EH Deluxe Electric Mistress chips & switches

[Ben N]

(1) Are there any worthwhile chip subs, seeing as Mr. Matthews was kind enough to put sockets in: say, a 5532, TL072 or Burr-Brown dual in place of the 4558.  There is also a CD4013, an LM324, an LM311N, and a chip reading "RET     9532  RD5106ANP   -011", whatever that is.

(2) The switch doesn't connect to the input jack directly.  Does this mean the bypass is buffered (unlike the schematic I have found)?  Is there much benefit to a TBP mod, and if so, how?

Just to be clear:  I went back and re-read Arons's faq about putting an 072 in a DMM, but I'm not sure how that applies here.  Also, I happen to have a few 5532s handy and no TL072s. 

Thanks,
Ben

[StephenGiles]

What do you want to achieve by doing this? Quieter opamps in the audio chain will not make the BBD (5106) any quieter, which is where any noise will come from. The 324 is for the LFO so not worth changing either.

[Ben N]

Yup, quieter, lower distortion, that is the idea.  I was really only asking about the opamp, mainly becauses I have a little handful of 5532s sitting around looking for something to do, and listed the other chips kind of just in case.  I went ahead and stuck a 5532 in there, and it is surely no worse, although I can't swear that it is better.  While I was inside I took a look at the input wiring, and realized that the bypass is not buffered, so I will go ahead with a TBP mod.  I was also surprised to see that the Direct Out is not a switcher, just a double of the input--it does not affect the mix at the flanged out.  When I do the TBP, I will look for a reaonably easy way to change that.  There are also a couple of unused pads on the board for outboard connections (marked E#), the purpose of which I am curious about.

Ben