I need savvy suggestions about music slowdown

I have an old audio tape of a former band of mine that was recorded live in a nightclub with a portable non-professional recorder. My problem is that it was recorded at 3 3/4 ips–I have had no luck in finding an old set with 3 3/4 for playback.

I was able to borrow a TASCAM 32 from the local college but it plays back at 15 ips. The tape seems to have reasonably good sound quality judging from the chipmunk audio. I would like to gt it copied at its normal speed/pitch at some point, but right now I just want to hear it at least close to normal.

I am DLing Audacity. I want to record the tape playback at the 15 ips on my pc, and use the software to slow it down with listenable pitch. I read that Audacity has the slowdown/pitch change effect, and am wondering what anyone with experience would have to say to help me accomplish this the best I can expect from the process.

I read the specs for the Transcribe Pro app slowdown/pitch effect also, which appears to be technically optimal to a layman like me. Could someone comment on how Audacity compares in that respect? (I am not asking to make a choice to DL, as I will keep Audacity regardless.) I can get a free trial for Transcribe.

The thing is, I have the apps and ability but am not ideally set up for audio recording and need the info necessary to make this as easy as possible while getting some reasonable idea of what the music on the tape sounds like. I have been quoted something like $200 to get the tape copied professionally so I need to hear it to decide if it is worth the expense.

Any comments will be greatly appreciated.


Yes you can slow a track down by a factor of four in Audacity no problem; just change the playback rate on the chipmunk to ¼ the sample rate it was recorded at …

However a problem you’ll encounter is huge loss of high frequencies after you have slowed it down: it’s gonna sound a like a telephone,

The bandwidth of a pro tape will be about 20KHz, but after it’s slowed down by a factor of four that’s only 5KHz,
i.e. it’ll sound exactly like you’re hearing it down a phone: at the correct speed but missing all the frequencies above 5KHz.

BTW this high-frequency-loss problem is not curable with expensive software, the cure is a tape player which plays at the correct speed.

Oh, it’s far worse than that. Unlike the single RIAA curve for vinyl records, each tape speed has its own equalization curves on record and playback and for each tape type. This gives you the conversation with the radio station engineer where he tells you, “We’re a Scotch 808 house.” That’s the tape type that all his machines are set up to use.

The difference between successive speeds is pretty serious (3-3/4 > 7-1/2) but the difference between three speeds is very damaging.

So you’ll probably be able to recognize the title of the song…

Do you know the tape format? Full-Coat Mono? Full-Coat Stereo? Four Track (stereo one way, flip the tape over, and then stereo back the other).

No home recorders used Dolby, so you’re probably safe there.

Happy I could brighten up your day.


In case it wasn’t bright enough, be careful with the alcohol while you’re cleaning the tape transport pathway. You can probably get away with paper towels, but lint-free is probably best. I compromised and use western cotton bandannas from the local cowboy store. I clean my computer screen with those, too. That and a special solution I make.

Also be careful with the head demagnitization. Turn the machine off before you degauss the heads.



If it hasn’t been done in a long time, head magnitization can cause your tape to sound muffled and even worse than it is.


An alternative method is to use the “Change Speed” effect in Audacity 1.3.12 (it’s in the effects menu).

The frequency response of tape that is recorded at 3 3/4 inches per second is not usually very good even when played on equipment that can play at the correct speed. Also, tapes will tend to loose high frequencies with age, (and generally loose quality) particularly if kept in less than optimal conditions.

There may be an additional problem. The Tascam 32 was a “half track” recorder - that is, it would record the left channel on half of the width or the tape and the other channel on the other half. Most domestic tape recorders were “Quater track” machines - they would use 1/4 of the tape with for each track and could therefore record 2 tracks on one “side”, then turning the tape over could record another stereo pair. Some would also provide an option of recording 2 different mono recordings on each “side”.
If your tape has been recorded on both “sides” then you are likely to get the sound of the other side playing at the same time but in reverse.

Some half track machines had an additional playback head so they could play quarter track recordings but I don’t think that the Tascam 32 has that option.

One of the video editors came in with a million year old tape machine and a box of tapes he got from Goodness Knows Where. I got the machine running long enough (at the right speed, thankyouverymuch) to discover he had long lost tapes of a world famous singer now dead.

We removed the last tape from the machine and it threw up blood and died.


You might be able to talk the company into a “taste test.” Listen to a minute or two of the tape to determine whether the expense is worth it.


Is that what they’re calling moonshine these days ? :slight_smile:

keep looking
there are machines ARE out there - mostly used
google - bay - craigslist -
repair shops that sell used machines
antique electronics dealers
school old lab gear
old ham radio andor electronics hobbyists
(3 in my basment - who knows if they still work)
small studios that may have one lying around
(i have a teac 2300xx with Dolby B and 3.75 capability 1/4track)
(have not used it in nearly 30 years - does it work???)

check web sites for repair and sales of tape or machines
they may have pointers or know someone who has one

<<<Is that what they’re calling moonshine these days ?>>>

In California, that would be “Sunshine.” As in, “Have some of this Sunshine I made last week. It will knock you on your keister, but in a good, laid-back, comfortable way”

It does involve distilling, but not what you think. If you read most display panel literature, they expressly forbid you to use an alcohol-based solvent on the screen. That pretty much kills off Windex® and other glass cleaners and on up to Vodka which is a markably good solvent/cleaner if you can stop using it for its intended purpose long enough.

I use 16oz/500ml distilled and de-ionized water with one (1.00) drop of concentrated dish washing detergent. Stick the clean handle of a spoon into Dawn For Dishes (in the US) and let one drop fall into the water.

Package and use. The combination dries with no residue and the Dawn is just enough to break down most fingerprints.

Remember Minox® film cameras? “The Minox lens may be cleaned with a clean, well-laundered men’s handkerchief.” I use a cotton western bandanna, clean and well-laundered.

After a couple of months, the solution may get cloudy or exhibit flocculance. Throw it out and make more.