Dual sub pre-outs from receiver? (1 Viewer)

[Rick Radford]

My Onkyo 989 has dual pre-outs for the sub. If I get lucky and am able to pick up a 2nd SVS, what benefit, if any would I see by using this?

My current setup is:

Onkyo sub pre-out1 into BFD1124p left channel (input #1) into Samson input #2 (stereo mode).

If there's no benefit to using the 2nd pre-out, I would save some $$ by not having to get more interconnects (Onk to BFD to S700), and could just change the BFD #1 out to S700 input #1, change to parallel mode, and only need some speaker wire for the 2nd SVS.

If I use the 2nd pre-out, I'd need an interconnect from the Onk to the BFD, then from the BFD to the S700. However, this would allow me to use the 2nd channel (engine) of the BFD to set up different filters (of the same preset) to control the 2nd sub. Right now I have only one BFD engine running (to cut down on light pollution).

I guess another alternative would be to get an RCA to dual 1/4 Y adapter for the receiver to the BFD? Or is there a downside to splitting the one pre-out from the Onk?

If I do nothing but just change the S700 input to #1, switch to parallel mode, and connect a 2nd sub, the current filters I'm using on the BFD would apply to both subs, right? And maybe that would work if they are both in the same corner?

Help! My brain is full!

Is there an optimal setup for the above?

 

[Brian Fellmeth]

Using a Y splitter on one of the sub outs is the equivlent of using both sub outs. They are just wired together inside the chassis. I see no benefit to running separate equalization engines for the two subs whether they are side by side or not- seems better to me to just equalize the sum of their output by equaloizing them as a unit through one BFD engine. As far as the other question- would the Sampson perform better in 2 channel mode with two separate input signals or in parallel mode with one copy of the signal- I have no idea.

 

[Dan Hine]

Rick,

If I do nothing but just change the S700 input to #1, switch to parallel mode, and connect a 2nd sub, the current filters I'm using on the BFD would apply to both subs, right? And maybe that would work if they are both in the same corner?

If you will be placing your subs side by side then I would doubt you would have any problems. Run the amp in parallel and just get some extra speaker wire.
If by some chance/reason you will be placing the second SVS elsewhere then using the second sub output into the second channel of the BFD I think would be a good idea as it would give you more tweakability (if that is a word). It seems like an either or situation to me. Just play around with it and tell us what you think.
Oh, how far away is High Point from Charlotte? I'd love to stop by sometime to hear an SVS in action if that is alright with you. I've also notice that there are a ton of Carolinians on the HTF. Perhaps a local HTF meet is in order?

 

[Rick Radford]

Brian,
>Using a Y splitter on one of the sub outs is the equivlent of using both sub outs. They are just wired together inside the chassis.<
Good. That may simplify my task (assuming the budget committee chairperson approves the acquisition of the 2nd sub!)
>I see no benefit to running separate equalization engines for the two subs whether they are side by side or not- seems better to me to just equalize the sum of their output by equaloizing them as a unit through one BFD engine.<
If I were to place a sub in each of the front corners, I've already seen that the LF corner is a one note corner, but has about 5 or 6 dB more rise than the RF corner. It would seem to me that the desirable EQ process would be to EQ each sub seperately, then see how they blend and tweak from there. I think this would require both engines and that would be the subject of another thread!
I can put them both in one corner, which would likely simplify this. OTOH, the WAF might like a more balanced look with the subs in both corners.
***********
Dan, you've confirmed what I was thinking. Thanks.
High Point is just up I85 from Charlotte about 90 miles. Come on up!
> Perhaps a local HTF meet is in order?<
Sounds good to me! Maybe we could invade Conrad's place and solve the mystery of his lost spls.

 

[Brian Fellmeth]

If I were to place a sub in each of the front corners, I've already seen that the LF corner is a one note corner, but has about 5 or 6 dB more rise than the RF corner. It would seem to me that the desirable EQ process would be to EQ each sub seperately, then see how they blend and tweak from there.

Rick, you may well be right here, but here is my logic. Lets say your in different corners using 2 engines. Use one engine and get one sub flat. Switch to the other engine/sub and get it flat. Now, what do you think will happen when you play them together. Not flat, not even close. Both constructive and destructive interfearence will generate peaks and valleys in the FR that may be as bad as completely uneqalized. OK, now you tackle these new peaks and valleys. Each engine already has 2-5 filters active. Which engine do you tweak ? Pretty soon each engine will have 8 or so filters active and you've got a mess.

 

[Rick Radford]

Brian,
>Each engine already has 2-5 filters active. Which engine do you tweak ? Pretty soon each engine will have 8 or so filters active and you've got a mess<
Yep. That sounds like my MO.
Point taken.
So does everyone with dual subs just EQ the 2 subs together.. while trying different placements?