Jump to content

Power Question


shake777

Recommended Posts

A salesman suggested I buy amplifiers that would put about 200w/channel through my speakers. I wonder about this since Klipsch are so efficient. Would that be a waste of money? I currently am running an 11.3 system with a Denon 4810 which is rated at 140w/channel for nine channels and a Denon 4306 (rated at 130/channel) for the 2 wide speakers. I understand that only a small percentage of that wattage reaches my speakers when everthing is pumping. I have no issues with volume as the sound is much louder than I can tolerate when turned up and there is little if any distortion. Thanks for your help. Nic

Link to comment
Share on other sites

  • Replies 85
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

The only thing I can tell you is to listen and compare. I power my 2 channel system with an old Kenwood

Basic M2A@ 220 old school watts per channel. I have never had it past 1oclock on the dial and normally

listen to it around 9oclock on volume setting. The "ONE" time that I had it at 1oclock position, I think my Chorus IIs

were close to their 121db max [6]. That being said the sound is outstanding at low listening levels and

there is something to dynamic headroom.

.

Link to comment
Share on other sites

There is no magical number of watts required. That depends on the efficiency of your speakers, the size of your room and how loud you listen, among other factors. Many fine loudspeakers would be damaged if you fed them 200 watts RMS. If your system plays as loud as you need without clipping (distortion), it is fine as is. There is a good article "How much amplifier power do I need?" from the Crown website here:

http://www.crownaudio.com/amp_htm/amp_info/how_much_power.htm

And an amplifier power calculator here:

http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

Link to comment
Share on other sites

It depends on:

How loud you like it

How sensitive your speakers

Listening room

Type of music (how much low bass)

I don't agree with the idea that you can't have too much power.

A lot of high power amps that test clean at rated power (where the distortion is tested) sound horrible in the low power levels (where the majority of the music is).

Read the Dope from Hope, it makes a lot of things clearer.

DOPE from HOPE!!!.pdf

Link to comment
Share on other sites

I like this reference and the calculator, because it causes the buyer to think about their problem a bit more before buying--and avoiding possible rationalization that follows that decision. The calculator doesn't include room acoustics, but that's okay for making a rule-of-thumb decision.

I sit about 3 meters from my front speakers--Jubs and Belle--but some folks here may sit farther than 10 meters away--and still expect to have SPLs at that listening position of 105 dB(SPL) or even higher (Coytee, where are you...?)

On the flip side, I see folks using 100 dB/W speakers with amplifiers that can't put out more than 2 Watts without starting to distort/clip. What they aren't talking about is the fact that either they don't listen at anything approaching realistic concert levels (ever) and/or they are basically sitting within 8' of their speakers.

I prefer the peace of mind that I can achieve just about any realistic level of SPL, i.e., I'm not talking about contrived home theater SPL levels "above real life". For me, that means about 105-110 dB(SPL), but not sustained at that level, i.e., this is a peak or "crest" level. Why not have the available power? Power is relatively cheap as long as one isn't demanding tube electronics (...using whatever reasoning appealing to that type of approach...).

On a related note: I find that bi-amping significantly increases the effective power of my amps, since I don't have to worry about woofer channel-induced clipping vis-a-vis the expensive compression drivers. It also results in cleaner and lower distortion sound, IMHO.

Chris

Link to comment
Share on other sites

I don't agree with the idea that you can't have too much power.

A lot of high power amps that test clean at rated power (where the distortion is tested) sound horrible in the low power levels (where the majority of the music is).

I never have, a good amp may not measure as good at lower power but I've never heard a quality amp sound bad at low volumes. But heck what do I know, my tube amps have a totally suck distortion measurements but still sound great? Perhaps distortion isn't a measure of sound quality?

Link to comment
Share on other sites

russ69,

I'm sure you know that tube distortion is mostly 2nd and some 3rd harmonics (easy on the ears) as opposed to solid state distortion (additional higher order harmonics). If folks prefer high power to have enough reserve headroom to never approach clipping, I can see that aspect supporting the "never too much power" perspective. Especially for solid state amps.

The design of the amp (tube or solid state, class A/AB) will determine if the low levels show any crossover notch distortion. This is the distortion I was refering to at low levels. Since it happens when the signal crosses the "0" line, and since with complex music waveforms this crossing frequency is not harmonically related to the music; even a little it is very disagreeable. And since its level is constant, its portion of the signal is greater at lower levels where one is most likely to hear it. I'm sure that very fine amps that have their bias set properly do pretty well to avoid it.

I wonder how many folks using less power make the move to class A, especially with tube amps?

Link to comment
Share on other sites

Pauln,

Very nicely stated, well done.

I don't have any big brute amps right now, my last one put out 365 watts @ 8ohms on the weak channel but it did give me the appreciation for high power amps and the things that they do. PWK didn't want big power amps and his Klipschorn didn't NEED them. I heard over the years that it is best to run an amp closer to it's power rating for best measurements but I've never heard low level harshness from quality big amps. I'm usually listening at well under one watt. I'm just saying low distortion measurement doesn't relate to sound quality. Amps in the 70s had .001 harmonic distortion and they did not sound all that good. I just think it is something you should try (big power) so you know what the advantages are. It's kinda fun.........for a while, anyway.

Link to comment
Share on other sites

I did try high power a while back, although it was an older amp (Carver M-500t 250W/ch). It was impressive and pretty good sounding; even at low levels you could certainly tell that the amp had a strong hold of the speakers and was quite eager to make them move!

