Define power hungry...B&W speakers


I need to know what is important in amplification to power my B&W CDM 1NT's. Rated from 50-125 I believe. How much minimum power is necessary, damping factor, etc. What specs are important to me?
Thank you!
tntate
They're not particularly fussy. Reasonably sensitive at 88db and not dipping below 4.6 ohms according to their specs.

How much power depends on what kind of music you listen to, how large your room is and how loud you listen.

In a smallish room, 30 watts would probably be minimum if you like to listen at reasonable levels, but not particularly concert levels.

For larger rooms and/or realistic concert levels or for widely dynamic music such as symphonic orchestras, 100+ watts wouldn't be too much and you would likely want to add a subwoofer.

I've used 15 watt amps with similar speakers in a smallish room with no complaints, but I don't listen to music all that loud anymore. I probably average around 82db these days.

Post some room measurements and preferences for loudness and you'll get a better response from the membership.
search the archives of the forums here at Audiogon. this topic has been discussed over & over again - plenty of info available for you to read....
"How much minimum power is necessary, damping factor, etc. What specs are important to me?"

No 2 companies measure their amps exactly the same way. You can have 2 amps rated at 100 watts/ch into 8 ohms and there can be a huge difference between how much power they put out in the real world. You need to take each amp on a case by case basis.
Room 10 X 13, carpet with lots of furniture and high ceilings. Music all type's, acoustic, classical, vocals, etc. No high volume levels.

In the archives I cannot seem to find the answers I'm seeking.

There has to be a place to start that is written, not subjective...

I hear the phrase "high current", how is that defined?

Thanks everyone!
"I hear the phrase "high current", how is that defined?"

It depends on who you ask.
More power is always better, it provides headroom and plays out with more weight and solidity, better definition throughout the range. For anyone with real world listening volumes like me. I listen to my system between 35-350 watts, because I like to feel the music too. B&W's are traditionally easy to drive 8 ohm speakers and watts are cheap! Unlike my Dynaudios that suck power up like a cat drinking milk.
B&W's are traditionally easy to drive 8 ohm speakers and watts are cheap!
wow! that's a new one on me. B&Ws are easy to drive 8 ohms speakers? Really? I did not know this - from my experience & every time I've heard them they've been nothing short of a difficult load for the amp.
I might be missing something here.......
"I might be missing something here......."

They are easy to drive. (For a powerful amp)
Any answers... Amplifier specs don't really matter then? If specs are so subjective why do manufacturer's post damping factor, slew rates, etc. Where do I go to get a foundation of data, that counts, to begin a short list of amplifiers that meet a minimum criteria.

Question then: I've read a 50w Naim has no problem with B&W speakers. I've also read that I should focus on 100+watts to get the detail out of my
"Power Hungry" speakers. What details in the Naim specs should I look at to see how they do it?

Frustratingly fun! Thanks for your response.
Your speaker B&W CDM 1NT's. Rated from 50-125.
I always use the highest number 125 as my minimum criteria to avoid any frustrating tweak and just enjoy music. So far it's working for me.
"12-17-14: Tntate
Any answers... Amplifier specs don't really matter then? If specs are so subjective why do manufacturer's post damping factor, slew rates, etc. Where do I go to get a foundation of data, that counts, to begin a short list of amplifiers that meet a minimum criteria."

I didn't say that amp specs don't matter, or that they are subjective. I said that there's no set standard that all of the manufacturers use to measure their amps. There's a big difference. I don't have time now, but I'll post later with more details on what I mean.
Ya, you are missing something Bombay.....WATTS! Its amazing how some people try to skimp on what's needed most for a lot of speaker brands...is just plain ole clean power! That's all B&W's need is power and ANY amp can drive a 8ohm load with ease!
Thanks for the input, please keep it coming! I do need the communities help.
Tntate,

the power ampselection will depend upon tubed or solid-state. Over the years, I have heard many, many power amps n the various B&W speakers.

The newest Conrad Johnson Classic 60 is more than enough to drive at concert levels. On the SS side, Classe' , Mark Levinson, Rotel and Bryston all sound excellent as well.

Most importantly, which brand(s) of cables/power cords are you planning to use?

Keep me posted and Happy Listening!
I have a pair of B&W CDM 1NTs mated to a Musical Fidelity A5 integrated amp.

Marvelous synergy, good dynamics from soft to 'stupid loud' and the A5 never runs out of juice, great control on the bottom end, smooth sound. Power is always your friend.
The Musical Fidelity and Classe' brands keep coming up in my research, also Creek and Naim. I have not even considered special cables, power cords etc. I think I prefer a integrated amp to keep costs down. But again, trying to figure out specs to create a short list.

