NAD 2200 Vintage Amplifier Review

[restorer-john]

Mine has had the entire OPAMP board removed so it's pure stereo only (no bridged mono).

So you've also re-labelled (changed the black to red) of the right channel speaker output jack from (-) to (+) I hope.

 

[Doodski]

This review makes me wonder how my Rotel RB-991 would fare.

That might require the test circuit's load Wattage capacity increased and possibly the test AC supply mains being up'd too. The Rotel is a beast for sure. @amirm might chime in as per if his circuit parameters can test a Rotel RB-991. What is the max test parameter for a home amp?

 

[pjug]

Hehe. Since it is for good cause, here you go:

View attachment 68262

I also tested at higher bandwidths and it just increased the noise level. There is no correlated crosstalk distortion that I can see at zero crossing.

Don't you have to do this at high power to see anything through the noise?

 

[restorer-john]

I have Ncore based amps, and there isn't a single microcontroller in it. I'm not saying there isn't one in the M22, but why would it be "full of microcontrollers" .

The NAD M-22 is full of microcontrollers. There's three of them! Yes, in a two channel power amplifier...

One in each NC-400 OEM module. (PIC16F690) x2. (the 20 pin IC I have circled)
And another (PIC18F26K20) for general housekeeping. (on NAD's MCU board)

NC-400 OEM:

NAD M22 block. One channel shown.

PICs are fragile. Their A/D lines are easily damaged and when they fail, you are screwed basically. Code is protected, so they can't be cloned, even from another functioning controller. You can buy a PIC16F690 for a dollar or two, but you can't load Hypex code into the EEPROM. Will they sell you a coded micro? Nope. What hope do you have in 20 years when Hypex is long gone? Answer: E-Waste.

Wherever you have high voltages and high currents (in power amplifiers) things go wrong now and then, and little micro-controllers are often the first to go. Let's see if the EU regulations force companies like Hypex and others to release source code (or set the code protection flag to 0) so people can legitimately repair their gear. I won't be holding my breath.

Anyway, as for the wait and see approach, we all know that simply is doomed to fail. The NAD 2200 is 35 years old and has proven itself. It didn't need no stinkin' microcontrollers back then to achieve state of the art performance and doesn't need them now.

 

[restorer-john]

Don't you have to do this at high power to see anything through the noise?

The goal here is to see what is happening with X/over artifacts at low power (1W/8R), and even lower. That is supposedly where there are 'night and day' audible differences between certain amplifiers due to these artifacts. @SIY , @amirm and others are simply investigating some of the wild claims made by manufacturers...

As seen here, the NAD 2200 is free of crossover distortion artifacts.

 

[oldsysop]

Unnecessary technology, unnecessary components. Scheduled obsolescence.
And on top of that they are not even real amplifiers made by the company, just buy the modules from another company, some cables, a cabinet and that's it.

 

[Doodski]

PICs are fragile.

I stopped reading at this comment. PICs are not fragile. I was qualifying PICS to 177C constant operating temp with a unknown amount of extremely high G's in a 20KPSI environment. Used in down-hole petroleum drilling and other geophysical metering operations like what appeared to be volcanoes.

 

[restorer-john]

I stopped reading at this comment. PICs are not fragile.

Electrically fragile. You can tell the bag of dead ones I have here otherwise. I've completely lost count of dishwasher, oven and refrigerator PICs that render entire controller boards and appliances a write-off. And my other favourite? Gate controllers. One electrical storm and your board is toast- thanks PIC.

They are better than the AMTEL ATMEGA MCs though, I'll give them that.

 

[Doodski]

Electrically fragile. You can tell the bag of dead ones I have here otherwise. I've completely lost count of dishwasher, oven and refrigerator PICs that render entire controller boards and appliances a write-off. And my other favourite? Gate controllers. One electrical storm and your board is toast- thanks PIC.

They are better than the AMTEL ATMEGA MCs though, I'll give them that.

