Output mute mod...Amazing!

bobhayes · 17th September 2004, 03:41 PM

I pulled the output mute transistors out of my ancient Technics SL PJ27A cd player yesterday and I can't believe the improvement in focus and treble clarity. What a difference... sounds like a new machine. Cymbals and female voices shine where they used to be quite dull and all the instraments overtones are so much clearer.
I'm sure the transistors must have ageing problems otherwise surely the manufacturer wouldn't have put them in? Next I'm going to change the output coupling caps to Sanyo Polyphenylene electrolytics (www.cpc.co.uk) and see what happens then.
Could anyone suggest any other mods I could make without spending a fortune on the old dog?
I'm hooked now!

DigitalJunkie · 17th September 2004, 03:54 PM

I modified my cheap Sony 51-disc changer a bit..
I added Sanyo OS-Con bypass caps (free samples they sent me) in the power supply,along with some small film bypass caps,and replaced the LM4558 op-amps with TL082's (I think?) and noticed a bit more "control" over the sound.The bass was a little bit more controlled,and the treble was a bit more clear..A pretty subtle difference,but not bad for a $3 trip to RadioShack. I had planned to remove the muting transistors and replace them with a relay,but never got around to it.
The power supply,output stage,and clock seem to be the most modded areas of CD-players...Maybe you could add a tube output stage,inplace of the op-amps in there.

bobhayes · 17th September 2004, 04:04 PM

Thanks Digitaljunkie,
Was the 4558 you replaced driving the outputs?
The output op amp in mine is an LM833 and it looks pretty good on paper, although slightly inferior to the NE5532. Would it be worth bothering changing this.
Also there is a 4558 in there but I don't know what it does as I've only traced the circuit back to the output op amp and I have no schematic.
I looked it up on the net and guitar effects use it a lot and was described by some as 'legendary".
What was the mod I saw with a .47uF polyprop over the mains input?

17th September 2004, 03:41 PM	#1
bobhayes diyAudio Member Join Date: Sep 2004 Location: Bungawalbyn, NSW	Output mute mod...Amazing! I pulled the output mute transistors out of my ancient Technics SL PJ27A cd player yesterday and I can't believe the improvement in focus and treble clarity. What a difference... sounds like a new machine. Cymbals and female voices shine where they used to be quite dull and all the instraments overtones are so much clearer. I'm sure the transistors must have ageing problems otherwise surely the manufacturer wouldn't have put them in? Next I'm going to change the output coupling caps to Sanyo Polyphenylene electrolytics (www.cpc.co.uk) and see what happens then. Could anyone suggest any other mods I could make without spending a fortune on the old dog? I'm hooked now!

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17th September 2004, 03:54 PM	#2
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	I modified my cheap Sony 51-disc changer a bit.. I added Sanyo OS-Con bypass caps (free samples they sent me) in the power supply,along with some small film bypass caps,and replaced the LM4558 op-amps with TL082's (I think?) and noticed a bit more "control" over the sound.The bass was a little bit more controlled,and the treble was a bit more clear..A pretty subtle difference,but not bad for a $3 trip to RadioShack. I had planned to remove the muting transistors and replace them with a relay,but never got around to it. The power supply,output stage,and clock seem to be the most modded areas of CD-players...Maybe you could add a tube output stage,inplace of the op-amps in there.

17th September 2004, 04:04 PM	#3
bobhayes diyAudio Member Join Date: Sep 2004 Location: Bungawalbyn, NSW	Thanks Digitaljunkie, Was the 4558 you replaced driving the outputs? The output op amp in mine is an LM833 and it looks pretty good on paper, although slightly inferior to the NE5532. Would it be worth bothering changing this. Also there is a 4558 in there but I don't know what it does as I've only traced the circuit back to the output op amp and I have no schematic. I looked it up on the net and guitar effects use it a lot and was described by some as 'legendary". What was the mod I saw with a .47uF polyprop over the mains input?

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