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calibration and observation about dubbing.

MetalFisher

MetalFisher

Semi-Vintage fan
So I recently calibrated all my decks (two each on my Pioneer and Kenwood, and my walkman) ONE of them was spot-on so I made a home-made speed calibration cassette. Using a multimeter capable of measuring frequency, having a frequency generator I found online etc... Yeah it was a hobbyist's version alright but best I could do. Given they are old decks and my limited equipment, the job went better than expected.
So I take my calibration tape and test all decks at 1000 hz and 5000 hz (two of several frequencies on the tape). Even with wow and flutter of cassette decks, they held very close.
Now I cannot tell if I am playing the pioneer or kenwood. Both sound excellent. :yes:

I noticed one thing though - when I went to do a test dub of the calibration tape. neither deck seems to like high-speed dubbing. It works but during the high speed portion (when played back), the frequency drops to about average 995 instead of holding average 1000. I am not real worried since I probably won't be high-speed dubbing much.

But - does this signify a problem with something else or is it just because dubbing at high speed imposes yet another obstacle for an already-imperfect medium (cassette in general)
 
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MetalFisher - nice work! I have a couple of vintage cassette decks I'd like to check the calibration on. Any chance you'd consider doing a short / summary write up of the procedure or "How to Guide"? I know I certainly would appreciate it as a learning tool. Evening just know what tools you used and the steps would be great help. I've just been tweaking my head alignment by ear and I know it's not the best or right way to go.

Thanks for sharing the info. The talent of the folks on AK are what makes this place great!
 
I knew I had speed calibration problems cause when I recorded from my kenwood to pioneer, I could hear speed problems...
Well first - I am not a pro. I wasn't about to drop $60 on a speed calibration tape. Even so, here is what I did to set speed...
I knew all the belts were good cause of no flutter and everything worked.

Find a pre-recorded cassette in good shape with a song you know note by note. Have same song ready on youtube or a music site. The song should be 3 to 5 minutes and NOT have a fading intro. I used the Doobie Brothers song "The Doctor" (and a few others). Go listen to the beginning and it will make sense why I used it.

Amplifier input should be MP3 source. Play and pick a note a few seconds into the song and pause the MP3.

Switch amp input to your tape deck. Put the tape a few seconds before your chosen song. Press play.

Run back to your desk and wait for that same note to play on the tape and as soon as it does, unpause the MP3.

Go to your receiver and switch between tape and whatever input your computer/MP3 player is hooked to. The songs will not likely be perfectly in sync but that is OK. The idea is to listen to whether the MP3 or tape hits particular notes first and if the timing gap increases as the song plays. Say at the beginning, there is a split second difference but by the end, one or the other is noticeably ahead. Like if the "gap" went from 1/4 second to almost two seconds during the 3 minute song.

From here, you just need to tweak the tape speed and play the tracks again like described before. Sooner or later that "Gap" in timing will be miniscule. Also can PM you my address if you want to come by and beat my ass because by the time the speed is correct, you will hate the song you chose.

Once I managed that mess...

I played a 1000 hz tone on some website and recorded it for 5 minutes, using my "calibrated" deck. 10 seconds of recorded silence, then 5 minutes of 3000 hz. BTW, use one of your better blanks for this. I used a Maxell XLII.
This became my calib tape.

I put on the website and tuned in 1000 hz.

Opened up the tape deck. Put the calib tape in the "bad" side of the deck. I hooked my multimeter to the speaker wire on one channel, then I played the tape. It was putting out 989 hz (average) so I turned the speed pots up and down quite a bit then tuned carefully til the meter read 1000 hz average.

If you do not have a meter, you can still do this by ear. On the website, try 980, 1000, 1020 hz just to get a feel for the variance and exactly what 1000 sounds like. then just play the 1000 hz on the site and play the calib tape. Switching between your computer sound and tape, try to get them to sound exactly the same pitch.

Once again, do the "tape VS MP3" sync test.
Have some headache pills ready for when you are done.

This is not a professional method. The pros use ACTUAL calib tapes, frequency generators, oscilloscopes etc. Like I said, mine is a "making due with what you have" method. Keep in mind also when measuring frequency from a played tape, the hz might jump around very quickly due to analog but should hover around your chosen frequency.
Mine is still not "perfect" but it would probably take a pro to know the difference.
 
Ur method does indeed work for the diy people I've used this trick except with my CD player or turntaple playing the same song that I have on tape switching back n forth getting the song to closly match up with the CD or record in time n pitch, works every time but yes u will need some Advil n u will hate the song by the time ur done lol ask me how I know both my Yamaha K960 needed belts n to adjusted speed, but both are now all good n up and running

Yamaha A-500, T-1, 2 K-960, 2 CD-2, GE-5, DT-60, C-45, P2050, T-500
Denon DCD-1290, DRA-350
Technics SL-1200M3D
Nak DR-3
Rotel RD-965BX
Apple iPod Classic 160gig w dock
Klipsch Image 1 headphones
Kef C40
4 EV FR12-2
 
The speed calibration tape is good, I tested it in another known-good deck.

As far as adjusting speed, the kenwood has a normal and high speed potentiometer for both tapes. Adjusting one or the other (for deck A or B) will result in proper tape speed when normal speed recording or playing a tape. I ran into problems when I did a high speed dub. I am hoping to get some help with this.
 
I'm going with "another obstacle".
Since high speed dubbing is almost always going to result in lower fidelity anyway (in my experience) I never used it on anything that mattered (like music).
 
Consumer grade double well decks that high speed dub are not capable of high fidelity or high speed stability, as for_p1 stated, voice quality only. Don't waste your time. Even if it had a lo-fi limit of 12kHz, the record head would have to be capable of 24kHz at double speed, and those 2 head units have no chance in hell of that.
 
Naptown Rob said:
I'm going with "another obstacle".
Since high speed dubbing is almost always going to result in lower fidelity anyway (in my experience) I never used it on anything that mattered (like music).
Click to expand...

Dig your avatar of one of my faves...Robyn "Clean Steve" Hitchcock!
 
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