Tech: Weird MiniDisc play problem ???

Subject: Tech: Weird MiniDisc play problem ???
From: GUEST,Perturbed Folkie
Date: 22 Sep 08 - 11:11 PM

Hello. I'm encountering a very perplexing playback problem ?

I recently rediscovered my mint condition Minidisc equipment,
stored safely in boxes for at least 5 years.
Lately I recorded about 5 or 6 of my bands gigs with no problems.
But, at a venue with a proper PA, the in house sound tech guy
offered to record direct off the soundboard into his rack mounted
Minidisc recorder.
So I gladly opened up a brand new [new old stock] disc from its sealed wrapper.
When I played this disc at home.
It played well for most of the songs then suddenly sounded like it was playing back at rapid speed.
So I 'rewound' it a bit and it then started playing normally again.
That was about a month ago.
Tonight I tried playing that disc and now it wont play at all .
I just get a garbled noise that sounds like over-excited chipmunks.

All the other discs that were recorded recently on this machine still playback OK.
This machine is an Aiwa AM-F80

As a control test, I just got my Sony MZ-R70 out of its box.
The results for all discs are exactly the same.
Only the gig recorded on the Venues rack mount recorder
plays back like rodents on amphetamine.

I therefore, initially suspected there might have been a problem
with the venue's minidisc recorder....

So as a further control test, I dug out some discs that were recorded
on the Aiwa
[this particular machine, or other identical AM-F80s used in a college AV dept]

And strangely enough, all these old recordings now refuse to playback on either the Aiwa or the Sony.
They all exhibit the same demented small chirping furry animal sounds.

So that finding must exonerate the Theatre venue's recorder.

If I listen carefully, very faintly beneath the fast squeaky sounds
I can make out faint traces of the origional signal playing back at normal speed ???

Any ideas..

Please help

Subject: RE: Tech: Weird MiniDisc play problem ???
From: Jim Lad
Date: 22 Sep 08 - 11:32 PM

What do you have for a soundcard?

Subject: RE: Tech: Weird MiniDisc play problem ???
From: The Fooles Troupe
Date: 22 Sep 08 - 11:35 PM

I can't find anything specific to your model - and for the generic problem, there are just too many responses.

Many Mini Disk systems have a playback speed / pitch converter system.

This going wrong may give you the higher pitch (chipmunk voice) sound.

Subject: RE: Tech: Weird MiniDisc play problem ???
From: GUEST,Perturbed Folkie
Date: 22 Sep 08 - 11:40 PM

thanks for response mates,

I just found a disc that was recorded on the Sony about 5 or 6 years ago.

This disc plays well on both machines..
and after playing that disc.....

now all discs play properly on both machines !!!!?

this is getting mental

Subject: RE: Tech: Weird MiniDisc play problem ???
From: GUEST,Perturbed Folkie
Date: 22 Sep 08 - 11:42 PM

ps, I'm listening on headphones direct out the minidisc headphone sockets

Subject: RE: Tech: Weird MiniDisc play problem ???
From: Jim Lad
Date: 22 Sep 08 - 11:51 PM

You're welcome!



Heh, heh!

Subject: RE: Tech: Weird MiniDisc play problem ???
From: GUEST,Perturbed Folkie
Date: 22 Sep 08 - 11:59 PM

..and now after 3 or 4 wasted hours I've solved the problem.

The studio quality headphones connect to the machines
via a stereo full-size jackplug to mini jack converter.

There must have been a slight misallignment that was cancelling out
the audio from the discs that weren't working,
at the same time creating that weird 'rodent like' signal distortion.

But I was still perplexed why some recordings were still playing correctly..
Until I realised that the 'faulty' discs were all mono recordings,
while the discs that all played correctly were stereo.

Somehow, I guess the mono signal must have been affected by some kind of phase cancellation maybe ???

A small accedental tweak to the jack connecters while swapping from one machine
to the other obviously restored a good true audio path.

oh well, live and learn !

Subject: RE: Tech: Weird MiniDisc play problem ???
From: The Fooles Troupe
Date: 23 Sep 08 - 12:43 AM

I don't wish to be called so condescending as to give an unwanted lengthy detailed technical explanation, but faulty signal paths could easily have done that. If you had said originally about the headphones, it would have been a good clue as to whether the socket connectors could have been the hassle.

Subject: RE: Tech: Weird MiniDisc play problem ???
From: treewind
Date: 23 Sep 08 - 03:02 AM

Been there, done that.
The noise you get when you record a mono source on a minidisc (which always records L and R separately) and then play it back through a headphone with a missing ground connection, is the weirdest thing I have ever heard in my life.

You're listening to the difference between L and R when that happens.

Anahata