Amplifier Dynamic Power question

[pearsall001]

I previously posted about my interest in a multi channel amp. I've looked at quite a few (Parasound, Rotel, B&K, Outlaw, Emotiva, Sunfire) & I have a few questions about rated power & how to do a fair comparison. Case in point, the NAD M25 Masters Series amp (so far my favorite) seems to be rated low on the power scale as compared to others. Most of the others I've looked at are rated between 200-250w per channel. Whereas the M25 is rated at 160w (all 7 channels driven). The M25 is also rated for IHF dynamic power at: >220 @8ohm, >385w@4ohm, & >485w@2ohm. I don't believe I've seen these ratings with the other amps, (unless I missed it).

Do I need to concern myself with the M25's lower power rating at 160w or maybe it's not even an issue. How do you compare these different amps to come to a fair conclusion?

 

[markw]

Dynamic power is power that's only available for short bursts, such as musical peaks and the like. It it not "sustainable". When comparing with other amps, use the continuous, or RMS power ratings. The fact that it says all channels driven says it's available all day, every day.

It's not that dynamic power is useless. It's not. It comes into play for those momentary peaks that do occur every day in music and believe me, it can come in handy.

When you consider that you generally use a watt or two for normal listening levels and every "doubling" of perceived loudness requires ten times the watts, every little bit of headroom helps.

 

[Lordoftherings]

Orchestral Classical music demands high dynamic peaks.
If you're into that, look for an amp with lots of high capacitance (block capacitors; 20,000uf per channel or so), lots of heat sink area (about 300" square per channel) and a generous power transformer, or even two (2KVA or so).

But if you don't listen a high volumes for that type of music, you'll get away with much less.

 

[PENG]

Do I need to concern myself with the M25's lower power rating at 160w or maybe it's not even an issue. How do you compare these different amps to come to a fair conclusion?

I think you probably do. The other amps you listed do not tend to exaggerate their ratings either. If you compare their "headroom" ratings they will all be similar but the NAD does specify an impressive 3.9 dbW abeit for 4 ohms.

You are right on quoting the NAD's IHF dynamic power of only 220W at 8 ohms. That is exactly why I thought may be you do need to be concerned if you are using 8 ohm (I know, nominal only) speakers. I just find it hard to believe the 160W M25 can provide the "dynamic" power that the 250W Parasound, Sunfire or Emotiva can, for 8 ohm speakers. For 4 ohm speakers it will likely be able to compete with them in terms of dynamic power. I am not sure still, but it should have a better chance. Again, this is just my educated guess.

 

[mtrycrafts]

I previously posted about my interest in a multi channel amp. I've looked at quite a few (Parasound, Rotel, B&K, Outlaw, Emotiva, Sunfire) & I have a few questions about rated power & how to do a fair comparison. Case in point, the NAD M25 Masters Series amp (so far my favorite) seems to be rated low on the power scale as compared to others. Most of the others I've looked at are rated between 200-250w per channel. Whereas the M25 is rated at 160w (all 7 channels driven). The M25 is also rated for IHF dynamic power at: >220 @8ohm, >385w@4ohm, & >485w@2ohm. I don't believe I've seen these ratings with the other amps, (unless I missed it).

Do I need to concern myself with the M25's lower power rating at 160w or maybe it's not even an issue. How do you compare these different amps to come to a fair conclusion?

Speaker sensitivity, listening distance and room size matters
As does your listening habits, volume wise. My amps have a power indicator on the center speakers; mostly well below 1W. So, even with a 30dB dynamic on classical, there is plenty of power if the meter indicates, usually, 0.1W Plenty loud

 

[pearsall001]

Speaker sensitivity, listening distance and room size matters
As does your listening habits, volume wise. My amps have a power indicator on the center speakers; mostly well below 1W. So, even with a 30dB dynamic on classical, there is plenty of power if the meter indicates, usually, 0.1W Plenty loud

Speakers are 86db-8ohm, room is approx. 3000cuft (13x32x7) & listening position is 12' from the mains. My listening habits are rather conservative, meaning nothing really loud. Also, I set all speakers to small & my dual Velo SPL-1200R subs handle the botton end. I believe this configuration also takes a load off the amp.

From what I can gather an amp at 250w@8ohm really doesn't have a substancial edge over one rated at 160w@8ohm. Am I correct in my statement? Or does the 250watter have a substancial edge over the 160watter?

