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This wasn't weird, rather ignorance on the part of NAD. When I got my 2200 amp there was a lack of bass. Turns out they used the wrong caps to decouple the low voltage regulators. They were 1uF and should have been at least 470uF.

125V as I recall but since the rails are only 18V you can use lower voltage caps.

OK thanks. For some extra HF decoupling I connected 2.2uF polypropylene caps across C215-C218. Every little helps.

C215-C218 are 1000uF in my 2200. Been in there for over thirty years with no problems.

Since this thread has been resurrected I thought I would add my two cents worth. My NAD2200, now 37 years old, was an excellent design, spoilt by cheap components and a few mistakes. Replaced the duff components and fixed the mistakes and now it will blow most amps in its class into the weeds...

Using my NAD 2200 as an example, it sounded very flat - like listening to wallpaper if you get the analogy. Changed all the ceramics to polystyrene and now it had dimension. There was a lack of bass, due to insufficient decoupling on the 18V stabilisers. Replaced the 1uF caps with 1000uF and...

I installed tantalum beads into my Sony CDP302 over thirty years ago and they're working just fine. So long as the working voltage is at least twice the rail voltage you should be OK. Tantalums are susceptible to spikes and surges and that's usually the problem. The rail voltages in the Sony...

I added 6.8uF mylar caps across the 10000uF PS caps in my NAD 2200, and 2.2uF mylar across the 1000uF caps. Won't really affect the sound but will improve HF decoupling and stability. Been in there for over 30 years without any problems.

Sony CDP302. Bought it new in 1984 and it's still going strong. With all the mods (see Solid State forum) it still sound better than most players.

Joe is correct. I replaced C406/7 with 1 microfarad stacked mylar and C215/6/7/8 with 1000 microfarad caps. The 2200 is now 37 years old and still going strong with plenty of bass. This is a common problem. I recently fixed a friend's tuner which was unstable. Replaced the 47 microfarad cap at...

I had the same problem with my NAD 2200. The capacitor at the output of the low voltage regulator was much too small at 2 microfarads. Replaced it with 1000 microfarads and there was the missing bass. Seems like NAD engineers didn't know the difference between static and dynamic regulator loads.

Tantalums are OK. I replaced several regular electrolytics in my CDP302 with tantalum beads and they are still OK after 37 years. The sound was improved due to the better HF response of beads. Just make sure that the working voltage is at least twice that of system voltage.

Did you change the input opamps by any chance? When I was doing my upgrades I tried various opamps and at one point I tried 5532s. These gave an audible thump, particularly on switch off. And they didn't sound any better than the originals. I finally settled on the OP275 as the clarity I...

The reason why the tone controls don't appear to do much is because Mr BEE (Bjorn Erik Edvardson) has the strange idea that only the very top and bottom of the range need altering. I have the same problem on my C165BEE. Been meaning to modify it but haven't got around to it yet.

I had a similar problem with my Sony V-55 except that it wouldn't tune at all. I traced the problem to the chip which does the tuning (µPD2819C). This chip seems to be unobtainable so I retired the V-55 after 30 years of excellent service. It is possible to rig up a manual tuning control but it...

Have a look at the DC offset adjusters, SVR201/202. They tend to get a bit noisy after a while. I replaced mine with cermet multi turn pots and havent had any problems since.

No particular brands. I just used whatever components I had to hand. As long as they are good quality it doesn't matter. What matters is the type of cap. Polycarbonate caps aren't available any more so use polypropylene. Polystyrene are hard to find these days (because of surface mounting) so...

While the 2200 is rated at 100W it's actually a 150W amp.I measured it just to make sure. Above 150W the higher voltages switch in.

Had a look at the schematics and they appear to be the same. So either will fill the bill.

Yes. As I mentioned before there is a difference between the static and dynamic output impedance of voltage regulators. So if you measure the amp with just a steady sine wave the frequency response will seem OK. However, with a continuously varying load such as music, then you will notice a...

Seems to have worked this time. As you can see, there are some mods to the main amp. The first differential stage now has a proper current mirror and I left the emitter resistors in so I could keep the adjuster. The emitter resistors are now one tenth the size because the originals reduced the...

Just uploaded the attachment again. Hope it works. I suggested 125V just to be on the safe side. One cap that needs to be 125V is a 22pF polystyrene in the main amp.

Well, I uploaded an attachment but I don't know what happened to it. Should have mentioned that changing the input op amps to OP275 will improve things.

Pay no attention to Zoom - he is somewhat misguided. I used polycarbonate caps as I had some handy but polypropylene will do nicely. I added two servos from output to the first differential stage to enable DC coupling and bring the output DC to zero. The other two were round the input op amps in...

I've had the 2200 for 30 years now and it's working just fine. The basic design of power amps hasn't really changed in that time, so once you get an amp to work as it should then there won't be any difference between one amp and another. As you can see, the distortion is extremely low and while...