My POKEY experiments using nonstandard settings

[ivop]

56 minutes ago, emkay said:

How is this recorded? 

There's no metadata, but looking at the waveform in Audacity, this is a recording with Altirra. Running the binary sounds the same to me.

 

It also sounds quite good on atari800, and hence on the latest Atari800MacX, if I recall its name correctly

Edited March 1 by ivop

[emkay]

5 minutes ago, ivop said:

There's no metadata, but looking at the waveform in Audacity, this is a recording with Altirra. Running the binary sounds the same to me.

 

It also sounds quite good on atari800, and hence on the latest Atari800MacX, if I recall its name correctly

Would be great to have a recording from the real thing. 

[rensoup]

On 2/27/2021 at 6:08 AM, Synthpopalooza said:

Final .xex for E.X.O. Area 5.   Enjoy

Great sounds!

 

(but somewhat out of tune ?)

[Synthpopalooza]

I'm going to try a recording from real hardware tonight after work.  Curious to see if it sounds radically different from emulation.

Edited March 2 by Synthpopalooza

[VinsCool]

Just for fun I recorded a few executables I had around since I was playing around on my machine for some other tests and recordings  
Those were recorded off a NTSC 800xl.

This sounds pretty damn cool!

[Synthpopalooza]

So some explanations:

 

On Area 5 music, the setup is SKCTL two-tone, 1.79 plus 15 khz.  The frequency carrier is the second channel, and it takes values from the 15khz $Ax distortion table.  The modulation in first channel puts it into a saw wave which transposes it up an octave from the standard 15khz mode.  This means that the high part of the arpeggio may be a bit out of tune.  The delay echo effect is from using a higher modulation of that same saw wave, but a smaller frequency value decreases the apparent volume.

[emkay]

14 hours ago, VinsCool said:

Just for fun I recorded a few executables I had around since I was playing around on my machine for some other tests and recordings  
Those were recorded off a NTSC 800xl.

This sounds pretty damn cool!

 

 

Thanks for the recordings. 

They really show that POKEY sounds better than the emulations.

It's just that those high sounds have a lot more power than the low sounds. It's how Pokey generates the waves (density of voltage switches).

A little less volume on the high sounds really would be great. Particular the gen 2 sound. 

 

[Synthpopalooza]

Still busy.

 

Latest task:  Documenting the AUDCTL=$40 SKCTL=$8B two tone mode using $4x distortion in the first channel, and $Cx frequencies in the second.

 

This mode is complex because it is subject to all the quirks of polycounter behavior:  Specifically,  frequencies are dependent on the prime numbers of 3, 5, and 31.

 

One of the first discoveries I made is that if you place a mod 15 (divisible by 15) setting in the first channel,  you get the standard $Cx distortion using those frequencies in the second channel, but as the modulation increases in the first channel, a fuzzbox distortion effect is introduced.   

 

Another discovery:  Using the other mod 5 settings in the first channel, gets you several distinct electric guitar timbres, tuned to the $Cx mod 3 settings.  I have a partial table here.  Note that the $Cx frequencies have to be varied occasionally,  and in some cases you have a range that can be played.

 

More work remains ... several other combinations and note tables are possible.  There is also a setting using mod 31 frequencies that makes eerie alien sounds.

 

AUDCTL40_SKCTL8B_AUDC14x_table_2.0.txt

Edited March 8 by Synthpopalooza

[Synthpopalooza]

Also ... Thanks to some suggestions, I made another discovery ... When using reverse 16-bit mode, in some cases playing both channels will add harmonics to your notes.  This method works with A and C distortions at 64khz ... And also 2, 4, and 8 poly9 as well at 1.79 mhz.  Will experiment with these soon.

[Synthpopalooza]

A partial documentation of $4x $Cx SKCTL has been finished.

 

First table:  AUDF1=mod 15.  AUDF2=standard C distortion.  As AUDF1 increases, a fuzzbox distortion effect is introduced.

