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Amstrad CPC volume decibel table?

Started by mr_lou, 09:44, 10 April 24

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mr_lou

Here is a nice table showing Amiga volume decibels.
http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node00F1.html

Does anyone know where I can find a similar table for the Amstrad CPC volumes?

McArti0

AY3-8912 has manual and amplitude curve. Resistors mixer at mono line is another then resistors mixer at stereo lines.
CPC 6128, Whole 6128 and Only 6128, with .....
NewPAL v3 for use all 128kB RAM by CRTC as VRAM
TYPICAL :) TV Funai 22FL532/10 with VGA-RGB-in.

mr_lou


Targhan

These are the 16-bit values I use for Arkos Tracker. They are more accurate than the datasheet you can find, as they were tested electronically by Grim and Zik.

0, 231, 695, 1158, 2084, 2779, 4168, 6716,
8105, 13200, 18294, 24315, 32189, 40757, 52799, 65535
Targhan/Arkos

Arkos Tracker 2.0.1 now released! - Follow the news on Twitter!
Disark - A cross-platform Z80 disassembler/source converter
FDC Tool 1.1 - Read Amsdos files without the system

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McArti0

Hmm ay3 manual show different values.

2 steps down = half values down.

1, 0.707 , 0.5 , 0.303 , 0.25 , 0.1515 , 0.125 ......

CPC 6128, Whole 6128 and Only 6128, with .....
NewPAL v3 for use all 128kB RAM by CRTC as VRAM
TYPICAL :) TV Funai 22FL532/10 with VGA-RGB-in.

Targhan

They're probably wrong :). Grim and Zik recorded the values directly from the CPC.
Targhan/Arkos

Arkos Tracker 2.0.1 now released! - Follow the news on Twitter!
Disark - A cross-platform Z80 disassembler/source converter
FDC Tool 1.1 - Read Amsdos files without the system

Imperial Mahjong
Orion Prime

McArti0

But from sound or one stereo channel?
CPC 6128, Whole 6128 and Only 6128, with .....
NewPAL v3 for use all 128kB RAM by CRTC as VRAM
TYPICAL :) TV Funai 22FL532/10 with VGA-RGB-in.

eto

Quote from: Targhan on 13:16, 10 April 24These are the 16-bit values I use for Arkos Tracker. They are more accurate than the datasheet you can find, as they were tested electronically by Grim and Zik.

0, 231, 695, 1158, 2084, 2779, 4168, 6716,
8105, 13200, 18294, 24315, 32189, 40757, 52799, 65535

That's quite a difference to the expected values. At which point did they test those values? IC output pin of each channel? Or after the sound is mixed? 

I once started testing the output levels (to be fair, with a multimeter only) and it was very close to the theoretical value based on the data sheet and how the CPC mixes the channels. 


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