Apparently-To: john.smith@gravis.com


GUS Programmer's Digest     Tue, 22 Feb 94  4:26         Volume 9: Issue  13  

Today's Topics:
               GUS Programmer's Digest V9 #12 (2 msgs)
                        pitch of musical notes
                             which pitch?

Standard Info:
	- Meta-info about the GUS can be found at the end of the Digest.
	- Before you ask a question, please READ THE FAQ.

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Date: Mon, 21 Feb 1994 12:59:09 -0500 (EST)
From: Phat H Tran <ptran@sciborg.uwaterloo.ca>
Subject: Re: GUS Programmer's Digest V9 #12

On Mon, 21 Feb -1, GUS Programmer's Server wrote:

> Date: 21 Feb 94 11:03:00 MET
> From: "VISX80::GRECNER" <GRECNER%VISX80.decnet@musx53.zfe.siemens.de>
> Subject: GUS D/A converter
> 
> Does anyone know how many bits does GUS's A/D converter use ?
> For the full 32 16-bit voices it needs 21 bits in fact. Since it's
> only 14 voices in the best quality, it still needs at least 20 bits.

The GUS uses a 16-bit DAC.

> I know that in proffesional devices (synths) they normally use 
> 24-bit internal signal processing and 18-bit output A/D converters.
> So, how is it with GUS ? Does it utilize 16 bit ADC only ? How is
> then polyphonie implemented ? I'm asking because i find my new GUS
> not dynamic enough (when compared to Ensoniq EPS-16 +, for example,
> which is a proffesional 16 bit sampler with 20 voices ).

The GUS' MIDI drivers put a cap on how loud the samples get played.
For example, the percussions don't play loudly enough for my tastes.
The GF1 is capable of much greater dynamic range than the MIDI
drivers allow.  Good MODs (especially those that use 16-bit samples,
like tek2.ult) played on a good player (such as Metal) have much 
better dynamic range.

Phat. 

------------------------------

Date: Mon, 21 Feb 1994 11:33:01 -0700 (MST)
From: "Shawn T. Rutledge" <rutledge@enuxsa.eas.asu.edu>
Subject: Re: GUS Programmer's Digest V9 #12

> From: "VISX80::GRECNER" <GRECNER%VISX80.decnet@musx53.zfe.siemens.de>
> Subject: GUS D/A converter
> 
> Does anyone know how many bits does GUS's A/D converter use ?
> For the full 32 16-bit voices it needs 21 bits in fact. Since it's

Why do you think this is the case?  It doesn't seem to me that it would
have to be.  The GUS's onboard processor could mix the voices together
in software and then divide by a number that reduces the largest value
that occurs to a 16-bit number.  You would not lose any headroom
that way; I mean you would, but the sum still has 16-bit resolution, 
which is most of our range of hearing, and the card can still be
advertised as a 16-bit synth.

> only 14 voices in the best quality, it still needs at least 20 bits.
> I know that in proffesional devices (synths) they normally use 
> 24-bit internal signal processing and 18-bit output A/D converters.

By doing what I just explained perhaps?

> So, how is it with GUS ? Does it utilize 16 bit ADC only ? How is
> then polyphonie implemented ? I'm asking because i find my new GUS
> not dynamic enough (when compared to Ensoniq EPS-16 +, for example,
> which is a proffesional 16 bit sampler with 20 voices ).
> Thanks for comments.

-- 
  _______                                                             KB7PWD
 (_  | |_)                                            shawn.rutledge@asu.edu
 __) | | \__________________________________________________________________
* GUS * sci fi * Internet * ham radio * C * techno * packet * anti-Macintosh * 

------------------------------

Date: Mon, 21 Feb 94 13:11:00 CST
From: eason@ncrnd3.StPaul.NCR.COM (Dale Eason)
Subject: Re: pitch of musical notes

Shawn T. Rutledge wrote that A is 400 hz and that middle C is 256 hz.
That is incorrect. 

The A above middle C is 440 hz  each adjacent note is called a half step.
Assending half steps are found by multplying the current note by the 12th root of
2 (approximately 1.059) and decending steps are found by dividing the current note
by the 12th  root of 2.

