Tape speed Calibration

[T-STER]

So i have a speed calibration tape and i have a multimeter capable of measuring frequency, it has two leads that i plug into the com port and port marked "Hz" but my question is how do i connect the meter to a boombox or tape deck to measure?

The leads have 2 pins on the ends of the leads how to get these to interface?

I see on some videos people simply say stuff like "connect the meter to the outputs on your tape deck" but how to connect them?
What about on a boombox that doesn't have a line out?

 

[thinkchronicity]

Get yourself a stereo mini-jack to two phonos lead (always handy to have anyway) and plug it in the headphone socket. Then pick one phono jack and press your probes on that. You'll need to whack up the volume till you get enough signal for the meter to read. The job's a good'un.

 

[Ken]

You might try googling the tape manufacturer and part number. It could give you access to documentation that would allow you to make the proper connections you seek.

 

[Transistorized]

If I am not mistaken, com would be short for "common" meaning ground / negative speaker terminal and Hz for frequency in hertz would be positive speaker terminal.

Basically an amplifier outputs low voltage AC signal in hz (frequency) and the speaker turns that into a wave form that can be heard. If you connect your meter to the speaker terminals you can read the Hz in the voltage being applied to the speaker during tape playback and then adjust the motor speed to match the Hz the tape is calibrated for.

You can determine the Hz of anything with a meter utilizing the Hz setting. The picture below basically shows in the US a 60Hz AC cycle on my meter.



The way I calibrated mine was to use my quarts locked Sony to record a test tone (frequency) of my guitar tuner on the high E string note of a guitar. Then I played it back on the deck needing adjusting and let the guitar tuner hear the tone and tell me when the frequency was in pitch. Works great.

I would like to mention that the Hz through a meter is deemed to be more accurate though.

Its important to note that just because your deck is set to the correct speed...any recording you play made in another machine will still play at a different speed in relation to sound. This goes for prerecorded (store purchased factory) tapes as well. One good thing though, once you set all of your decks in your house, at least you will know they are all in tune with each other and will all play at the exact correct speed

I could get as complex as to throw in tape stretch and a few others that would cause playback that is not "perfect" as it relates to speed but unfortunately...and I hate to say it. Digital is the only perfect true playback that will match the exact length of the recorded track. I know..it sucks to admit it..but it's true I realize that there are analog machines (like my Sony) that play at a perfect speed all the time but keep in mind that this is microprocessor controlled (digital) so unlike a true analog device like most boomboxes (excludes M90 and a few others with microprocessor speed control). Speed control via VR trim pot you can get close but not perfect monitored speed all the time.

So, how do you know when your cassette player is playing well enough to pass in this digital age? Well...use your smartphone and download SoundHound (or similar app). If you can play your tape and it finds your song quickly then your player is doing as well as can be expected