What really is a powerful amp?

I have been running an Arcam A80 with 65w per channel lately which I know isn't a great deal. At the end of the month I am going back to Music Matters to collect a Musical Fidelity A5 which has 250w per channel at 8ohms which I thought would be one of the highest but after reading a few magazines like Hi Fi news some of the reviewers are talking about using at least 300w per channel which apart from the KW550/750 I have'nt seen in an amp.

I know huge power ratings don't mean its the best amp but what amps are there above 250w per channel into 8ohms just out of interest really.
 

alexs2

Distinguished Member
This one may help...

http://www.avforums.com/forums/showthread.php?t=491165&highlight=musical+fidelity

To put things into perspective,its not just the power of the amplifier in raw terms,but it's ability to deliver that into difficult loads,on transients,and a few other factors,PLUS the efficiency of the speakers that its being used with.

As an example,a low powered SET amp coupled with horn-loaded speakers may give an equal or greater dynamic range than a 200W+ S/s amp coupled with an inefficient set of speakers.

There are in fact a large number of power amps developing over 300W per channel,and a number from Krell,Boulder,Levinson and Bryston spring to mind,not just those from MF.

Not forgetting the MF KW1000,the real powerhouses around would be the Krell MRA(1000W/c),Boulder 2050(1000w),and Bryston 28BSST(1000w)....it is worth remembering though,that for a given speaker and sensitivity,that a 1000W amp will produce an SPL which is only 3db greater than a 500W amp,although the extra headroom at normal levels may be much more important.

A lot of this is marketing hype,although coupled with a degree of common sense,given that most of us dont use horns.

I would be surprised if you didnt find your 250W MF to be quite sufficient in all but the largest rooms,and with speakers of average efficiency and good power handling.
 
Many thanks for the detailed reply alex. I do understand about difference loads etc on the amps and room sizes I was just wondering about actual speaker output at 8ihms and did'nt relaise there was 1000w per channel amps :eek:

The MF A5 sounded wonderful when I auditioned one with some b&w 805s like I have. It really opened the speakers up and was the best option I heard in the price range!
 

alexs2

Distinguished Member
Many thanks for the detailed reply alex. I do understand about difference loads etc on the amps and room sizes I was just wondering about actual speaker output at 8ihms and did'nt relaise there was 1000w per channel amps :eek:

The MF A5 sounded wonderful when I auditioned one with some b&w 805s like I have. It really opened the speakers up and was the best option I heard in the price range!

I've got a pair of the older 805s(not the most recent version),and as those from the TAG forum will know,I originally heard them with a well specc'd 100w AV amp,which just didnt do them any kind of justice....mine are run with a set of Krell KMA 100s,nominally 100W/c amps which will double the output all the way down to 1 ohm,and arent upset by any load I've found....one of the old Krell ads allegedly used a KMA to drive an electric jack-hammer without trouble.
 
I understand the 800 series takes a fair amount of driving and heard a lot of people say they love to be bi-amped as well but I'm not really too bothered about doing this this time around.

I had a l isten with a Cyrus 8/Naim/Primare I30/Musical Fidelity A5 and they all offered a huge improvement over my trusty little arcam amp. I would of loved the KW550 but well out my price range and probably a bit ott at the moment for what I want.

I had a look at them other amps you said which would deliver 1000w per channel and there specs look awesome and I can easily believe the statements when they say " they'll drive any loud speaker in the world"

Thanks again.
 

alexs2

Distinguished Member
The 800 series when first released were mostly difficult to drive and quite demanding,although more recent versions have got progressively easier thanks to improvements in drive units and crossover design.

All do still benefit from high powered,high quality amplification if you want to get the best out of them,and especially so with the bigger models.....bi-amping though is another subject altogether,and I havent found the need to do that with mine,although for whatever reason,bi-wiring did make an audible improvement,which was clear to my wife,who didnt know what had been done to the speakers.

Hope you enjoy the MF.
 

drblind

Standard Member
I drive some 703's into oblivion (nearly as hard to drive as 804's) with a 130w amp, granted its a GOOD amp, but I wouldn't get to hung up on wattage, its the sustained current the amp can deliver thats important.

If your really wanting wattage, go for a digital (class-D) amp, but personally I think they make the music sound like an MP3.
 

lazarus

Member
years ago i heard a 25w valve amp that blew a 200w solid state out of the water - cant remember the specifics but i do reember being amazed at the sheer power.
 

