Axiom Home Page Forums General Discussion Technical Questions Mains=large: bass redirection for stereo material?

On a typical AV receiver, setting mains=large, sub=on, and crossover=80Hz will (for Dolby 5.1 material) send ONLY the LFE track to the sub, whereas the mains get full range material. IOW there's no bass redirection from mains to sub -- the crossover is typically not used (for mains->sub redirection).

Likewise setting mains=small, sub=on will send LFE + redirected bass below crossover to the sub. Again this assumes discrete 5.1 material, say Dolby Digital 5.1.

But what about stereo material? If mains=large, sub=on, will any bass redirection happen from mains to sub?

Various receivers have different settings for this. Look for a R/L+LFE setting or similar.

Joe, no redirection of the bass from the mains to the sub occurs in general in that situation. Most receivers have a setting(LFE+Mains, Both, Double Bass, etc.) which applies only when the mains are set "Large" and which would duplicate the lowest bass from the mains to the sub so that both the mains and the sub would be reproducing it(not a good idea in my view).

Oh, so that's what Double Bass is. I didn't know what the setting meant, so I turned it off.

(1) It depends on the bass management of the AV receiver. There are others besides Outlaw (H/K for one) that let you operate in stereo with the subwoofer and the mains set to Large or Small (the double bass thing) with a selectable crossover setting.

As to setting mains to Large with the subwoofer and DD 5.1, there are users who simply want tons and tons of bass, so-called "bass-heads." I know plenty of them.

I'd agree that with other receivers that don't permit the above, then it would indeed leave the subwoofer silent.

(2) It could, but for bass-heads, it isn't a "problem."

(3) I've tried to explain this previously but other articles may omit it because it's technically complicated and the number of AV receivers and preamp/processors that enable this is in the minority. (And I might have omitted mention of it in some of my pieces because it's tricky to understand. . .)

Incidentally, lots of naive listeners equate bloated, fat bass with "warmth" in a loudspeaker's tonal balance. And it sells in retail outlets' speaker demos.

Regards,

Alan, thanks.

My problem is this is typically poorly documented in the user's manual for various receivers. Many times I've read the section in various manuals on bass management, and thought "what does THAT mean?".

Sometimes the only solution is simply doing tests in various modes with various material and writing down what the subwoofer apparently does for each configuration.

However I think the generally "safest" receiver configuration for a 2.1 or 5.1 speaker system is all speakers=small, subwoofer=on, bass->sub only (not both mains+sub).

But when you're listening to stereo, there is no sub channel. Therefore, the sub would be doing nothing.

This isn't as straightforward today as it was a couple of days ago...

But kcarlile, in some AV receivers, including H/K, in stereo you can set your mains to Small, pick the crossover frequency (80 Hz or whatever), choose Sub "On" and the bass management will re-direct bass to the subwoofer, so you'd have a 2.1 system.

I think I need a little drink. ..it's Friday.

Regards,

I've already started. Cheers !

How would that be different from doing Mains+LFE in Stereo? I guess you probably wouldn't have that option... Gah. I need a drink too. Or several hours of sleep.

drink! I'm going to opt for a white wine. (review in the wine thread)

Joe, this has gotten tangled-up a bit, but in my view there's no good reason to set the mains "Large" when a modern HT receiver with good bass management together with a good sub are in use. The sub can always be used with either 2-channel or 5.1 material. There's no problem when the mains are set "Small" with the appropriate crossover frequency.

I'll drink after I finish replacing the motherboard in my wife's Powerbook.

Actually, I went to bed--ah, life with an 8 week old. The Powerbook works, though!

I hear ya Ken, although ours is just now at 11 weeks.

So why do we bother buyiing the 80's if they need to be run in small mode.
Why can't they engineer and pro that when set to Mains=lrg and a Sub. set it at cut off =80
then have addition settings that Mains from 80 - 60 hz would roll off so that at 80 thier would be decent level of bass but at 60 it would be very minimal almost unheard. There fore the Sub would pick up at 100hz and get louder as it gets to the 80 and then take over all bottom end.

Troy, that was awfully hard to follow. Maybe if you could clarify a bit a good response would be possible.

Perhaps if you're on some medication, you could wait until just before taking your next dose?

Yes, yes it was bad .....

Ok, to clarify
Why do we buy MT80's for our systems if we run them in small mode …. Are they not full range? Why not buy the MT22 and pair them with a EP500.
Just seems to be wasting money on the MT80's if I am not going to use them as full range speakers.

as to the other part
We would have MT80's and a Sub. What I am getting at here is the 80's are good to about 35hz ...So engineer an receiver or Processor that you could setup as Mains + LFE ( as in my Denon settings ) Now the mains (MT80) would get all frequencies down to 35hz, but with the exception that at the specified cut off say 60hz. Now once the frequency hits 60hz it would start to tail off until it gets to say 40hz were there would actually be no signal going to the Mains
At the same time when to sound goes into the 80hz area the sub would get little signal as it gets closer to 60hz more signal goes to the sub bring up the db's , as the frequencies get in the 60hz - 50 hz zone the MT80’s would more or less pass off to the sub.

Kind of like if I had a fire hose and on the end is a Y splitter with a dial on it. Now the water in the hose can be a trickle at times to full force ……Letting water represent frequency ( the more water the lower the frequency), all the water coming down the hose is going out channel "A" as the water pressure builds up, I turn the dial water starts trickling out channel "B" this is the point where the sub is starting to get some frequencies below 60hz, so as more water flows out Channel B the frequencies go lower ( turning the dial )more water goes to channel B. At the same time the pressure gets less in Channel A to the point where the water representing 60hz and below is all going to Channel B. At this point the MT80's will only be getting 60 Hz and above while the sub gets 60hz and lower. It is at this point where if I had 100lbs of pressure 25 % would be going through Channel A and 75% would be going to channel B.

I hope this makes sense

Oh and sorry
my apologies my writing is terrible actually worse than terrible

Troy, that's a bit clearer now, and as Dave commented, what you're proposing is similar to what can happen now. If the mains/sub crossover would be set at 60Hz the mains would be rolled off at 12dB per octave below 60Hz, while the sub would be rolled off at 24dB per octave above 60Hz. So, there's a blend of the mains and sub in the crossover area and as the frequency got lower the mains would do less and less, while as the frequency got higher than the crossover set the sub would do less and less.