This gives the what is called equal temperment tuning.

I think middle C is midi note 60. That makes the A midi note number 69.

Dale Eason

------------------------------

Date: Tue, 22 Feb 94 14:55:22 EST
From: stephen@csis.dit.csiro.au (Stephen Barrass)
Subject: which pitch?

 ..More about pitches and fundamental frequencies

freq+halfstep = freq * 2^(1/12)

This equation given in a previous post is correct but will cause significant
round-off errors if used recursively.

An alternative is to use a note number to freq conversion as follows

freq = rootF * 2 ^ (notenumber/12)

where rootF is the frequency of the 0th note.
Since we are using midi this is midi note 0 = C0 = 8.175Hz
(based on C5 = middle C = 261.6 Hz : reference from "Keyboard" March 1993 pp 56)


          Table 2: Summary of MIDI Note Numbers for Different Octaves
 (adapted from "MIDI by the Numbers" by D. Valenti - Electronic Musician 2/88)


Octave||                     Note Numbers
   #  ||
      || C   | C#  | D   | D#  | E   | F   | F#  | G   | G#  | A   | A#  | B
 -----------------------------------------------------------------------------
   0  ||   0 |   1 |   2 |   3 |   4 |   5 |   6 |   7 |   8 |   9 |  10 |  11
   1  ||  12 |  13 |  14 |  15 |  16 |  17 |  18 |  19 |  20 |  21 |  22 |  23
   2  ||  24 |  25 |  26 |  27 |  28 |  29 |  30 |  31 |  32 |  33 |  34 |  35
   3  ||  36 |  37 |  38 |  39 |  40 |  41 |  42 |  43 |  44 |  45 |  46 |  47
   4  ||  48 |  49 |  50 |  51 |  52 |  53 |  54 |  55 |  56 |  57 |  58 |  59
   5  ||  60 |  61 |  62 |  63 |  64 |  65 |  66 |  67 |  68 |  69 |  70 |  71
   6  ||  72 |  73 |  74 |  75 |  76 |  77 |  78 |  79 |  80 |  81 |  82 |  83
   7  ||  84 |  85 |  86 |  87 |  88 |  89 |  90 |  91 |  92 |  93 |  94 |  95
   8  ||  96 |  97 |  98 |  99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107
   9  || 108 | 109 | 110 | 111 | 112 | 113 | 114 | 115 | 116 | 117 | 118 | 119
  10  || 120 | 121 | 122 | 123 | 124 | 125 | 126 | 127 | 


Using the equation and the table above the following table of root 
frequencies was calculated for each MIDI note

C0 to G10 in Hz
---------------
8.175   8.6614   9.1764   9.7217   10.300   10.912   11.561   12.249   12.977 13.749   14.566   15.432
16.350   17.323   18.353   19.443   20.599   21.824   23.122   24.497   25.954
   27.497   29.132   30.864
32.700   34.646   36.706   38.887   41.199   43.648   46.244   48.994   51.908
   54.995   58.265   61.728
65.400   69.291   73.412   77.774   82.397   87.296   92.489   97.989   103.82
   109.99   116.53   123.46
130.80   138.58   146.82   155.55   164.79   174.59   184.98   195.98   207.63
   219.98   233.06   246.91
261.60   277.17   293.65   311.09   329.59   349.18   369.95   391.96   415.26
   439.96   466.12   493.82
523.20   554.33   587.29   622.19   659.18   698.37   739.91   783.91   830.53
   879.92   932.24   987.64
1046.4   1108.7   1174.6   1244.4   1318.4   1396.7   1479.8   1567.8   1661.1
   1759.8   1864.5   1975.3
2092.8   2217.3   2349.2   2488.8   2636.7   2793.5   2959.6   3135.6   3322.1
   3519.7   3729.0   3950.6
4185.6   4434.6   4698.3   4977.5   5273.4   5586.9   5919.3   6271.3   6644.2
   7039.3   7457.9   7901.2
8371.2   8869.3   9396.7   9955.0   10547.   11174.   11839.   12543.

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