How big of an amp?

[etc6849]

Unfortunately, I know all to well about the loudness war  Which is why I said what CD can do, and not that all remasters sound better than vinyl.

 

There's likely still better options than vinyl though if one checks HDTracks and the other sites to see if there are any digital downloads of the original analog masters.  The Chesky audiophile test track I mention in the OP doesn't even use the full DR of what a CD can technically do, but it's one of the more dynamic tracks that I have!

 

etc6849,

 You sure said a mouthful when you stated "what a CD CAN do".  Problem is it is hardly ever used to its potential. Google 'loudness wars' if you have never done so before. Its enough to make you ill.

[garyrc]

 

If 115dB is what I need, this means I really do need a big amp according to this online calculator.

 

I have read online some music such as a symphony can have a DR of 60dB, so this makes since if you assume a room's noise floor is 55dB (55dB + 60dB= 115dB).

 

Definitely some of the movies I've watched this week and last sound really really good and have benefitted from the bigger amps.  This is a subjective comment though.

 

amp size calc.png

 

Paul Klipsch said you need peaks of 115dB "at your ears" to simulate "The blood stirring sound of a symphony orchestra."

 

 

All of the following is strictly IMO.  I think that particular online calculator overestimates the dB loss for 10 feet, INSIDE in a room of average liveness.  I think that OUTSIDE, at the top of a flagpole, one loses the 9.7 dB at 10 feet that they mention, but INSIDE, you have to add 3 dB back in for room gain if the loudspeakers are near a wall, and another 3 dB if you have two speakers operating (more, if you have more).  This last is controversial, because it assumes equal output from each of the front speakers, which isn't always true, depending on the music or the movie.  I tried another calculator with your data, and got 115 dB peak with a mere 100 watt amplifier (honestly rated, RMS power, i.e., not an AVR), assuming that your speakers are near a wall.  If they are not, you might need 3 dB more, or a 200 watt amp, etc., etc.  Yet, this might be too optimistic.

 

I can't seem to reproduce the linc here, so type into Google "online SPL calculator" and select the one that mentions peak SPL ... when you access the page the title will be "How loud will it go."    After getting the SPL, etc., if you read on, disregard the author's comments on average dialog levels -- normal dialog is actually much farther below peak movie SPL levels than he thinks.  Also, when he talks about hearing damage due to loud sound, he usually fails to distinguish between more or less continuous sound and peak levels, which is surprising, because he gets the OSHA hearing damage levels for given durations of sound right.   PWK made that distinction, albeit in separate publications.  He thought, as we discussed earlier, that brief peaks need to be at 115 dB to simulate the transient peaks of a symphony orchestra (he repeatedly recorded the Arkansas Symphony) yet he said that 115 dB, as an average level was "Too damn loud" (Dope from Hope January 1977, Vol. 16, No. 1)

 

It's possible that both the calculator I used and the one you used are somewhat wrong.  I've heard that INSIDE a typical room the SPL decreases an average of 3 dB for every doubling of distance (outside, it's more like 6 dB for each doubling).  PWK confirmed the approximately 3 dB/doubling in one of his experiments, in a room about 16 feet x 25 feet (height unknown to me).  He moved from 2 feet away from the speaker to 16 feet, and found an "9 or 10 dB" decline.  In your case, if the Palladium really is 99 dB @ 1 Meter (as the entry on the calculator you used implies; Stereophile measured it at 94.8dB(B)/2.83V/m), starting at 1 meter and moving to about 13 feet (to keep the math simple) away would be about two doublings, or a 6 dB decline, meaning that at about 1 watt you might get about 93 dB.  That might give you 115 dB continuous at about 171 watts.  If you have an amp that will really put out 3 dB dynamic headroom, you might get away with less.  So, a 200 watt RMS amp might be O.K., but I'd be tempted to favor a 300 watt RMS, just to be safe, and I'd use the best powered sub you can get, with the Palladiums set for "small."  All of this depends so much on placement in the room relative to the walls, real amp headroom, conditions under which the sensitivity of the speaker was measured, impedance quirks, etc.

 

Edit:  I think the linc is myhometheater.homestead.com/splcalculator.html  ...  I just can't copy and paste it for some reason

Edited December 20, 2015 by garyrc

[etc6849]

Thanks Gary!  I'm going to try and see if I can set up my digital oscilloscope up to give me a calculated instantaneous power output using v(t)*i(t).  I have an isolation transformer, so I feel safe hooking it up to the speaker terminals on the amp.  I will treat all grounds on the scope as energized...

 

For sure I can measure instantaneous voltage and estimate instantaneous power.

 

The 99dB at 1 meter from 2.38V is what Klipsch provides, and could be just for a 1kHz sine wave?: http://images.klipsch.com/p39f_-_Spec_Sheet_635738653350358000.pdf

 

I think technically the sensitivity should change when real life music is played (as we don't listen to just a single sine wave)?  Also, my original post should have pointed out these speakers are rated at 4 ohms, and not 8 ohms...  doh!

