I was checking into my own crossover settings for the Klipsch KSW sub... since the Onkyo 989 is THX Ultra rated, there is no manual setting: the specs are strict about requiring an X-ver of 80 Hz. So my sub would be best set between 80 and 90, based on "listening"... .

But, Zacha, you'd be helping me out a lot if you could explain "slope" in Dummy terms; apparently the slope is more critical than the crossover... .... Mike

PS: I guess no one picked up on the spelling of Home Theatre....

I should have thought of this page before:

[Link: audiovideo101.com]

and then, a list of octaves is linked off it at:

[Link: audiovideo101.com]

Those should be better explanations than I could give, but I'll try anyway. The cross-over slope describes the way that an amp, subwoofer, etc tries to make the transition from subwoofer to L,C,R,SR,SL etc. speakers as smooth as possible.

With, say, an 80Hz cross-over, a sub with a 24dB/octave slope and a pair of speakers run through the sub: Then at 100Hz from the left and right speakers, the sub might reduce its output by 24dB and increase the appropriate output to the speakers by 24dB (from 0 dB, I'd assume). At 170Hz (assuming the sub went that high..) then you'd get -48dB to the sub and +48dB (from zero) to the stereo pair.

BUT, I'm not exactly sure how the highest frequency of the sub comes into play, and whether the cross-over is above, below or on both sides of the cut-off frequency. Which is why I'm not the best person to explain this. But, I do know the point is smoothness.

I think, in the end, the cross-over is more important than the slope. If you set your amplifier to maximum cut-off (or no cut-off), then slope becomes the amplifier's problem. Not yours.

I hope that helps a little.

Have tried the THX frequency sweep as you sugested Zacha and am happy to say there was a nice smooth crossover. If i could only get hold of a SPL meter, in the uk they are a bit expensive as where im from they only seem to sell the digital versions and im still on the look out for either a website to import from (if thats cheaper) or a uk distributor.

This may make you laugh if you have one of these but you know the baby monitors that you plug into the other room, well i set my last amp up with this as its got the flashing lights that register the noise levels. I'd be really interested if anyone has an SPL meter and a baby monitor and could check to see how acurate this method is for setting up speaker levels especially including the sub.

Thanks for the links.
John

Hey John, the 'centre' comment was just a friendly joke to start off my message, I knew you were from England. Had no idea it would become an issue with some people.
bye
jeff

SPL meters are expensive here in Australia, too.

I got mine on special at AUS $50 (which still seems quite expensive). As opposed to the normal AUS $120, or so.

Good luck finding a cheap one.

Jeff, i didnt even notice, did i give the wrong impression? i think i spelled it the american way in one reply but forgot to put he! he! after it.

its a shame if people take it the wrong way but what the heck!

An interesting point! - in your sony manuals how do they spell center, as they are universal in most instances? even though i got a good english grade at school i still spell things fun-knee HE! HE!

one final thing i forgot to ask was about the Dynamic range compressor.

OFF reproduces the sound with no compression.
STD reproduces it with the dynamic range intended by the recording engineer.

which one do you recommend?

Thanks again and all the best to you all and your famillies (just been corected on the famllys spelling by the missus)
John

Hey John,

Some of the Sony Amp manuals used to even recommend setting it to the max setting for the most dramatic effect (even though the default was off).

The Dynamic Range setting on the Sony receivers sets the range of the softest sounds to the loudest sounds. So something like a horror movie scene, where its real quiet and then you have a sudden scream and all kinds of other noise, the amount of volume difference between the two is the most dramatic when set to max. I have always set it to Max on installs and that is where I would recommend it for theater installs.

And no, I did not get the wrong impression at all. I have lived in the same town all my life and its kind of cool to me to talk to someone from another country.
One thing I like about England is the Beefeater Gin. Every birthday I have and Christmas my wife gets me a bottle (the bigger the better).

jeff

Um. Dynamic Range Compression set to OFF is the dynamic range that the sound engineer wanted you to hear. So is Dynamic Range Compression set to STD.

Both are encoded into the Dolby soundtrack by the engineer.

Dynamic Range Compression is designed to reduce the sound of the louder sounds, and increase the level of the softer sounds. So, if you left the volume at the same level, and turned it on, the dialogue would sound louder.

It's designed so that you can turn the volume down and still hear the dialogue clearly. It's designed to let you listen to Dolby Digital soundtracks late at night without keeping other people up. It's sometimes called 'Midnight Mode' or 'Night Listening', etc mode on some receivers.

