NAD 3240PE overheating

[Chrism3513]

Hi all, hopefully this is the correct section for my question 

 

I have a second hand system I have only just put together in recent weeks. A nad 3240 paired  with monitor audio rs6 silver speakers. 
 

when it’s working I’m very happy with it however as soon as I have it at a decent volume (probably 50-75%) it seems the amp overheats , usually this results in the music suddenly getting crackly but once it actually stopped altogether and the soft clipping light turned from yellow to orange. 
 

upon advise I have tried tidying my speaker wiring , and tried swapping from speaker channel A to b on the amp. 
 

firstly i wonder if this amp is powerful enough for the job or am I asking too much of it ? Reviews I have read for the speakers say they are quite power hungry so is 40w enough? 
 

 

I really like the look of the nad amp and obviously have only just bought it and would like to keep it, so was thinking of adding a power amp in the hope that would alleviate the problem but I’m not sure if that is the right course of action 

 

im a real novice with this sort of stuff so any help appreciated 

 

oh also music is either coming from a audio technica turntable or an iEAST streaming dac. The problem occurs either way 

 

Chris 

 

 

 

 

[eman]

Welcome.

 

While I can't solve your problem I had a couple of those for years. They did like a bit of maintenance every few years and if that one's 'original' it's getting pretty old.

 

I had it acting as a preamp for a NAD power amp and they work fine for that.

[Ihearmusic]

Sounds like it needs a service. The bias adjustment has gone way off as well hence the heat and the clipping.

Off to a tech.

[Chrism3513]

Thankyou both for your responses. I think I’ll do both actually, it has a 3 month warranty so I can take it back to the shop to get them to look at 

 

but additionally I’m also thinking of ordering one of these 

 

https://nadelectronics.com.au/product/c268-power-amplifier/

 

Hopefully that way I will have the best of old and the best of new 

 

Chris 

[RCAJack]

IME the 3240PE soft clipping circuit is fragile but have you tried switching soft clipping off? (The switch is on the back.) NAD equipment from that era had some QC problems and if you have the option to return it I’d strongly recommend it. 

 

Your speakers aren’t super power hungry. Personally I’d turf that NAD. and get a better integrated rather than add an expensive new power amp. 

 

 

[wen]

I had an original NAD 3020, had it serviced and modified by StereoNet member hastag, an absolute beast on return, turning it any where near half would blow you out of the room,i also have MA RS6 speakers, they are 6ohm, so if your amp is old it may be working harder than you think into that load. Currently running 100wpc ss into the RS6's, sound brilliant

[mbz]

On 02/08/2021 at 7:16 PM, RCAJack said:

Personally I’d turf that NAD. and get a better integrated rather than add an expensive new power amp

+1 kinda... no objection to going seperate power amp but set aside some funds for a better preamp, restored kenwood C1 can be had for about $300-, unrestored up market preamps for a little more. Would make a mess of the 3240.

 

I've refurb'd 2x3150, 1x3140, 3x3020 and got a stack of PE's in the shed that need work. Certainly this era of NADs provide good bang for your buck tone/pace wise however they fall short with image. Also most don't have relay speaker protection, they rely on FET based muting (exception 3150)

[Chrism3513]

I ended up returning the nad to the vintage hifi store I bought it from where the guy blamed the problem on my speakers but at my insistence he said he will get his repair guy to take a look at it (supposed to have a 3 month warranty) 

 

I bought a new amp in the end , musical fidelity m3si, which I’m super happy with and hasn’t replicated the problem yet which makes me even less convinced by the shop mans deflection onto blaming my speakers (I wasn’t convinced as It was) 

 

thanks everyone for the replies and pms I received, much appreciated and I’m happy with the outcome

[andyr]

18 minutes ago, Chrism3513 said:

I ended up returning the nad to the vintage hifi store I bought it from where the guy blamed the problem on my speakers but at my insistence he said he will get his repair guy to take a look at it (supposed to have a 3 month warranty) 

 

I bought a new amp in the end , musical fidelity m3si, which I’m super happy with and hasn’t replicated the problem yet which makes me even less convinced by the shop mans deflection onto blaming my speakers (I wasn’t convinced as It was) 

 

thanks everyone for the replies and pms I received, much appreciated and I’m happy with the outcome

 

I don't think you're being quite fair to the NAD - and the store you bought it from.

 

You haven't listed your spkrs in the above post (and I'm certainly not going to spend my time scanning all the previous posts to try to find out this vital piece of information) - but it's entirely possible that your spkrs drop to a low impedance ... which makes them a punishing load, requiring an amp with a grunty PS.  Which the M3SI has ... but the NAD didn't.

 

So a simple matter of the wrong amp for your spkrs.

