Power amp design in Naim UnitiLite

[TDI]

I was Googling for reviews of the UnitiLite, and came across this video showing the innards: http://www.youtube.com/watch?v=ncxYU0ZjYHY

What intrigued me was that the power amps are using fully complementary output transistors from Sanken. (See about 1 min 15 secs into video). I thought that Naim were staunch supporters of the quasi-complementary approach to PA design ? Is this change of design philosophy unique to the UnitiLite, or is it a more general shift ?

 

[davidsrsb]

They still like those tantalum bead capacitors. The design could easily be a Cambridge Azur

 

[nudgerwilliams]

This thread has got me reminiscing about my (very) early 20s when I was an electrical engineering undergrad. I would have understood what you were talking about then.

Thanks for the memories

 

[kozolov]

As I know, the original Naim design was based on John Linsley Hood circuit. The same circuit was used by Exposure, Onix, etc.
The old quasi-complementary power amp not a special Naim design by JV. Maybe the NAP 140 was something else, and the new powers are based on this circuit.

 

[john.luckins]

This appears to be a departure for Naim. I've never seen them use a complementary output stage like this. Linn used those same output devices in their 1990's integrated amps but as part of the power supply regulation. The original Naim designs for their 70's, 80's and 90's amps was based on the original RCA quasi complementary circuit (including the 140). The JLH design was a departure from this Quasi circuit but the Naim one was near identical and remained class AB. Even the NAP500 uses this same circuit, though in bridged mode.

Nice marketing video. Even my wife might fall for that.

John

 

[SimonB]

I thought the Naits and the unitis all used the same basic amplifier topology?

So does this mean Nait 5i and 5XS are now complementary output types?

Not that it changes things....

Simon

 

[Pete MB&D]

I see they are now spacing the power resistors off the board, should help in the event on a output transistor shorting.

Pete

 

[Paul R]

There is a complementary output stage in Naim's past. Perhaps the NAIT 1.

Paul

 

[Arkless Electronics]

This appears to be a departure for Naim. I've never seen them use a complementary output stage like this. Linn used those same output devices in their 1990's integrated amps but as part of the power supply regulation. The original Naim designs for their 70's, 80's and 90's amps was based on the original RCA quasi complementary circuit (including the 140). The JLH design was a departure from this Quasi circuit but the Naim one was near identical and remained class AB. Even the NAP500 uses this same circuit, though in bridged mode.

Nice marketing video. Even my wife might fall for that.

John

The JLH 75W design from 1972, although very similar to the RCA/Naim circuit, is rather more sophisticated

 

[MJS]

There is a complementary output stage in Naim's past. Perhaps the NAIT 1.

Paul

Nait 1 was fully complementary, Nait 2 went quasi.