i actually just did this last night. took its supply down to like 4 watts
and couldn't hear any difference. seems to like 7.5v just as much as 9, and
500mA just as much as 1000....
i still want to find those voltage-gain-control and HF-control pins,
though...
On 8/17/07, Scott Nordlund <gsn10@...> wrote:
>
>
> I looked around a bit on google and apparently found the same thing you
> did (soft saturation and frequency adjustment pin)- neat but not exactly
> helpful.
>
> It might be an interesting exercise to run the amplifier chip from a
> separate power source and deliberately give it a low voltage or current to
> see if it starts acting up in a pleasing way. I suspect that it would be
> more worthwhile to try with something a little more analog-based or with a
> built-in speaker (connecting the adapter input to a bench supply), but if
> you want to play around without a datasheet, it could be worth trying.
>
> To: CZsynth@yahoogroups.com <CZsynth%40yahoogroups.com>
> From: ezra.buchla@... <ezra.buchla%40gmail.com>
> Date: Fri, 17 Aug 2007 04:16:51 +0000
> Subject: [CZsynth] cz101 amp: LA4138 (WAS: DIY AC Adapter for Casio
> CZ-101)
>
>
> well sure, it's good to think about the amplifier draw.
>
> BUT i'm not positive that a slightly (or considerably) low current
>
> would be a problem in this case. i'm also not sure it wouldn't be.
>
> the power amp in the cz101 is a sanyo LA4138. i can't find a pinout or
>
> a detailed datasheet for this chip, but other chips in the LA4x series
>
> are self-regulated, with max power output varying between like 2 and 4
>
> watts.
>
> i'd be very curious to know more about the LA4138, if you have any
>
> more detailed information than "hey, didja know? amps draw power!"... :)
>
> i'd especially be curious to know the pinout, cause then i could
>
> determine the actual operating conditions that the chip experiences in
>
> the cz101; without that it's a little hard to figure it out from the
>
> circuit board (or even the schematic if i had one).
>
> it'd be interesting to figure it out, cause there seems to be a couple
>
> possibilities for mods: an external resistor to fix voltage gain (the
>
> chip is reputed to have some kind of smooth saturation), a pin to
>
> change the high-frequency response...
>
> apparently there's an LA4140 series with the same pinout but i can't
>
> find that either.
>
> - eb
>
> --- In CZsynth@yahoogroups.com <CZsynth%40yahoogroups.com>, DJ Pat
> <djpat@...> wrote:
>
> >
>
> > Just some "common sense" for everybody...
>
> >
>
> > Anything with a TRS (a 19th century technology) output socket on it
>
> has an analog amp inside. The amount of juice you need to drive that
>
> amp is going to vary according to what you are playing, how many notes
>
> you play in a certain time frame, the velocity of those notes, etc, etc.
>
> >
>
> > And more importantly, the analog amp is going to drain as much power
>
> as it wants regardless of anything else going on inside the box. And
>
> if there isn't enough power, its going to suck up however much it can
>
> get, leaving less than enough behind for the guts of the synth.
>
> >
>
> > To get the best sound quality out of the beast, you are going to
>
> want the volume as high as possible without distortion, and you need
>
> to feed it an adequate amount of juice to provide that volume in a
>
> CLEAN manner, meaning you are better off giving it exactly what casio
>
> originally provided (or slightly more) than you are by under powering
>
> it. You can always turn the volume down and it won't need as much
>
> electricity... but then your signal to noise ratio gets worse...
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > ezra buchla <ezra.buchla@...> wrote:
>
> clues:
>
> >
>
> > my cz101 runs fine off 500mA.
>
> >
>
> > 300mA didn't cut it.
>
> >
>
> > -eb
>
> >
>
> > On 8/2/07, Fulfil Objective <kasploosh@...> wrote:
>
> > >
>
> > > Sweet math equation! I did a similar calculation myself last night
>
> > > and came up with almost the same answer.
>
> > >
>
> > > The thing is, most Casio keyboards will work form varying degrees of
>
> > > current and voltage. For example, I have a Casio MT-68, and the
>
> > > original adapter for it was 7.5V at 600mA. I cobbled together an
>
> > > adapter for it, by splicing a good plug onto a 7.5V at 200mA
>
> power supply.
>
> > >
>
> > > 600mA
>
> > > -200mA
>
> > > ------
>
> > > 400mA - That's how much power (current) I'm missing.
>
> > >
>
> > > Using your sweet equation I find out that I'm missing 400mA. And yet
>
> > > it works fabulously. An MT-68 is not very computery though, and can
>
> > > run from lower power. If you lower the power enough it will actually
>
> > > play quieter, rather than not operate at all (I think).
>
> > >
>
> > > The CZ-101 needs more current, but I'm guessing it also has a
>
> narrower
>
> > > range of operation. So the question is really: for people who have
>
> > > made their own power supplies, do you have any clue about the
>
> range of
>
> > > operation in a CZ-101?
>
> > >
>
> > > Thanks!
>
> > >
>
> > >
>
> > > --- In CZsynth@yahoogroups.com <CZsynth%40yahoogroups.com><CZsynth%40yahoogro
> ups.com>, PAJeff
>
> > > <pajeff@> wrote:
>
> > > >
>
> > > > 850mA
>
> > > > -210mA
>
> > > > ------
>
> > > > 640mA - That's how much power (current) you're
>
> > > > missing. I'm not surprised it doesn't work.
>
> > > >
>
> > > > Radio Shack has power supplies with multiple
>
> > > > plugs.
>
> > > >
>
> > > > PAJeff
>
> > > >
>
> > > >
>
> > > >
>
> > > >
>
> > > __________________________________________________________
>
> > > > Be a better Globetrotter. Get better travel answers from
>
> someone who
>
> > > knows. Yahoo! Answers - Check it out.
>
> > > > http://answers.yahoo.com/dir/?link=list&sid=396545469
>
> > > >
>
> > >
>
> > >
>
> > >
>
> >
>
> > [Non-text portions of this message have been removed]
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > [Non-text portions of this message have been removed]
>
> >
>
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