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Poweramps - Sugden, MF - can anyone explain please?

gsrai

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Gents

My house resembles a power house at the moment as I have an MF X-AS100, MF A% and Sugden Bijou apmaster poweramps lying around to test.

As expected, the A5 power is better than the other 2 with the clearest difference being the spaciousness of the sound and ease with which it flows :)only problem is it is a bit of an ugly looking beastie
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On to the other 2, The Sugden baby really surprised me as I can't really tell the difference between this 35w and the 100+W X-AS100. I've read around the design (dont understand it) so how come the little Sugden is able to drive my hard to drive PMC GB1's (I always thoguht the strong point of MF was the current drive and I know the Sugden isn't class A).

Does anyone understand why less WATTS at relatively low volume sounds similar - I'm confused :?and cal somebody also tell MF to but the big powerhose A5 in a small package so I can keep it :Upset:

 

yoda900

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HiFi Trade?
  1. Yes
Sugden Watts are like Yorkshire Tea. Strong and will put hairs on your chest
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A

Alex A

Guest
Hi Grasi,

I had the A5 at home myself when looking for a power amp to replace my Sugden a21aP (which is of course class A). I think the A5 is a cracking design (not so common among the newer MF stuff), and with a normal load (87dB or so) did demonstrate the advantage of having something more powerful than the Sugden. Into a more efficient load, however, I doubt it would be the better choice overall. Of course synergy isnt all about power/efficiency matching, but it's a good first step.

Ultimately I went for the Krell, which is about 2.5 times the size of an A5, and weighs 3x as much, and is ugly as sin. But it sounds damn good being so powerful and class A. Though the A5 ran it close!

Doesnt surprise me that much that the X-AS100 sounds similar to the ampmaster (which is indeed AB), as I have found that the Sugden house sound isn't too dissimilar to MF kit in many ways (especially when both are AB).

But the A5 is a great choice. If you want small, perhaps look at an XP-200 or two. Possibly better still...

 

gsrai

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Aug 18, 2005
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Alex_A wrote:

Hi Grasi,I had the A5 at home myself when looking for a power amp to replace my Sugden a21aP (which is of course class A). I think the A5 is a cracking design (not so common among the newer MF stuff), and with a normal load (87dB or so) did demonstrate the advantage of having something more powerful than the Sugden. Into a more efficient load, however, I doubt it would be the better choice overall. Of course synergy isnt all about power/efficiency matching, but it's a good first step.

Ultimately I went for the Krell, which is about 2.5 times the size of an A5, and weighs 3x as much, and is ugly as sin. But it sounds damn good being so powerful and class A. Though the A5 ran it close!

Doesnt surprise me that much that the X-AS100 sounds similar to the ampmaster (which is indeed AB), as I have found that the Sugden house sound isn't too dissimilar to MF kit in many ways (especially when both are AB).

But the A5 is a great choice. If you want small, perhaps look at an XP-200 or two. Possibly better still...
Alex

Some good points there - I tend to agree with you on the newer MF stuff and quality
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I don't really know what the difference between class A, AB etc is apart from class A is probably more current based and therefore runs hotter and needs less power - is there a hierarchy.

The thing I'm struggling with is this power rating malarky - how does it work :Not Sure:

I used to have the X-P200's and good poweramps but ultimately not for me.

 
A

Alex A

Guest
Class A amps aren't less powerful because they don't need to be as powerful. Very rudamentally, their output transistors are fully biased to 'on' all the time, regardless of the signal feed. This means that they have to dissipate a huge amount of energy that isnt used for actually amplifying the music signal, and this is dissipated as heat. So the more powerful a class A amp is, the larger power supply you need, bigger case, and more heatsinks/fans.

Power ratings are misleading. There was an article in Hi-Fi World about it recently, and basically in order to double the output of your speakers, you have to multiply the amplifier power by 10 (logarithmic).

So very roughly, an 250W A5 is only twice as loud into particular speakers as a 25W Sugden A21a.

 

darrell

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Apr 16, 2006
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gsrai wrote:

GentsMy house resembles a power house at the moment as I have an MF X-AS100, MF A% and Sugden Bijou apmaster poweramps lying around to test.

As expected, the A5 power is better than the other 2 with the clearest difference being the spaciousness of the sound and ease with which it flows :)only problem is it is a bit of an ugly looking beastie
sad.png


On to the other 2, The Sugden baby really surprised me as I can't really tell the difference between this 35w and the 100+W X-AS100. I've read around the design (dont understand it) so how come the little Sugden is able to drive my hard to drive PMC GB1's (I always thoguht the strong point of MF was the current drive and I know the Sugden isn't class A).

