UAS: Ultimate Atari Sound, reproducing the UAV audio companion

[tane]

I'd like to share this audio improvement project I've been working and testing last weeks, recreating the audio companion for the UAV developed by Bryan, taking the Pokey output to generate a new signal. In a phrase: it's like to listen an "old sound in a new machine" instead of to listen an "old sound in an old machine". And it works.

 

 

Quality sound:
Time ago I was looking for an audio improvement, unfortunately there wasn't a good comparison or comments about a difference of this kind of projects with the original Atari sound, so I decided to build my own and play with it. I played changing components several times to get a clearer and smooth sound, and also increasing the power. The feeling is like listening an mp3 at 96kbps and then to listen the same song at 128kbps. You can hear some improvements in some frequencies, and it feels better, but of course it's far away from a 320kbps mp3. The main noticeable changes are with bass related sounds, now they are not lost in the background. With the sharp sounds the difference is less noticeable, but in overall I'm happy and it's a recommended improvement.

 

(For this post I tried to make a video if we are talking about sound, but for some reason when connecting the 3.5mm cable to the camcorder, it appeared a noise not noticeable with the speakers and with the TV, so it wasn't a good comparison test to be published).

 

 

Further works:

 

Pseudo-stereo improvement:

Since the 99.9% of the games and demos are mono, and the only way to convert them to stereo is to tell each developer to re-write the code, I've been searching for a way to have some kind of stereo sound. I started with splitters to divide the signal in 2 according to its frequency, but those tests were unsuccessful and with undesired results. So then, an approach to have some kind of stereo is to generate 2 signals (left-right) with different tone. And so far so good. It's not stereo but if you move around the room it's possible to hear some louder sounds to the right, and others heavier to the left, instead of to have the same mono sound to the left and to the right.

 

Internal speaker:

And the last sound-related improvement I'm testing is to install a small speaker inside the Atari, with an amplifier. Having an untouched 3rd signal with the original tone at low volume in the room, it will create a more spatial effect. It'll require more energy and it's not tested yet, but I think it will be fine, and also I will add a switch to turn it off if it becomes louder.

 

 

[Kyle22]

That's all nice and everything, but I love the audio and video of my original 800. Maybe on some XL models this would be helpful? Or maybe just remove a capacitor or 2.

[JoSch]

(For this post I tried to make a video if we are talking about sound, but for some reason when connecting the 3.5mm cable to the camcorder, it appeared a noise not noticeable with the speakers and with the TV, so it wasn't a good comparison test to be published).

 

If the noise is a constant humm, most likely it is because the recorder and the computer have no common ground, but speakers, TV and the computer have.

This ground loop is the bane of many audio/video productions.

[+Nezgar]

Sounds interesting.... Maybe you could record and post some example direct audio output from your circuit, playing some well known tunes like BallBlazer or M.U.L.E.?

[tane]

Having fun today with this. The final changes. Worth to try.

 

 

 

 

 

[jamm]

Interesting.  What kind of Atari are you testing on?

[tane]

3 minutes ago, jamm said:

Interesting.  What kind of Atari are you testing on?

XE

[ivop]

Do you plan on also mixing in GTIA consol speaker and SIO Audio In?

 

A common way to turn mono into pseudo-stereo, is phase shifting one channel slightly relative to the other channel. 180 degrees is the easiest, because there you just flip/mirror the signal. Reversing the polarity

 

 

[tane]

1 hour ago, ivop said:

Do you plan on also mixing in GTIA consol speaker and SIO Audio In?

I usually don't use the SIO.

 

1 hour ago, ivop said:

A common way to turn mono into pseudo-stereo, is phase shifting one channel slightly relative to the other channel. 180 degrees is the easiest, because there you just flip/mirror the signal. Reversing the polarity

I tested something like the following, but it didn't work as expected.

 

 

 

There are others projects, but not tested:

 

Edited March 31, 2020 by tane

[ivop]

Perhaps this could be helpful:

 

http://zpostbox.ru/how_to_create_stereo_from_mono_signal.html

 

https://www.aaroncake.net/circuits/stereosynth.asp

 

The last one uses the TDA3810 (notice the D and not TBA as some sources say).

 

They are around a dollar each on ebay.

 

TDA3810.pdf

 

 

[tane]

Uploading 6 Mono to Pseudo-Stereo Projects in PDF, there is one with a note to the previous PDF.

 

This website has some audio examples at the end:

https://theramsgatehovercraft.com/2013/05/11/mono-to-stereo-effect/

 

Examples:

First mono, then pseudo-stereo, sounds promising. Hopefully someone will try it for the Atari.

 

 

Piano: First mono, then pseudo-stereo:

 

 

How to create stereo from mono signal.pdf Mono To Stereo Synthesizer.pdf Stereo Simulator – Electronics Project.pdf Stereo Simulator.pdf Mono to Stereo Effect.pdf Stereo simulator based on TDA3810.pdf demo-piano.mp3 demo-suvarna.mp3

Edited March 31, 2020 by tane

[tane]

Added the keyboard sounds from the GTIA: