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NAD 1600 Monitor Series Tuner/Preamp... sonic upgrades?

MWH901

MWH901

Active Member
Evening all,

I recently picked up one of these off the 'Bay in a "will not power up" state. One new relay and a few reflowed solder joints later, she's alive and kicking!

Unlike many NADs I've worked on, the cheapo caps all test surprisingly good, and as such I do not intend to recap the unit. That said, I would greatly appreciate if anyone has worked on one of these and can recommend a few select caps or other components to upgrade to improve sound quality. Also, any common modes of failure where a pre-emptive part swap would help ensure longevity.

Thanks in advance...
-Mike
 
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You might consider replacing the caps in the audio path.

For example (as yes these just feed the headphones,but they are a good example), Q401/Q402, from 1uf electro to 1uf polypropylene, also the IC feedback caps from ceramic to polyprop. The IC's could be replaced as well as there are better alternatives to the NJM 2043D (the NJM2043DD is the low noise version,and there are also many thoughts on alternative IC's that are improvements). Again the 100uf /10v electro at the output of the IC's would benefit from using Nichicon MUSE UES Bipolar

This will measurably reduce THD+N and increase S/N.

Also the power supply caps are certainly worth increasing in value
 
pwauk12 said:
Also the power supply caps are certainly worth increasing in value
Click to expand...

Appreciate the advice! The filter caps are 1,000uF... you think going to 1,600uF is the right move?

EDIT: Found some Nichicon UPW @ 1,500 uF that will fit. I think I'll go with those.
 
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I think you could comfortably go to 2200uf- I use either UPW or UHE
 
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MWH901 said:
Unlike many NADs I've worked on, the cheapo caps all test surprisingly good, and as such I do not intend to recap the unit.
Click to expand...

Why?

You've already used the words "cheapo caps". They are also now old "cheapo caps". They won't get any better with age. If you are able to do this work yourself, it would probably only cost you about $50-80 in caps. You could upgrade them as you replace. PWs in the power supply, KLs or Wimas in the signal path, KWs everywhere else. Maybe an op-amp replacement as others have stated?
 
There was a company that rebuilt NAD Amplifiers and Receivers. They charged a few hundred dollars to do the 1600 preamp/Tuner. Apparently it was a very good design, but sub standard parts handicapped it's performance.

They replaced the power supply, some op amps, caps, etc. When they are done it was said to compete with some high end component's costing much more then the 1600 + the modifications.

I had a stock one myself and was quite pleased with its overall performance. It has a good FM tuner too. Note the empty space in the right side of the cabinet. For another $100 I could have got a 50wpc power amp...the receiver version. I wish I had done that but I had a 100 wpc power amp. IIRC the receiver had preamp outputs.
 
as @leesonic suggests it would be wise to recap the complete unit and install new opamps, the result will be a measurable improvement
 
Thanks to all for the feedback. No issue on doing the full recap... I've always been a little leery of op-amp swapping due to oscillation horror stories. How is the LM833 as a replacement for the NJM2043? Seems like the relatively high supply voltage (18.5V) is a limiting factor. The big parts houses don't seem to have too many alternatives in stock.
 
Found some inspiration, and left over caps.
So started to change some in my 1600.

Changing pwr supply is mentioned..
Will that benefit the sound, less noise or?

LM op amps are direct fit, no need to change surrounding components?
 

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Watching, because I have the 1700, which was produced right before or after the 1600.
I assume a lot of the circuitry is the same. I do like the different functions/controls the 1700 has compared to the 1600.
 
I have been a member of the forum, the lurking in the back type, and this is my first post. Hello to all of you.

I am refurbishing a nad1600. I saw a video in YouTube that repair it. Seems that the brown goop that hold the mid size electrolítics and the flat ribbons gets conductive with age , and my unit is about 30 years old. I proceded to remove the brown goop and then use a little bit of rtv to secure the flat ribbons. Also, a full clean up of the board with IPA. It came out good with no problem. getting rid of the goop and cleanup, for me ,was a first stage modification. I have two bad caps on the power supply. Looking at what your modification, but probably opamp caps, opamps and carbon to metal resistors may be the first to do. One of the ribbons with the bronw potentially conductive goop , not my unit but it looked the dame and my unit after removing the brown stuff and using some rtv to secure the flst ribbons
 

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MWH901 said:
Appreciate the advice! The filter caps are 1,000uF... you think going to 1,600uF is the right move?

EDIT: Found some Nichicon UPW @ 1,500 uF that will fit. I think I'll go with those.
Click to expand...

My caps are bad also. Do you have the part number of the Nichicons?
 

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These are the ones I can find, all at 7.5 mm lead spacing. Length is not an issue. As of now, the UHE are on order. The 50 V UPW looks like the best option.
nichicon.png
 
Swopped the op amps, soldered in some IC sockets as well, and changed some caps that I had laying around...

Think I'll put in one of these cheap bt modules, just to simplify the daily life with spotify

Seems the saved some bucks on screws.
Some off the boards are not fastened properly, not even holes for the small screws.
Gonna test it against my 2400 pwr amp later
 

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