Hi all, this is my first post yet I've been involved in DIY audio for almost 40 years and I also lurk around this site often. I thank you all for your well thought out contributions.
Recently I picked up a NAD 2140 just because I've never owned NAD equipment and I was interested in the circuit having 2 regulated supplies for the buffer and gain stages. I liked what I heard when I received the amp from a ebay seller. So I bought another one and configured both for bridged/mono.
I was dissatisfied with the lousy speaker and RCA connections as well as the A B speaker switches so I bypassed all of this and mounted a new RCA jack and a decent set of speaker binding posts on the rear to accommodate mono/bridged operation. As of today, I also replaced C648 and C650 on the right channel (used only in bridged mode) with high quality Nichicon audio quality caps. The results were quite nice. Since it sounds promising, I ordered replacements for all power supply caps and all other electrolytics. I'll bypass all the power supply caps with PPS film caps.
Here's some pics of the mods. The speaker switch bypasses are done with nice quality Alpha silver coated 99.999 OFC teflon insulated wires.
Sorry about the pics, I don't know how to inbed pics in the post.
Negative speaker connection
Negative
Positive speaker connection
Positive
Right channel input (bypasses the Lab Input resistor and cap)
Input
Input, cap, series resistor and speaker outputs on underside of board. The input cable comes down a notch in the rear board.
Board underside
Here's the RCA and the binding posts on the rear panel
RCA and Binding Posts
And C648 and C650 locations
C648
C650
Recently I picked up a NAD 2140 just because I've never owned NAD equipment and I was interested in the circuit having 2 regulated supplies for the buffer and gain stages. I liked what I heard when I received the amp from a ebay seller. So I bought another one and configured both for bridged/mono.
I was dissatisfied with the lousy speaker and RCA connections as well as the A B speaker switches so I bypassed all of this and mounted a new RCA jack and a decent set of speaker binding posts on the rear to accommodate mono/bridged operation. As of today, I also replaced C648 and C650 on the right channel (used only in bridged mode) with high quality Nichicon audio quality caps. The results were quite nice. Since it sounds promising, I ordered replacements for all power supply caps and all other electrolytics. I'll bypass all the power supply caps with PPS film caps.
Here's some pics of the mods. The speaker switch bypasses are done with nice quality Alpha silver coated 99.999 OFC teflon insulated wires.
Sorry about the pics, I don't know how to inbed pics in the post.
Negative speaker connection
Negative
Positive speaker connection
Positive
Right channel input (bypasses the Lab Input resistor and cap)
Input
Input, cap, series resistor and speaker outputs on underside of board. The input cable comes down a notch in the rear board.
Board underside
Here's the RCA and the binding posts on the rear panel
RCA and Binding Posts
And C648 and C650 locations
C648
C650
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