Tape speed adjustment when you have no test equipment - solution !

[Markoneswift]

Hey all, I found a great way to adjust the playback speed of a deck, despite having no test equipment. My solution was to use a musician (a drummer, to be exact). My friend has played drums for years in a variety of bands, so I figured who else could be better to tell me if my tape speed was too slow or too fast.

We played several pieces he was really familiar with from pre-recorded cassettes and he kept time whilst I adjusted the speed pot on the motor. I reckon we got it pretty dead on after a few very small adjustments

Best thing about drummers, compared to test equipment, is that they generally do all manner of things for free

 

[tapetech]

That is not an accurate method (tuning motor speed by what someone remembers the pinch of the song to be).

A far more accurate method (that doesn't use test equipment), is to compare your pre-recorded tape to a CD or internet version of the same song. Both iTunes and Youtube have any song you can think of that you could play back for comparison. Both the CD and internet versions will have the exact, correct pitch. Adjust the tape deck so that both versions are the same pitch.

 

[Markoneswift]

That is not an accurate method (tuning motor speed by what someone remembers the pinch of the song to be).

A far more accurate method (that doesn't use test equipment), is to compare your pre-recorded tape to a CD or internet version of the same song. Both iTunes and Youtube have any song you can think of that you could play back for comparison. Both the CD and internet versions will have the exact, correct pitch. Adjust the tape deck so that both versions are the same pitch.

I already tried that method, I just couldn't quite get the start of the tape track synched up with the start of the digital track. I may well go back and give it another shot now that I know my tape speed is pretty close anyway. It's another one of my ghetto solutions (and my friend is a bloody good drummer lol)

 

[tapetech]

And using a pre-recorded music tape for a reference has it's own possible error. Was it recorded as the the exact, correct speed? Maybe yes, maybe no. Quality control is not very strict for those tapes. So even if you perfectly synced the CD and tape (same pitch), the speed of your deck could still be off due to an error in the pre-recorded tape.

 

[Markoneswift]

And using a pre-recorded music tape for a reference has it's own possible error. Was it recorded as the the exact, correct speed? Maybe yes, maybe no. Quality control is not very strict for those tapes. So even if you perfectly synced the CD and tape (same pitch), the speed of your deck could still be off due to an error in the pre-recorded tape.

Absolutely, that's something that I had already thought about too. I would really like to be able to invest in some test gear but sadly availability is very very low here and my budget is limited. Trying to get my gear working as optimally as possible with what I have available is what I'm all about. Appreciate your advice and comments as always.

 

[phantomrebel]

Old school analog solution, I like it. But I could have just lent you this:

 

[GPS16]

Hi,

I like that one!!! Made me laugh!!! 10/10 for abstract thought, the economical aspect and having the presence of mind to collar your mate!! May be dependent on mood though!!

I thought that was a form of contraception!!!

This got me away from the blinkered, narrow "Engineer" frame of mind. Nice one!!!

GPS16

 

[drumbum]

A technique that requires a couple systems in the same room AND a deck that you know is running @ correct speed.
With the known good deck, record a 400hz tone off the internet to a 60min tape . Record about 15min in the middle of the tape.
Now take tape you made and put it in the "needs adjusting deck".
With first system, play the internet test tone, and adjust volume.
With second system, play the tape you made and adjust volume (on the deck that needs ajust.)
Adjust motor speed until the tones match and sound like one tone (no oscillation)
Japanese decks are usually a touch fast.
Voila and Bobs your uncle. Any questions? Did I make that clear?

P.S. some decks have an internal 400hz test tone.

 

[redk9258]

TDK MA-90 tapes say they are 135 meters. My JVC deck always clocked around 47:08 - 47:14 from the start to end of a side using the stopwatch function using these. 47:14 on the first pass, 47:10 on the second, 47:08 on the third.
If you do the math and add for 5 seconds of leader tape at the beginning and 5 seconds at the end...
135 meters = 5315" / 1 7/8" (1.875") I.P.S. = 2835 seconds (rounded to nearest whole number).
2835 seconds = 47.24 minutes = 47:14.
47:14 + 10 seconds leader = 47:24 (2845 seconds). So, if your speed is perfect, this is what to expect on the clock.

The motor went bad on my deck, so I had to replace it. I first set the speed of the new motor by ear. I played one of those MA-90 tapes from beginning to end. The time was off by a minute or two, I don't remember. Do the math for the percentage the speed is off. Then figure out what would make a 3000 Hz tone played at proper speed and record it. Let's say the speed is running fast by 3 minutes (180 seconds). In this case start to stop would be 44:24 (2,664 seconds) on the clock. This is running 6.794% fast! 3000 x 6.794% = 3,204. Now use Audicity or other program to generate a 3204 Hz sine wave and record it on a blank tape. Now use a DMM with a frequency counter function. Play the recorded tone and set speed as close to 3000 Hz as possible. Now play from beginning to end to see if you did your math correctly and have the proper time. If you don't have access to a DMM with a frequency counter, download a spectrum analyzer app for your smartphone and use it instead.

