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Sugden Masterclass ANV 50

simon g

simon g

Older, wiser but no longer retired
Has anybody heard this, or even own it? I'd be interested in any feedback you may have.

It seems a bit of a departure for Sugden, as it uses a switched power supply but remains a Class A amp. Power is at 50W which makes it suitable for a much wider range of 'speakers. Plus it's much lighter, which is a great boon for me.
 
Looks great, I’ve huge respect for Sugden and they’d be right at the very top of the list if I was new amp shopping, but I am very confused how they claim to have got 50W (8 Ohm)/100W (4) of class A out of a fairly compact amp with no external heat-sinks etc. 50/100W of class A tends to be huge and very hot!

PS I can understand that a switch-mode PSU would be more efficient and take up less case-space, but even so it still needs to heat-sink 50W of class A somewhere. The other Masterclass stuff has huge heatsinks on the case sides.
 
It sounds a bit like the Quad current dumping idea. Not what most people would understand as class A, but knowing Sugden, it may well be rather good nonetheless.
 
JemHayward said:
It sounds a bit like the Quad current dumping idea. Not what most people would understand as class A, but knowing Sugden, it may well be rather good nonetheless.
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I was going to mention current dumping, but have never fully understood it. I did buy the Quad 405 new when it first came out. Still have it, but converted it to 405-2 about 1987.
 
Quoting Sugden
"When the ANV-50 does not receive an input signal it has a very low power consumption of only 20 Watts, making it extremely efficient. As the heatsinks are mounted internally with minimum contact to the outer case it only runs slightly warm to the touch."
So either a current dumper (Quads patent is long expired) or something like Devialet
 
Further from the Sugden site:

"features a comparator and correction circuit so that errors which could occur in the power output section due to varying loads and distortion, are corrected to match the output of the high impedance input amplifier. Whilst maintaining the signal authenticity, it also increases the load stability and forces the output impedance to zero."

I don't really understand what a comparator and correction circuit is and having an output impedance of zero? Sugden has never been a bullsh*t merchant, quite the opposite, so I presume that their explanation holds water. I'd like to hear one, but there just aren't any dealers close to me. I might try and arrange a loan unit. It'd be interesting to hear from anyone who has actually heard one though.
 
In the KSA Mark 2 range Krell had a heat reducing technology, I can't recall the details. There's a website somewhere which describes it, but I just can't find it again.
 
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Radfordman said:
A lot of people are fooled when class A is mentioned, decades ago Technics came out New Class A. Nerveless, they seemed to be good amplifiers. I still have a SU-V303 https://www.picclickimg.com/d/l400/...303-Amplifier-Integrated-stereo-New-class.jpg
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This whole area is a total nightmare, a real area for rip off because companies who make the amps are sometimes misleading.

I wouldn't buy anything thinking it was class A, wanting class A, without getting the advice of someone independent who was able to confirm it.

Neither would I trust a company whose publicity was misleading in this respect.

Of course Class AB or Class A/AB, Class AB/A, Class A+, Class AA or whatever may be fine, better even. But that's not the point.
 
But it was, I think, about running less hot because it’s power consumption was low when it wasn’t receiving an input signal, maybe Sugden have better heat sinks. And anyway it’s a less powerful amp than the KSA 100.
 
davidsrsb said:
Quoting Sugden
"When the ANV-50 does not receive an input signal it has a very low power consumption of only 20 Watts, making it extremely efficient. As the heatsinks are mounted internally with minimum contact to the outer case it only runs slightly warm to the touch."
Click to expand...

The Masterclass ANV-50 at the most does only run slightly warm to the touch.
 
Sugden do not claim 50W of Class A - their advertising is accurate.
100W into 4 Ohms is a clue that the output is NOT Class A
The classic Class A dissipates the most power idling. You can do tricks with dynamic supply rail voltages and quiescent current to reduce the idling power. In the limit you can make the power supply closely track the music, so that the output devices have a very small drop across them - basically what Technics did
 
It's definitely not class A and does sound like a current dumper.... the vague description above could also apply to class S/Technics "class AA" (pretty much the same thing).
Strangely enough it occurred to me just last week that Quads patents have long expired and so I've designed a couple of current dumping power amps myself of an evening.... and come up with another brand new topology!
 
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