How many watts per channel do you NEED?

[SHAXOS]

Dear All,

I previously asked this as part of an other question but got no answer. I am awaiting delivery on a pair of B&W 804S and will be buying a suitable amplifier in the near future. I currently have a Cambridge Audio 540a knocking about which has 50wpc. Can I use this amplifier to drive the speakers (lightly of course) or will this damage my speakers? Whilst I understand the speakers are a completely different class and ideally I should be looking at something way more powerful to drive them, I am just interested in any potential damage I could cause by using a 50wpc amp. Sorry im a bit of noob on this topic.

Massive thanks to all in advance.

 

[Covenanter]

Oh many! As many as many might be.

Chris

 

[CnoEvil]

FWIW. I think the CA will be out of its depth with those speakers, which really deserve something more in line with their original cost.

Only you can be the judge of the sound that you hear.

 

[Thompsonuxb]

Yes, is the short answer - driven sensibly it''ll probably sound nice too.

Nice speakers.

 

[chebby]

In your case bucketfuls of it. B&W would probably use them with big, hunky 300 Wpc Classe amps that can double up to 600 Watts into 4 Ohms without a shrug. (B&W own Classe so it's extremely probably those speakers of yours were developed using them.)

Having just looked at the impedance curve for the 804Ds (solid line), I noticed they dip to 3 Ohms in the upper bass around 100 Hz and stay under 4 Ohms for a fair bit of mid frequencies too...

I can't find plots for the 804s' so I hope they are kinder

 

[SHAXOS]

Thank you all for your input. Yes, as I stated - I know I WANT more power and I will get a more suitable amp in the near future. I just want to know of any potential dangers to using the CA at hyper sensible levels. Thanks Thompsonuxb, hopefully you are right!

 

[CnoEvil]

The CA will drive the speakers at sensible levels, but will only give a small taste of what the speakers are capable of producing.

Due to the speaker's revealing nature, the quality of the Source will also be important.

 

[SHAXOS]

Thanks! Im actually considering getting the Rotel 1570 to drive them. I heard the pairing when I demoed them and really liked the sound and at levels I would listen to I think it is plenty powerful. I am also really tempted by the peachtree audio 220 se but no opportunity to hear that.

 

[gasolin]

In your case bucketfuls of it. B&W would probably use them with big, hunky 300 Wpc Classe amps that can double up to 600 Watts into 4 Ohms without a shrug. (B&W own Classe so it's extremely probably those speakers of yours were developed using them.)

Having just looked at the impedance curve for the 804Ds (solid line), I noticed they dip to 3 Ohms in the upper bass around 100 Hz and stay under 4 Ohms for a fair bit of mid frequencies too...

I can't find plots for the 804s' so I hope they are kinder

It says that it goes down to 3.0 ohm, unless it's a used nad 325 or bigger i wouldn't like to use the cambrigde amp

http://www.bowers-wilkins.com/downloads/product/archive/eng_fp20265_804-s_info_sheet.pdf

Can't for the life of me imagine why someone would buy a pair of B&W 804s if they only have a small cheap but reasonable budget amp(that's like using all year tires on a big mercedes with a v8 engine).

Why not at the same time buy both, mabye a cheaper (so theres money for a better amp) B&W cm 8 and a bigger cambridge amp or just a marantz PM8005, rotel is surpose to sound good with B&W so one of the bigger models would be a good choice

 

[Andrewjvt]

In your case bucketfuls of it. B&W would probably use them with big, hunky 300 Wpc Classe amps that can double up to 600 Watts into 4 Ohms without a shrug. (B&W own Classe so it's extremely probably those speakers of yours were developed using them.)

Having just looked at the impedance curve for the 804Ds (solid line), I noticed they dip to 3 Ohms in the upper bass around 100 Hz and stay under 4 Ohms for a fair bit of mid frequencies too...?

?

I can't find plots for the 804s' so I hope they are kinder

It says that it goes down to 3.0 ohm, unless it's a used nad 325 or bigger i wouldn't like to use the cambrigde amp?

http://www.bowers-wilkins.com/downloads/product/archive/eng_fp20265_804-s_info_sheet.pdf

Can't for the life of me imagine why someone would buy a pair of B&W 804s if they only have a small cheap but reasonable budget amp(that's like using all year tires on a big mercedes with a v8 engine).