MadamePresident

Active Member
im toying with the idea of this dussun v8i import amp

http://chinese-hifi.co.uk/Dussun.htm

Amplifier

Input Impedance:100KΩ

Voltage Gain: 29.5dB±0.5dB(1KHz)

Output Power: 2×250W(8Ω) Class A / 2×500W(4Ω) Class A,

Frequency Response: 5Hz~20KHz ±1dB

THD+Noise: ≤0.2%(20~20KHz,250W,8Ω)

Damping Factor: ≥200

Signal to Noise Ratio: ≥116dB(A-weighted)
 
looks very smart. what is the deal with valve amps....i.e how does a 25w valve amp drive a pair of speakers to decent volume :confused:

I've just recently got a Musical Fidelity A5 amp which delivers 250w per channel and is very good but might get a classe CAP 2100 if I ever get the chance!! :D
 

Scott_Mac

Distinguished Member
This one is fairly powerful..

http://www.chordelectronics.co.uk/products_detail.asp?id=38

14000&
 

alexs2

Distinguished Member
looks very smart. what is the deal with valve amps....i.e how does a 25w valve amp drive a pair of speakers to decent volume :confused:

I've just recently got a Musical Fidelity A5 amp which delivers 250w per channel and is very good but might get a classe CAP 2100 if I ever get the chance!! :D

Valve amps generally have a much softer clipping behaviour than S/s amps,and can be driven towards that point without the sound hardening too much,as mostly even order harmonics are produced.

However,you also have to bear in mind that many low powered valve amps,esp some of the SETs are used with very efficient speakers.

On the other hand,there are some truly powerful valve amps around....a few examples...

Audio Research 610T....600w

VTL Manley Seigfried....600+W
VTL Manley Wotan.......1200W

So if you wanted a very powerful tubed amp,and have the cash,the products are there.
 

harv

Active Member
Current delivery employs an important role as well as power... the Krell has built its rep on the fact that its early amp doubled output as impediance halved. Some amps power outputs are measured into 8ohms but fail to double often indicating a weaker power supply. Admittedly if you don't have difficult load speakers or highly insensitive ones its not as much of an issue.
 

alexs2

Distinguished Member
Current delivery employs an important role as well as power... the Krell has built its rep on the fact that its early amp doubled output as impediance halved. Some amps power outputs are measured into 8ohms but fail to double often indicating a weaker power supply. Admittedly if you don't have difficult load speakers or highly insensitive ones its not as much of an issue.

Very true,esp with low impedance or highly reactive loads....one of the initial selling points for Krell was that theirs was about the only amp capable of running Apogee's Scintilla,which was then a 1 ohm load.

Luckily,I have no worries on the current score!
 

Mr_Sukebe

Active Member
looks very smart. what is the deal with valve amps....i.e how does a 25w valve amp drive a pair of speakers to decent volume :confused

Easy answer, get a decent set of efficient speakers. 25w would acheive around 108dbs with my speakers. Is that loud enough for you?
 
wow that chord amp looks huge and extremely powerful.

I don't think I'll even start to look at valve amps yet just a little curious and also curious about electrostat speakers but that's another topic altogether.

I don't think I'll ever part with my 805s as I plan to eventually use them as rears in a 5.1 system. If the offshore job comes up I've applied for I might look at building a dedicated 2 channel hi fi with a very decent budget for speakers,amp and cd player.

Some of the hardest speakers I've seen for a while are top of the range Nautilus speakers by B&W which need to be driven actively by 3 amps :eek:
 

Londondecca

Active Member
......... one of the initial selling points for Krell was that theirs was about the only amp capable of running Apogee's Scintilla,which was then a 1 ohm load.

I could be mistaken but I do have a vague memory of some EAR amps driving the Scintilla speakers but in anycase the Apogee's always sounded glorious
 

alexs2

Distinguished Member
Some of the hardest speakers I've seen for a while are top of the range Nautilus speakers by B&W which need to be driven actively by 3 amps :eek:

In truth,the Scintilla was probably the worst amp-breaker of all time and was still pretty difficult when the crossover was redesigned and the impedance raised to the heady heights of nearly 4 ohms.

Londondecca said:
I could be mistaken but I do have a vague memory of some EAR amps driving the Scintilla speakers but in anycase the Apogee's always sounded glorious

Probably yes...in any case with transformer coupling and the later crossover revision,a tubed amp would have coped well,even if the total power would have been down compared to the Krell which would have been pushing about 800W into the original!
 

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