Does anyone understand why less WATTS at relatively low volume sounds similar - I'm confused :?and cal somebody also tell MF to but the big powerhose A5 in a small package so I can keep it :Upset:
In the past, I gave these kind of questions a lot of thought, and a bit of research, and I think I understand it, but anyone, feel free to correct me...

Amplifer power

You need 10 times the power to double the volume, so the difference between a 35 watt amp and a 100 watt amp is not as much as the figures might suggest.

Amplifier gain

That is, the step up between the input to the power amp (or power amp section of an integrated amp) and its output to the speakers. This is a constant for any given amp, and normally quite similar between different amps. It is not related to the power output. A 20W amp and a 200W amp (especially from the same manufacturer) may well have identical gain. The volume of the system is controlled by the level of the input to the power amp (section), i.e. the level of the output from the pre-amp (section).

The difference between the 20W amp and 200W amp will be the level at which they run out of steam - i.e. the level at which the amplifier's gain, when applied to the input signal, will result in the amp being asked to output levels in excess of its power rating. One consequence of this is that it is perfectly possible to bi-amp with two amps of identical gain, even though one is much more powerful than the other, as long as the weaker amp is not asked to deliver more power than it is able to.

Input sensitivity

Most modern sources (I'd say all digital ones, and even many phono stages) deliver an input voltage far greater than that needed by the amplifier to deliver its maximum output. For example, my Arcam A85 has an input sensitivity of 250 millivolts, which means that in order to deliver its rated output of 85 watts, it needs an input signal of 250 millivolts. The Compact Disc specification is 2 volt max output (ie input to the amp), and many CD players deliver even more. So in my case, my CD player is delivering at least 8 times the voltage my amp needs for maximum output (at least during the loudest passages of music). The upshot of this is that when playing a modern source, most amps will enter clipping, distortion and general amp-and-speaker-frying nastiness, long before the volume is up to maximum. As a general rule, at about 12 or 1 o'clock on the volume control, most amps are delivering as much clean power as they are able to.

Listening

So, if most amps have somewhat similar gain and input sensitivity, and vaguely linear volume controls (as I believe to be the case for mainstream hifi amplifiers), the volume they deliver for a given position of the volume control will be similar. You'll really only notice the difference in power output at headbanging levels with most rock and pop music. With classical music, the dynamic range of the recording is much greater. With the volume control set so you can just about hear softly plucked violin strings above the background noise of the central heating boiler, traffic, the kids, the dog, etc, etc, a low power amp driving insensitive speakers will give up the ghost when the timpani and brass come in at full pelt (I listen a lot to Lizst, whose music contains occasionally insane dynamic contrasts). Which is why a strong, powerful amp is a good thing, despite all of the above.

 
P

purplepleaser

Guest
Hi Gobind

I think amps are like car engines.

A=Some car engines have loads of B.H.P but not torque. Not very good.Will not pull the skin of a rice pudding.

B=Some car engines havegood B.H.P and good torque. The perfect engine. Pulls very well in low gears at low speed.Great power across the rev range.

Some amps are built like A and some are built like B

I think that Sugden are built like B. Not the most powerful amps in the world but have the all important torque.

My class A Musicmaster runs cooler when playing music than just sitting idle.This is why i have been told to switch it off when not listening.Plus its expensive to leave on. It only takes 10 minutes to sound its best from cold.

What i have typed might be total balls and completely wrong. Its the best way i can describe what i think the differences are.

Lee:)

 

gsrai

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Aug 18, 2005
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DARRELL and LEE

Thankyou very much for your thoughts (cleared up a lot in my head - left some questions as well but that's the nature of the game I suppose :Not Sure:).

Lee, what is it that gives the "torque" as you put it (great analogy
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) - is it current?

Darrell, your conclusion (If I understand it right) is that the transients (sudden changes) in the music is where power is important, is that right?

Since I only listen at low volumes (say between 7 and 8 o'clock) - what would be the best answer/compromise?

ICE - you must be mad
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P

purplepleaser

Guest
Hi

I haven't got a clue what,where the torque is/comes from. I do know that the Sugden amps are quite simple in their designs.Nothing is put in the box thats not needed. They don't believe in after market power supplies,asking is like asking to do their daughters:shock:. Maybe its the power supplies or what they are called.explaining any further is way out of my knowledge. I will take a picture of the inside of my Musicmaster,from memory there is not a lot going on inside the box. Its what comes out of my speakers that count.
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.

Sorry for being a bit dim.

Lee

 

gsrai

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Lee

Don't be sorry mate - this journey is all your fault anyway
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I think I'm being a tad dim by not understanding what makes it all work but like you say, its the music that counts!

 

gsrai

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Aug 18, 2005
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The good thing is I am at least ventyuring outside of the MF nest that has been home for so long!:djermaica:

 

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