WHEN I SET THE SPEAKER SIZE TO SMALL ON MY SONY STRDB-940 I CAN THEN SET THE BASS CROSSOVER FROM 60HZ TO 180HZ. IF I LEAVE IT AT 120HZ DO I THEN SET THE SUBS HIGH CUT TO 120HZ? ALSO THE PHASE SWITCH ON THE BACK HAS ME CONFUSED. WHEN SET ONE WAY THE BASS THUMPS IN ANOTHER ROOM BUT IF SET THE OTHER WAY THE THUMP DIES CONSIDERABLY. WHICH WOULD BE THE CORRECT WAY TO SET IT? THUMP OR NOT TO THUMP? THANKS IN ADVANCE FOR ANY ADVICE.

I am pretty familiar with the sony line but do not recall a str-db 940 but there is a recent discontinued model str-de 945 which has now been replaced with the str-de 975. I have always had better sound setting the crossover to the highest level on the amp and then adjusting the subwoffer crossover adj to my own personal tastes. I does usually end up aroud the 120Hz range. As far as the phase control, most subs I have installed tell you simply to try it either way and leave it where the bass sounds the strongest. It helps if you have a sound level meter but you can usually tell the difference with your own ears. Rooms are all different and the distances of your sub and your other speakers to the listening area all effect how the sound pressure travels and the whole key is making sure the sub is adding to the sound from your other speakers instead of detracting from it.
jeff

im in the uk so i dont know if this is an area pacific model. i also have found setting the crossover higher gives a better sound. as for the phase switch when i set it the way that gives the strongest base that is when it thuds like hell in the other room and kind of detracts from the other speakers, so i guess when you said trust your own ears then thats what i'll do. will try higher crossover settings as at the moment i have it set at 90hz. thanks for the advice jeff, it alsways helps to hear it from someone else.

thanks
john

FYI, the DB-940 is sold in North America too.

The DB series is closer to Sony's high end ES series.

The DE line is their lower end.

Wow, I did not know there was a db line of receivers. We have been selling Sony for some time and its either been the regular de line or es line.
I learned something new today.
jeff

"I have always had better sound setting the crossover to the highest level on the amp and then adjusting the subwoffer crossover adj to my own personal tastes. I does usually end up aroud the 120Hz range."

This would leave you with a hole between the lowest frequency of the amplifier, and the highest frequency of the sub.

What you should proabably do is, set the subs frequency to its highest setting (or turn the cross-over off, if it will let you do that). Then adjust the cross-over on your amplifier. That way, only the amplifier is applying the cross-over, and there will be no low frequencies that your system won't produce (assuming that the sub is actually capable of producing them).

To pick the cross-over frequency: this is usually determined by your main speakers. If they go down to, say, 50Hz, then 60Hz or 70Hz might be a good place to put the crossover. If all else is equal, 80Hz is a good number, but all else is never equal.

The lower you set the cross-over on the amplifier, the better the low frequency sounds will appear to come from specific directions. This is because sounds below 80Hz (or so, the number is sometimes debatable) are effectively directionless to the ear.

Is that any help?

Zacha, ive set the speakers to small on my amp because when they are set to large i find the sound a bit muddled. on the small setting i set the crossover on the amp to either 120hz or 90hz i havent decided what i like best, on the sub i then set it higher than the amps crossover as it will only send either below 120hz or 90hz to the sub.

is this what you mean by their will be a hole?

Pretty much.

The only other thing is, in addition to bass frequencies from the speakers set to small, the sub also gets fed the Low Frequency Effects (LFE, or the .1 in 5.1) channel. The range in this channel goes up to 120Hz, so if you set the cross-over to, say, 110 Hz, the last 10Hz range would be more-or-less cut out.

Which leads to the final thing, that cross-overs have 'slopes'. So, a 80Hz crossover would continue to send frequencies below 80Hz to the 'small' speakers, but at, say, -3 decibels/5Hz. Which would be the 'slope'.
That's why you'd leave a bit of room between above the 120Hz ceiling of the sub, because he subs' cross-over may work in such a way that it fades up frequencies from the cross-over, so sounds closer to 120Hz would be softer. I'm not to well-informed on this issue, however. None of my products with crossovers are helpful enough to tell me what their cross-over slopes are.

The cross-over on a sub is generally used for when the left and right speaker wires ran via the sub, and for prologic decoders with a 'LFE' output, but no crossover options. With a digital decoding for Pro-Logic and Dolby/DTS (like your Sony, I assume)its generally better to let the receiver do the the bass-managment. That way you only get one set of cross-overs, and one cross-over slope.

Maybe someone else can post something a little more detailed (and accurate?) on the issue of slopes.

Good luck.

