They sound good and punch above their weight but every NAD integrated amp I have ever owned has failed... Luckily I have only owned a couple. This time I am really disappointed because this little c315 BEE integrated was really doing a nice job in a modest media system--which was a new thing for us.
I had been leaving the NAD in "standby" so it could be turned on/off via remote since the mechanical on/off switch is on the back of the amp and is not convenient to reach in my rack. The amp is less than a year old. Today, instead of turning on and playing nicely it produced low output with heavy distortion for about 10 seconds then shut down with the red LED glowing. After cool down this sequence is repeatable. This model NAD does not have the external jumpers to allow separate testing of the pre- and power amp sections. During the brief distorted output phase I could hear the tone controls working so I believe the preamp section is okay. The L and R outputs both distort. Power supply? I would be happy to do some probing--if I had a schematic.
Anyone happen to know what usually fails from prolonged standby in this amp? Anyone know where I can get a schematic or service manual? The amp has a 2-year warranty but I am the second owner and per the manual the warranty is not transferable.
I had been leaving the NAD in "standby" so it could be turned on/off via remote since the mechanical on/off switch is on the back of the amp and is not convenient to reach in my rack. The amp is less than a year old. Today, instead of turning on and playing nicely it produced low output with heavy distortion for about 10 seconds then shut down with the red LED glowing. After cool down this sequence is repeatable. This model NAD does not have the external jumpers to allow separate testing of the pre- and power amp sections. During the brief distorted output phase I could hear the tone controls working so I believe the preamp section is okay. The L and R outputs both distort. Power supply? I would be happy to do some probing--if I had a schematic.
Anyone happen to know what usually fails from prolonged standby in this amp? Anyone know where I can get a schematic or service manual? The amp has a 2-year warranty but I am the second owner and per the manual the warranty is not transferable.
Common failure on these amplifiers are the 10000uF smoothing cans. Take the top off and see if they have leaked or are bulging.
I have repaired a few of these now with these caps failed, also a couple of the smaller capacitors on the LT rails have a habit of drying out so just check for any bulging/vented caps.
I have repaired a few of these now with these caps failed, also a couple of the smaller capacitors on the LT rails have a habit of drying out so just check for any bulging/vented caps.
Perhaps there is a better explanation but there are 2 raw DC supplies here. One is of 45V rails and this linked via the the bulbs, one in either + and - rail, to a lower set of 35V rails.
Presumably, this produces a safer form of rail sag, as exploited in some designs to prevent excessive dissipation with low (4R) loads.
It might make a bit of a light show with heavy bass!
Presumably, this produces a safer form of rail sag, as exploited in some designs to prevent excessive dissipation with low (4R) loads.
It might make a bit of a light show with heavy bass!
Have you read Nad's white paper about it NAD Upgrade Software and Documentation -- License Agreement/Disclaimer - NAD Electronics
Yes, nice wording and justification for rail sag. It has worked in various forms since the dawn of audio. Almost every mid-range Japanese amplifier manufacturer exploited it for cost savings throughout the 1980s. NAD used to require you to switch the transformer windings between 4 and 8R loads to get the most out of their undersized transformers but this use of light globes eliminates the switch and typical user "dohhh" factor - that's the only clever part! The larger models introduce a more sophisticated switching arrangement.
I don't think you understanding it correctly. This is the evolution of the Power Envelope system from earlier models. It enables a moderately powered amplifiers to output short bursts of power for a few milliseconds. This gives the impression of a much larger power amplifier without the expensive power supplies, hence it being a budget amplifier. The switch you refer to from earlier models is not part of this circuit.
That "paper" reads like sales blurb - whoa, it is sales blurb!
Look at the schematic of the C315. (There is a good quality download at Hi-fiengine.com) The amplifier PSU consists of the 25 and 36V windings of a transformer, a bridge rectifier on each winding and 2 light bulbs bridging them. Now, what is there to the technology that makes it different in operating principle to a transformer wound to have it's voltage sag under load in a similar manner? Can the heating/cooling cycles of incandescent bulbs really track a musical power envelope with less distortion? Both approaches achieve their primary aim of protecting the undersize amplifier and transformer by simply sagging the power rails at high current.
Yes, that does suggest that brief powerful transients, if they actually exist in modern recordings, may still be at least partly reproduced, as actually occurs with both systems. The same claim for high transient power capability was made for my Technics amplifier more than 25 years ago. It claims 120W peak for a 70W/8R amplifier.
I don't wish to criticise the product's performance or it's value for money - just show that this technique is simply a new, if more versatile hat on an old head. New, pretentious terminology and spin don't make it any less recognizable.
Look at the schematic of the C315. (There is a good quality download at Hi-fiengine.com) The amplifier PSU consists of the 25 and 36V windings of a transformer, a bridge rectifier on each winding and 2 light bulbs bridging them. Now, what is there to the technology that makes it different in operating principle to a transformer wound to have it's voltage sag under load in a similar manner? Can the heating/cooling cycles of incandescent bulbs really track a musical power envelope with less distortion? Both approaches achieve their primary aim of protecting the undersize amplifier and transformer by simply sagging the power rails at high current.
Yes, that does suggest that brief powerful transients, if they actually exist in modern recordings, may still be at least partly reproduced, as actually occurs with both systems. The same claim for high transient power capability was made for my Technics amplifier more than 25 years ago. It claims 120W peak for a 70W/8R amplifier.
I don't wish to criticise the product's performance or it's value for money - just show that this technique is simply a new, if more versatile hat on an old head. New, pretentious terminology and spin don't make it any less recognizable.
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