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 Post subject: Modding a JVC cd player
PostPosted: 06 Jan 2009, 19:32 
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I've just purchased an old JVC cd player from Value Village for a whole 10 buck. My first Idea was to mod the output stage with a tube preamp instead of the opamp used.

I found the output to the DA converter and hooked it up to my 25EH5 amplifier to find that there was much more detail and clarity.
I have been thinking of were to go from here since the output of the converter has more than enough gain to drive my amplifier to full volume.

The first thing I would like to do is upgrade the power supply and replace all of the small value ceramic caps with silver mica's, the question I have is how big of a difference can I make with these mods in terms of performance?

I suppose other people could do the same thing to other cd players it is just a question of finding the DA converter output.

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PostPosted: 06 Jan 2009, 19:53 
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Here are some of the big changes you can make:
  • Remove or upgrade the DC blocking capacitor. You will only want to remove the DC block capacitor on the output if that next stage you use (preamp or amp) has a DC blocking cap.
  • Upgrading the voltage gain stage. Use a better opamp or try tubes. See this thread for Tube ideas.
  • Damp / stiffen the transport.

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PostPosted: 06 Jan 2009, 21:32 
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The funny thing with the converter is that there is no coupling cap, I ran it without one straight into my amplifier which does not have one. I had no noise or DC feed back what so ever and the output is high enough that I don't see a need for a output stage, I think the converter my all ready have one built in, at least thats how it seems.

The converter is the LC7881 by Sanyo, I would post a pic but my camera cable is missing so I can't put pictures on to my computer.

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PostPosted: 08 Jan 2009, 17:23 
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Did some mods to the cd player. changed all of the really low value caps to silver micas and changed a whole bunch of electros caps to non polar types by Elna, and beefed up cap values in the power supply.

It sounds so amazing, way better detail than I ever remember being in some of my recordings, especially the Brothers in arms cd.

I think I will leave the output as is but would like a way of controlling the output volume and should probably put a coupling cap at the output as well, sound like an idea?

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PostPosted: 08 Jan 2009, 19:24 
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Okay, you have to fix your camera! :) Driving me nuts. I want to see the guts of that CDP.
As long as its working right now then why change it except to place a pot inline between CDP and Amp.
Ri

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PostPosted: 09 Jan 2009, 16:27 
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Well I took a good look at the "Lampizator" and learned some stuff about good/bad cd players, but have officially decided to go without a tube stage since the converter uses voltage output, which means I should have no issues driving amps.

Where is that darn camera cord I soon won't have space to take any more pics, I wish I could just keep the cord with the camera because this is the second one I've lost.

When I do find it I will post as many pictures as I can, and there will be allot because I am also building a new PS with proper regulators and a seperate PS for the D/A.

stay tuned for the pics!

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PostPosted: 09 Jan 2009, 22:28 
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CrazzyAbtTubes wrote:
stay tuned for the pics!

We are dieing out here. Either find the damn cord or stop promising to post. ;)

Seriously, I can't wait to see what you've done. I have six players in my workshop that are waiting to be modified with tube outputs.

alan

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PostPosted: 22 Jan 2009, 22:15 
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I finally got my pics loaded onto my computer, this is the moment you have all been waiting for I know, I enjoyed the suspense :lildevil:


So here you have it, I shall post more pics and information later on...

Enjoy!!! :mrgreen:


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PostPosted: 23 Jan 2009, 07:52 
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YAY!
So now what :)
Thanks for posting the pics. Its always cool to see what people are doing. Supply looks nice!
Ri

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PostPosted: 23 Jan 2009, 17:00 
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Well, I need to do some finnishing touches, complete the case, and then I plan on building a seperate tube output using a 6SN7 with LED bias.

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