PCE Audio Amplification

[mackdanger]

I did a search of threads here and found a little info, but not exactly what I was looking for. I knew the audio from the PCE was a little weak, but I had no idea how weak until I looked at the wave forms in a video editor. For my original RGB mod, I used the old schematic from the Japanese "All About PC Engine" book. On the schematic, it shows both audio lines going through a capacitor. Will that help boost the audio, because I left that off. Also, I was rummaging around on some Japanese blogs and found a guy that made an audio amp that you can see here:

http://blog-imgs-64.fc2.com/f/c/2/fc2canned/th_PCE_SOUND.jpg

Two of those would have to be made, one for each line. Would something like that be good? Just to clear up any possible confusion, I am not talking about low audio due to bad capacitors.

[SignOfZeta]

Yeah, you can build that circuit, or you can just turn up your stereo. I prefer the later method since it works perfectly for every system.

[mackdanger]

Yeah, you can build that circuit, or you can just turn up your stereo. I prefer the later method since it works perfectly for every system.

Really? Turn up my stereo you say? Works for every system you say? Well, my reasons for asking go beyond just volume.

[Fidde_se]

That's a really cooked up circuit you found there, there are some serious questions with answers that don't respond to what people want to hear.

On the 5v, why are there 3 capacitors? they will smooth out any AC, polarized is usually used for that, and they will charge up and give some more energy to the amp but the 0.1uF will do diddily squat when the other two are there, it would be better to use a 330uF then 3 with the combined value of 267.1uF....

The electrical symbol for the speaker is just what? combining the symbols of a speaker and a crystal! is it a piezo speaker?

Caps in the signal line will not higher the volume, the one closest to the speaker will make it high pass, exact crossover frequency would depend on the impendance of the speaker vs capacitor value.

The other capacitor (in parallel) would make it lowpass (before the high pass) making everything become midpass or... no pass, to add it up the resistor there would make that capacitor become a impedance rise compensation circuit.... so that the impedance would be flatten out at the capacitors crossover frequency.

[bust3dstr8]

Yeah, you can build that circuit, or you can just turn up your stereo. I prefer the later method since it works perfectly for every system.

Really? Turn up my stereo you say? Works for every system you say? Well, my reasons for asking go beyond just volume.

He like......


We like......



Zeta gains 100XP and levels up

[SignOfZeta]

Yeah, you can build that circuit, or you can just turn up your stereo. I prefer the later method since it works perfectly for every system.

Really? Turn up my stereo you say? Works for every system you say? Well, my reasons for asking go beyond just volume.

And what are those reasons? I know PCE audio is terrible, but I'm not seeing how this circuit will fix that. I think it's just always scratchy and quiet. Looking at this circuit I can't say I exactly understand it, but is it going to do more with a line level audio signal than my home stereo can do? Is it possible all those caps attenuate the specific frequencies where most of the noise is? Maybe, but again, I have filters and EQs whatnot on my actual stereo and they are almost certainly better, more flexible for sure, and a lot easier to pull off.

Can anyone read Japanese well enough to understand what the point of this modification is? Nobody had home theaters in 80s Japan, maybe the guy whipped this up in a hurry so that the volume from his 13" TV was audible in anything but a perfectly quiet room. If that's the case, it probably increases the noise. 

[mackdanger]

Can anyone read Japanese well enough to understand what the point of this modification is?

I can. The audio amp was part of an RGB mod installation into a Ten no Koe 2. You can see the whole thing here: http://fc2canned.blog54.fc2.com/blog-entry-1031.html

As for the audio amp itself, he says that he installed it because the  PC Engine audio output is extremely low. He only gives details about a few parts of it. He ran a 10uf cap between 1 and 8 to increase voltage output. The 10uf cap on the #7 bypass reduces noise. If the 220uf, 47uf, and 0.1uf caps aren't placed on the voltage line, the shortage in electricity will cause picture distortions. Beneath that he states that while the capacitor placement can cause changes to the sound, the placement he has in the schematic produces low noise and good sound detail.

As far as my reasons for asking about audio amplification, they have to do with my capture, compression, and editing experiments. I wanted to know if anyone had any experience amplifying the audio, and what their results were. That being said, I would like to restate one of my initial questions if anyone knows the answer. In the old RGB amp schematic, it shows each of the audio lines running through a capacitor. What was the purpose of those?

[SignOfZeta]

Buffering, I would assume.

[mackdanger]

Buffering, I would assume.

I see. I was curious about that because I saw someone on another forum say they amped their audio "with a cap", so I thought that might have been what he was talking about. Before I built that RGB amp, I asked The Steve if those caps on the audio lines were necessary and he said no. So I never bothered finding out their purpose. I am going to e-mail the blog owner who made that circuit later and ask him some questions about it. The blog post was made mid 2014 so hopefully he is still around. Thank you for your input.

[SignOfZeta]

Let us know what you find. This might be the perfect circuit for quieting down the PCE's screechy squelchy sound chip, or it might just be a waste of time.