I definitly agree with the hole issue we are discussing and that is a good point. I guess to restate in my experience with most install since the powered sub can reproduce the lows much better than the inwall or bookshelf's our customers typically use, I have found that sending more of the the low frequencies to the powered sub (setting the amp to 120Hz)has produced stronger bass than letting the inwalls or bookshelf handle it. But that is right about not adjusting the subwoofer crossover setting below the amps setting or else a hole can be created. Although the roll off of the amp and sub setting are usually not a real strict cutoff, thanks for pointing that out.
One other reason I like to do that is also having the powered sub do more of the work so the the actual AV amplifier is not requiring as much power output trying to drive the bookshelfs with those power absorbing low frequency bass notes.
jeff

wow, it just aint easy this set up lark is it?

If i set the sub crossover to 150hz (its max) and then set the amp to small speakers and 120hz crossover, the bass below 120hz will go to the sub and because ive set the sub at 150hz it will play the signal? also because Zacha said the LFE goes all the way up to 120hz on Dolby Digital and i presume DTS also that i will be getting all the affects of the bass?

Also my centre speaker ranges from 60-20.000hz. If i were to set the crossover on the amp to 60hz for the centre and the sub to max would this create a hole?

Finally...if my fronts are set to large at what frequency would the amp send bass to the sub? Both for cd music and DVD purposes?

Thanks for the input it has been most educational.
John

Strange way you spell 'center'. Yeah, things can get overly complex than what it really is. Just curious if you were even able to tell any difference in your settings?, it is usually quite subtle.
I did not quite follow some of the earlier topics, but setting the sub crossover on the amp is a fixed entity for whatever you are listening to. Also according to the literature on the Sony amps I have installed, setting the speaker sizes to smaller simply reinforces the bass level to the other speakers you have set to large and the subwoffer, it does not effect the crossover setting.

One thing though after reading your last letter, the sub crossover setting that we talked about is in your 'setup' section of the amp. The frequecy settings you see in the equalizer section of the amp, such as center, rear, or front frequency settings are not crossover settings. They are parametric EQ settings that put more emphasis into the range you select. I usually only adjust the mid range frequency from its 1.2kHz setting to around 3.1kHz for the fronts and center. I have found that in most installs the voices sound more natural when the midrange setting is bumped up a bit.

I hope that I have been able to help in some way. It really just takes some playing and you get a feel for what adjustment does what.
jeff

'Centre' is how it's spelled in Australia, and the UK, and New Zealand..

That 60Hz centre setup sounds good, John. (Speakers do go a bit lower than their specs, but at decreasing volumes - like a cross-over slope. Hopefully, your centre will produce decreasing frequencies below 60Hz to match the subwoofer. Listening to them, or checking out their corresponding slopes, would be the best way to check it out. Once again, the area of slopes isn't my strongest.)

If you have a THX 'optimode' featured DVD, then the last audio test is a frequency sweep that you could try as a check for the cross-over. Turn the volume down, unplug your left and right speakers, and listen to the sweep. If everything on the centre cross-over is working, then the sweep should sound smooth, and not drop out from the centre before switching to the subwoofer.

If it doesn't work, try taking the cross-over up to the next highest frequency your amplifier will allow, and trying again.

As for your second question: when a speaker is set to 'large', then ALL bass information is retained by them. So, on a CD in stereo mode, the bass would all be sent to the large left and right speakers. In a Dolby-Digital or DTS mode, the left and right channels would get all 20Hz-20kHz of their information, and the subwoofer would only play the LFE channel + frequencies from centre and surround speakers, if they have a crossover.

Left and Right speakers should generally only be set to large if they can go all the way down to 20Hz. Otherwise, they are usually only set to large if you don't have a subwoofer - so that the bass from the other speakers is redirected to them. If they're set to large when they don't go down to 20Hz, then the frequencies from their lowest frequency down to 20Hz will be more or less lost.

Zacha, how could you not mention CANADA, where a centre channel is very important for Home Theatre...

Jeff, sure is a strange way to spell centre, im english so that probably explains everything.

anyway, yes the differences are very subtle and im probably being a bit picky about it. As for the parametric EQ settings, i have now adjusted them to 3.1 as you do, i'll try it out now to see what i think.

Yes you have been most helpfull and i very much appreciate you taking the time to converse with me on the subject jeff.

Zacha,

Thanks also for your input,you also have proved most helpful. I myself do not possess a THX optimode DVD as in the UK we do not have the luxury of its inclusion on THX certified DVD's. I can get hold of one off of my friend though, so i shall try the sweep test in the next few days.

Thanks once again to all who have educated me.
John

Sorry, Mike. I wasn't sure about Canada. I think missed out on The Republic of Ireland, too.

Yeah, we have to import Optimode DVDs here in Australia too.

No problem, John.