Thanks again!
I know exactly what you are looking for when you're asking for amp specs that you can use to make a decision. It definitely makes sense, but it's not going to happen. I'll give you a couple of examples of why that is. One of the more popular specs when it comes to power amps is thd. The designer for brand A may say that for 100 watts into 8 ohms, 2% thd is acceptable amount of distortion. If you give the same exact amp to Company B to rate its power, they may say that 2% is too much distortion for a 100 watt amp into 8 ohms. Maybe they feel anything above 1% is not acceptable. So if that's the case, company B may rate the amp at 75 watts instead. Or they could go the other way and say 3% is OK and give the amp a higher power rating like 125 watts. That's what I'm talking about when I say there's no standard. It explains why you can go into Best Buy and get a 100 watt/channel for $200, and then find a high end company that's selling a 100 watt/channel amp for thousands of dollars.

Another example is what makes up a watt. Watts are volts x amps. 10 amps and 10 volts is 100 watts. 50 volts and 2 amps is 100 watts. 20 volts and 5 amps is 100 watts. You get the picture.

Of course, there's more examples than what I list here. So if you're now thinking, what are you going to do as far as picking an amp? You need a way to go beyond the limitations you now find yourself in with regards to specs. The way you do that is by listening to whatever amps you are considering. Audio a very hands on. You need to listen to as many different components as you can. As you gain experience over time, it gets easier.

Looking at your system, the B&W's are not big floor standing speakers, and your room is not that big either. You really won't have any trouble finding an amp that will work for you. I would be more concerned with sound quality than watts. Also, you mentioned above that B&W recommends a high current amp, and they don't do a good job of defining exactly what that is. Its expected that you'll be working with a dealer that can help you make a selection. Speaker companies usually recommend a high current/powerful amp because they want their speakers to sound good. If you go in under powered, sound quality will suffer. And if that happens, there's always the chance you'll blame the poor sound quality on the speakers, and not the amp.
Thanks ZD542. I appreciate you taking the time to explain, it does make sense. My hope was to have a firm base of specs as I will probably buy used from this site. Without the ability to demo the gear its hard to make the best decision. I do know in the end that this all comes down to my room, my gear, and my own ears.

Thank you!

Any other thoughts out there?
Here's one more example for you that may help in your selection. You picked your B&W's for a reason. On paper, your CDM 1NT's look like countless other small speakers. You can find another pair of speakers of a similar design and specs, and for much less than what you spent on them. The reason you went for the B&W's is because you like the way they sound. You took the necessary step, and crossed over from the objective to the subjective. If you didn't do that, you couldn't justify the purchase. It's the same thing with any other component. If you set some goals as to what you expect from a new amp or integrated amp as far as sound quality, it will be a great help. You can still make a mistake, but you lower the chances. Try not to worry too much about the specs. I think you easily have the ability to make a sensible choice as to how powerful an amp you need. If you're not sure, just post what ever amp you are considering, and someone here should be able to tell you if it will drive your speakers, or not.

One last thing. Don't get sucked into the cable trap. Cables do make a difference, but so many people put way too much money into cables when it could have been used to buy better components. Not only that, but if you get good components and match them well, cable choice is very easy.
I use the 700 series which replace the CDMA NT. Both use the Nautilus tweeter (NT). I also own 600 and 800 series and these are a sweet spot. Easy to drive like 600 series but much more refined.

You do not need a massive amp but a good 100 wpc integrated is ideal in my experience. My 50 wpc Linn and Rega integrated were fine but at low volume, I found my 100 wpc McIntosh or modern Yamaha integrateds were a lot better. A big NAD works well too. A nice tube amp will be a good choice too as long as it is not one of those really small one. A 75 wpc Cary or McIntosh is a good choice.

These are very high quality and revealing speaker so they will reward care in your set up. I use Transaprent audio cable as the little network boxes were very good at suppressing line noise which the NT are reproducing. I use some level of isolation on all components in the chain, even the amps. Again these speaker will allow you to hear the differences that small tweaks make. Enjoy.
I use the 700 series which replace the CDMA NT. Both use the Nautilus tweeter (NT). I also own 600 and 800 series and these are a sweet spot. Easy to drive like 600 series but much more refined.

You do not need a massive amp but a good 100 wpc integrated is ideal in my experience. My 50 wpc Linn and Rega integrated were fine but at low volume, I found my 100 wpc McIntosh or modern Yamaha integrateds were a lot better. A big NAD works well too. A nice tube amp will be a good choice too as long as it is not one of those really small one. A 75 wpc Cary or McIntosh is a good choice.