 

The second category is for AUDF1=mod 5 values.  There are four subcatgories:

 

* AUDF2 roughly equals values from distortion C mod 3 (RMT C)

* AUDF2 roughly equals values from distortion C non mod 3 (RMT E)

* miscellaneous frequencies

* AUDF2= 0 to 11, which produce solid tones only (not yet finished)

 

Still to do:

 

AUDF1=mod 3

AUDF1=non mod 3

 

AUDF2=mod 5 (all AUDF1 instances ... more guitars)

AUDF2=mod 31 (which mainly produce only C# notes, but a wide variety of timbres!)

 

AUDF1=mod 31 (alien heartbeat sounds)

 

More soon!

AUDCTL=$40, SKCTL=$8B AUDC1=$4x table 2.0.txt

[Synthpopalooza]

Just an update:  Working my way through mod 3 ... we are getting guitars here with a tuning range up into the 5th octave.

 

So there are three subtables:

 

mod 3/mod 3

mod 3/mod 5

mod 3/no mod

 

Each has different behaviours.

 

 

[Synthpopalooza]

The latest:  Area 2 music from the upcoming EXO game on the 7800.

 

Setup is:

 

AUDCTL=$60 (1.79 mhz on first and third channels)

SKCTL=$8B (two-tone mode)

 

00 - $4x @1.79 mhz ... frequency modulation

01 - $Cx distortion ... frequency carrier for 00

02 - $Cx @1.79 mhz ... high saw lead

03 - $Ax standard square wave ... arpeggios

 

This uses the SKCTL mode I was trying to document above.  In this case, we use frequencies divisible by 5 in the first channel, when paired with frequencies from the standard $Cx table in the second channel, guitar modulations are made.  When a frequency divisible by 15 gets used in the first channel, the effect is a fuzzbox-distorted C distortion.  Playing the carrier frequency in distortion C on the second channel thickens out the sound.

 

Playing distortion C on the second channel only works when using mod 5's or mod 15's in the first channel.  Other combinations (mod 3's or non mod's in first channel) won't work with C distortion in channel 2.

 

 

exo-area2.s exo-area2.xex exo-area5.asm

[Kyle22]

deleted.

Edited April 27 by Kyle22

[rensoup]

8 hours ago, Synthpopalooza said:

The latest:  Area 2 music from the upcoming EXO game on the 7800.

Seems impossible to download the file... not sure if there's a problem with AA whenever there are audio files on the page ?

[Synthpopalooza]

AA is mrssing up.  It's just an .xex plus sources.  😳 ... no idea why

[Synthpopalooza]

del ... dupe post

Edited April 27 by Synthpopalooza

[rensoup]

8 hours ago, Synthpopalooza said:

AA is mrssing up.  It's just an .xex plus sources.  😳 ... no idea why

I meant mp3(?) files that Vinscool posted earlier, could be a coincidence but whenever there are audio files in a thread, loading issues crop up.

[Synthpopalooza]

ahh yes those ... good to know for next time. 

[Mathy]

Hello guys

 

The xex-file downloaded just fine here.

 

Sincerely

 

Mathy

 

[Synthpopalooza]

Next up:  SKCTL $4x distortion,  1.79+15khz.  Some of the same qualities as above,  but you get to use 15khz, if you wanted distortion A bass on another channel.  Demo soon. 

[rensoup]

Well I was never able to download those files, instead of showing the download count, they're now in a permanent "fetching info" state

[Synthpopalooza]

Just sent you a PM with the files again ... give it another try

[rensoup]

On 5/1/2021 at 4:57 AM, Synthpopalooza said:

Just sent you a PM with the files again ... give it another try

I had to LZSS it!

 

works pretty nicely with custom SKCTL...

 

(DOH can't even attach files either in this thread...)

[Synthpopalooza]

So as an update:  Working my way through SKCTL $4x distortion, 1.79+15 ... discoveries so far:

 

AUDF1=mod 15 gets you the $Cx bass in 15 khz, with fuzziness added the greater AUDF1 is

 

AUDF1 mod 31 gets those alien sounds again

 

Others get you varying guitar timbres.  Each AUDF1 setting has a unique note table and timbre,  which opens up the possibility of dozens of note tables.

[Synthpopalooza]

Dupe post.  Damn android phone ...

Edited May 15 by Synthpopalooza