We ran ~8% qualifying PIC rate in the oven overnight and then when MODs where made to the assembly and construction process the rate went to ~15%. We where apparently purchasing the best PICs that we could source.

 

[DualTriode]

Thanks for posting this NAD review.

A couple of months ago I purchased two NAD 216 THX power amplifiers for cheap on EBAY. Both amplifiers have output relays that cycle several times before they settle.

The APx555 shows a SINAD ~97dB on one channel and 84dB ish on the other. Sometimes doing a restart both channels would settle near 97dB, most times not. (at 5 watts output)

I found a guy that changed out capacitors and relay with good results.

https://fittingmedia.wordpress.com/2013/01/16/nad-214-poweramp-refurbishment/



Thanks DT

 

[CDMC]

This amp is class G, not AB

Don’t tell, people will get confused.

A Class H amp owner.

 

[CDMC]

That might require the test circuit's load Wattage capacity increased and possibly the test AC supply mains being up'd too. The Rotel is a beast for sure. @amirm might chime in as per if his circuit parameters can test a Rotel RB-991. What is the max test parameter for a home amp?

Isn’t testing one redundant since there is a good test result from when they were new? All it would show now is if a sample size of one still performs to spec.

https://www.stereophile.com/content/rotel-rb-991-power-amplifier-measurements

 

[pjug]

Don’t tell, people will get confused.

A Class H amp owner.

Is it the ABH2?
Edit: Ha ha I flubbed that one up! Is it the AHB2?

 

[LJN]

The "Crown" of NAD Poweramplifier: NAD 208 THX https://hometheaterhifi.com/volume_3_2/v3n2h.html

 

[Laederofmen]

A lot of old NAD amplifiers: https://quirkaudio.com/?page_id=707

Resized and optimized

View attachment 68073

That's a lot of heatsink!

 

[CDMC]

Is it the ABH2?
Edit: Ha ha I flubbed that one up! Is it the AHB2?

Nope. Sunfire Stereo. I believe Emotiva currently sells Class H amps in their XPA line.

 

[audio_tony]

So you've also re-labelled (changed the black to red) of the right channel speaker output jack from (-) to (+) I hope.

Yes, the phase has been taken onto account of course. (it's quite obvious on the schematic!).

 

[Snarfie]

There is one online review and it showed very similar power and distortion figures to mine. So I say they are probably close.

Now i'm realy qurious how my NAD C370 will measure. It will come close or surpass the NAD 2200 i guess.

 

[Snarfie]

The main culprit with NAD is that they often fail and you can be sure they do. It's a good amplifier to buy if you can get it for cheap and fix it yourself.
Their AVR's and C3xx series are the best (worst?) example - mediocre solder job, cheapest capacitors money can buy and very questionable if not stupid design decisions to place capacitors in pretty much sealed cans with class A driver stages or directly next to a hot heatsink of a voltage regulator.

I've done a 370 once, never ever again. Had to replace almost every electrolytic capacitor and have spent hours fixing bad solder joints on the thing.
You have about 100% chance it's already partially decayed if you find one for sale online.

And don't even start me on their CDP's....great while they work but they break down due to mysterious reasons, not only because of laser and electrolytics failing.

It's a shame because otherwise NAD gear really does sound very good and often delivers more than what they promise.

Hm i have a NAD C370 that runs now for more than 17 years no problems what so ever. I think the amount of NAD's produced like the C370 in the ten or hunderd of thousends can obtain some problematic amplifiers in comparison to amplifiers brands that are producec a few thousend or less i guess.

 

[pjug]

Now i'm realy qurious how my NAD C370 will measure. It will come close or surpass the NAD 2200 i guess.

I have a C370 too. You can find measurements here. Unfortunately it does not stack up to the 2200 in power or THD+N, In fact, here is an example where the elusive crossover distortion seems to be showing itself a little bit.
https://www.stereophile.com/content/nad-c370-integrated-amplifier-measurements

I still think it is a decent enough amplifier though.