Noob technical question - Amp Power vs Sound quality

[garyrc]

9 hours ago, JJkizak said:

Surprising that you would say to run your speakers as "Small" with a sub. Why buy a $6600.00 K-horn to run it as a small?

JJK

 

4 hours ago, JJkizak said:

 

He owns K-horns so I wondered why he would say to use the "small" setting.

JJK

 

3 hours ago, CECAA850 said:

Most receivers won't send anything to your sub unless you select "small" in the bass management area.  It has nothing to do with the size or capability of the speakers.

 

3 hours ago, polizzio said:

 

Not true. Both my new Yamaha and older Sony AVR receivers will allow you to run the mains in large and have a sub output. Mains full range + sub output. Then use sub amp panel low pass setting for sub cutoff frequency. Yamaha rx-v685 and a Sony STR DH 520. The Sony is seven years old.

 

Now you can set the mains to small and set a XO point in the AVR software, but my point is you don't have to set mains to small to get a sub output signal from the receiver.

 

I had exactly the same opinion as @JJkizak for about the first two years I had my Home Theater with Klipschorns, and I ran the Khorns "LARGE."   I didn't want to loose the bass cleanness of attack of the Khorns.  I tried subwoofer low pass filter at 40 Hz, 60 Hz and 80 Hz.  It was a crap shoot as to which was best.  Person after person on various forums -- some of them reputed experts -- urged me to set the Khorns "SMALL," to avoid multipath distortion/comb filtering, just plain phase cancellation, to save headroom in the amps (hardly necessary, since the Khorns were putting out 107 dB --- 2 dB more than Dolby/THX/SMPTE standards for the loudest peaks --- at the listening position, at an expenditure of just 16 watts), etc.  They all pointed out that the terms "SMALL" and "LARGE" were misnomers, and had nothing to do with the size of the speakers ( I pointed out that there was a correlation between size and bass response, and they pointed out it was not a high correlation, and some smaller speakers have more full bodied and extended bass than the Khorn, etc.).

 

Soooo, I decided to run exhaustive tests.   The end result, after another several months of tests, was that there seemed to be a little added bass clarity with almost all music, and especially, movies with the Khorns set to begin rolling off at 80 Hz, set on "SMALL."  This was a huge surprise to me!  They still were 'in charge of big bass peaks at 100 Hz, 125 Hz 150 hz, etc -- their forte -- and they were delivering substantial bass down at 50 Hz, 30 Hz below he crossover.   With a few movies, where clean bass attack impact is more important than tonality, multipath, etc., like Ben-Hur (1959 version), for example, I still run the Khorns "LARGE;" otherwise, "SMALL."

 

The subwoofer won't work on regular "bass management bass -- music" if you use the "LARGE" option UNLESS you set the system for LARGE LFE + MAIN, which means that any bass being sent to the main speakers is ALSO sent to the subwoofer.  With my pre/pro, the true, sound effects only, LFE gets sent to the sub at all times if the sub is set to"YES" in the pre/pro.

[vivekdeshmukh]

20 hours ago, oldtimer said:

It involves a few concepts, probably better suited for a pm conversation.  I would be glad to explain my limited understanding, but give me a couple of days since I am currently out of pocket.

Will PM you - thanks man! 

[vivekdeshmukh]

20 hours ago, billybob said:

What problems are you encountering with the Denon?

How many speakers are hooked to it ?

Have you listened to higher volume and noticed distortion?

Thanks!

Welcome...

Clarity especially mid and high end is the pain point. At mid-high volume i should say that i didnt notice any distortion . I havent made it too high (more than 50% yet) living in an apartment.

I tried all variations - just 2 fronts with and without bi-amp, all 7, and in between. 

[vivekdeshmukh]

19 hours ago, garyrc said:

 

Yes, at low volume, the two hypothetical amps should sound the same, providing they are equal in other ways.  Amplifier power is not the salient variable at low volume.

 

A conservative guess is that your 95 watts per channel AVR should push your main (right front and left front) speakers to about 107 dB peak at about 12-13 feet away in a typical room.  Since the standard peak of peaks ("full scale") that Dolby, THX, SMPTE, AES, and the other royalty of the cinema world expect you to provide to your main speakers is 105 dB, you are probably O.K. ... BUT, if you have all of your channels, including surrounds, pumping away at full tilt, your AVR probably cannot deliver 95 watts to each of your channels.   Few, if any, manufacturers specify their AVRs with all channels operating, which they really should do.  IMO, though, you should be able to squeak by, since you have a couple of dB to spare.

 

Your canter channel speaker may or may not need more power, because it may or may not be of lower sensitivity.  SVS rates it at a sensitivity of 86 dB/2.83v/1meter in "full space."   AES assumes they rate it 1/2 space (backed against a large flat surface) so I'm guessing that would provide another 3 dB of sensitivity, making it really 89dB/2.83v/1m.  Klipsch rates your main speakers at 98 db/2.83v/1m in a typical listening room, which translates to 94 dB/2.83v/1m in 1/2 space (according to a Klipsch engineer).  That's the figure I used to calculate your available Sound Pressure Level (SPL or volume).  If your listening room is neither dead nor live acoustically, that probably provides you with a fudge factor of 4 dB. 

 

Your subwoofer is another matter -- do you have one?  You really should.  Almost all of them (name brands) are self powered with an appropriate sized amplifier built in.   The overlords of cinema feel that your sub should be able to hit 115 dB SPL.  Run all of your main speakers as "SMALL" to avoid multipath distortion; this will also give you more "headroom" -- spare power from your AVR -- since there won't be a demand put on it for deep bass, which is power hungry.

 

A speaker's "power rating" (in your case, 150 RMS for RF 82 IIs) is not very useful.  The idea that your amp should be more powerful than the "power rating" of your speakers is just a rule of the thumb (not quite as hideous as the origin of that term).  Paul Klipsch was once asked what it meant; he replied, "Probably not much."

 

 

Wow - i am probably going to read this post a couple more times  I do have a subwoofer Klipsch 10i. I have my fronts as Large - so will try changing that tonight to see if that changes anything.

You know one interesting thing to mention is the SVS center seems to run effortlessly than the Klipsch fronts - i expected opposite.

I will come back to this post.

[billybob]

2 hours ago, vivekdeshmukh said:

Clarity especially mid and high end is the pain point. At mid-high volume i should say that i didnt notice any distortion . I havent made it too high (more than 50% yet) living in an apartment.

I tried all variations - just 2 fronts with and without bi-amp, all 7, and in between. 

How does 2 channel stereo sound? Just taking it that you are listening to music. The center may be easy to run but, is it clear and with clarity.

Yes can be a problem with apt. living., understand.

Thanks!