NAD 3020A recap assessment.

[Hifibythekg]

Hi,

Have just recapped my owned-from-new NAD 3020A.

Sounds good on first outing and have managed to get 0mV DC on the speaker posts.
Attaching some photos.

Prior to buttoning it up, please could anyone knowledgeable on the recapping of this particular amp let me know if I’ve made any obvious mistakes or omissions?
I used Nichicon UKL in the audio signal path (hope I got the correct locations…), UPW elsewhere, except 4 UKW 33000uF for the power supply.
A sprinkling of Wima caps.
(Have to say that most of the pulled caps gave reasonably good readings on a cheap transistor tester.)

Many thanks all.

 

[Hifibythekg]

Forgot to say that I especially want to use this amp for PHONO duty.
Can anyone highlight the components of this section on the board, or point out anything I should do that would optimise it's phono performance?

 

[onanysunday]

You can replace these single layer ceramic disc caps in the phono section as indicated by the pink dots with something better, while keeping capacitance the same of course. Matched, complimentary pairs of mkp, pfr, phe, or MLCC's would sound better here. Look for the 1% or 2% tolerance rating.

 

[Hifibythekg]

Thanks Onanysunday, seems like a good idea.
Any views on which type might be best? Have you tried it yourself?
Might start a thread on this specific mod.

 

[onanysunday]

I forgot to also mention the fkp and cbb polypropylene types which are also very good. Look for these boxy little blue, red, or green caps with the longer leads in the cut-tape packaging format. Or, the MLCC caps, which look similar to the regular ceramic discs, but are smaller, dipped, and much higher performing. Cbb's are also dipped- usually red.

 

[Hifibythekg]

Thanks for posting these, very helpful.
Based on your initial suggestion, and being new to this, I’ve posted a fresh thread in the hope of getting further feed back from others who’ve attempted to push the 3020A’s preamp section to it’s limit..

 

[onanysunday]

You can also purchase these in kit form to save time and money on the most commonly-used values/ voltages.

 

[onanysunday]

Look at it this way, judging from your photo, all you have to work with are the original capacitors (electrolytics, green mylars & ceramics) carbon film resistors, and a bunch of transistors.

I wouldn't mess with the transistors unless you suspect them of any wrongdoing, and only after it has been recapped and you are convinced something sounds terribly off or imbalanced. In all likelihood they are fine. With carbon film resistors, you either keep them or change them to metal film. I suggest keeping them. Metal would give you 1% precision with better detail but also a colder, more analytical presentation. You can also upgrade the green mylar chiclets if you want, to the same aforementioned polypropylene types. That's about it, or at least all I'd consider doing.