I have been recapping and modding NAD 2200s for a while now- and wanted to give some details back to the community:
I have now done a considerable number of these upgrades and based a number of mods from AK and DIY Audio and others listings, as well as my own tests, have settled on what I thin optimizes the performance of these amplifiers:
C215-218- These support the 18v rails that provide the power to the initial VAS stage of the power amplifier boards, and as such larger values provide a greater local reservoir. Replacing the original 2.2uf 50v with 470uf 50v makes quite a difference, “more bass” and better dynamics, I have settled on Nichicon HE (ultra low impedance)
C111-114- I have replaced these with COG Ceramics and have added 47uf 50v in parallel with each of these (across the 18v supply lines to the IC) and this again seemed to provide better dynamics, these are Nichicon PW
I tried Pilots (posted in AK) swapping of C109, C110 to 2.2uf 50v Wima- but ended up going back to Nichicon FG 10uf 50v- which gave more solid square wave response at frequencies below 100Hz
C107,C108- these were 820pf ceramics (circuit states 1000pf film)- so replaced these with WIMA 820pf 50v FKP.All other small value capacitors on the input board are replaced with WIMA FKP, except for C111..114 as mentioned and the three 27pf ceramics, which are replaced with C0G MLCC versions
C203, C204- I tried a few versions (2.2uf Film, 10uf Film- both WIMA, Nichicon KL, Nichicon FG) and finally settled on ELNA SIMLIC II 10uf 50v- for me this kept the detail and was smoothest- also kept the LF square wave tidy. I have now evolved to a Nichicon MUSE Bipolar 47uf, as this is similar to what was used on the 2600A/2700.
I now replace all the ceramic capacitors on the main amp board with FKP WIMA polypropylene except the 1uf which I use an MKS polyester. There is one 22pf ceramic C305/C306 which I replace with a 22pf C0G ceramic. On the 2600A /2700 NAD use a silver mica cap here. The 68pf feedback capacitor is also mica on the 2600/2700, though i could not detect any difference between the Mica and an FKP.
I replaced the 2043DD IC’s with LM4562NA- I had tried the OPA2134 (which is an IC I like), but again for me the LM4562NA is better suited to the amp-perhaps as it is BJT as is the 2043DD
All the other electrolytic capacitors have been replaced as follows:
Power supply- Nichicon PW same values
Power amp- all PW except c223, C224, C311, C312, C313,C314- all FG and C203,C204- ELNA Simlic II as mentioned-now UES MUSE Nichicon.
input amp- C109,C110 Nichicon UES MUSE BP , C115,C116 Nichicon FG.
plus the 47uf mentioned above across the 18v supply lines
10000uf 80v with Nichicon or equivalent
the 10000uf 120v are unobtainable, and the 160V versions are both expensive and dont fit- so I now have settled on Nippon Chemicon 10,000uf 100v (125v surge) replacements, which given that the high power rails are 95v, work very well indeed. These have been operational for over 48 months with no problems.
The Nippon Chemicon series capacitors have been discontinued, so I now use KEMET ALC for the 120v capacitors which are rated at 100v with 115v surge. The 80v capacitors are Nichicon.
for me this is the best NAD mod yet- more bass, better dynamics and measures well, though there is some low frequency phase shift and roll off from about 50hz downwards-the LAB inputs less so as expected.
one thought is to bypass the 10k ufs with a film cap (1uf?)- I did try this and count not measure any difference.
