Sega MD/Genesis Audio Amplification

Hi all! My moddified Mega drive is a High Def. Audio model, and I want to put in the back of the console two RCA audio jacks. My problem is that I don`t want to get the audio from headphone jack because there is a little hum in there. I want to connect my MD to my Hifi`s amplifier (in stereo), so I don`t need the console amplifier.

When I connect my headphones to headphone jack and power the console on, I heard a little hum, even without any cart on it. If I connect to my Hifi by headphone jack, this hum is going to be amplified...

Is there a way to get stereo sound from the console before it gets amplified?

I need to look into my MD1 for the spots... you will have to amplify the sound you get with pair of transistors for each channel (the sound you get in those spots is clean, but rahter quiet).

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Originally Posted by TmEE

you will have to amplify the sound you get with pair of transistors for each channel (the sound you get in those spots is clean, but rahter quiet).

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Even connecting them directly to an Hifi`s amplifier?

You can get the audio from the head amp chip pins 2 and 6 (I don't remember which is left of right...). The chip in my MD1 is CXA1034.

The signal is lot more quiet than what you usually feed your HiFi with (such as output of a tuner for example).

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Originally Posted by TmEE

The signal is lot more quiet than what you usually feed your HiFi with (such as output of a tuner for example).

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So, if I connect this signals directly to mi hifi (L-GND, R-GND) I am not going to hear anything, right?

of course you can hear something, you just have to turn the volume knob further compared to other devices you have hooked up to the HiFi.

I tried it, but I don`t hear anything :(. All I want is to clean that hum. I think it comes from volume slider but I`m not sure...

wrong pins then... I'll give you the right ones probably tomorrow...

Ok, I wait.

Just an OT: In Csync mixer that 1k resistor is connected to ground and B-leg of the transistor right? This is because I had replaced the resistors by variable resistors, but the image still the same, even when I change values of resistors... The circuit improved a bit the position but the image still a little to the left and I am afraid to be doing something wrong. :daze:.

The 1K resistor must stay as it is... you need to adjust the 120K one. I can wildly adjust the position on my MD2 by just putting my finger on the 120K transistor...

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Originally Posted by TmEE

I can wildly adjust the position on my MD2 by just putting my finger on the 120K transistor...

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:shock: Ok. My circuit is definitely wrong... So, I`m going to rebuild it. 1k is to ground and B-leg right?



EDIT: Success with Csync!!!:rofl: The problem of Csync mixer was in transistors position. I saw this fault by following your tutorial of transitors for dummies. :D But now I am a happy dummie! :notworthy:TmEE:notworthy:

And for audio, pins 1 and 8 are what you need... YM2612 output is much cleaner than what comes from these pins though. I need to work out some mod for MD1 aswell... problem is that I don't use MD1 much so there's no motivation.

My transistor guide is not 100% accurate for all transistors, but luckily, most of them use that pin sequence :)

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Originally Posted by TmEE

YM2612 output is much cleaner than what comes from these pins though.

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http://upload.wikimedia.org/wikipedi...612_pinout.gif


Oh yeah!!!! Glad you talk about YM2612. I tried pins 21 and 20 of him and, yes, this output is what I need, nice and clean to do the RCA's. :cool:

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Originally Posted by TmEE

I need to work out some mod for MD1 aswell...

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Yes indeed!!!:D:D

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Originally Posted by TmEE

problem is that I don't use MD1 much so there's no motivation.

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I understand that, but MD1 has much potencial... I love MD1 because of their retro look, and has much space on it.

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Originally Posted by TmEE

My transistor guide is not 100% accurate for all transistors, but luckily, most of them use that pin sequence :)

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I changed your image of Csync for I understand what I was doing. I can send you the image if you want.

you need to mix the PSG too if you want to grab the sound directly from YM2612... beware, YM2612 outputs REALLY quiet sound compared to PSG.

I totally forgot that. Do you know the PSG source ? And how to mix them?

you need some resistors to mix the signals together... you can get PSG from one of the caps near the FM caps. Just see what has been done on the existing circuit.

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Originally Posted by TmEE

I need to work out some mod for MD1 aswell...

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Hell, yes! It could come in handy on VA2 Model 2s as well, as FM is overblown compared to PSG, Sega CD PCM/CDDA and 32X ADPCM, not to mention that its PSG output is distorted.

Unless I can somehow use the existing amplifying circuit and add/remove components to get proper volume on the VA2 Genesis 2?

Hi there. It's just to say that after tests to the levels of cxa1034p and ym2612, I'm going to give up of this idea of pre-amplification. The levels are really quiet to my amplifier, and when I'm pulling up the volume of the amplifier the noise is inevitable. So, I'm going to get the sound from headphone jack, it's the easiest and safest way (for me). But I'm allways open to receive new ideas.