Adding sub to "full range"...

[glaufman]

Hi there... I've been running a pair of Klipsch RF-3 Towers for afew years as my mains, recently added a used RC-3II as center (used) and a pair of tin cans for rears... (not that bad really, just not worth the details)...

the RF-3's are spec'd to roll off at 37Hz, which is supported by my scans in REW... I'm now thinking of adding a sub to extend down for movies, and perhaps add backup even in music... music is and has always been the primary goal of my setup, but movies are gaining traction...

I'm aware of the "normal" 80 Hz crossover between mains and sub, but I would rather use my RF-3's to their fullest extent, and only use the sub to fill in where necessary...especially important in music, in my opinion, not to mention I spend the money on the towers, why use them as monitors? at any rate...

The issue becomes, my AVR, once the setting of the fronts is moved from large to small, only allows a cutoff as low as 60 Hz, more than half an octave above where my fronts are usable down to... so I'm looking for ideas...

One I've come across is leaving the sub set to off in the AVR and the fronts set to Large, and pulling the preamp out from the AVR as my sub signal, and using the crossover in the sub to limit it to lower than 37Hz... this sounds like a good idea, except I'm afaid that certain scenes could overdrive the fronts, as I already hear what I think is them flapping (yes, I turned it down right away...)...

So then I thought I could turn down the LFE mix on the receiver to a point where the fronts are safe, and turn up the gain on the sub... what does everyone think of this?

Obviously another option is to connect the sub to the sub output, and leave the fronts as large, but as I understand it, then the whole LFE could be pumped into the fronts, which doesn't do me much good...

Help?

[superchad]

Can you hook up main speakers in sub and use it a s a high pass filter? I think there are ways you will be able to get what you want but I have always had full range speakers and my Rotel pre can set each speaker from 40HZ up 150Hz so I never had to think that hard, I run full range fronts, 40Hz for center, and 80Hz for surrounds. Also I couldnt agree more about driving your speaker lower if it can handle it, there is alot of debate about the strict 80Hz rule (which I feel was mostly established with smaller speakers in mind, not the best ones) but I think that only applies if you can safely do it any better, after trying it both ways 80HZ across the board doesnt cut it.

[atledreier]

I have very capable fronts. They can easily handle 40Hz at reference, and lower down if I don't go mental. Still, they sound so much sweeter when I cross them over at 80Hz. A properly set up subwoofer will "always" outperform a fullrange speaker down low. You are not using your system to it's full potential if you DON'T cross them over at 80Hz.

[jakewash]

If you have a very capable sub that will blend well with the mains having the crossover at 60 isn't that bad of a deal. I am able to set my crossover to 40 or 60 and I really can't hear much difference if any with that setting for music or movies and like you my mains are good to below 40hz. Before trying all the other ways, try the 60 hz setting and see what it is like, you may find you like it.

[WmAx]

The only way to get ideal integration and sufficient main protection as you seem to desire, it seems, is with an external active crossover with a great deal of flexibility/adjustment that your internal AVR crossover lacks(nearly all receivers have limited crossover adjustments). You could use, or example, a Behringer DCX2496, which would allow perfect integration, as this is a very powerful DSP outboard crossover/filter processor. But unless your receiver has a way to feed out the pre-amp signal AND feed the now processed signal back into the amplifier section of the AVR - you will not be able to use this method. The only way to get this method to work would be to use an outboard amplifier for the mains, thus using the AVR only as a pre-amp for the mains. The total cost, best case scenario, to add both the procesor and the amplifier, is probably in the $500 USD range.

-Chris

[hddummy]

what is the model number of your AVR?

[Mike Cason]

I too, have a Rotel receiver/amp with the ability to crossover the subs. Xover points are off, 40,60,80, 100, and 120 hz.

I built some really large custom mains and the dual sub tower in my avatar. I've played with the speaker setups in all configurations many, many times. My final optimal quality listening results for both music and movies to get the full benefit of the mains and the subs, is to set my mains to small, even though my mains are monsters, and have set my xover to 60 hz cutoff to the subs through the LFE sub outs.

This does two things that help me get the most out of my speakers. It doesn't "muddy" up my subs with anything higher than 60 hz because that's not what I built them for. Any higher freqs really have an impact on the quality of the bass my subs produce because they are also carring those extra higher frequencies that the mains are intended to produce, not the subs.

