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[jjkale]

I have a 5.1 setup but like the idea of multiple subs.  My mains are Revel F208s which have dual binding posts and are bi-amp capable.  Currently I just bass manage in JRiver by crossover from the center and surrounds (and the mains at 50 Hz) to my sub.  I would like to also send LF from the center and surrounds to my mains to implement a "multiple sub" setup.
Would any of you offer me some hints on how to accomplish this using the Parametric Equalizer?
Based on measurements from Dirac, I would like to send all five channels below 50 Hz to the sub, 80-50 from surrounds/center to the mains.
The center is a Revel C205 and the surrounds are Revel M105s.
I have plenty of power in the 7 channel amp.
Thanks very much for your comments and suggestions.

[blgentry]

Currently I just bass manage in JRiver by crossover from the center and surrounds (and the mains at 50 Hz) to my sub.  I would like to also send LF from the center and surrounds to my mains to implement a "multiple sub" setup.

I totally understand the thinking behind this and I've done something sorta/kinda similar in the past.  My results were "eh".  Not bad and certainly not great.  Later, I had a long conversation with a man who's been in audio forever, has written course material for training recording engineers, and has worked for numerous high profile audio manufacturers.

Barry's position on subwoofers is that mains should not produce any sounds in the subwoofer range.  He has written an extremely detailed and well reasoned white paper on this, which you might enjoy reading.

http://soundoctor.com/whitepapers/index.htm

You might also want to read the instructions for his Test CD, which outline the steps for properly setting up a subwoofer.  I think it's very impressive work.

Would any of you offer me some hints on how to accomplish this using the Parametric Equalizer?

Should you decide to pursue this, you'll want to use the Mix Channels function of the PEQ.  It would be easier to figure out the steps if you could outline in sort of an equation form, what you want to end up with.

I think you probably want something like:

Sub Output 2 = Lowpass filter( L + R + C + SurL + SurR)

But I'm not super sure based on your description.

Seriously though; have a look at the white paper.  Barry has worked wonders using the techniques there.

Brian.

[mojave]

You can use the User 1 and User 2 designations in PEQ to accomplish this.

User 1 gets the signal added the center and surrounds
User 2 gets the signal added from all 5 channels

Mains get a high pass at 50 Hz
Center\Surrounds get a high pas at 80 Hz
User 1 gets a low pass at 80 Hz and a high pass at 50 Hz and then gets routed to the mains
User 2 gets a low pass at 50 Hz and then gets routed to the sub

Don't forget you will have to figure out level adjustments for the rerouted audio to make it work.

[jjkale]

blg and mojave,
Thanks very much.  Your replies are helpful.
blg:  Thanks for the soundoctor reference.  I did read three of the papers and found them to be interesting.  I noticed that he referred to Harman and Dr. Toole.  Some of what soundoctor wrote seems to contradict Toole.  I will stick with Toole and his associates who have performed extensive double-blind testing.  Toole has some very current articles on Gene DellaSalla's audioholics.com website.  Well written and informative. 
I agree that the results may be mediocre, but that's part of the fun of this hobby; trying to find that last 1 or 2% of performance.
You may find it informative to investigate Dirac.  I am using it with very good results.  It is able to solve impulse issues that soundoctor writes about.  It also takes 9 different spatial measurements which can be done over a pretty wide area.  Highly recommended.
Thank you again.

mojave:  Thanks for the specifics on User 1 and 2.  I have not experimented with that before as I did not understand what it was.  I will take a look.  Are there any threads on User 1 and 2 techniques?
This is the intial scratchpad work I have (it needs a few more steps and just guessing on -db's):
hpass 50 LR
hpass 80 CSLSR
add C to R -1db
add C to L -1db
add SL to R -1db
add SL to L -1db
add SR to R -1db
add SR to L -1db
add L to Sub -1db
add R to Sub -1db

And thanks again.

jjk43

[mojave]

mojave:  Thanks for the specifics on User 1 and 2.  I have not experimented with that before as I did not understand what it was.  I will take a look.  Are there any threads on User 1 and 2 techniques?
This is the intial scratchpad work I have (it needs a few more steps and just guessing on -db's):
hpass 50 LR
hpass 80 CSLSR
add C to R -1db
add C to L -1db
add SL to R -1db
add SL to L -1db
add SR to R -1db
add SR to L -1db
add L to Sub -1db
add R to Sub -1db

And thanks again.

jjk43

The user1 and user2 are temporary holding channels when you need to combine other channels.

You workflow above won't work and is backwards from what I suggested. You will end up copying everything above 80 Hz from all channels to the R, L, and Sub.

User 1 gets the signal added from the center and surrounds
Add C to U1
Add SL to U1
Add SR to U1

User 2 gets the signal added from all 5 channels
Copy U1 to U2
Add L to U2
Add R to U2

Send all 5 channels below 50 Hz to the sub
Low Pass at 50 Hz on U2 (recommend 24 dB/octave)
Add U2 to Sub

Send C, SL, and SR from 80 Hz and down to the mains
Low pass U1 at 80 Hz (recommend 12 dB/octave)
Add U1 to L
Add U2 to R

Remove bass from Mains
High pass at 50 Hz (L, R) (recommend 24 dB/octave)

Remove bass from other channels
High pass at 80 hz (C, SL, SR)

[jjkale]

Beautiful, Thanks Mojave.