 

Regardless, I definitely hear a difference on peaks of certain songs.  At these peaks, things don't sound harsh anymore, but they would before.  Before, I would always grab the remote and lower the volume during these peaks, but don't anymore...

 

The problem is I've rerun dirac in between changing the amps out, so there are other variables to consider.

 

 

 

Edit: I think the linc is myhometheater.homestead.com/splcalculator.html ... I just can't copy and paste it for some reason

[etc6849]

http://myhometheater.homestead.com/splcalculator.html

 

Gives the attached showing ~760 watts assuming 94.5dB sensitivity.  I just put in one speaker to be conservative, as the peak will likely come from just one channel (I think), although it could come from multiple channels at once for a movie I suppose.

 

I still plan to measure things in a week or two, and can post some screen shots.  I just have to finish rearranging my rack and clean up my office first and post things to sell.  I'm going to start my testing on some cheap speakers and amp first though

Edited December 23, 2015 by etc6849

[Paducah Home Theater]

Paul Klipsch said you need peaks of 115dB "at your ears" to simulate "The blood stirring sound of a symphony orchestra."

 

I for one won't be listening to any horn section at 10 db above reference.  Y'all have fun with that.  

[Paducah Home Theater]

I'm not sure what frequencies a gun shot or explosion in a movie would have...

Explosions seem to have a lot of energy around 30-40 hz, basically about the lowest that a commercial theater sub can produce very loudly. Most aren't as low as most people think.

Gunshots seem to be getting lower, just based on what I hear, I am guessing that there's a lot of 60-80 hz material. Cross over at 80 and much of it comes through your subs. Cross over at 60 and your mains get more of it. It's a pet peeve of mine, when pistols sound like cannons. You cannot accurately record a gunshot though, so some artificial magic gets worked on the sound.

[garyrc]

http://myhometheater.homestead.com/splcalculator.html

 

Gives the attached showing ~760 watts assuming 94.5dB sensitivity.  I just put in one speaker to be conservative, as the peak will likely come from just one channel (I think), although it could come from multiple channels at once for a movie I suppose.

 

I still plan to measure things in a week or two, and can post some screen shots.  I just have to finish rearranging my rack and clean up my office first and post things to sell.  I'm going to start my testing on some cheap speakers and amp first though

 

Does Klipsch provide placement advice in the manual for the Palladium?  I think I remember that they do mot measure the sensitivity of any of their speakers out in a room.  I think they measure near or against a wall in the chamber.  But that info was from before the Palladium came out. 

[garyrc]

 

Paul Klipsch said you need peaks of 115dB "at your ears" to simulate "The blood stirring sound of a symphony orchestra."

 

I for one won't be listening to any horn section at 10 db above reference.  Y'all have fun with that.  

 

 

PWK was talking about instantaneous peaks.  A horn section alone probably (almost certainly) wouldn't get there; if they were playing a very loud, passage they might average about 95 dB for a few moments at a time, with relatively blunt (v.s. sharp) peaks above.  My guess is that everything they produce would be below the fs of 105 dB of reference level.  The swelling of the orchestra up to its highest levels might reach 105-115 dB.  With percussive help (the Telarc big bass drum, timpani, and piano at full tilt), the leading edges could easily reach the 115 dB level (note that reference level for deep bass is 115 dB).   Not everyone thinks of 115 dB as the ceiling; I've heard 120 db bandied about, somewhere on this forum, re: rim shots, close up.  It's plausible to get 115 dB when cymbal crashes, as measured by a peak reading meter, ride on the crest of big orchestral climaxes.

 

People can't agree on the duration of an instantaneous peak.  I've seen specs ranging from less than 2 ms to 200 ms.  

 

With my Klipschorns, RSW15 sub, and Belle center channel, my miserable Radio Shack SPL meter (definitely not peak reading) has gone as high as 105 dB on the end of Mahler's second, Fanfare for the Common Man (due to timpani, tam-tam, big bass drum, not the brass), and The Great Gate of Kiev.  My RS meter is analog with a needle.  According to PWK, to get an estimated peak reading, one has to add up to 13 dB, due to needle ballistics.  That would imply very brief peaks of 118 dB.

Edited December 24, 2015 by garyrc

[garyrc]

duplicate 

Edited December 24, 2015 by garyrc

[Ski Bum]

The myhometheater.com peak spl meter seems geared to wide dispersion, direct radiator type speakers.  I consistently was getting calculated results higher than actual measurements unless selecting "in a corner" as the placement option in the calculator, regardless of actual speaker proximity to walls/corners.

Edited December 24, 2015 by Ski Bum

[etc6849]

This is very interesting!  Thanks!

 

According to PWK, to get an estimated peak reading, one has to add up to 13 dB, due to needle ballistics.

 

[jjptkd]

This reminded me of the Carver M-1.5t description and the "scissor snip."