Why not at the same time buy both, mabye a cheaper (so theres money for a better amp) B&W cm 8 and a bigger cambridge amp or just a marantz PM8005, rotel is surpose to sound good with B&W so one of the bigger models would be a good choice

Hes got good speakers now and can get a decent amp later. Once the op gets an amp with enough current to drive the speakers its going to sound like an upgrade to the speakers all over again.

Just be careful not to damage the speakers by playing loud with that amp if you can resist.

If it were me id buy a cheap nad c370 on ebay now and then save up for a good quality powerful amp when i could afford one.

 

[NSA_watch_my_toilet]

You must be careful on the amp you will connect to that. All the B&W's I know about are tending to have very low impedances, generally around 2.7 ohms. Since the introduction of the brand new D3 series, the legendary powerhungriness of those speakers get down a little bit. But the D2 series will need a good amount of power too. The critical amount of low impedance didn't change from D2 to D3 generation. I cheated many times when it come to B&W and used some Lab Gruppen amplifiers on them with great results but it's not a "beautiful hifi" solution. Generally, I realised that the rendering quality goes up when the amp is able to give more than 90w per channel. 100w better. 120w better again. I didn't experimented with other things that Lab Gruppen for more higher power (2x300w).

 

[CnoEvil]

Try to hear the contenders from Arcam, Creek, Rega, Musical Fidelity and Hegel.

 

[CnoEvil]

That is not a straightforward question...as it depends.

Talking in general, things that effect "loudness" are:

- Robustness of the power supply in the amp...ie. Check power into 8 Ohms and 4 Ohms and a really good amp is stable into 2 Ohms.

- Ability to double power as impedance of the speaker halves, is the ideal.

- An amp's damping factor gives an idea as to how well it will control the bass unit.

- Speaker Sensitivity and Impedance have a major effect on the stress put on an amp and how loud a system will sound.

 

[ID.]

And probably more than how many watts per channel, something with a power supply that can handle those dips - i.e. the kind of amp that doubles, or comes close to doubling, its output into 4 ohms. Personally I would be targetting something at the level of the Luxman L-507u (or uX). Not saying it needs to be a Luxman, but 110W+110W/8Ω, 210W+210W/4Ω

But something like the Luxman 590AX would also work depsite only having 30 watts per channel because of the current it can supply to handle those dips.

 

[Thompsonuxb]

You have to tilt your hat at all this techno mumbo jumbo.....lol.

Once set up Shaxos pls let us now how it sounds.

Your amp won't deliver anything that will require your speakers to dip down to 2ohm and should sound 'cosy' at normal levels (don't push the amp into clipping mind & best not to bi-wire)

Better psu's more wattage and higher currents will improve things but best to enjoy what you have now till you are ready to step up.

Frankly while you're saving for your amp this'll be a good time to sort out quality cables.

That little Cambridge may even surprise you......

 

[ID.]

Should be enjoyable enough if not pushed into clipping. I've heard the 805s powered by the first version of the Aura Note all in one, and it sounded very good. Just not the jaw droppingly beautiful sound I heard with Luxman's top of the range class A integrated amp.

 

[SHAXOS]

OK, so i've had my 804s for around 3 days now and the CA 540A has been on the other end. How do they sound? Well honestly, very good. I am completely thrown back at how the little Cambridge manages to drive them. Obviously im not listening at high volumes and its not the best I have heard them sound but they do sound good. The bass is a bit loose and the soundstage is not the best I have heard on the speakers but seriously, my amp cost 50 pounds used. - around 30 times less than the speakers. Taking that into cosideration im very happy and will be able to take my time with finding a more suitable amplifier.

 

[drummerman]

OK, so i've had my 804s for around 3 days now and the CA 540A has been on the other end. How do they sound? Well honestly, very good. I am completely thrown back at how the little Cambridge manages to drive them. Obviously im not listening at high volumes and its not the best I have heard them sound but they do sound good. The bass is a bit loose and the soundstage is not the best I have heard on the speakers but seriously, my amp cost 50 pounds used. - around 30 times less than the speakers. Taking that into cosideration im very happy and will be able to take my time with finding a more suitable amplifier.

Ah yes but does it make your ear lobes flubber in the pressure wind waves?

