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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 14th Jan 2022, 6:42 pm   #1
andrewferguson
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Default Muffled sound on cassette player (Akai AD-F300)

I was helping my father transfer some cassette tapes to the computer using his Akai AD-F300 cassette deck (purchased for a few pounds at a jumble sale over ten years ago), and in the process discovered that it is rather muffled.

I checked another tape to see if it was just the tape (it wasn't - and the tape plays fine in my deck), then tried cleaning the heads with isopropyl alcohol and a cotton-swab, which made a bit of a difference but it is still noticeably muffled.

I'm not sure what to do next. I can open it up and search for capacitors that look 'suspect', or perhaps I should demagnetise the heads (something I've never done and know very little about)?

Advice would be greatly appreciated!
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Old 14th Jan 2022, 7:06 pm   #2
paulsherwin
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Default Re: Muffled sound on cassette player (Akai AD-F300)

It's probable that either the replay head azimuth is out, or the head that recorded the tapes was out. You should be able to adjust it by ear using a small screwdriver. It's best to listen on a good pair of headphones while doing this.

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Old 14th Jan 2022, 8:20 pm   #3
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Default Re: Muffled sound on cassette player (Akai AD-F300)

Before you start twiddling screws, just take another look at the face of the playback head. On well-used recorders, it's quite common to find a hard 'baked on' spot of old oxide from the tape. Casual cleaning with isopropyl and a cotton bud may not shift this easily. You may need to apply a bit more pressure and try several times before it finally clears. Don't be tempted to poke at it with anything metallic.
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Old 14th Jan 2022, 8:27 pm   #4
paulsherwin
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Default Re: Muffled sound on cassette player (Akai AD-F300)

It's also possible the head is actually worn, though this is unusual with domestic recorders that have only seen light use. A worn head will have a very pronounced wear channel where the tape makes contact.
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Old 14th Jan 2022, 8:52 pm   #5
andrewferguson
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Default Re: Muffled sound on cassette player (Akai AD-F300)

Thanks Andy and Paul for the suggestions. I hadn't considered the azimuth - I assume a simple way to check if it is out beforehand is to record a sample on the Akai and see if it is not muffled when played back in the same machine?
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Old 14th Jan 2022, 9:51 pm   #6
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Default Re: Muffled sound on cassette player (Akai AD-F300)

A point of order - it's probably an *Aiwa* AD-F300, isn't it?

Anyhow, you can make a test recording on it to see if the sound quality is better and the deck itself is healthy, but I wouldn't bother.

In my experience the azimuth on cassette decks is always wrong for the cassette you're trying to play. There's a good reason why top-end Nakamichi cassette decks have their clever auto-azimuth system.

If I'm transcribing a cassette in to a digital format, which is the main reason I play cassettes these days, I always adjust the azimuth to suit the tape before starting the transcription. On a deck of unknown provenance like your AD-F300, it's likely to have been twiddled at some point in its past. Find a suitable screwdriver (that isn't magnetised!) and try adjusting the azimuth with a cassette playing. Make small adjustments at first and listen carefully to see whether you're making it better or worse. If it's getting worse, try turning the other way. Sometimes it'll take a moment for the tape to settle down after an adjustment so be patient and take it slowly. You probably won't need more than half a turn of the screw, if that.

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Old 14th Jan 2022, 9:54 pm   #7
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Default Re: Muffled sound on cassette player (Akai AD-F300)

One more thing: check that you haven't got Dolby C switched on. That will make anything sound muffled, even a tape which was recorded with Dolby C, unless the machine is perfectly lined up to suit the recording.

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Old 14th Jan 2022, 11:58 pm   #8
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Default Re: Muffled sound on cassette player (Akai AD-F300)

I second what Andrew2 has said.

I have a decent Yamaha deck that started playing back badly - muffled as you describe. I may have played a poor tape without realising, but whatever the cause, it took a good clean to get a hardened patch off the head. It plays nicely now.

That's not to say its the problem in your case, but I'd certainly look very closely at the head to be sure.
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Old 15th Jan 2022, 12:39 am   #9
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Default Re: Muffled sound on cassette player (Akai AD-F300)

Many years ago, I spent hours trying to solve the same problem on a good quality cassette deck - cleaned everything in sight, adjusted azimuth, etc - nothing made any difference. Eventually I found that there was a back-tension adjuster for the feed spool on the deck. Increasing the back tension restored correct operation.

I don't know if all decks have such an adjustment, but this one did. I would have assumed that the normal friction inherent in the cassette mechanism would provide sufficient back-tension, but apparently not.

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Old 15th Jan 2022, 12:41 am   #10
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Default Re: Muffled sound on cassette player (Akai AD-F300)

If possible, view the head face in a good strong light with magnification, perhaps magnifying reading glasses. It's easier to see any muck on the head face as well as any wear.

The main error people seem to make is to merely "go through the head cleaning motions" without actually checking their work. Carefully clean it (not too much pressure or it may bend the head out of alignment) until you can see the surface is shiny clean and polished like a mirror.
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