From what you're saying...it looks like at even 1w you're getting a lot of juice. At what point does the amps capability of producing dynamic power come into play? Only on rare demanding musical passages or somewhat more frequent?
Thanks

 

[mtrycrafts]

Speakers are 86db-8ohm, room is approx. 3000cuft (13x32x7) & listening position is 12' from the mains. My listening habits are rather conservative, meaning nothing really loud. Also, I set all speakers to small & my dual Velo SPL-1200R subs handle the botton end. I believe this configuration also takes a load off the amp.

From what I can gather an amp at 250w@8ohm really doesn't have a substancial edge over one rated at 160w@8ohm. Am I correct in my statement? Or does the 250watter have a substancial edge over the 160watter?

From what you're saying...it looks like at even 1w you're getting a lot of juice. At what point does the amps capability of producing dynamic power come into play? Only on rare demanding musical passages or somewhat more frequent?
Thanks

That 90 watt power difference from 160W is about a 2dB spl change. Not very much at all when you are already at very high dB spl with such power.
That 160W would be outputting around 104dB spl at its max power, then you add any dynamic range if need be.
One should also ask can that speaker handle such peaks and at what THD. Speakers increas in THD rather quickly.

At 1W you would output about 80dB spl at the listening seat. How long can you stand a constant 80dB spl? I bet you don't have a constant 80dB. Not sure if I should recommend you try pink noise at 80dB and see how you like that
The dynamic power comes into play at some peaks that are not very frequent and of short durations in the mid bands and below. Tweeters don't do well with such power levels they would give up the ghost and I am not sure you would like that spl in the tweeters range anyhow.

 

[highfigh]

Orchestral Classical music demands high dynamic peaks.
If you're into that, look for an amp with lots of high capacitance (block capacitors; 20,000uf per channel or so), lots of heat sink area (about 300" square per channel) and a generous power transformer, or even two (2KVA or so).

But if you don't listen a high volumes for that type of music, you'll get away with much less.

OTOH, most pop and non-high-end recordings are now recorded to sound good when played on an iPod and have very little dynamic range. Gene did an interview last year and they discussed this. Used to be that a recording would have over 30dB of dynamic range and with processing, that has been squeezed down to about 6dB.

It sucks that people who care about realistic sound have been kicked to the curb.

 

[pearsall001]

That 90 watt power difference from 160W is about a 2dB spl change. Not very much at all when you are already at very high dB spl with such power.
That 160W would be outputting around 104dB spl at its max power, then you add any dynamic range if need be.
One should also ask can that speaker handle such peaks and at what THD. Speakers increas in THD rather quickly.

At 1W you would output about 80dB spl at the listening seat. How long can you stand a constant 80dB spl? I bet you don't have a constant 80dB. Not sure if I should recommend you try pink noise at 80dB and see how you like that
The dynamic power comes into play at some peaks that are not very frequent and of short durations in the mid bands and below. Tweeters don't do well with such power levels they would give up the ghost and I am not sure you would like that spl in the tweeters range anyhow.

You're right...80db is pretty darn loud. I calibrated with my SPL meter at 75db. I went to 80db out of curiousity & that didn't last long. Pink noise at 75db is annoying enough. So it sounds like any well designed multi channel amp (say between 150-250w all channels driven @8ohm) will get the job done without any problems.
Thanks

 

[john72953]

You're right...80db is pretty darn loud. I calibrated with my SPL meter at 75db. I went to 80db out of curiousity & that didn't last long. Pink noise at 75db is annoying enough. So it sounds like any well designed multi channel amp (say between 150-250w all channels driven @8ohm) will get the job done without any problems.Thanks

Although your room is a fair size and your speakers have a relatively low sensitivety factor, the 160-watt NAD M25 you're considering will drive those speakers easily with headroom to spare.

John

 

[PENG]

From what I can gather an amp at 250w@8ohm really doesn't have a substancial edge over one rated at 160w@8ohm. Am I correct in my statement? Or does the 250watter have a substancial edge over the 160watter?

My response to your first post was based on technical information. In your real listening environment I do agree with what others are saying. 250W does not offer you substantial edge. For short burst, the M25 could pump out 320W even into an 8 ohm load.

If under steady and average conditions you are getting 80 dB at 1W in your listening position now as mtrycrafts suggested, then your amp won't get into trouble until it has to deal with a peak >18 to 25 dB depending on the loudspeaker's impedance and phase angles at the time of the peak. My guess is that you would only get that kind of peaks from movies so the sub would take care of them. Even if not, I doubt you can hear the distortion from explosion scenes.

On the other hand, whether the extra watts matter to you or not, I would take more for the same money.