 

[Jota180]

Plus how big is your room and how loud do you like playing your music. At 'normal' levels you'd perhaps get away with an amp that wouldn't hack it if you like to play at party levels. The amp is the muscle for your system so it needs to be able to comfortably provide what you expect of it.

 

[Jota180]

OK, so i've had my 804s for around 3 days now and the CA 540A has been on the other end. How do they sound? Well honestly, very good. I am completely thrown back at how the little Cambridge manages to drive them. Obviously im not listening at high volumes and its not the best I have heard them sound but they do sound good. The bass is a bit loose and the soundstage is not the best I have heard on the speakers but seriously, my amp cost 50 pounds used. - around 30 times less than the speakers. Taking that into cosideration im very happy and will be able to take my time with finding a more suitable amplifier.

Ah yes but does it make your ear lobes flubber in the pressure wind waves?

It's a known phenomenon that people generally prefer louder than quieter.

 

[Paulq]

OK, so i've had my 804s for around 3 days now and the CA 540A has been on the other end. How do they sound? Well honestly, very good. I am completely thrown back at how the little Cambridge manages to drive them. Obviously im not listening at high volumes and its not the best I have heard them sound but they do sound good. The bass is a bit loose and the soundstage is not the best I have heard on the speakers but seriously, my amp cost 50 pounds used. - around 30 times less than the speakers. Taking that into cosideration im very happy and will be able to take my time with finding a more suitable amplifier.

That's not the point. You NEED more wpc. Even if it's perfectly adequate for you, ignore your common sense and your ears and go out and buy a much more powerful amp. It's the way around here. *blum3*

 

[davedotco]

OK, so i've had my 804s for around 3 days now and the CA 540A has been on the other end. How do they sound? Well honestly, very good. I am completely thrown back at how the little Cambridge manages to drive them. Obviously im not listening at high volumes and its not the best I have heard them sound but they do sound good. The bass is a bit loose and the soundstage is not the best I have heard on the speakers but seriously, my amp cost 50 pounds used. - around 30 times less than the speakers. Taking that into cosideration im very happy and will be able to take my time with finding a more suitable amplifier.

That's not the point. You NEED more wpc. Even if it's perfectly adequate for you, ignore your common sense and your ears and go out and buy a much more powerful amp. It's the way around here. *blum3*

Amplifier power and quality is fundamental to the performance of a decent system. In real world systems power is important because, despite the oversimplified 'calculator' posted recently, loudspeakers are complex devices that will, under certain circumstances demand a lot of power from amplifier.

Low impedance, awkward phase angles, thermal compression all conspire to demand more power from your amplifier than you think. Personally I think the difference is obvious, my experience, common sense and yes my ears tell me that. Sadly good, powerful amplifiers are not cheap and comparisons between 50 and 100 watt mid-fi amplifiers are meaningless in my view.

 

[gasolin]

Depends of what sensitivity your speaker have

I have a marantz PM6005 and 87 db sensitive speaker, in my small livingroom it's enough

In a big room i would say around 93 db like Q Acoustics 2050i (92db), if my spakers can handle it i would say above 100watt in a big room, low sensitivity in a big room minimum 200watt, if sensitivity is normal (86-88db) and a mid sized room, any good 40-50 watt amp will get you alot of loud music (just make shure the size of the woofer is the right size according to room size, small room 4-5½" big room mabye 4x8" or 2x12" or you would gett muddy,boomy bass or not enough bass)

 

[Thompsonuxb]

OK, so i've had my 804s for around 3 days,now and the CA 540A has been on the other end. How do they sound? Well honestly, very good. I am completely thrown back at how the little Cambridge manages to drive them. Obviously im not listening at high volumes and its not the best I have heard them sound but they do sound good. The bass is a bit loose and the soundstage is not the best I have heard on the speakers but seriously, my amp cost 50 pounds used. - around 30 times less than the speakers. Taking that into cosideration im very happy and will be able to take my time with finding a more suitable amplifier.?

 

Told yah..... :-D

 

[Vladimir]

No speakers were ever damaged from a powerfull amp. Every blown driver and crossover came as a result of underpowered amp for the application (or appetite) that were clipping. Much easier to destroy a speaker with 30W amp than 300W.