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-   -   NAD 1020B tweaking and schematic (http://www.diyaudio.com/forums/solid-state/58078-nad-1020b-tweaking-schematic.html)

spzzzzkt 28th May 2005 07:50 AM

NAD 1020B tweaking and schematic
 
I've just noticed the current interest in the NAD 3020, so I've dragged my 1020B out of the closet to see if the pre-amp is worth putting back into service. I'm interested in trying out some of the mods described on http://gnu.295.ca/peak/audio.html, but it seems that there were quite a few "generational" changes. I'm wondering if there is a source for the 1020B or 3020B schematics on the 'net?

The volume pot has been previously upgraded to an ALPS 50K "black beauty", and I've replaced the 0.1uF green caps in the preamp section with "pooge grade" panasonic stacked film caps. I'm looking at replacing the electrolytics with either panasonic FA or elna starget, and doing a wholesale upgrade of the resistors to Draloic's. What else should I be looking at upgrading?

cheers
Paul

spzzzzkt 31st May 2005 04:57 AM

As a "test" I've replaced the carbon resistors in the pre-amp stage (R5xx directly behind the volume pot) with generic 1% metal film resistors from the parts bin. I'm surprised at the difference this change has made. Imaging is vastly improved and the top end seems to be a lot more transparent, with the veiled character (compared to a passive pre) of the standard unit significantly reduced. On the basis of this improvement, it seems like the parts upgrade path is well worth pursuing :) I'm able to source beyschlag 207-50Series resistors at a fairly good price, but I'm wondering if they will provide a worthwhile improvement over the generic resistors. My other alternative is to use welwyn RC55C 0.5% metal films, but I'm not sure they are worth the significantly higher cost over the beyschlag's?

cheers
Paul


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