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6 subs 2 outputs

 
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jeffslife




Joined: 17 Apr 2010
Posts: 4181
Location: ohio usa


PostLink    Posted: Wed Sep 28, 2022 8:45 pm    Post subject: 6 subs 2 outputs Reply with quote


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So I got 6 subs. My pre pro has 2 outputs. If I split each output using rca splitters am I losing sound ? Would the splitters send
less signal since it is being split up ?

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kal
Forum Administrator



Joined: 06 Mar 2006
Posts: 17850
Location: Ottawa, Canada

TV/Projector: JVC DLA-NZ7


PostLink    Posted: Thu Sep 29, 2022 12:25 pm    Post subject: Reply with quote

Your sub outputs are likely line level signal?

To split this I'm assuming you plan on using something completely passive (the equivalent of a Y cord or multiple cords). This changes the impedance load that the receiver needs to drive since you're hooking up all of the subs basically in parallel.

So how well this works depends on what sort of loads the subs present and how they end up adding up, how long the cables are/what type, and how well the output circuitry in the receiver can handle this likely non-standard output impedance. So difficult to know, but will probably be fine. It doesn't get "split up" like you say necessarily with each getting 1/6th of the signal. The receiver just tries to drive more and maybe able to (no way to know). You may want to try using an active line level splitter to see if there's a difference.

Now that said, 6 (!) subs ?!? That's a bit nuts. What subs? What's the room like?

Using two or three (or *maybe* four tops) isn't that uncommon to balance out a room to avoid standing waves. But 6? Why? What are you trying to accomplish or fix? It's not a "more is better" scenario. You should read this: https://www.avsforum.com/threads/guide-to-subwoofer-calibration-and-bass-preferences.2958528/

Kal

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barclay66




Joined: 27 Jun 2011
Posts: 1291
Location: Germany

TV/Projector: Marquee 9500 Ultra


PostLink    Posted: Thu Sep 29, 2022 12:35 pm    Post subject: Reply with quote

Hi,

It depends on the ratio between output impedance of the source and input impedance of the subs.
Just as an example:

Let's assume that output impedance of the source is 10 KOhms and input impedance of each sub is 20 KOhms.
With the splitter You basically connect all subs in parallel which results in a total input impedance of 6.66 KOhms which is smaller than the output impedance of the sub. In this case, only ~40% of the signal would pass to the subs due to the mismatch of the impedance. In addition, the load on the source output could cause distortions and the frequency response could end up with anything else than flat. BTW: With only one sub attached it would be >65% which still is suboptimal. Recommended impedance ratios are between 1:10 and 1:100 (output vs. input).

I think You will be on the safe side if the output impedance of Your source is well below 1KOhm and the input impedance of each sub is higher than 100KOhm (which combined will result in ~33.3KOhms).

Kal was a bit faster than me but that left room for some additional thoughts:

Maybe You could cascade the subs if they have an output connector or if their speaker outputs can be tapped and fed into the high-level input (if existing) of the following subs? That would leave only one (the first) sub connected to the source output.
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jeffslife




Joined: 17 Apr 2010
Posts: 4181
Location: ohio usa


PostLink    Posted: Thu Sep 29, 2022 4:41 pm    Post subject: Reply with quote

Thank you both. 3 subs are amplified by 2 sub amplifiers. The other 3 have built in amplifiers. I use 2 in the front , 2 in the back and one on the left side.
On the other end of the room is my bar. I have a set of speakers connected to the B side and one self powered sub. The sub kicks in whether or not I am
using the B side speakers it is set pretty low, just enough to make the bar speakers shine a little. I like the way the subs sound. It is just that I have to turn
up the power more for low volume and sometimes its a little much at higher volume. (mostly during movies) It just seems like they are all not getting the same input level. I will probably go back to the one 15 and the 3 12's. It just works. I didnt think about cascade. I am going to try that once. The room is my basement and it is in need of some room treatment.
I am working on that now. DIY treatments that cant be seen so they just need to be functional. That makes it a lot easier (and cheaper). That is a subject for
another day.
Thanks again.

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Curt Palme
CRT Tech



Joined: 08 Mar 2006
Posts: 24296
Location: Langley, BC

TV/Projector: All of them!


PostLink    Posted: Sat Oct 01, 2022 6:03 pm    Post subject: Reply with quote

What you really need is a DSP between the sub outs and your amps. DSP (digital signal processor) will let you fine tune each sub for eq, time delay, and even crossover frequency if you run full range into the subs.

A 4 in, 8 out is probably ideal, or you could get an 8 X 8 if you want additional processing for your main speakers. You do need to set up the DSP with a laptop, so you need to know a bit about how to set a DSP properly.

Used ones can be had on ebay for under $200, to up to $1000 depending on what you get.
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