Is speed change in Audacity same as speed change in recorder

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Is speed change in Audacity same as speed change in recorder

Permanent link to this post Posted by digicube » Sun Jul 09, 2017 12:07 am

Since reel to reel recorder has many 5 different speeds, instead of getting multiple machines, can I just capture the audio at one speed and then change it in Audacity? Will the quality be the same as changing the speed on the recorder? Does Audacity do equalization changes during speed change?
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Re: Is speed change in Audacity same as speed change in reco

Permanent link to this post Posted by kozikowski » Sun Jul 09, 2017 1:56 am

Audacity doesn't apply equalization during speed change.

If you play a tape at the wrong speed on the player, equalization damage will be burned into the show and be very difficult to remove.

The digital sample rate of 44100 will only manage perfect audio up to around 20,000Hz. If you play a slow tape on a fast machine, audio tones will go above that and be permanently lost.

This is a terrible idea.

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Re: Is speed change in Audacity same as speed change in reco

Permanent link to this post Posted by steve » Sun Jul 09, 2017 4:55 pm

kozikowski wrote:The digital sample rate of 44100 will only manage perfect audio up to around 20,000Hz

The analogue electronics in the reel to reel machine probably top-out at around 20 kHz as well. So if you play a tape at x4 speed, and the analogue electronics reproduce up to 20 kHz, then you slow down the recording to normal speed, the maximum frequency will be 5 kHz (just a little better than telephone quality).
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Re: Is speed change in Audacity same as speed change in reco

Permanent link to this post Posted by Mack Caster » Tue Jul 11, 2017 6:59 am

digicube wrote:Since reel to reel recorder has many 5 different speeds, instead of getting multiple machines, can I just capture the audio at one speed and then change it in Audacity? Will the quality be the same as changing the speed on the recorder? Does Audacity do equalization changes during speed change?


When converting analog to digital, it is always recommended that you start with the proper input, in your case, reel to reel audio. Your first goal is to get the analog signal into your computer at the correct speed that is was recorded at. They still sell reel to reels with multiple record and playback speeds. Back in the day, there were really three standards that the high dollar manufacturers tried to conform to for the average homeowner. 7 & 1/2 ips, 3 & 3/4 ips for music and 1 & 7/8 ips for speech. (ips = inches per second). However, depending on who was doing the recording and what their experience level was, these figures can vary widely. The slower speeds were used mostly by homeowners on a budget to cram more audio onto one reel or someone who wanted to record a lecture that went on forever.

At this time I am helping with a project that requires transferring cassette tapes to digital MP3's for our Troops around the world. It is tedious, extremely time-consuming as well as aggravating at times as some of these tapes are close to 20 years old. It is also a labor of love as well as a great sense of satisfaction when the 1.5-hour tape, that took 10 to 12 hours to reproduce, is completed. There are two things to keep in mind: 1. There is no one size fits all for this type of work. 2. There is always a limit of what can be improved depending on the original recording. I would love to hear more details concerning your project.
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Re: Is speed change in Audacity same as speed change in reco

Permanent link to this post Posted by digicube » Tue Jul 11, 2017 4:57 pm

I don't have any project at the moment. Was just curious of the idea of using today's technology to emulate old hardware. I guess it's not possible at the moment. This means I need at least 2 reel to reel audio machines.
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Re: Is speed change in Audacity same as speed change in reco

Permanent link to this post Posted by digicube » Sat Jul 15, 2017 10:43 pm

But for dictation tapes, it should be fine changing the speed in Audacity.
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