NAD 1020 Preamp Problems

[anatech]

Hi GG,
The muting circuit will help the turn on and off thumps. Switching noise - maybe. The intention is to replace the muting circuit, right?

Hey, Italian blood is full of the good stuff! Garlic, tomatoes, MEAT, on and on. I had an Italian girlfriend once. Really nice person and knew how to cook!!! Apparently the bugs can tell eh?
-Chris

[planet10]

Originally posted by GG
With regards to upgrading capacitors in the signal path, what options do I have to upgrade 4.7uF and 47uF capacitors (25V max)? Poly caps for those values will be expensive and very large in size making it difficult to fit on the board. Would adding some small poly caps in parallel help much?

I cooresponded extensively with a fellow who replaced almost every cap (and a lot of Rs) in his 7020. he used mostly blackgates. The results were reportedly stunning. Swapping critical coupling caps with poly is a good idea thou.

dave

[anatech]

Not to be a kill joy, and I don't intend to be, replacing a couple critical caps can bring an improvement. But the replacement part has to fit in the original space.

I've been called on to repair many swap'em out jobs. Many write-offs and lots of foil damage.

Keep in mind that new electrolytics are much better than the older ones, and there are other limitations to deal with. Unbiased electrolytics are still a bad deal though.

-Chris

[gmilitano]

Originally posted by anatech
Not to be a kill joy, and I don't intend to be, replacing a couple critical caps can bring an improvement. But the replacement part has to fit in the original space.

I've been called on to repair many swap'em out jobs. Many write-offs and lots of foil damage.

Keep in mind that new electrolytics are much better than the older ones, and there are other limitations to deal with. Unbiased electrolytics are still a bad deal though.

-Chris

Yup, getting poly caps to fit will be a problem. There are two (per channel) 4.7uF in the signal path of the phono and one 47uF in the linestage. I don't have anything suitable on hand, so I will put this off for the time being until I make an order for some other parts. I will likely try blackgates as several people speak so fondly of them.

All the pots are scratchy so I will try some contact cleaner on them. Does upgrading to a blue velvet seem like money well spent?

Considering the age of this unit, I think it sounds very good. The phono stage is esspecially nice.

[anatech]

Hi GG,
Why not replace them with new electrolytics now. Then bypass them with about 1 uF Poly - whatevers and see if there is a positive difference. Bypass the supply caps while you are in there. 100uF to 470uF and some films. This may make the biggest difference.

Use either De-Ox-Id from GC (I think - Active may stock it) or Caig DeoxIT DP5. Either will work extremely well. You only need a small amount on the metal wiper, not the carbon track. Always use only as much needed to do the job.

-Chris

[planet10]

Originally posted by anatech
Bypass the supply caps while you are in there. 100uF to 470uF and some films. This may make the biggest difference.

Reminds me of a local who swapped in a bigger power trafo with reported improvements.

dave

[planet10]

Also note that ir seems the values in the regulator are fairly critical. The fellow with the 7020 tired larger caps & went back to the stock size.

dave

[gmilitano]

Originally posted by anatech
Hi GG,
Why not replace them with new electrolytics now. Then bypass them with about 1 uF Poly - whatevers and see if there is a positive difference. Bypass the supply caps while you are in there. 100uF to 470uF and some films. This may make the biggest difference.

-Chris

Originally posted by planet10
Also note that ir seems the values in the regulator are fairly critical. The fellow with the 7020 tired larger caps & went back to the stock size.

dave

The supply caps are small, only 330uF on each rail. Like Dave mentioned, I have read of others having problems with larger caps on the supply. I am thinking of a nice cap (pannasonic) same size with a small 1uF poly bypass. I don't have capacitors on hand right now, so if I have to order, I may as well go with blackgates or pannasonics.

[chicco_36]

I had Nad 3020i and a lot more expensive gear, my expirience is that paraleling elcos with bipolars in signal path always means worse results. Like to diferent caps trayng to fight with eachother. I have best sound in Nad integrated amps and preamps with Blackgate nonpolars (47uF/16V) in input positions.
All the best!

[chicco_36]

Nad equipment have sometimes very upfront highs and mids, leading to agresive sound. Blackgates are known to be dark sounding and thair merit is "garantied", if someting like this is possible at all.