These are very high quality and revealing speaker so they will reward care in your set up. I use Transaprent audio cable as the little network boxes were very good at suppressing line noise which the NT are reproducing. I use some level of isolation on all components in the chain, even the amps. Again these speaker will allow you to hear the differences that small tweaks make. Enjoy.
I use the 700 series which replace the CDMA NT. Both use the Nautilus tweeter (NT). I also own 600 and 800 series and these are a sweet spot. Easy to drive like 600 series but much more refined.

You do not need a massive amp but a good 100 wpc integrated is ideal in my experience. My 50 wpc Linn and Rega integrated were fine but at low volume, I found my 100 wpc McIntosh or modern Yamaha integrateds were a lot better. A big NAD works well too. A nice tube amp will be a good choice too as long as it is not one of those really small one. A 75 wpc Cary or McIntosh is a good choice.

These are very high quality and revealing speaker so they will reward care in your set up. I use Transaprent audio cable as the little network boxes were very good at suppressing line noise which the NT are reproducing. I use some level of isolation on all components in the chain, even the amps. Again these speaker will allow you to hear the differences that small tweaks make. Enjoy.
Tntate,
i found these measurements for the next rev of your speakers - B&W 705:
http://www.stereophile.com/content/bw-705-loudspeaker-measurements
could not find any such measurements for your CDM-1NT speakers but my guess (from my personal experience & seeing B&W's other speakers) is that the CDM-1NT & the 705 models measure about the same.
the impedance & phase plots are totally wild, IMO & this speaker will drive most amps crazy as it yo-yos from capacitative load (negative phase) to inductive load (positive phase). You see this happening in the 1KHz-3KHz region. As the amp deals with capacitive & inductive phase shifts, the impact is felt in the music as phase distortion which will appear as a brittleness or an unusual sharpness in the vocals - the 1KHz-3KHz is a sensitive region for the human ears.
Also, due to the wild phase shifts of this speaker, your amp will be wasting a lot of power into the reactive components (capacitor & inductor) of the x-over. The effect of this will be that your amp's instantaneous power will be reduced by the phase angle at that particular freq. For example, look at the 100Hz freq. The phase angle is -45 degrees. Let's say that you are cranking 10W into the speaker for your desired volume. Due to the -45 deg (capacitative) phase shift, the real power is only 7.07W & an equal amount of power is burnt up in the reactive component of the x-over. So, your amp will be working hard but only half the power makes it to the speaker drivers.
That's why B&W are traditionally very hard to drive & require big amps that are almost always high-current amps. Higher the current in the amp's output stage, the more current the amp has to piss away into the x-over reactive components and STILL have enough to create a large enough voltage signal in the speaker driver to create a sufficient pistonic action to create a sufficiently large SPL for your listening pleasure.
Zd542 has already given you some examples of how we can make a 100W amp - 50V*2Amps OR 25V*4Amps, etc. The higher the current the better for B&W and at the same time you will need higher wattage to ensure signal headroom for better (music) dynamics.
Driving a B&W speaker is generally an expensive option because finding a high(er) wattage amp with high current that sounds nice is more often than not puling from a very small pool of amplifiers. Yes, you can use many amps in the market but you will never realize the potential of your B&W & you will generally remain unsatisfied with a perpetual itch to upgrade.
Maybe more than you wanted to know but to tame the B&W beast it helps to know what you are doing..... ;-)
I have always heard B&W's with big McIntosh solid state amps, makes sense now. Thanks for the info Bombaywalla.
I'll throw in my experience. I used to have B&W CM4 driven by Rotel RB1080. I liked it a lot. Eventually I moved to the 804S, and those speakers started revealing the weaknesses in the Rotel amp. I auditioned some amps and liked McIntosh SS with B&Ws.

Eventually I auditioned in the same system the 804S with a McIntosh MC252 (250W solid state), and MC275 (75W tubed), and decided for the tubes. Goes to show how nominal Wattage means little, even from the same manufacturer if moving from SS to tubes!

Once at home I had a long time to try the Rotel vs Mc275. I was contemplating biamplifying with the Rotel on the bass. Funny enough, the MC275 had more weight and body than the Rotel in the bass. So again, Wattage means little. I went with what sounded better to me.

