I just sent Proac an email asking for the impedance curve of the k10. Let’s see what the response will be @Thomas. Thanks for the help.
3 Likes
The message was not addressed to you. We probably even wrote simultaneously 
I just wanted to point out that by replying to @Zackwater I did not intend to diminish the value and qualities of the NAP500DR (which I bought new, and which I have enjoyed, a lot!).
1 Like
Indeed, whereas an underpowered amp is more likely to cause damage to the speaker.
That does not necessarily mean that the better speaker driven by a lesser amp can’t sound better than a lesser speaker driven by a better amp - it is all complicated by things like the room and loudness levels…
2 Likes
I’ve heard plenty of mega-buck/mega-watt amps and none of them hold a candle to my 552DR/500DR. They make sterile-lifeless-dead-sounding watts compared to the NAP500.
5 Likes
I’m driving a pair of Focal Scala Utopia V2s off the back of my NAP500DR. It drives them with ease in my experience, and much better than the NAP300DR I had previously (which was not bad by any stretch of the imagination). I can’t find any impedance curves online for them, so not sure if they are as challenging in the bass region as the bigger Maestros reviewed in Stereophile.
3 Likes
The second speaker I’m considering is the Kudos 808’s which I know several members own and enjoy.
The K10 performance will be in another universe by comparison. (No offense to my Kudos friends.)
2 Likes
Maybe, if a speaker cannot be driven adequately by a NAP 500, the problem is with the speaker and not the amp?
1 Like
That’s what I said all along. I’m not complaining about the 500. I’m changing speakers not amps.
2 Likes
There really is only one meaningful spec for power amps besides of course listening. What does the amp output in to decreasing loads.
ie, 200 wpc RMS both channels driven into 8ohms 20hz - 20khz. Then into 4 Ohms should be 400 wpc RMS … then into 2ohms should be 800 wpc RMS and if it’s a monster 1600 wpc into 1 Ohm RMS. This shows us the amps true current capability. Amps like Bolder, Krell, D’Agostino, Levinson, Solution, Constellation and a few other can do this.
And of course don’t want to forget Regulated power supplies. All good power amps will have fully regulated input sections. The great ones will have Regulated outputs also!
What has RMS to do with music? Maybe the drone of a low organ pipe but that’s about it.
Or perhaps there is no problem at all.
It is clear that if we restrict ourselves to seeing things from one angle only, based on our subjective tastes, we cannot appreciate diversity and its richness.
I am not reacting to your particular comment, Daniel.
I notice that the conversation is falling, again, into the usual “my toy is better than yours”.
1 Like
B&W agree with you. From the 800D series manual:
“We can give guidance on what to look for when choosing ancillary equipment, but cannot recommend specific items. …
You can often tell how good an amplifier is at driving complex speaker loads by looking at its power rating into both 4Ω and 8Ω loads. The nearer this ratio is to 2:1 the better, as it indicates a good current capacity.”
I haven’t been able to find this information for my NAP200 - can anyone point me in the right direction? I’m just curious.
Mark
Isn’t the question “how does a NAP500DR sound being driven very loud”? I’m pretty sure that my 500 will drive most speakers up to a point. That ‘point’ will vary from speaker to speaker. I know from personal experience that I can get my DBL’s to replicate ‘real band’ sound levels but there is a point, if I over do it, where things just start to sound uncomfortable. This, for me, is the volume limit of my NAP500.
By contrast I’ve driven my DBL’s with a Nait and achieved that ‘uncomfortableness’ at about half that volume but the Nait still easily drives DBL’s up to a point.
On the other hand a friends Statement system could drive his S800 so cleanly and effortlessly that the only sign of stress was when smoke started to come from the drive units. This was his single biggest problem. At no time did the amp sound under stress and it was very easy to keep upping the volume until you effectively arc-welded the speaker coils!
2 Likes
@Thomas i consider you “my impedance expert” so let me ask you a question. For the focal maestro utopias that I own, I read the review of the impedance drop to 1.7. When does this occur and how does the problem manifest itself (clippings, weak thin sound or just not top performance from the speaker).
Here is an impedance curve for my speakers Focal Sopra-3 published by Stereophile magazine. Would you consider these difficult to drive? Using the NAP 500. Speaker are rated as 8 ohms nominal and 91db sensitivity.
Interested in opinions
@Thomas ?
I’m not the impedance guru but I owned a pair of Sopra 3’s. That impedance drop is around 3 according to that chart, the maestro utopias are 1.7. I did not consider the Sopra 3 hard to drive.
Probably worth adding that in this chart the impedance line is solid and phase is dashed.
As Stereophile writes,
However, as fig.1 shows, the Sopra No.3 is a difficult load for an amplifier to drive, with a minimum magnitude of 2.75 ohms at 96Hz and a combination of 4 ohms and a –56° electrical phase angle at 68Hz, both frequencies where music can have high levels of energy.
It’s not an easy load indeed, but as the Naim amps can live with “into 2 Ohms for extended time without a discernible effect on performance” (as per the website), it doesn’t look scary with a 500
Hi @Zackwater ,
I am not an expert, at all 
Impedance is a relatively simple concept that we all probably studied in high school.
What is different from high school is that, in the case of a loudspeaker, impedance varies with frequency.
Added to this is the phase shift, which has a massive impact on the amplifier as well. The concept is a tad more confusing. But having this piece of information is just as essential as the impedance curve.
For this reason, the impedance is always considered in conjunction with the phase shift over a wide frequency range. Usually between 10Hz and 50kHz.
Your Focal Maestro Utopia III’s are a peculiar case.
I read the Stereophile report diagonally. What jumped out at me was “2.3 ohms and +40° at 62Hz and 126Hz”.
That’s brutal! 
These speakers are really demanding. Focal’s specifications made me smile…
Next to that the Magico M2’s appear to be an easy load.
To answer your question more specifically, how will the NAP500DR react?
I don’t know.
What I do know is that it will heat up, especially at a phase shift of +40° in conjunction with an impedance of 2.3 Ohms (a phase shift of 45° is the worst case scenario). If you turn up the volume and the load becomes severe it will enter protected mode.
I don’t think it’s a big deal and believe Naim would probably tell you the same thing.
But, clearly, your Focal Maestro Utopia would be better driven by a slightly more powerful amplifier.
There are plenty of speakers that the NAP500DR will be able to drive with ease.
I’d be wary of the ProAc K10, and wouldn’t make a purchase until I had the impedance curve (and phase shift of course!).
You have a lot of options for your NAP500DR.
If you like the sound of Focal you’ll probably like Raidho, YG Acousitcs or Magico.
ProAc, Kudos and Wilson are quite different.
I find that very transparent speakers like the first group work well with Naim. It’s a good balance.
You should give it a try.
But whatever you choose, ideally the NAP500DR should have plenty of headroom. That’s how you’ll enjoy it the most.
I was very careful about this when I bought the Magico S3 MkII.
My NAP500DR drove the S3 MkII very easily and was able to express itself fully without struggling. On symphonic music at a comfortable volume it was a delight.
I hope you find the speakers that will make you happy and allow you to fully enjoy your NAP500DR.
4 Likes