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Nap140 SOA removal HELP PLEASE

Mynamemynaim

Mynamemynaim

38yrs a Naim owner
Can someone please point me in the direction of a thread that CLEARLY shows how to and which components to ... remove to disable the SOA circuit on a Nap 140 power amp
Thanks
 
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If you believe that your power amplifiers SOA protection is getting in the way, buy a bigger amplifier.
The designer did not include it for fun and a blown output transistor ends up killing a speaker
 
As nothing has changed, start with the Acoustica site here: http://www.acoustica.org.uk/t/naim/power_amps.html
Go to 'Basic Mods', then #2 - Remove protection circuitry. Use the circuit diagram marked ''Original series Amp schematic (fig 1)'' for component reference. (You can just cut a lead on D2, R6, R11 and D1, R7, R10. That disables the SOA completely and is reversible if you re-solder the leads.)

If you really need pictures, those that were posted mostly do not display any more, but there are thumb nails still visible if you google NAP110 or NAP140 SOA removal.
 
Snowman that's perfect thanks
It was the reference diagram that originally threw me ...but diagram 1 makes sense

Cheers

Ps ..David ... I have a "bigger amp" but that doesn't stop me wanting to mod my 140 thank you.
 
davidsrsb said:
If you believe that your power amplifiers SOA protection is getting in the way, buy a bigger amplifier.
The designer did not include it for fun and a blown output transistor ends up killing a speaker
Click to expand...

It won't safeguard you from a blown output transistor killing a speaker, all it does is cut the signal to the output stage if is over driven, it looks at the voltage across the emitter resistors.

Pete
 
I’ve added loudspeaker protection to my 120 monos though I use Jim’s Audio boards rather than the usual Vellemans. The SOA had already been removed before I acquired them.
 
Pete MB&D said:
It won't safeguard you from a blown output transistor killing a speaker, all it does is cut the signal to the output stage if is over driven, it looks at the voltage across the emitter resistors.

Pete
Click to expand...
If the designer was competent and got the SOA protection close to but not over the limits, exceeding the SOA limits by disabling the circuit is a very quick way of shorting the output transistors.
You still need a protection relay circuit to be sure, but well designed amplifiers are very reliable.
 
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