At 60 hz with all the speakers set to small, all 60 hz signals and below are sent to the sub through LFE and the rest of the signals are sent to my mains and surrounds. I get the cleanest and highest quality music and movie reproduction in this mode. Most mains and satellites should be able to reproduce 60 hz and up very clean in this mode. I used to have the mains set to large, but I have since changed them back to small with much improved results. You'll just have to keep working with your testing.

Different AV receivers have different features, settings, and outputs, so it would do you well to spend a bit of extra time with demos of different types of music and movies until you are tweaked in to your best.

I would definately use your LFE output to your sub(s), and set the mains to small and give it a try. That's what those LFE outputs are for. I think you will be very happy with that setup. I've seen the daisy chain of the main speaker wires from the receiver wired to the sub, then out of the sub to the mains. I've never liked that and have always had less than desirable performance this configuration. I've tried it on a couple of systems.

You mentioned you're desire was intended for music so I've included a chart showing the range of most musical instruments. By looking at this chart, you can see how much more musical reproduction has to be carried by the sub between 60 and 80 hz.

I hope this helps and have fun.....

Mike

[glaufman]

Glad to hear I'm not the only one on that...I've always felt the 80Hz number was more to get the speakers off the floor to allow ideal placement for imaging that it was abuot being the actual point hearing becomes non-directional... In my case I don't have any problem getting the driviers into the place I want for imaging, so no need for small speakers, so I can afford the lower crossover if I can figure out how to do it...
a friend suggested connection using the sub to cross the fronts, just as you say... I don't have any reason not to, other than making sure that whatever sub I get doesn't color the audio it then sends to the fronts... suggestions?
Other than that requirement, I would have said I was counting on getting a Klipsch sub, but seeing their offerings, I don't think any help with this kind of connection, so I'm open to suggestions...

[glaufman]

atledreier wrote:

I have very capable fronts. They can easily handle 40Hz at reference, and lower down if I don't go mental. Still, they sound so much sweeter when I cross them over at 80Hz. A properly set up subwoofer will "always" outperform a fullrange speaker down low. You are not using your system to it's full potential if you DON'T cross them over at 80Hz.

Are you suggesting this for music as well as movie mode?

[glaufman]

jakewash wrote:

If you have a very capable sub that will blend well with the mains having the crossover at 60 isn't that bad of a deal. I am able to set my crossover to 40 or 60 and I really can't hear much difference if any with that setting for music or movies and like you my mains are good to below 40hz. Before trying all the other ways, try the 60 hz setting and see what it is like, you may find you like it.

Fair enough... only 1 thing: since I don't yet own a sub, and have no friends who's subs are "portable," I have to make a purchase before I can run the taste test, therefore I want to make sure before I purchase that the sub is capable of a backup plan just in case...

Also, knowing myself, I'll always feel bad that I'm not using the lower range of the towers... especially for music...

[glaufman]

WmAx wrote:

The only way to get ideal integration and sufficient main protection as you seem to desire, it seems, is with an external active crossover with a great deal of flexibility/adjustment that your internal AVR crossover lacks(nearly all receivers have limited crossover adjustments). You could use, or example, a Behringer DCX2496, which would allow perfect integration, as this is a very powerful DSP outboard crossover/filter processor. But unless your receiver has a way to feed out the pre-amp signal AND feed the now processed signal back into the amplifier section of the AVR - you will not be able to use this method. The only way to get this method to work would be to use an outboard amplifier for the mains, thus using the AVR only as a pre-amp for the mains. The total cost, best case scenario, to add both the procesor and the amplifier, is probably in the $500 USD range.

-Chris

I was thinking about an outboard crossover, sounds like fun, but I'm jhoping for a more elegant solution... I'm not familiar with teh 2496, but I'll look it up...

[glaufman]

hddummy wrote:

what is the model number of your AVR?

Sony, DTB940... I think...

[glaufman]

Mike Cason wrote:

I've played with the speaker setups in all configurations many, many times. My final optimal quality listening results for both music and movies to get the full benefit of the mains and the subs, is to set my mains to small, even though my mains are monsters, and have set my xover to 60 hz cutoff to the subs through the LFE sub outs.

