Replacing hard to find calibration cassete tapes with an adapter from phone

Thread Starter

Sergio Aristizabal

Joined Oct 11, 2017
So I am a novice with electronics, please bear with me.

I am trying to restore a Sony TCK-33 cassete deck. The mechanical part is done and only the calibration is needed. The left side is significantly lower level than the right one. So I would like to do the calibration procedure as the service manual suggests.

It demands for some cassete tapes:
WS-48 (3khz, 0dB) Speed cal.
P-4-A81 (6.3khz, -10dB) Rec/play Head azimuth, phase check.
P-4-L81 (333), 0dB) Playback level.

I am wondering f at least for some of this tests, a cassete to 3.5mm jack could be used so I can generate signals with a phone.

Jon Chandler

Joined Jun 12, 2008
The speed cal obviously won't work – it's playing back a known tone recorded at the correct speed. The difference in frequency between the recorded tone (what it's supposed to be) and the played back tone is due to error in the tape recorder speed.

Playback level is doubtful as well. You can't precisely control the signal level from the phone and you don't know the sensitivity of the head in cassette or the coupling between it and the playback head.


Joined Oct 5, 2017
You could use your adapter and phone to at least adjust the gain of each channel to be the same, even if not able to perform other adjustments such as speed.

The playback levels you set may not be correct to the manual, but perhaps close enough to sound acceptable.

Audioguru again

Joined Oct 21, 2019
I remember the antique compact cassette tape recorder/players. They began being produced by many companies 58 years ago and people stopped using them 32 years ago. I still have a fairly new Yamaha recorder/player with Dolby B and C noise reduction that I have not used for many years.

Thread Starter

Sergio Aristizabal

Joined Oct 11, 2017
Thanks, guys. Yeh the speed thing is not important now, it sounds ok. I was thinking of playback levels. For some reason the left side seems to be much quieter than the right channel.


Joined Jan 27, 2019
The problem with those adapters is they are the antithesis of precision. They use a very dodgy method of inducing the signal into the playback head and they don’t really care about quality or channel balance.

Why are you reluctant to use a tape? Do you not have another deck that can record good tapes?

You can get tapes, though they don’t come cheap. Also, variously on eBay.

One more thing, just a thought. I used to service cassette decks (in the 80s) and sometimes what appeared to be electronics trouble was actually just the need for a good head cleaning. If you haven’t done that, it’s worth a try.