Having said this, it is generally accepted bigger 800-series need a lot of power to shine. But I don't think your speakers fall in that camp.
Thanks for your input Levinskih01 - good for you that you liked the (more expensive) MC275 over the Rotel 1080. :-)
Your comparison is not exactly fair but those were the 2 amps you had on-hand, I understand.
The RB1080 sold for $990 when it was new back in 2002 & it seems like a very capable amp - even had THX certification back then. But at $1000 selling price + made in China, this amp has to be considered a budget amp with serious compromises to make that $1000 selling price.
The MC275 was & is a superior built amp from all that I have heard, read & listened (at shows). It currently sells for $4500. It's commemorative edition sold for $3500 & even it's 1st edition of 1961 in today's prices would be a $3500 amp. So, it's no wonder that it sounded better than the RB1080.

All-the-same, all B&W speakers that i know of are voltage paradigm speakers (as opposed to power paradigm). So, they are most likely the best sounding with SS amps - that's been my experience so far be it floor standers or stand-mounts, friend's houses or shows. Not saying one cannot use tubes but choose one's tube amp carefully - not any tube amp will suffice.....
Lewinskih01, All,
please do not mis-read my post to mean that selling price is a direct measure of audio performance. it is not. In this case of the RB1080 & the MC275 it just so happens that the selling price does reflect the superior performance of one amp over the other.
Bombaywalla,

I think you misread my post. I was comparing the MC275 to the MC252, rated 250W per channel, solid state, by the same manufacturer, retailing at basically the same price from what I recall. From those two, in the same system, heard at the same time, with my same speakers, I opted for the MC275.

The reference to the RB1080 was used to point at the bass, where one usually reads comments saying tubes don't sound as good in that region. In this case the tubes sounded better even in the bass.

Obviously I was not surprised by the MC275 sounding better than the RB1080 - at the end of the day that is why I purchased it!

Not sure I agree with your comment about solid state amps being better for B&W. I know in my case it isn't, and I remember over at the Audiokarma McIntosh forum I used to visit long ago there was a technical guy from McIntosh who sweared by using MC275 as monoblocks to drive 803D.
And I remember listening to 802D driven by $30k huge VTL monoblocks that sounded outstanding. 802D are indeed power hungry and those VTL heaters could certainly output a lot of tube-Watts. But who would buy 30k amps to drive 802D?? Not me, even if I had the money.
Buying very powerful and outstanding solid state amps from McIntosh, Classe, Rowland, etc would be much cheaper, less bulky, and wouldn't generate as much heat...

My point being I don't buy B&W 800-series works better with solid state. They do need power, and power is more practical to get from SS than from tubes. That's all.
So, assuming my speakers line up with the 700 series, how many watts minimum and what current specs would you recommend? Where do I find those current specs on an amplifier or receiver?
Thanks again!
Tntate,

I thought by now, after twenty-something replies, it would have been clear to you there is no such answer.

An approach could be to search A'gon Virtual Systems and threads and look for what amps people use with your speakers, or very similar B&Ws, make a list, drop those beyond your price range, read about the amps left in your list, arrive at a short list. And by all means, try and listen to them. No need to go nuts about, at least in my view.

Why are you so focused on Wattage? Sorry if you mentioned this already - I don't recall reading it.
Your speakers call for 50 to 125 watts into 8 ohms and their nominal impedance is 8 ohms with a low of 4.6 ohms. Buy an amplifier that has 50 to 125 watts per channel into 8 ohms, and that is 4 ohm capable. Do that, and the spec sheet on your speakers will match the spec sheet on the amp. Problem solved.
Lewinskih01,
thanks for clarifying - indeed, I did misread your post! :-0

well, we do agree to disagree w.r.t. SS being better for B&W.
But I will agree with you that the huge tube power amps (like the VTLs you mentioned) will do much better than most other tube amps - but then these large tube amps are designed to supply a lot more current into a difficult load & their price reflects it.

12-25-14: Tntate
So, assuming my speakers line up with the 700 series, how many watts minimum and what current specs would you recommend? Where do I find those current specs on an amplifier or receiver?
Thanks again!
you'll never find the current specs for most (If I may be so bold as to say "any") amp. you'll have to do the math & find that out for yourself. Make sure that the amp has plenty of current capacity for example in the 5Amp-8Amp region while ensuring that you have sufficient watts.
I had a pair of CDM 1NTs and they were a great speaker.....I used them with a 40 watt Anthem Amp 1 and also a 50 watt VTL amp. Both amps sounded great and played plenty loud. 17x15x9 room. I wish I had kept those.....
Thanks for the response. I am considering an Anthem integrated 2 hybrid. Good to know it can power my speakers.