 

And

 

[Chrism3513]

Yes maybe you’re right. If that’s the case I’d be happy as I like the old nad and wouldn’t mind putting it in another room with a set of cheap book shelf’s as another set up 

[andyr]

16 minutes ago, Chrism3513 said:

Yes maybe you’re right. If that’s the case I’d be happy as I like the old nad and wouldn’t mind putting it in another room with a set of cheap book shelf’s as another set up 

 

Why do you think a "set of cheap book shelf spkrs" will provide a good load for the NAD?  If it's got a wimpy PS (which it appears to have) - then you need to find a pair of spkrs whose impedance doesn't drop below 8 ohms.  Spkrs like this may not fall into the "cheap" category - nor the "bookshelf" category!  

 

Andy

 

[Wimbo]

30 minutes ago, Chrism3513 said:

Yes maybe you’re right. If that’s the case I’d be happy as I like the old nad and wouldn’t mind putting it in another room with a set of cheap book shelf’s as another set up 

I used to sell these NAD amps and receivers and found them wonderfully reliable. My service department rarely saw them. The problem would be age and dust.

They had a warm tonal balance and were easily oven driven because of this. 

[Chrism3513]

1 hour ago, andyr said:

 

Why do you think a "set of cheap book shelf spkrs" will provide a good load for the NAD?  If it's got a wimpy PS (which it appears to have) - then you need to find a pair of spkrs whose impedance doesn't drop below 8 ohms.  Spkrs like this may not fall into the "cheap" category - nor the "bookshelf" category!  

 

Andy

 

It was a cheap amp. It will be a second system probably in the garage / workshop. I don’t have any intention on putting expensive or floor standing speakers in there. 
 

thanks for your help 

[andyr]

14 minutes ago, Chrism3513 said:

It was a cheap amp. It will be a second system probably in the garage / workshop. I don’t have any intention on putting expensive or floor standing speakers in there. 
 

thanks for your help 

 

My post was merely to try and prevent you from making another mistake, Chris.

 

It would seem the NAD needs spkrs which don't go below 8 ohms.  I personally have no idea which spkrs meet this criterion ... and are a. small and b. cheap.

 

Andy

 

[trobbins]

There are some suggestions about the first post's amp in this thread, but a surprising number of conclusions - all based on no technical input (no tech report feedback, and just a "it seems the amp overheats" and one observation of LED indications).  No one knows if the amp was properly checked prior to 2nd hand purchase, or what the speakers actually were, of if the amp had developed a fault.

 

The amp age is getting on for e-caps, but unlikely they would have been replaced before any sale.  The bias setting is very twitchy and dependant on pot wiper contact, which with age makes for suspect idle performance.  Although the output stage has base protection resistors, there is no emitter ballast protection.  A few other opportunities for past servicing/repair to get it wrong.  Even the OP could have wedged the amp where it didn't get sufficient ventilation.  Who knows ....

Edited August 11, 2021 by trobbins

[RCAJack]

On 10/08/2021 at 6:41 PM, andyr said:

You haven't listed your spkrs in the above post (and I'm certainly not going to spend my time scanning all the previous posts to try to find out this vital piece of information)

This thread, first post, second paragraph (scroll up)
 

On 10/08/2021 at 7:13 PM, andyr said:

Why do you think a "set of cheap book shelf spkrs" will provide a good load for the NAD?  If it's got a wimpy PS (which it appears to have) 

Why would somebody expect cheap speakers to present a load that a cheap amp could handle? Whuh?

 

Anyway congratulations @Chrism3513 and I hope you’re enjoying your new amp. 

 

Back in the day I certainly found my 3240PE had plenty of power and NAD boasted of its ability to drive low impedance loads when it was new. Maybe it ‘only’ needs a service but that’s a great way to overcapitalise a 30 year old amp if you’re paying a tech by the hour. 

 

There’s a lot of interesting discussion online about faults and repairs for the 3240PE. Search for threads on DIYAudio.com or find a couple here, such as this one from a few years back:

 

[Gregco]

On 10/08/2021 at 7:13 PM, andyr said:

 

Why do you think a "set of cheap book shelf spkrs" will provide a good load for the NAD?  If it's got a wimpy PS (which it appears to have) - then you need to find a pair of spkrs whose impedance doesn't drop below 8 ohms.  Spkrs like this may not fall into the "cheap" category - nor the "bookshelf" category!  

 

Andy

 

Nice concept if any speakers dont drop below 8 ohms. Look the NAD 3240 PE has a switch on the rear to select either 8 ohm or 4 ohm impedance. It's generally a safe bet selecting the 4 ohm setting if you're not sure of the swings and roundabouts of speaker impedance versus frequency. A nominal figure on a speaker is always very general and likely refers to the DC resistance of the coils but doesn't account for dips and peaks where the speaker impedance can go from 3 ohms to 18 ohms within 20hz to 20khz. 

The 3240PE has ample headroom and drive current capability at 4 ohms so it shouldn't be a big deal. 

The power supply is adequate given its peak current of 45 amps..... not wimpy at all.