I'm not saying it was not a good match for the La Scalas, it was kinda fun, but then I'm sure if I had left it hooked up for any length of time it would have eventually ended up testing the local police response time. ;)

I have an old Sansui from the early seventies that I put in sometimes. It's rated 28W but the power transformer and caps are the size usually found in 100W amps. It sounds pretty sweet with a lightly rolled off top end and a firm bass with no real low bass - similar to my SETs but not as amazing; still a very fine sound.

I guess I'm a SET kind of guy. As the lead guitar player in a few bands, I get my fill of the thrill of loud music, so when I listen at home I just play it easy.

Link to comment
Share on other sites

The only thing I can tell you is to listen and compare. I power my 2 channel system with an old Kenwood

Basic M2A@ 220 old school watts per channel. I have never had it past 1oclock on the dial and normally

listen to it around 9oclock on volume setting.

My first concern with high-power amps is the high amount of gain they frequently have. This can mean excessive magnification of preamp noise, which can show up in spades with Klipsch efficiency. In that case, solving an electronic hiss problem means chasing after and sorting out pre-amp gain in its circuitry following the VC (pre-VC noise is usually not the problem) vs. amplifier gain. It's best IMO to have a low-gain power amp when using a pre with high line-stage gain (the VC is frequently just before the line stage.)

Also, 9 o'clock may put the preamp's VC below its best-sounding range, another reason to be cautious about using a high-power amp.

Link to comment
Share on other sites

The only thing I can tell you is to listen and compare. I power my 2 channel system with an old Kenwood

Basic M2A@ 220 old school watts per channel. I have never had it past 1oclock on the dial and normally

listen to it around 9oclock on volume setting.

My first concern with high-power amps is the high amount of gain they frequently have. This can mean excessive magnification of preamp noise, which can show up in spades with Klipsch efficiency. In that case, solving an electronic hiss problem means chasing after and sorting out pre-amp gain in its circuitry following the VC (pre-VC noise is usually not the problem) vs. amplifier gain. It's best IMO to have a low-gain power amp when using a pre with high line-stage gain (the VC is frequently just before the line stage.)

Also, 9 o'clock may put the preamp's VC below its best-sounding range, another reason to be cautious about using a high-power amp.

My ears do not hear any of the problems you are mentioning nor do the ears of anyone else that listens. My amp is hooked up to the

pre-amp where all controls (Bass/treble) are by-passed and only the volume control, hifilter, and contour control have any effect on the

signal to the amp. I can listen and have listened to music with volume set at 8oclock position and still enjoy what I hear.

Link to comment
Share on other sites

My ears do not hear any of the problems you are mentioning nor do the ears of anyone else that listens. My amp is hooked up to the

pre-amp where all controls (Bass/treble) are by-passed and only the volume control, hifilter, and contour control have any effect on the

signal to the amp. I can listen and have listened to music with volume set at 8oclock position and still enjoy what I hear.

That's why I qualified with "can mean" and "can have..." Some HP setups have high hiss, some don't. There have been forum threads by people with high-power amps who had very loud hiss and/or VCs riding at the bottom of their range. I should have mentioned these problems can be solved with an amp input level control -- just turn it down to lower the hiss and raise the preamp VC. Only some VC's degrade at the bottom.

I had both problems with a former CAT preamp. It's line-stage gain was a high 26 db instead of the standard 20 db, and I could only get away from hiss by using a very low-gain amp. And its VC didn't sound as good at 8 or 9 o'clock as it did at 11 or 12.

Link to comment
Share on other sites

Where you able to look at the website I posted? Maybe that has something to do with the performance of the amp.

Cliff,

No doubt my limited electronics knowledge, but I didn't understand what it had to do with gain and magnification of preamp noise.

Another example -- hiss from a conrad-johnson amp on my CAT and K-horns just about drove me out of the room. There was very little hiss when the preamp was off.

Link to comment
Share on other sites

. Amps in the 70s had .001 harmonic distortion and they did not sound all that good.

In the '70s, many amps had Harmonic and Intermodulation distortion as low as -- or lower than --- the .001 you cite, but had high TIM (Transient Intermodulation Distortion), which many manufacturers didn't mention. I believe it arose in part as a byproduct of using too much negative feedback to kill the types of distortion cited in published specs. See the Dope from Hope article on TIM. Perhaps that problem has been solved .... I've often wondered what happened to TIM, since nobody mentions it anymore.

Link to comment
Share on other sites

I assume that the SPL they are asking us to enter into the box is "continuous desired SPL during loud passages" and not momentary peaks ... otherwise even my K-horns would require hundreds of watts @ their 14.5 feet from the listener. . If my Radio Shack SPL meter (needle Vu) reads 105 dB during a loud passage, I assume I'm getting up to 118 dB during very, very brief and unread peaks, due to needle ballistics.

Link to comment
Share on other sites

The salesman may have told you about a bigger amp than what is contained in the 4810 because based on Sound and Vision Mag, the 4810 starts to die with 7 channels driven 1Khz at 60watts

http://www.soundandvisionmag.com/content/denon-avr-4810ci-1

Respectable.... though not 140 watts.

Good quiet clean amplification is not usually where an AV receiver lives. Many produce a fair amount of hiss especially in the surrond channels though again, quiet and clean. Oh did I forget, lots of guts if you want jump factor dynamics.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...