NAD preamp 1240 distortion

[SS4927]

Guess I'm a little slow this morning lol.

 

[Ian Finch]

Thanks for the update and the good news, Mark. DIYs and enthusiasts everywhere will appreciate this, if they haven't already discovered where you are. Let's hope you have a little time to continue with some projects or articles, however small, in the future.

 

[SS4927]

Hi, thanks for helping out I managed to get it fixed up, its very quiet now including the floor during playback. Excellent low dollar pre.

 

[rob211264]

Good morning SS4927

I found a post where you are reworking your NAD 1240 preamp. What did you use as a replacement cap on your bass control. 0.68uf .

I'm trying to recap the entire preamp and that value is the hardest one to find i don't know if there's anything other to replace it with any help would be most appreciated thanks in advance, Robert.


All caps is a violation of forum rules (Shouting) - changed capitalization. Please don't do this in the future. diyAudio Moderation

 

[sgrossklass]

For sub-1 µF values, try looking at film capacitors instead. It usually takes some improvising on the mechanical side (pin pitch tends to be at least 5 mm, vs. 2.5 mm for small electrolytics, so a more long-legged type would be preferable), but what can you do.

 

[rob211264]

NAD 1240 PREAMP

Thanks got it covered with a polypropylene film capacitor just waiting on the mail.

What about the Opamp NJM2043D does anybody know of a good replacement I understand I hear of the LM4562.
Can someone help me with this.

Sounds pretty good with my leach amp
but I'm figuring with the faster slew rate of a nice Opamp may pump things up a bit more.

How about the jfets 2sk363(GR) I have a couple matched 2sk369(BL) just after the opamp to clean things up...lol

I replace all the polyester caps to polypropylene.
And all the electrolytics to Elna silmic ll .
Bumped up the power supply from I think it was 330uf to 1000uf each rail.
And bridge rectifier.

Any additional information or help would be more than appreciated.

I wish I had the knowledge of a lot of you guys here I'm usually in the background but I'm usually pretty good about reading drawings and applying what skills I have to them to have a decent outcome but do not have the engineering understanding in implementing redesign.
Thanks in advance