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  • From: sindi keesan <keesan AT sdf.lonestar.org>
  • To: baslinux AT lists.ibiblio.org
  • Subject: Re: [BL] Re: Interrupts and isapnp
  • Date: Fri, 10 Jun 2005 02:12:49 +0000 (UTC)

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




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