I was able to get damn close to the original speed... within a few seconds. I notice the newer motor gets slightly faster after playing a couple of sides than the original. Depending on the tape brand, they may be longer or shorter.

 

[Markoneswift]

Wow that's a pretty cool and somewhat complex method, thanks for sharing !

I played my 'set by ear and drummer' 990 last night for about three hours and it sounds absolutely bloody fantastic ! Played both sides of Def Leppards' 'Pyromania' and least twice, plus some other stuff and I can finally say I've got this deck playing awesome

 

[Markoneswift]

Ah hah ! Just realised - 1000 posts !! (well, 1001 now) woohoo

 

[Djcoolray]

Sounds good to me...

 

[Steven Tate]

A technique that requires a couple systems in the same room AND a deck that you know is running @ correct speed.
With the known good deck, record a 400hz tone off the internet to a 60min tape . Record about 15min in the middle of the tape.
Now take tape you made and put it in the "needs adjusting deck".
With first system, play the internet test tone, and adjust volume.
With second system, play the tape you made and adjust volume (on the deck that needs ajust.)
Adjust motor speed until the tones match and sound like one tone (no oscillation)
Japanese decks are usually a touch fast.
Voila and Bobs your uncle. Any questions? Did I make that clear?

P.S. some decks have an internal 400hz test tone.

I'm going to try this. I have a Marantz 5025b that "sounds" spot on, and a 5020 that sounds fast to me. I'm going to record a 400 hz tone on the 5025b and play it back on the 5020 while adjusting as described. This sounds like a good way to get very close.

 

[woofmytweets]

here's what i would do. make a nice long recording, as close to the length of one tape side as you can, using a digital source and a known calibrated tape deck. then play it back on your test unit and time the playback with a stopwatch. whatever difference in the total play time, expressed as a fraction of the length of the recording, is how much you need to adjust your tape speed plus or minus.

or playback of a signal-generated single tone is almost certainly a better method, and faster.

 

[drumbum]

I'm going to try this. I have a Marantz 5025b that "sounds" spot on, and a 5020 that sounds fast to me. I'm going to record a 400 hz tone on the 5025b and play it back on the 5020 while adjusting as described. This sounds like a good way to get very close.

Spend the time to get the screwdriver in the motor and engage the adjuster first. It can be a little frustrating. The speed adj. can be a little touchy (damn, to far, back up, to far, crap) But with both tones playing, you can hear the beats clearly. I'm sure you will get those decks running the exact same speed

 

[Steven Tate]

Spend the time to get the screwdriver in the motor and engage the adjuster first. It can be a little frustrating. The speed adj. can be a little touchy (damn, to far, back up, to far, crap) But with both tones playing, you can hear the beats clearly. I'm sure you will get those decks running the exact same speed

Good advice. I'm going to give it a try. Thanks!

 

[Markoneswift]

All great advice, I think the only thing I'm lacking is a 'known, calibrated, tape deck'...

 

[redk9258]

All great advice, I think the only thing I'm lacking is a 'known, calibrated, tape deck'...

Look at my post above. Get a known quality tape, TDK, Maxell, Fuji. etc. Look at the length on the package and calculate it out. Then play one side to see how close it is to the calculated speed. I agree with the post above, getting the screwdriver in the motor can be frustrating. Make sure it is insulated too. IIRC, I used a screwdriver that was meant for eyeglasses and put a piece of insulation on the shaft from a wire that I stripped to make sure it couldn't touch the edge of the motor and ground something out. The adjustment is very touchy. A frequency counter is probably the easiest to adjust to.

 

[KentTeffeteller]

To do this right, the tapes must play well on most machines if not all. If this is not, it is not correct. And a frequency counter is wise to adjust to. Standards and procedures are there for a reason.

 

[oldvinyldude]

To compare a known digital source file length with your deck, you could download and install Audacity, which is a freeware program. If you play your recording from your deck into it, and you have chosen a reference digital version music file, with sharp start and endpoints (ie-no fade in/out), it should be pretty easy to see the run time of the recorded tape version, to compare with the digital reference.

Of course, speed alignment would involve recording from the digital source, playing into Audacity, calculating time, adjusting deck, recording again, and so on, until you were as close as humanly possible, or just tired of the process.