Baslinux mailing list

[sindi keesan <keesan AT sdf.lonestar.org>]

On Thu, 9 Jun 2005, David Moberg wrote:

> ----- Original Message -----
> From: "sindi keesan" <keesan AT sdf.lonestar.org>
>
> > What the Vibra16X appears to be lacking is 'full duplex', the
> > ability to play and record at the same time, for which you
> > supposedly need a high DMA channel.  The Opti is set to two
> > different low DMA channels, the Vibra16X both DMAs to the same
> > channel.  Another site said you can play and record at the same
> > time if both channels are the same.  I don't follow all this.
> > Unless I start recording I won't try too hard to follow.
>
> I don't use full duplex, anyhow.
> /usr/src/linux/Documentation/VIBRA16 says that VIBRA16 full-duplex
> mode is "unsupported".

Vibra16C does full duplex (DMA16 = 5, 6 or 7) but Vibra16X does not.  I 
actually found them listed this way - the X is half-duplex.  You can't 
play and record at the same time.

 >
> [Opti]
>
> > No matter how low we turned the volume, with jumpers set to
> > 'speaker' it sounded bad.  Dying transistor?
>
> Or dead transistor. Some amplifier designs use two transistors,
> one to amplify each half of an audio wave. When one dies, you
> only get half of the wave, which sounds terrible. Somewhat like
> a cranked amp, only worse.

Some cards have one or two large transistors on heat sinks.
Vibra16C CT2960 has two (and speaker or line out).
Vibra16C CT4180 has only line out, and nothing resembling a transistor.
But there is a speaker/line jumper and speaker sounds louder.

Creative CT2940 - two cards, both have one large transistor on a heat 
sink, and one smaller transistor.  One has line and speaker out, but one 
is missing the speaker out and the line out is soft. A few other chips and 
capacitors are also different.  The transistor may be leftover and not 
serving any purpose.

The older CT1470 Creative cards have 2 transistors and vol dial (but no 
speaker out).

The newer AWE64 4520 has both line and speaker out, but no transistors 
that I can see.  What does the 4000 series use to amplify?  These cards 
get quite warm with minimal sound playing.

The Opti has only line out, and only one very small transistor.  It came 
with a vol. control and I had to use it to turn down the volume to avoid 
the poor sound quality, so it is probably one tiny transistor going bad.

> > Some have a choice of speaker or line and no
> > heat sinks, and we will set those to line to avoid overheating.
>
> I doubt a 5-watt amplifier will overheat anything unless there's
> a short in it.

Well, we will still set them to line (if no heat sink) and use with 
powered speakers for better sound.

> [MIDI trackers and similar software]
>
> > So do you specify the pitch, duration, and volume of each note with
> > software?
>
> Yes. With a MIDI keyboard which cannot sense the amount of force
> with which a key is pressed, the volume is either all the same
> or you need to set that manually (probablly by adding forte,
> mezzopiano, etc. marks or by using a volume slider)

I will listen for volume changes in midi files, but what I have is mainly 
harpsichord music.  Since harpsichords cannot vary volume, they must be 
easier to record to midi.

> > Are there OCR type programs that can automatically convert
> > a musical score into an uninterpreted midi file?
>
> I'm sure there are. Google "music ocr" without quotes.
>
> > You might want as many as four channels for each violin part.
>
> MIDI allows for chords on one channel, so you only need one
> channel for each kind of instrument. Of course, General MIDI
> specifies more than one instrument for each major class (e.g.
> Acoustic Grand and electric pianos. also e.g. wood, fingered,
> slap, acoustic, and electric bass). But for multiple notes
> with one instrument (say, acoustic grand piano) only one
> channel is needed.
>
> > Can you hear differences in quality between various sound cards?
>
> I'm not Ron, but I can hear big differences between different
> sound cards. For instance, noise level (compare with and without
> amplification).

I will try listening to a ripped music CD with various cards.  The Opti 
may go at the bottom of the list.

> David