One question I have is: when you had the cross set lower than 60, did you play a bit with altering the positions of the mains to avoid interference? different listening positions?

I would definately use your LFE output to your sub(s), and set the mains to small and give it a try. That's what those LFE outputs are for. I think you will be very happy with that setup. I've seen the daisy chain of the main speaker wires from the receiver wired to the sub, then out of the sub to the mains. I've never liked that and have always had less than desirable performance this configuration. I've tried it on a couple of systems.

Sorry to get semantic, but strictly speaking, the LFE is a channel on the program media, not an output from the decoder or preamp... the decoder/preamp processes this channel (in conjunction with the other channels and the settings its given) to create a sub output... strictly speaking, the LFE is not intended to necessarily be the sub output... see this article from Dolby... http://www.dolby.com/assets/pdf/tech_library/38_LFE.pdf

You mentioned you're desire was intended for music so I've included a chart showing the range of most musical instruments. By looking at this chart, you can see how much more musical reproduction has to be carried by the sub between 60 and 80 hz.

Yes, indeed... I've seen the chart before... I'm in agreement about preferring 60Hz to 80Hz crossover... another question... how does say a bass drum fit into this chart? How about a bass guitar?

I hope this helps and have fun.....

It certainly does start to help... and if this isn't fun, why are we doing it?

Thanks everyone for all the info and help... I hiope this continues a while until I figure out what I want to do...

[WmAx]

glaufman wrote:

I was thinking about an outboard crossover, sounds like fun, but I'm jhoping for a more elegant solution... I'm not familiar with teh 2496, but I'll look it up...

Elegant - certainly not. But it is the best solution from a functional standpoint. The unit allows for precise variable control and virtually any type/slope of crossover that you could practically want to use. It also has dynamic protection systems that you can set to limit output at specific frequencies at specific output levels. You will not be limited as to your options to find the best crossover point/type/rate. You can also use the DCX to apply room correction filters for bass in order to compensate for some room acoustic issues. You can also use the DCX to customize the roll off characteristics of your sub-woofer: this is a huge bonus because many subjective sound quality preferences(subjective bass 'tightness' is one very largely effected factor, for example) are directly related to the bass cut off point and slope of the LF system. It offers transparent operation and is very easy to use, especially if you use a laptop PC to hook up to it using the Behringer GUI software. You can do all settings from the front control panel of the DCX as well, but it takes more time to do so for many parameters. Main problem with this approach as I stated before: having to use an outboard amplifier for the main speakers due to lack of method to re-feed the processed pre-amp signal back to the internal AVR speaker amplifiers.

-Chris

[hddummy]

I think I would use the 60Hz crossover point from mains to the sub and connect the sub to the sub-out on the AVR. If you crossover too close to the lower range of a speaker then the natural roll-off of the speaker combines with the crossover roll-off to make a total roll-off slope steeper than expected by AVRs. You could potentially have a dip in the systems response in the crossover region.

However, if you really want to take mains to their full range, I would set them to large and set the AVR to send the LFE to the mains. Run pre-amp mains to the sub and use the sub's built in Low pass crossover to limit it's upper extension. I've never seen a powered sub that didn't have one. You can then use a passive crossover before the mains to limit their low end to whatever frequency you want. A first order high pass filter should do it. This is basically a capacitor (or group of capacitors) in line between the receiver and the speaker and should cost about 15$ per side. I believe speaker makers already build this into their crossovers to keep you from over-driving the speaker with material that is too low. Granted that the built in ones are probably better tuned and a little more sophisticated, but the concept is the same. Regardless, it isn't as flexible as the active crossover/external amp solution, but it is a very inexpensive thing to try.

[glaufman]

hddummy wrote:

I think I would use the 60Hz crossover point from mains to the sub and connect the sub to the sub-out on the AVR. If you crossover too close to the lower range of a speaker then the natural roll-off of the speaker combines with the crossover roll-off to make a total roll-off slope steeper than expected by AVRs. You could potentially have a dip in the systems response in the crossover region.

Never thought of that... on first inspection at least...I wonder what other people have to say about that...

Don't the "guidelines" usually state to set the crossover at the rolloff point of the mains (and of course to set the crossover control on the sub to maximum)? Woudn't this then cause an issue more often than not?

