+3 Audio problems (Again) - Sinclair

This is a discussion on +3 Audio problems (Again) - Sinclair ; Hihi Since nobody seemed to have a spare +3B board, I've been trying to replace the audio entirely, aiming for a speaker inside the machine Since pins 1, 4 and 5 on the AY are connected together, I just cut ...

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  1. +3 Audio problems (Again)

    Hihi

    Since nobody seemed to have a spare +3B board, I've been trying to
    replace the audio entirely, aiming for a speaker inside the machine

    Since pins 1, 4 and 5 on the AY are connected together, I just cut the
    track leading from pin 1 and connected a small LM386 based amplifier
    direct to chip

    This one in fact: http://web.mit.edu/6.s28/www/schematics/lm386.htm

    However, it didn't work, if I feed it the output from the tape socket
    I get (very loud) 48K audio but nothing at all from the AY

    It's possible from what I've read the AY output just isn't enough but
    I thought I'd hear something even if very quiet and I don't..

    Some people have suggested lifting the pins instead of cutting the
    track, would that make any difference? from what I can see on the
    other side they're just connected together on the bottom and don't
    seem to go anywhere..

    Suggestions would be helpful...

    Thanks

    (PS: I tried the single resistor fix for TR5 but it was still badly
    distorted so I took that out again)

  2. Re: +3 Audio problems (Again)

    Long time ago, but I seem to recall, you need to terminate the outputs at a
    resistor potential divider circuit and also attenuate the 48 k sound as well
    before mixing them into an amp. The person who designed the input and output
    obviously must have been deaf and using a 50w amp to play tapes in...
    :-)
    Brian

    --
    Brian Gaff - briang1@blueyonder.co.uk
    Note:- In order to reduce spam, any email without 'Brian Gaff'
    in the display name may be lost.
    Blind user, so no pictures please!
    "Adam" wrote in message
    news:12f2cae9-a16e-4265-9338-f577a0e81f93@f63g2000hsf.googlegroups.com...
    > Hihi
    >
    > Since nobody seemed to have a spare +3B board, I've been trying to
    > replace the audio entirely, aiming for a speaker inside the machine
    >
    > Since pins 1, 4 and 5 on the AY are connected together, I just cut the
    > track leading from pin 1 and connected a small LM386 based amplifier
    > direct to chip
    >
    > This one in fact: http://web.mit.edu/6.s28/www/schematics/lm386.htm
    >
    > However, it didn't work, if I feed it the output from the tape socket
    > I get (very loud) 48K audio but nothing at all from the AY
    >
    > It's possible from what I've read the AY output just isn't enough but
    > I thought I'd hear something even if very quiet and I don't..
    >
    > Some people have suggested lifting the pins instead of cutting the
    > track, would that make any difference? from what I can see on the
    > other side they're just connected together on the bottom and don't
    > seem to go anywhere..
    >
    > Suggestions would be helpful...
    >
    > Thanks
    >
    > (PS: I tried the single resistor fix for TR5 but it was still badly
    > distorted so I took that out again)




  3. Re: +3 Audio problems (Again)

    Hihi

    On 21 Jun, 13:35, "Brian Gaff" wrote:
    > Long time ago, but I seem to recall, you need to terminate the outputs ata
    > resistor potential divider circuit and also attenuate the 48 k sound as well
    > before mixing them into an amp. The person who designed the input and output
    > obviously *must have been deaf and using a 50w amp to play tapes in...


    Ahh, the amp I made has a seperate input for the 48K sound and can mix
    it in at the right level, the AY sound is what concerns me ;p

    When you say terminate the outputs at a potential divider circuit do
    you mean cut between R72 and C38 and take it from there?

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