It's not something that you leave 'on' or 'off'. You turn it to 'STD' when its late at night, and 'off' when its not. Dolby Digital has a dynamic range of 120dB or so (from 0 - 120 dB, I think), so dynamic range compression reduces that range.

When dynamic range comperession is off, a digital sources generally seems softer than a 2 channel source, because 2 channel sources have gain (additional volume) added by their players. Dolby Digital and DTS don't have this gain, so they need to be turned up, but only relative to normal 2 channel sources. If your amp is set up so that it runs from, say, -50 to +12 dB, then setting the volume to 00 is the 'reference' level that the mixer hears in the recording studio (I think). If not, maybe about -19dB on a Sony. (But be careful testing this, it will sound incredibly loud. I've only done this, myself, once in the last 6 months.)

Assuming an absence of remixing between the cinema and home versions of a soundtrack, dynamic range set to 'off' would be the version of a soundtrack that you hear in a cinema.

With Dynamic Range Control at 'STD', then you should turn it down to about the level of your other 2 channel sources.

Dynamic Range:
[Link: dolby.com]
[Link: audiovideo101.com]

'Reference' level:
[Link: audiovideo101.com]
(note: in the home, 75dB is standard for calibration)

Only Dolby Digital has Dynamic Range Compression. With DTS, the best you can do is set the LFE to 'music' - or -10, or 0 as opposed to +10, depending on what your receiver calls it - and turn the volume down a bit.

Is that any help?

Hey Zacha
Well I don't have the manual for his receiver right in front of me, it's Sunday I'll check it tomorrow, but in reading on all the past Sony amps like his, they all had a paragraph that explained what that adjustment does in relation to the Sony amps that have it. I remember it stating that the dynamic compression recorded on many DVD discs is such that the overall dynamic range of the audio on the disc can be somewhat lackluster. Sony, on its upper end models like the one in question, has a dynamic range adjustment that can be set to OFF, STD, 1 through 9, and MAX. The purpose of the adjustment was to extend the dynamic range recorded on the disc to create a more dramatic sound track, not to further dimish it and MAX provided the most dynamic range to the audio. I'll recheck tomorrow, but I think we need to look at the particular Sony amp in question and how the adjustment relates to the Sony amp and not amps in general.

jeff

Zacha

One other thing that I think is causing this contradiction, is that when you get to this setting on a Sony receiver, it says "DYNAMIC COMP ADJ" on the receiver itself. From my memory of installing sony amps for years, this does not mean dynamic compression adjustment. When you look in the manual, its full name is "DYNAMIC RANGE COMPENSATION ADJUSTMENT" and again its purpose is to increase the dynamic range of the audio since many DVD's are recorded with varying degrees of dynamic range compression.

On the Sony amps that you have been installing, what is the setting you leave it at?

jeff

Compression and compensation both mean the same thing, in this context.

I have a Sony product, with that function, and the purpose is to DECREASE dynamic range.

This is from the manual:
"Lets you compress the range of the soundtrack. This may be useful when you want to watch movies at low volumes late at night."

DVDs are recorded with pre-engineered dynamic range compression, but it's only engaged when you turn on the Dyanmic Range Compensation/Compression. Otherwise, you get the FULL dynamic range. See this diagram from the Dolby website:

[Link: dolby.com]

If you want to boost the volume on a Sony receiver, then you could engage one of the 'Cinema Studio' modes. These distort the soundtrack a bit, but they do make it sound louder. Or you can just turn up the volume.

There's no need to 'boost' dynamic range in Dolby Soundtracks. As they already go as soft as 0 dB, and as loud as 120dB - which is the audio pain threshold.

One other thing to check, is that your DVD player doesn't have Dynamic Range Compression on as well. This could lead to double compression (I guess), just like double cross-overs.

And, as I just read on another newgroup, don't forget to turn it off when you're done.

Okay, it's 2-cents-worth time again!!

First of all, there's the speaker-size settings, which are basically like this:

With the satellite speaker settings, whether center, L & R, or rear, the large setting produces a full-spectrum signal, with only the LFE sound going to the sub. Only with the subwoofer set to 'no', will the LFE signal go to the mains (L & R). In addition, any satellite speaker set to 'small' will have it's lows redirected to the sub (if on), or the mains (if sub off). If mains are set to 'small' and the sub set to 'off' the lows will get lost in the ozone, EXCEPT if the rears are set to large, THEY get the low stuff!

Second, about dynamic range and compression:

Dynamic range is the difference between the loudest and the softest sound, usually expressed in the decibel, which is a tenth of a bel, named after Alexander Graham bell. The decibel was created because the bel became too coarse of a scale when instrumentation became more sophistocated.

