Tape Dubbing Speed

Ron Resnick

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If an original master tape was recorded originally at 15ips and you wish to make a copy of this original master tape is there any sound quality advantage of any kind to recording the copy at 30ips (even though the reproducer you are dubbing from is spinning at 15ips)?
 

Tapetech

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Apr 10, 2014
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When making a dub, it helps to have a recorder that "out specs" the tape being copied. This way you will capture the entire dynamic range of the tape being copied (as in you won't add any noise or distortion to the playback tape)

So you have to determine the "specs" of the playback tape. What operating level is the playback tape? What brand/model of tape was it recorded on?

For example, if a 15ips play tape was recorded at a +3 operating level (0 VU = 250 nWb/m) on SM911 tape, then all you have to do is record with a better tape like SM900 and a slightly higher record level (+6 op level or 370 nWb/m). There would be no real need to record at a higher speed or a larger track size (like 1/2").

Now if the playback tape was recorded at 15 ips with SM900 or ATR tape at a +9 operating level (0VU = 520 nWb/m) then it would help if you recorded at a higher speed or a wider tape. That being said, if you dubbed that tape at 15 ips at +9 and SM911 tape, it would still sound quite good. It would just have a bit more distortion and noise than the original tape.

One disadvantage of recording at 30 ips is that the bass response can be less extended than a recording at 15 ips. 22.5 ips recording is a good compromise. I once recorded a concert at 22.5 ips and it was noticeably better quality than 15 ips and the bass was fine.
 

Ron Resnick

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Thank you TapeTech, thank you Bruce.

But if I do not know the level at which the original tape was recorded, and bass response aside, is there any conceivable sound quality reason at all to dub a copy at 30ips?
 

Bruce B

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Short answer.... No

The same analogy would be dubbing a CD at 96/24
 

Ron Resnick

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Thank you!
 

rockitman

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Thank you!

why would you want to dub at 30ips anyway ? You won't hear the difference from the 15ips source and the amount of tape doubles for the same length tracks...about 15 minutes of playback per tape (2500' reels)...what a pain to keep spooling up reels every 15 minutes....
 

Ron Resnick

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When do we ever do anything in this hobby to avoid inconvenience, if we can eek out one more iota of sound quality? ;)
 

Tapetech

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Thank you TapeTech, thank you Bruce.

But if I do not know the level at which the original tape was recorded, and bass response aside, is there any conceivable sound quality reason at all to dub a copy at 30ips?

You can find out the operating level of the original tape by playing it on a tape deck that has calibrated meters. As in you know what flux level/operating level 0VU is on the playback deck. It is good to always know what flux level/op level 0VU is set to on any play or recording deck.

Lets say your playback deck is calibrated so that 0VU= +6 operating level (370 nWb/m). So you play back the mystery tape and the max VU indication is -3VU. This tells you that the tape is recorded at a +3 operating level (250 nWb/m). If you play back another tape and the max VU indication is +3VU, this tells you that the tape was recorded at a +9 op level (520 nWb/m).

Re your 2nd question: I already gave you an example of a tape that may benefit from a 30 ips dub (or a dub using 1/2" tape at 15 ips). This is if the playback tape was recorded at 15 ips and at maximum level (+9 op level) with the best tape available (ATR or SM900).

TTP makes their dubs (running master) on a one inch 2-track deck! This pretty much eliminates any degradation at all when making the copy. As in no noise or distortion added to the copy.
 
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Ron Resnick

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Thank you, Tapetech. Thank you, Christian.

I officially conclude that dubbing at 15 IPS is just fine!
 

astrotoy

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What I have been doing is copying my 1/4 track safety masters from 1/4" to 1/2" tape. That seems to minimize the loss in dubbing quality. Like copying at 30ips you have twice the real estate to record with. No issue with shorter record times. Of course you need to be able to record and playback 1/2" tape. I do like 1/2" tape for its ease of handling compared with 1/4". I don't do 30ips, only 15ips.

For vinyl, the late Stan Ricker did a lot of cutting at 1/2 speed. Helps the high frequencies. I suppose one could record at half speed (both playback and record machines run at 7.5ips) and then play the newly recorded tape at 15ips. Of course it would take twice as long to make the dub. Anyone try that?

Larry
 

c1ferrari

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How about recording in reverse -- seriously. :confused:
 

astrotoy

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Sam, you are on to something. Actually, in the old days, the 7.5ips 1/4 track stereo tapes were recorded in one direction only, with the side 1 tracks (1 and 3) recorded backwards and the side 2 tracks (2 and 4) recorded forwards. The reason was to minimize the copying time (they also recorded at very high speed for the same reason). So when they were finished duplicating a bank of tapes, they was on their reels with the head of side 1 out - ready to be labelled, packaged and shipped.

People have talked about minimizing pre-echo by recording backwards. Post-echo is usually disguised by the trailing edge of the music. Would you have the same issue with post-echo sounding at the leading edge of notes? Any comments from our experts?

Larry
 

c1ferrari

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Ron,

A theoretical advantage to recording/dubbing at 30 in/s is to increase the surface area of the magnetic media to the signal.
 

Ron Resnick

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Ron,

A theoretical advantage to recording/dubbing at 30 in/s is to increase the surface area of the magnetic media to the signal.

Sam, that makes some theoretical sense to me. That is why I have been asking leading questions to see if anyone, as a practical matter, supports the proposition that dubbing from 15 IPS master 30 IPS copy improves the sound quality of the copy. So far I have not received any affirmative vote on this practical sound quality improvement question.
 

c1ferrari

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Of course, and it may have been alluded to earlier, another method to increase SA is to utilize wider tape while maintaining said speed.
Obviously, utilizing wider tape and increasing speed offers the greatest magnetic media surface area available.
Applying +9 tape would allow the hottest recording level sans distortion, but the record deck must be optimized for it. :cool:
 

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