done on analogue medium no sensible archivist would ever have made a dub copy of a LP master at 7.5 ips, it would be sort of like preserving 2001, a space odyssey on VHS. For radio stuff, yes it could possibly make sense.

Consultation copies don't need to be the same quality as the original: convenience and being able to play them on the consultation equipment. As long as the original and dub copies are preserved, you can do what you want. It is the only situation in which a systematic 7.5 ips copy really made sense.

Ok, I admit I am talking about the serious archivists here, LOC, INA, etc. I know there has always been a bunch of not-so-serious people doing just about anything. I won't take them as an example to follow

If you want to know what archivists really do, go to the ARSC web site, they have a lot of online literature re. good archiving practice.

When discussing the choice of tape speed, we should remember that there will be a choice of optimal head gap for each machine, based on the intended speed or speeds of the machine. A narrow gap permits higher frequency signals to be recorded for a given tape speed, but requires more bias signal and reduces high frequency headroom.

For a given machine and head gap, the lower speed will usually give slightly lesser HF performance and possibly slightly less total dynamic range, though at the gain of longer playing time. OTOH, a machine optimized for slower speeds may maintain full bandwidth, though probably not exhibit quite the dynamic range of a machine optimized for running at higher speeds.

Otto

It's true. But as you say the choice of the head gap is under the responsibility of the manufacturer of the deck, who specifies or manufactures the heads according to the available speeds, and usually aims for the best performances at the highest available speed. The user does not need to know the gap, the only information he needs is the overall performances of the deck and the bias level for his tape - which does depend on the gap width but cannot be guessed from it. Both are (or should be) given in the manuals of the deck. It all boils down to choosing the best deck for your needs and your budget, and adjusting it for your tape.