Fisher 400 - Rebuild Question

idadude

Super Member
I have been reading on the Fisher 400 receiver for a few weeks now, but don't recall any specific information about the two small .047uf caps hooked to the 12AX7s on the front end. I'd like to change these out. Do these stay the same value?
I know that the four couplers are recommended to be changed to 0.1uf 600V along with the corresponding grid stopper resistor change to better suit the newer EH 7868s, but do the other two stay at 0.047uf?
Thanks for the help.

Larry
 
Larry,
Those are for the preamp stage. They can be the same value. You might get a few more low HZ moving to .1uf, but it's like 22hz to 17hz.
 
So, preamp stage eh? Suppose that putting in a copper foil cap would make it a little nicer/sweeter sounding? Won't be so spendy since there are only two.
 
If the originals are ceramic, and I think they are (I've got 2 different FISHER receivers pictures floating around in my head right now) even an orange drop will clean it up a bit. It's not gonna be much but it will sound better.
 
If the originals are ceramic, and I think they are (I've got 2 different FISHER receivers pictures floating around in my head right now) even an orange drop will clean it up a bit. It's not gonna be much but it will sound better.

Interesting, I don't recall any ceramics in signal path when I worked on mine. I do recall the eurofoils.
 
I have the two Eurofoils in mine.
Changing the couplers in the amp section to K-40Y PIOs and changing all the axial lytics made a huge difference. I listened through a complete CD after I got the caps changed (I usually just sample the songs). Couldn't believe how good it sounds now.
I'm not wanting to lose that improvement, but I want to retain the reliability of the parts over time and at the same time make the sound sweeter, if I can.

Larry
 
I typically use Sprague 716P orange drops upstream of the final couplers. I tried using Jensen Copper Foil in Oil all through an amp and it was too much of a good thing. I yanked out all but the final Jensen couplers and replaced them with orange drops and it was like the unit snapped back into focus.
Jim McShane recommends mixing up caps and not using the same all the way through. I have to say that in this case it worked.
 
Interesting, I don't recall any ceramics in signal path when I worked on mine. I do recall the eurofoils.

That's why i put the rejoinder in there about 2 different Fishers Pics floating around in my head.
 
I was thinking of using AudioCap PCU or Cardas Clear caps. Both are copper and non-oil. PCU is copper foil and Clear is metallized copper film. The Jensens are usually too big and I wanted to stay away from using all PIOs inside the chassis since I already had K-40s in there for couplers.
 
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