[hddummy]

I've just always followed that rule and I don't think any guidelines would convince me otherwise. If recommendations don't agree then I'll bite my lip about it. I'm sure the crossover slopes built into the AVR also have an influence on how close to the speaker roll-off you can crossover. That is one of the nice things about external active crossovers...you have complete control over these sort of things.

[conchyjoe7]

Why not set up your system for no sub at all during music playback? If your mains as you say can go below 40hz, it's unlikely a sub will help much depending on how loud you listen, the type of music you listen to (hip hop/rap will require a sub) and the power of your AVR. I listen to music in stereo (most of the time) with my mains set to large and my subs off. When viewing movies, I go ahead and cut in the subs (I have 2) which are crossed over at 80hz (I use the recommended THX crossover point despite the fact that my mains are easily usable to ~24hz). In most cases, IMHO your speakers will handle 90% of all music no problem, but as others have said; you should try it both ways as simply by crossing over at 60hz or 80hz will take a huge drain off of your AVRs output as well as the bass drivers of your speakers and in all likelihood make your system sound a lot more "open", "detailed" and "smoother".
Just my 2 cents worth...hope it helps!
Cheers,
Konky.

[atledreier]

The thing is, and like I said before, a properly set up sub will outperform your mains. A properly set up sub will have EQ and freedom of location that you don't have with your mains. The response from a properly EQ'ed and placed sub will be smoother and have more headroom than your mains. Music or movies, there is no fundamental difference. It's all sound. Movies often put more of an emphasis on extension, where music demand more agility and precision. This is a broad generalization though. 50% of a movie soundtrack is music.*

*Non-scientific guesstimate

[Mike Cason]

glaufman wrote:

One question I have is: when you had the cross set lower than 60, did you play a bit with altering the positions of the mains to avoid interference? different listening positions?



Sorry to get semantic, but strictly speaking, the LFE is a channel on the program media, not an output from the decoder or preamp... the decoder/preamp processes this channel (in conjunction with the other channels and the settings its given) to create a sub output... strictly speaking, the LFE is not intended to necessarily be the sub output... see this article from Dolby... http://www.dolby.com/assets/pdf/tech_library/38_LFE.pdf



Yes, indeed... I've seen the chart before... I'm in agreement about preferring 60Hz to 80Hz crossover... another question... how does say a bass drum fit into this chart? How about a bass guitar?


It certainly does start to help... and if this isn't fun, why are we doing it?

Thanks everyone for all the info and help... I hiope this continues a while until I figure out what I want to do...

Well, I don't have an arguement with the Dolby link because I'm certainly not a pro. I'm just a novice builder but have built a system that everyone who has listened to it says it's the finest sounding they have ever heard, bar none. I'm just providing you with the settings that I've found to give me the most, and best, sound I can get with my system. I usually listen to music and some concerts in two channel only because the mains are so good.

My Rotel has the sub output and that's the one I use. I am to assume that is the LFE rca jack as well. The Rotel was their top of the line unit so that may explain why my subs get the freqs I set the crossover to.

As far as bass guitar reproduction, I hear everything, even the real low bass that leaves your shirt sleevs wobbling in the air due to the long sound waves. Joe Satraini and the Blue Man Group is literally chest pounding at high levels. Kick and kettle drums are clean. I've ordered the Reckhorn B-1 to fine tune it even better and am expecting a real treat.

As far as placement, my system is so large I can't move it around so I've stacked my subs as shown in the Avatar. I did try having them in two different places, but the co-locating works fantastic. I've even broken the seal in my 5' x 6' plate glass window in the living room. I'm attaching a photo to show why I can't move it around and still maintain decent seating.

Good Luck....

[tonyvdb]

The 80Hz crossover setting is the standard set by THX. Although this may seem high it is the best compromise as a good sub will easily handle the rest. I understand your concern for letting the mains do what they can do but this puts more strain on the receivers amp/power supply section and this in turn limits the maximum output the receiver can do for the surrounds.
The mains I have play down to 32Hz and in pure two channel mode they sound great but for movies I dont want that. Remember that even with a crossover setting of 80Hz this does not mean the frequencies below that dont get through it just means that at 80hz the curve will then fall off so blow 50hz there is no output. Does your receiver not have an independent eq for the mains? You could then just roll off the frequencies below 30hz.