Conference hips::uk_audioo

	I'd be interested in this too.

	I have a Pioneer double deck & I am sure that the playback deck is
slightly fast and/or record deck is slightly slow. I find that when dubbing
from tape/tape that the playback tape finishes first. Additionally if I record
my guitar then playback and attempt to play along to double track then it is
slightly out of tune (sharp). 

	I would be happy if I could confirm this and more especially fix it. 

Nigel

    Hart Electronics of Oswestry sell a triple-purpose calibration
    cassette. Basically it has two tones recorded on it at accurate 30
    sec. intervals; the first tone, 1kHz, is used to set the 0 VU meter
    calibration: the second tone, 8kHz, is used to adjust the head azimuth.
    Timing the interval between tones will obviously give an indication
    of speed accuracy. The tape comes with instructions, but you'll
    need the appropriate manual for your machine to identify controls,
    etc. Mine cost me about two pounds, 3-4 years ago.
    
    Hart's address is Hart Electronic Kits Ltd., Oswestry, Shropshire,
    England, SY10 9AF. They take Visa, etc, over the phone but I don't
    have their number to hand.
    
    Be aware, though, that few cassette machines allow speed adjustment,
    but at least this cassette will give a yardstick. Make sure the
    capstan and pinch roller are clean, as these will determine how
    accurate the tape speed is, as well as affecting dynamics, detail,
    etc.
    
    Have fun.
    
    Dave

    In my experience all cassette decks have speed adjustment, it's
    just a case of twiddling the right pot (usually near the motor)
    and listening to the results!
    
    Stephen.
       
    
    PS The `right' pot is found by trying every pot on the PCB until
       you find one that works.

If you're using a cassette with a reference frequency and you want
the speed dead on you'll need a frequency counter.

As far as speed adjustment is concerned, I replaced the capstan motor
in my 6 year old Technics a few months back and found that the metal
cylinder that I thought was the motor in fact contained a smaller
cylinder which was the motor and a small PCB containing the speed
regulation electronics. There's a hole in the outer can so that the
preset on the PCB can be adjusted with a screwdriver.

Hope this is useful,
Steve.

    
    
    HI-FI News & Record Review sell a test tape produced by Ian Harrison
    of Derby.  The tape contains 6 tests to check Dolby replay level,
    azimuth, frequency response, Dolby B & C tracking accuracy, speed
    accuracy and a meter tone burst.  The tape is accompanied by a detailed
    manual to guide you clearly through all the tests.  Price 18.50.  

.4�If you're using a cassette with a reference frequency and you want
.4�the speed dead on you'll need a frequency counter.

    Or, better still, access to an oscilloscope, which will also allow
    accurate adjustment of the azimuth (head alignment) as well.
    
    Keith

.6�    Or, better still, access to an oscilloscope, which will also allow
.6�    accurate adjustment of the azimuth (head alignment) as well.
    
How would you adjust azimuth using an oscilloscope? The effect of
adjusting the azimuth is to make the sound more muffled away from
the  correct position and clearer towards it, so would you play a
tape of a sine wave and adjust the azimuth until the  best  wave-
shape is obtained?

I  suppose the best thing to have is a frequency counter *and* an
oscilloscope.

Steve.

    re .-1
    
    You play the azimuth test track (10Khz or similar) and adjust for
    maximum amplitude I think.
    
    Dave

    Yes, adjust for maximum amplitude. Of course, if you have a 'scope,
    you don't need a frequency counter (you can measure frequency with
    a 'scope easily).
    
    Keith

For what it's worth, I've managed to solve the problem:

The innards of my deck is largely empty space with just one PCB and only
two visible pots - for left and right channel bias adjustment.

The motor is a metal cylinder (totally enclosed, so rather difficult to open
in situ).  On the end is a small hole in the metal casing underneath which
is a piece of rubber with a cross cut into it.  Adjustment can be made by
inserting a precision screwdriver into this hole through the rubber and 
twiddling.

Now to get the reference speed:

I used two versions of the same album: a pre-recorded tape an LP.
I then played the album on the record deck, guaranteeing its speed by the 
strobe, and compared it against the pre_recorded tape in the cassette deck,
adjusted as necessary.  Of course, this assumes your tape is in good nick
and isn't stretched....


Re: -several  which suggested using an oscillator, recording onto tape then
	playing back, this will not work if you only have the one deck since
	it will record fast, then playback fast and therefore sound OK!

	While my wife was out last night I took the opportunity to open up my
deck without the usual objections that I would totally bugger it up in my 
efforts at repair (there are precedences for this). 

	Prior to opening it up I produce a test tape by playing a single note 
on my guitar and then using my electronic guitar tuner to check the accuracy of 
the playback. I had access to a total of four cassette decks all of which were 
running at slightly different speeds when I checked them, slight means less 1%. 

	However the playback deck in my double deck machine was definitely
running a good deal slower than the other transports. 

	I opened up the case to find that it was mainly air inside. There was 
one printed circuit board and prominently labelled were 4 presets: Deck 1 
normal speed, Deck 2 normal speed, Deck 1 high speed & Deck 2 high speed. By 
judicious twiddling & replaying of my test tape I was able to get them both 
running at the same speed both in normal & double speed mode.

	There were a number of other labelled preset potentiometers viz.
playback levels for left & right channels for Decks 1 & 2, recording bias
levels for left & right channels on the recording deck, and there was also a
pair of presets for recording level. The deck has automatic recording level 
which I know is anathema to hi-fi buffs but is convenient & produces acceptable 
results most of the time. The only criticism that I have had of it is that the 
recording level is a little low so that I have to crank up the volume on 
playback. A little judicious twiddling with these pots and I am now happy with 
the recording level.

Nigel

    These questions sort of come within the realm of this note title.
    
    They all apply to the Phillips cassette player in the car (I forget the
    model but anyone with a Cavalier/Astra will know which one I mean).
    
    1. It has recently developed a wow of about .5 - 1 Hz. I have used a
    cleaning cassette (the type with cams inside that scrubs the heads etc)
    but this doesn't improve things.
    
    2. I have one particular tape that plays at about 1/2 speed on on side
    only. This can sometimes be cured by starting and stopping the tape a
    few times.
    
    3. I have another tape that plays at about 2 times speed on one side
    only. This can be cured by playing that side in the other direction
    (it's an auto-reverse player).
    
    Any ideas? In the case of the last two I can see how the speed might be
    a fraction out but not by the amount I'm experiencing. In all cases the
    tapes in question play OK on the Grundig at home.
    
    Dick

        3. - 2 times speed.
        
                This is probably caused by the pinch roller not
                contacting the tape.  The tape is being pulled by
                the takeup reel instead of the capstan.
        
        2. - 1/2 speed.
        
                This is probably caused by a worn belt that is slipping.
                It could be caused by hardened rubber friction surfaces.
        
        1. Excessive wow.
        
                Hardened pinch roller, letting the tape slip by the
                capstan or slipping drive belt on capstan flywheel.
        
        What you need is a complete tear down of the cassette transport
        for cleaning, lubrication and renewal of friction surfaces.
        
        Bob

    Thanks Bob
    
    I was afraid that was what it might come to. I'll get to work on it.
    
    Still puzzled why 2 and 3 only happen on certain tapes though. However
    other people have told me similar stories.
    
    Dick