"Holy Grail" CD-4 Demodulator - Installation into QRX999

[JonUrban]

Got my "Quad Bob Modified Holy Grail CD-4 Demodulator" board in the mail today. For those of you that don't know, I had Quad Bob rebuild my QRX-999 (Blackfaced QRX-9001) a year or so ago, and since then he discovered that the CD-4 circuits in that receiver could be "tweaked" to improve performance considerably.

Bob sent me a modified board to replace the existing board in my QRX, and I could not believe how easy it was to swap. I took a picture of the process:

Here you see the old board, removed but still connected (except for one connector towards the bottom of the picture). All that is required is taking off the bottom metal plate of the reciever (keep track of which screws go where - they are different sizes!!), removing the exisitng board (very easy), installing the Holy Grail board, then moving the connectors one by one until you are completed. In all reality, it took more time to take the bottom cover off than to replace the board!!

My next mission is to drag a turntable up here and test it out!
More on that later!!.................

THANKS BOB!!!

PS - Question for QB: If i am going to connect this to my PC (No speakers on QRX), would I be better off connecting the Tape Outs to the Audio Ins on the PC Card, or the QB Installed Pre Amp Outs to the PC Card?

 

[QuadBob]

PS - Question for QB: If i am going to connect this to my PC (No speakers on QRX), would I be better off connecting the Tape Outs to the Audio Ins on the PC Card, or the QB Installed Pre Amp Outs to the PC Card?

I would recommend using the tape outs going into the pc, especially if you're going to be recording. The tape outs will give you a "fixed" output.

You could use the preamp output jacks, but then the pc would be getting the signals at a "variable" level, based upon the 999's volume, balance, tone controls, etc.

So, if you want to tailor the signals before recording.....balance, level, etc. then use the preamp output jacks. If you want to control everything in the pc........use the tape outs.

Thanks for posting the picture and directions.......I intended to do that, but you know how it goes! Now I can just refer others to this thread as they get ready to upgrade.