DTS-CD Theoretical Question About Half-Speed Mastering

[steelydave]

Let's say one was going to do some transferring of tapes in to the computer. If the tapes were transferred in to my computer with the tape deck running at half-speed, and then the wav files were doubled in speed using a wav editing program, would I see any increase in quality? My thinking here is that hiss is caused by the tape running across the play head...so if it's running across the play head at half the speed, is the hiss reduced? Are there problems associated with running tape at half it's intended speed? Benefits? Any thoughts or suggestions would be appreciated.

Dave.

 

[quadgdiaz]

Let's say one was going to do some transferring of tapes in to the computer. If the tapes were transferred in to my computer with the tape deck running at half-speed, and then the wav files were doubled in speed using a wav editing program, would I see any increase in quality? My thinking here is that hiss is caused by the tape running across the play head...so if it's running across the play head at half the speed, is the hiss reduced? Are there problems associated with running tape at half it's intended speed? Benefits? Any thoughts or suggestions would be appreciated.

Dave.

hi Dave

that's a good one ????? but i think it should be faster not slower ????? you get less hiss on a 10 inch reel 2 reel @ 15 IPS,?????? than a 7 inch @ 7 1/2 IPS , so you may want to speed up the tape ?????? thanks Gerardo

 

[neil wilkes]

You could get the effect you desire by doubling the samplerate.
Record in at, say, 44.1 with tape running at half speed, and doube up the samplerate to 88.2 would bring it back up to speed again.
In theory, you would get a quality increase, but then you would have to dither down to 44.1 again for the fina master.
I think it would be a case of "swings & Roundabouts". Probably no real gain here.

 

[Malcolm2010]

Please be aware that in all of this, your equalization will be incorrect. For example playback of a 7 1/2 ips tape at 3 3/4 ips will change the equalization curve, this will have to be compensated for in the digital conversion stages. at the end of the day I do not think it would be worth the effort, if your tape machine is in good alignment, then everything should be fine. Any artifacts can be reduced at the digital mastering end.


Malcolm

 

[winopener]

Let's say one was going to do some transferring of tapes in to the computer. If the tapes were transferred in to my computer with the tape deck running at half-speed, and then the wav files were doubled in speed using a wav editing program, would I see any increase in quality?
Dave.

Been there, done that.
For Q8, it's not worthy. Consider you have to deal with factory high-speed duplication, not real-time masters, so the quality is not affected by this process.
Much better going 24bit and 88.2.
I have no QR hardware or software, so i can't say anything on that.

 

[ndiamone]

Half Speed Mastering from Tape
``Please be aware that in all of this, your equalization will be incorrect.''
Also the pre and post echo inherent in all tape WILL drive you crazy
especially passed through such a low filter as 44.1 or 88.2.

Here at the Archives we tape at 192/32 unless we are dealing with session masters.

Half-speeded audiophile LPs work good though if you tape them into a Power Mac for Media
at say 192/32, and then declick and dehiss in an audio restoration prrogram like Diamond Cut Pro
like we use here at the Archives.

Session masters however are played real-time and recorded into the computer
at 13.75 MHz video rate and sent to Jaime Www.plangentprocesses.com to get
Plangentized i e have the original bias frequency resolved out and all the tape flutter
and wow removed as a result.

However this only works with session tapes which have at least one originally-recorded track.

As probably a lot of you know, a lot of the labels are trying to remix for 5.1 or 7.1 from
half-inch tape recorded in the 50's and 60's. So a lot of the time, the first reel of half
inch 3 track was for orchestra.

Mix that to mono and lay it on a 2nd reel. Lay in your 2 tracks of background singers
or supplemental players.

Mix those to mono and lay that onto a 3rd tape with the 2nd generation mono mix orchestra
and use the third track on the third reel for your lead vocal or your featured player.

So if you work for a firm that reassembles all those original stems to remix for 5.1 etc
all three reels with no timecode all have to lock up in sync.

Fortunately all tape has a constant frequency bias recorded along with the music.
So you can extract the 3 original stereo orchestra tracks from the first reel,
the 2 tracks of background singers or added sidemen from the 2nd reel
and the leadman or vocalist from the 3rd reel.

Jaime can lock all that up in sync with itself and it's almost like having one 1-inch 8-track
master with all the tracks lined up instead of how it is: 3 reels of half inch not synched up.

Yes it's many thousands of dollars an hour for Jaime's time and sync artistry.
But when your engineer gets 300.00 an hour for digital audio workstation processing
and it takes weeks and weeks for him to line it all up by hand, it's worth it.

Hope this is informative.

 

[ChristopherLees]

You could get the effect you desire by doubling the samplerate.
Record in at, say, 44.1 with tape running at half speed, and doube up the samplerate to 88.2 would bring it back up to speed again.
In theory, you would get a quality increase, but then you would have to dither down to 44.1 again for the fina master.
I think it would be a case of "swings & Roundabouts". Probably no real gain here.

Back in 1985, one of the engineers at mobile fidelity, claimed they did that with the MFSL lp release of Kenny Rogers greatest hits....i.e transferred the various songs to digital at half speed, then cut the lp at half speed, because they couldn't splice the songs out from the various original reels into one master greatest hits reel (either lazy or weren't allowed to)... and so they subsequently claimed that they were getting 88k digital from 44k digital equipment.(or was that 96k from 48k equipment ?...too long ago to remember exactly...and at the time he said it I was looking at all the JVC digital VHS decks and various tapes..)

 

[John Svensson]

I have to ask, what exactly are the archives in "we here at the archives" ?
Did I miss an introduction? John S.

 

[ChristopherLees]

I have to ask, what exactly are the archives in "we here at the archives" ?
Did I miss an introduction? John S.

I think only ndiamone probably knows.

 

[ndiamone]

I have to ask, what exactly are the archives in "we here at the archives" ?
Did I miss an introduction? John S.

Sorry. I thought that information was in the Profiles but I guess the machine hasn't got around to posting it yet.

We started out in the 90's doing reel to reel and acetate transfers of people's home-recorded projects (letters home from the front, high school dance mix reel to reels, early digital F-1 tapes, etc) and now we do transfers for a lot of people here, sometimes the National Archives, sometimes different University Archives, sometimes 2nd tier major labels (i.e. other than UMG Sony/BMG Capitol, WB etc).

The best thing will be when we can get the same grant as Carl Haber at the DOE Berkeley Labs and be able to get one of their confocal microscope-based LP optical transfer machines, completely eliminating the need for turntables, cartridges and turnover networks.

As far as Halfspeed Mastering in the computer the way Mo Fi did it, for Kenny Rogers, remember they have a LOT of extra correction tools than most people in most situations, and what they couldn't buy, they built. Sadly, most of what they built will remain one-offs for themselves and probably not be available to too many guys who want to work with a digital audio workstation. So we are left with what we get.

Sorry for the confusion.

 

[Q-Eight]

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I love to mix. My four-channel remixes of the Bob Marley multis that were out on the internet could be my resume!