Is bigger better?

[GregH2]

Hi All,

Firstly, lets assume cost is no object nor greenhouse emissions.

I do most of my listening at relatively low power levels, and currently get by quite well with a 50W gainclone amplifier. However, I am considering purchasing either Cambridge Audio Azur 840A or 840W. These are rated at 120x2 and 200Wx2 respectively and can be seen here:

http://www.cambridgeaudio.com/series.php?SID=35

Now my question is, which would be better for my usually quiet listening levels? I know I'm never going to need 200W for my purposes...but... both amplifiers offer a few good watts of pure class A before moving to class B, with the 840W obviously having more with its idle power consumption of 180 watts. I really like the relaxed, laid back sound of class A and this is my preferred amplifier mode (after building a few JLH/PASS LABS clones).

Now pros and cons I see for each are (excluding cost and power consumption):

840A Pros:
1) Fewer power transistors (and maybe smaller and faster devices). Less chance of poorly matched components and probably better intrinsic circuit performance.

2) Overall a smaller and potentially simpler (better?) driver circuit.

840A Cons:
1) Less class A capacity and therefore more likely to use some class b during my listening.


840W Pros:
1) More class a power, likely to never leave class a for my listening levels (I love class a sound).

2) More power overall. Never going to clip for my purposes. No clipping induced distortion.

840W Cons:
1) More output devices and therefore a greater chance of poorly matched parts and poor circuit linearity and speed.

2) Larger, more complicated and possibly slower circuit overall - does this equate to poorer performance?


So I guess what I'm wondering is do I get a more complicated, ridiculously overpowered and possibly slower amp that will run in class a at my listening levels, or do I go for a smaller, simpler amp that will run into class b? Which one would potentially provide the best sound quality at under 50W of power? Is bigger better?

Any advice you can provide on this matter would be most appreciated!

Regards,

Greg.



1)

[Charles Darwin]

When it comes to ss power I like to insist on a minimum of 12dB headroom because NOTHING is as bad as clipping ss amps. For any speaker of 90dB @1w/1m I recon 100w to be the absolute minimum.
My speakers (4way active) with a mean efficiency of 95dB (91dB woofer, 95 mids, 107 tweeter, 95 supertweeter) I use a total of just over 900w/ch.
Chances are my class ab amps will never leave class a in normal operation and they never sounded better, much more relaxed, less strained than with the 250w (albeit passive) I used before. Any hint of harshness is gone for good.

[sreten]

Hi,

I suspect the cost of the pre/power combo versus the integrated version
makes the latter far more cost effective. Alternatively you could build the
designers (Douglas Self) full on class A amplifier or the related Trimodal.

Class XD is not strictly class A operation, it offsets the operating point.

/Sreten,

[adason]

as this is diy audio site, I would advice you to build an amplifier, possibly class A like JLH or any of Nelsons designs
you will save money, preferebly to buy music, and you might end with better sounding sytem, plus the reward of diy
ed

[jez]

I would expect a well executed gain clone to easily beat the Cambridge Audio offerings...

[5th element]

Originally Posted by jez

I would expect a well executed gain clone to easily beat the Cambridge Audio offerings...

You say this, but the designer of those Cambridge Audio amplifiers in question is, as Sreten pointed out, Douglas Self.

There'd be something wrong if a gainclone out performed them. Self has a considerable chapter in his latest book detailing their design.

[Melon Head]

My vote goes for F5 if you decide to build an amp.

[Mooly]

I wouldn't get hung up over class of operation... it's pretty irrelevant to how the amp actually sounds... sorry I know some will see red at that It's a very personal choice and depends on what you are seeking.

If you are spending that sort of money on a ready built amp you owe it to yourself to hear several before commiting. A good amp encourages you to listen... it has to be compelling... and it should pull the trick off with most music, not a few selected recordings... and at all levels, even low.

Dougs designs show a truly remarkable grasp of the purely technical aspect of design, however IMO they fail (to me anyway) to really sing and make music.

Adasons advice is good... JLH's amps really do perform. It would give you an idea of where to go from here.

[Melon Head]

Not to mention his design is an almost blatant rip-off from Nelson Pass, and he has the hide to apply for a patent.
I wish I had of known this earlier before encouraging a friend to buy an 840A. I was even considering one myself at one stage.

Yes the JLH is a design that is hard to beat.

[nigelwright7557]

Originally Posted by Mooly

I wouldn't get hung up over class of operation... it's pretty irrelevant to how the amp actually sounds... sorry I know some will see red at that It's a very personal choice and depends on what you are seeking.

I agree totally, my class AB amps perform very well with a great clean sound.

Unlike class A they do it without cooking and wasting loads of power.