By the way, decibels are almost always used as a relative term, meaning one sound so many decibels louder or softer than another. The absolute decibel is a somewhat arbitrary level derived from 0db being the threshold of hearing (who's?) and 120db (originally 100, which derives from a 1-to-10 bel scale) being the threshold of pain (again, who's).

Unless some company is doing things really different from everybody else, all DVD dynamic adjustments, whether in the player or in the receiver, pre-pro, or amp, are used to decrease the dynamic range, so soft sounds are still audible when the volume is set low enough to let spousie and the kids sleep. You may have noticed that radio DJs use an incredible amout of compression, so the AVERAGE loudness is way up in the stratosphere. That's why they all sound so alike; dynamics are a large part of voices. Believe it or not, this is done because studies show that channel-flippers will tend to stop tuning on louder signals.

Next, there's the crossover and slope discussion.

Slope first:

The slope is the rate at which a sound level changes with a rise or fall in frequency, and the slopes are given as 6, 12, 18, or 24 db per octave, because that's just the way that electronics works. (I could explain why, but it would take too long here).

This means that, using 80Hz as our starting point, that a high-pass (or low-cut) filter (using a 2nd order filter, for example) will cause the sound level to be 12db lower at 40Hz, while a corresponding low-pass filter would produce sound 12db lower at 160Hz.

When a normal crossover is designed to divide the audio spectrum into segments for woofer/tweeter or woofer/midrange/tweeter drivers, the crossover frequency, or 'point' is actually where the sound is 3db below the level range of each driver, because the relatively gradual slopes let both drivers contribute sound around the crossover frequency. The -3db from each driver add to make a smooth transition from one driver to another.

Now, about those subwoofer controls:

When different frequencies are selected, there could either be a 'hole', where neither speaker is producing a range of frequencies, or muddiness, where BOTH are reproducing, usually not to a sonic advantage. However, some people intentionally use these controls to tame a bad resonance of the speaker/room interface. If there is a bad peak at, say, 100Hz, setting the subwoofer crossover to 80Hz, and the main/satellite crossover to 120Hz, the effect is to smooth out the hump. It takes a lot of skill and time to do this well.

The best bet is to start with all crossover controls set to the same setting, and try one adjustment at a time, listening carefully to the effect before trying something new.

By the way, the reason speaker systems use several ranges of drivers (woofer/tweeter or woofer/midrange/tweeter) is because of a phenomenon known as 'beaming', which is the inability of a larger driver to spread out the sound over an area, as opposed to directly in front of the speaker, i.e., poor dispersion.

As a given sound goes up in frequency, starting witth bass in the woofer, the sound-spread pattern narrows. Once the chore is handed over to the next-smaller driver, the pattern spreads out, until it begins beaming as the frequencies go even higher. The tweeter then takes over.

The trick is to use a crossover frequency low enough to send signals to the next-smaller driver before beaming becomes noticeable, but not so low that the driver can't move enough air to produce the desired sounds. Noticed that many speakers, especially towers, use two or more woofers, but somehow manage to only need one tweeter? That's because it takes a lot more air movement at low frequencies.

Also, speaker systems that have woofers that are relatively small, such as 10 inches or less, really don't need midranges, because the beaming isn't so bad from a 10-inch cone that a tweeter can't handle the required upper frequencies. Ever see the $29 Universal and other cheap mini-speakers? They really don't need midranges! Why do they have them? They sell well to the uneducated.

Did you know that it takes a DOUBLING of amplifier power to produce a barely audible 3db increase of sound, and a staggering TENFOLD of power to make what is percieved as a doubling of loudness, which is 10db??

Larry

Zacha, Larry: wow. Can I have permission to package your comments into a book and sell it to people like me? You'll get full compensation!

Seriously, thanks for the explanations. I'm a lot closer now to actually understanding some of this quagmire. I guess I really should have spent more time on Math in high school.

Zacha, question: My Klipsch speakers all have a horn over the tweeter (there is no actual separation of tweeter and horn). Some folks have commented that this is a cheating way to emphasize the upper end, but from your description of beaming it sounds like a pretty good idea. In any case, I really, really like the Reference speakers that I use now. Would you say thata further throwing out of the frequencies with this method is integral to the efficiency and sound envelope? ... Mike

Ok Zacha, I'm gonna eat crow on this one. I checked the manual for his receiver and it is compression on this model and you are right, the max setting will increase the compression, so I too would recommend not using it, especially since he has night mode that will basically accomplish the same thing. My memory failed me and I think I got it mixed in with another receiver that had dynamic compression and expansion on it. So just forget the last few messages I wrote.
brain damaged jeff