Playstation as CD-player

[Mick_F]

Some of the posts in this thread made me curious how a the PS1 would sound with a linear PSU. When revisited the linear supply I designed some time ago (and which I never built), I had some ideas how to improve the matter. As a result, I have now a completely new design for you. This time, it is tested

It is based on two LM317 regulators as the previous one, but now the 3.6 V supply line is double regulated with a Zener regulator. Also, the design suggests a splitting of the supply stages in an external case and the PS1 case, respectively. I have also added a small "reservoir stage" for the 7.6 line to be installed close to the PS1 board.

Schematic:

First regulator stages in case:

It works well and sounds marvellous.

Read more on my
website


Mick

 

[AnthonyPT]

Hi Mike,

Nice power implementation.-) Not quite sure of the actual size
of your box overall from your pics. The use of separate torroidals for analogue and digital seems good practice although not quite a trueism here. Is it so that there is less chance of digital RF leaking back and polluting the other side of a shared tranny? Was pondering on using an 80va plus 50va either 9+9v or 12+12v
or if the RF leakage is not an issue a 160va 9+9V Tranny.
Any thoughts? So now do you find that the sound is that much better than your outboard digital supplies?

Regards
AnthonyPT

 

[Mick_F]

The two trafos are not for a separate digital and analog supply. They are just for the two voltages required.
D and A supply are coupled by resistors on the board, as they have to be switchted in the right order. Full separation is therefore critical.

A 9+9 V trafo should be ok but the you may have to lower the value of the serial resistors. Calculate the maximum value by assuming current draws of about 0.5 A per line. This will of course lower the performance of the lpf.

Mick

 

[johnm]

Wow... awsome work Mick (as always) !! Could you tell us a little bit more about how this improved the sound? I'm guessing it's more powerful, and the silences are... well... more silent?!? Did it improve the solidity of the bass?

Would be fantastic to have some circuit boards made up for this project... anyone good with eagle??

- J

 

[phn]

I think I should be able to make one.

I also have a slightly different design for the 3.6V output. Ignore the output shown in the image. The value of the R1 sets the output.

 

[Mick_F]

Wow... awsome work Mick (as always) !! Could you tell us a little bit more about how this improved the sound? I'm guessing it's more powerful, and the silences are... well... more silent?!? Did it improve the solidity of the bass?

Would be fantastic to have some circuit boards made up for this project... anyone good with eagle??

- J

I have not yet made real AB comparisons, I will do that, as always, with a friend. Soon.

My first impressions, however are, that the bass considerably improves and the sound is altogehter somewhat fuller. Also, the stage extends, it is wider and there is more space between the instruments.

Mick

 

[Mick_F]

I think I should be able to make one.

I also have a slightly different design for the 3.6V output. Ignore the output shown in the image. The value of the R1 sets the output.

Where is the voltage reference in your circuit? And what is the advantage over the other one ?- yours needs much more parts

Also, is beta the hfe of the transistor? If so, the resistor between collector and base of Q1 is too large. Keep in mind that the current is 0.5A!

Mick

 

[phn]

I wouldn't know if it's better. The Zener is what worried me. People tend to not like it, say it's noisy. I wouldn't know.

I asked about regulated PSUs on the PSU forum some time ago trying to understand this stuff. This is the design I toyed with.

I do not need it. I have a trafo with four secondaries.

I do not know why it says beta.

 

[zBuff]

I've got a PS1 with a simplifed output path and the standard powersupply running through a TA2020 running on a SMPS. I got a computer surge board with a simple RFI/EMI filter just recently, so I thought what the heck I'll try out my audio equipment on it before it goes to use on the computer. I plugged just the PS1 into the board by itself and the Tamp was running directly off the other socket on the wall. I was absolutely dumbstruck, the imaging and clarity just bumped up another huge notch, the whole sound was just that much more natural and musical. Now I thought that maybe the mains power was just dirty so I thought I wonder how much improvement I was gain once I plugged in the Tamp to the same surgeboard, so in it goes and surprisingly the sound gets all muddy again and goes pretty much back to the way it sounded before with a surgeboard at all.

I'm guessing either my SMPS for the tamp is causing interference or the PS1 powersupply is, which is strange though as I thought the PS1 powersupply already has a basic RFI and EMI filter in it. Is this normal?

Could the PS1 be quite susceptible to RFI/EMI interference? I've honestly never noticed such a difference from using a powerfilter before.

 

[tubenut]

SMPS tends to pollute the supply for other components. Filters often work in both directions, ie you can use them to keep the noise generated in, and keep exterior noise out. If two pieces generate different levels and types of noise, putting them on the same filter cct may make things worse....

 

[Code]

I have just replaced the output stage as per Micks instructions.

Now i hear loud humming from both channels, with the music in the background. This happens with the playstation switched on or off, but stops when unplugged.

I have wires directly from pin 15 and 16 leanding to 1uf capacitors which then connect to the rca plugs. I have used 18k resistors to ground.

edit: strange occurance..

One channel is working perfectly, IF:
Both resistors are disconnected and the opposite channel is connected directly to ground.

unfortunatly this means the other channel is silent

 

[Mick_F]

Check all your connections. Check for shorts. Check once again.

Sorry, I have no better comment

 

[Code]

The value of the resistor seems to be the influencing factor.

I tried 10 18k resistors in parallel on each side, hum was reduced as i added each one!

So i then tried a 56 ohm resistor on each side and the hum is gone but the sound is very quiet and 'tinny'.

edit:

This calculation may provide the answer?

f = 1/(2 x Pi x R x C)

so..

1/
6.3
*18000
*0.000001
= cutoff frequency
8.8183421516754850088183421516755

Soo.. what is that 8hz? :|

 

[phn]

There should be no bass with a 56 ohm resistor. Also 18k is too low. I think 100k is closer to what you need.

 

[Code]

I dont have any 100k resistors, so i added 3 33k resistors in series to one side.

From this I get good sound on one side (although some low frequency hum) and silence on the other speaker.

If i try to add the same resistor configuration to the other rca plug, the sound returns to no bass and very little midrange? lower volume also.

maybe this image will help;
http://www.dicity.net/23.jpg

 

[phn]

The 8 Hz is the roll-off. You have a high-pass filter that lets through signals higher than 8 Hz.

I would drop the resistors for now. Get the PSX to work without them. You could drop the caps as well. Later you can add those things.

Edit: 47k will probably do.

 

[Code]

Ive dropped the resistors, changed the capacitors to 10uf, now im left with sound from the left channel only.

As far as im aware my amp doesnt have any dc blocking, would i be taking a risk removing the caps?

 

[phn]

No risk involved. Nasty sound at worst. Just ditch them.

Edit: I would ditch the volume pot as well. First get it to work.

 

[Code]

ah stupid mistake, the left rca was only connected to ground..

Now i have them:

chip - > capacitor - > amp

the grounds are unconnected and all i hear it hmzzmmzmmmmmzmmm.. lol

if i connect the ground on either side to the capacitor, the opposite channel begins to work

 

[Code]

Same situation without the caps

edit: ooh i can hear the music behind the humming now!