 

http://www.carversound.mobi/carver-amplifiers/m-1-5t/

 

"Our M-1.5t description starts out with a story instead of the usual superlatives. Once, Bob Carver visited a famous sound researcher who was attempting to recreate the "snip" of an ordinary pair of scissors. He used no less that TWENTY-FOUR 200-watt amplifiers for playback. Yet when viewed on an oscilloscope it was apparent that the top of that instantaneous transition was being distorted. Believe it or not, he needed more power! It was evident that real-world sound occurs very quickly and requires far more power than ANY current amplifier could produce."

 

"Why such massive amounts of amplifier power? Music is full of surprises such as explosive crescendos, combinant crests of demand created by multiple instrument sounds and the shock levels that some well-recorded instruments can instantly attain. This is what makes music live. These incredibly intense bursts of sound don't necessarily have to be loud. They are too short in duration. But, like the scissor snip, they are intense and demand power. Recorded music sounds dull without these constantly-occurring high instant peaks. If your amplifier cannot provide the instantaneous power to surmount these rigorous musical punches when they are presented at its inputs, it makes a sound of its own devising, literally an electronic gagging we call, clipping. The result is an audible degradation which has pervaded your listening for years."

[garyrc]

This reminded me of the Carver M-1.5t description and the "scissor snip."

 

http://www.carversound.mobi/carver-amplifiers/m-1-5t/

 

"Our M-1.5t description starts out with a story instead of the usual superlatives. Once, Bob Carver visited a famous sound researcher who was attempting to recreate the "snip" of an ordinary pair of scissors. He used no less that TWENTY-FOUR 200-watt amplifiers for playback. Yet when viewed on an oscilloscope it was apparent that the top of that instantaneous transition was being distorted. Believe it or not, he needed more power! It was evident that real-world sound occurs very quickly and requires far more power than ANY current amplifier could produce."

 

"Why such massive amounts of amplifier power? Music is full of surprises such as explosive crescendos, combinant crests of demand created by multiple instrument sounds and the shock levels that some well-recorded instruments can instantly attain. This is what makes music live. These incredibly intense bursts of sound don't necessarily have to be loud. They are too short in duration. But, like the scissor snip, they are intense and demand power. Recorded music sounds dull without these constantly-occurring high instant peaks. If your amplifier cannot provide the instantaneous power to surmount these rigorous musical punches when they are presented at its inputs, it makes a sound of its own devising, literally an electronic gagging we call, clipping. The result is an audible degradation which has pervaded your listening for years."

 

Perhaps no amplifier can provide the clean power needed for a scissors snip up close.  Or a rim shot fairly close (as close as the drummer).  I can live with that.  But, until an amplifier with that ability is available, the McIntosh MC2KW might do: "The MC2KW monoblock amplifier is designed to exceed the demands of true lifelike playback levels, capable of delivering 2,000 watts of continuous power and 8,000 watts of peak power into 2, 4 or 8 ohm speakers."  Of course, it's mono, so you would need at least two of them.  And what speaker would take that amount of power?  As PWK once said, "You'd better have a fire extinguisher ready."

 

Meanwhile, my little amps are rated at 150 w.p.c., with true RMS being about 120 w.p.c.  The most pessimistic rating of the efficiency of a Klipschorn (98 dB @ 1w @ 1m) allows an amplifier of 120 watts RMS to put out about the same SPL through a Khorn as an 800 watt RMS amplifier into a speaker of average efficiency (90 dB @ 1w @ 1m).  With the most optimistic rating of the efficiency of a Klipschorn (105 dB @ 1w @ 1m) an amp with a rating of 120 watts RMS would put out about the same SPL as a 3,800 watt RMS amp into an average speaker of 90 dB @ 1 w @ 1m.  I can live with that, too.

[etc6849]

He used no less that TWENTY-FOUR 200-watt amplifiers for playback.

 

Thanks.  I don't feel so crazy adding three XPR mono blocks and two XPR stereo amps to my theater now!  Definitely, peaks sound better to me.

 

MC2KW monoblock amplifier is designed to exceed the demands of true lifelike playback levels, capable of delivering 2,000 watts of continuous power and 8,000 watts of peak power

 

That makes the Emotiva XPR-1 amps seem small in comparison!  They are really a great sounding amp.  My average cost on the three is about $1000/amp versus $140k/amp for the MC2KW's?!?

 

"Some of the features offered by the XPR-1 include:

1. Fully balanced; fully differential - for the ultimate in audio purity and performance.
2. Superb sound quality - as with all Emotiva amplifiers, the XPR-1 was designed first and foremost to deliver outstanding sound quality.
3. Massive output power - 1000 watts into 8 ohms; 1750 watts into 4 ohms, of real continuous power.
4. Optimized Class H™ operation - with independently tracking power supply rails, provides better efficiency and cooler operation than Class A/B (and even other types of Class H designs), with no sacrifice in sound quality.
5. Huge power supply - with an enormous 2.5 kVA toroidal power transformer and 240,000 microfarads of energy storage, ensures stunning dynamic capabilities, and no loss of power under virtually any signal or load conditions.
6. Totally stable - with virtually all real-world speaker loads."

Edited December 24, 2015 by etc6849