# Help with dual passive sub hookup to old reciever



## maverick_goose (Feb 10, 2014)

I'm set on buying a pair of 10 inch Monoprice passive in-wall subs and I'm not sure if I could use my old receiver as a dedicated amp for them. 

Here's how I understand it but I'm not sure if it will work or if there's not a more suited solution as I have never done this before. 

So I would be connecting both subwoofer outs from my new receiver (presumably a Yamaha RX-A830 or another similar 7.2 receiver, I have yet to decide) to two rca inputs on my old Pioneer VSX-D1S. I'm guessing I would need a "Y" splitter to split the subwoofer out of my new reciever to connect to both left and right inputs on the old receiver. On the attached image I would be using VCR 1 and 2 inputs on the old receiver as signal in.

Then I would use speaker cables to hookup the front speaker output of my left and right channels to each of the two subs.

I would then set the old receivers volume at a balanced volume and leave it there using the new receiver for general volume adjustment (including the sub).

I'm no expert so any input is appreciated.


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## Kal Rubinson (Aug 3, 2006)

maverick_goose said:


> I'm set on buying a pair of 10 inch Monoprice passive in-wall subs and I'm not sure if I could use my old receiver as a dedicated amp for them.
> 
> Here's how I understand it but I'm not sure if it will work or if there's not a more suited solution as I have never done this before.
> 
> ...


Seems proper.


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## flamingeye (Apr 2, 2008)

I'm just curious but how are you going to set both VCR inputs to on at the same time so both subs are powered ? on my pre/pro I can only run one input at a time or am I misunderstanding how this would work


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## maverick_goose (Feb 10, 2014)

flamingeye said:


> I'm just curious but how are you going to set both VCR inputs to on at the same time so both subs are powered ? on my pre/pro I can only run one input at a time or am I misunderstanding how this would work


By switching between them back and forth, real fast :R 

Obviously, I hadn't thought this through. 

If I drop the "Y" splitter and send each sub out from the new receiver to the left and right channel of the same rca input (say VCR1), would that work? Any drawbacks?


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## tonyvdb (Sep 5, 2007)

Keep in mind that a receiver will not supply enough power to drive even a 10" sub . You won't get very good results going that route.


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## maverick_goose (Feb 10, 2014)

I was wondering about that. My old Pioneer VSX-D1S is rated at 130W x 2 for the front speakers. What kind of power would be required?


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## tonyvdb (Sep 5, 2007)

It would be very unlikely that you would get more than 90watts per channel out of it. Subs are very demanding on power and I would say that no less than 250 watts would be required to get anything reasonable out of them.


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## maverick_goose (Feb 10, 2014)

tonyvdb said:


> It would be very unlikely that you would get more than 90watts per channel out of it. Subs are very demanding on power and I would say that no less than 250 watts would be required to get anything reasonable out of them.


I'm sorry if these seems like really trivial questions, I'm sure there's a very simple logical audio explanation that I'm missing. Why would a 130 watt at 8 ohm rated receiver only deliver 90 watts? The other question would be why would we need a 250 watt amp for driving a 100 watt at 8 ohm rated sub?


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## tonyvdb (Sep 5, 2007)

Receiver companies test there receiver using a 1kHz test tone to get the wattage specification. As music/movies are much more dynamic than a 1kHz tone that number you see is over rated and well documented. The power supply in most receivers is unable to maintain enough current to power the internal amps to their full potential.
The sub may be rated to handle 100watts but will draw more then that before hitting its max output plus the receiver does not have a high pass filter meaning you will be sending whatever the audio signal is to the sub. A 10" driver wont handle frequencies below around 20Hz very well.


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## maverick_goose (Feb 10, 2014)

OK I think I get the power part, but I thought the sub out from the new receiver would handle the filtering part for the old receiver.

Just before I discard my old receiver for the job, I read reports of people driving one of these subs with a 100 watt (2 x 50) amp bridged to mono. How is that better than my situation?


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## tonyvdb (Sep 5, 2007)

The sub out on your current receiver only does the crossover not the HPF usually sub amps have a HPF built in that filters out anything below a set number IE: 15Hz
People using that amp are also likely not getting the full potential out of the sub but also that dedicated amp will actually likely hit 100Watts Bridged.


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## maverick_goose (Feb 10, 2014)

Thanks Tony, now I get it. I may still give the old Pioneer a try, I have it and it's free. If I don't like what I hear it's either that they are underpowered or bogged down by low frequencies they can't handle. Cheap, powerfull amps seems pretty common, it's the HPF feature that seem a little more difficult to find.

Maybe there's something that could be done on the main receiver end. I just received a spanking new Denon avr-x4000. I'm so busy with the whole building the HT room thing that I barely found time to open the box.


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## willis7469 (Jan 31, 2014)

+1 on all tony said. Just thought I'd add that you COULD use in line high/low pass filters like in car audio. They have female RCA ends, and Parts express has a good selection.


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## tonyvdb (Sep 5, 2007)

Given he has a new Denon 4520 sitting and waiting to be used he is good to go on that end


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## maverick_goose (Feb 10, 2014)

Thanks for the tip. I was wondering why you put the word COULD in capitals. After a little research, it seems that these in-line filters are a little contreversial. People are saying that they may attenuate the signal and something about mismatching input impedance impacting crossover... Reminds me of the lens filter/no-filter debate on DSLR forums.


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## maverick_goose (Feb 10, 2014)

tonyvdb said:


> Given he has a new Denon 4520 sitting and waiting to be used he is good to go on that end


Are you saying that the sub out on the Denon x4000 does HPF? I read that it's there for the amplified outputs.


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## tonyvdb (Sep 5, 2007)

No receiver has a HPF on the sub out. Most subs have that built on the plate amp. In your case you wont have one unless you get a proper external amp with one built in.


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## willis7469 (Jan 31, 2014)

I don't believe the denon will do any hpf out of the LFE. That's mainly what I meant by my suggestion of the in line thing. I used caps to reflect how I MIGHT say that vocally, indicating they might be a last ditch effort. My thinking was that since you won't be using a "sub" amp that it would not have a subsonic filter, to protect your drivers. The part that's above my pay grade is, the freq response of the "VCR" inputs might only be 20-20k. I'm not sure what would happen to content below 20hz.


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## XEagleDriver (Apr 15, 2010)

maverick_goose said:


> I'm set on buying a pair of 10 inch Monoprice passive in-wall subs and I'm not sure if I could use my old receiver as a dedicated amp for them.
> 
> Here's how I understand it but I'm not sure if it will work or if there's not a more suited solution as I have never done this before.
> 
> ...


M-G,

You are making this too hard. 

Referencing the picture you provided (thanks BTW) near the center of the picture are *two sets of jumpers* from *Pre-Amp* out to *Power In* with the bottom set labeled "*Front Amp*" (I can not see the label for the top set). 

*To use this AVR purely as a sub-power amp (i.e. bypass pre-amp):*
1) Remove both sets of jumpers. 
2) Run one RX-A830 sub-out (subout#1) through a Y-splitter into the Front Amp *Power-In * L/R input and the other RX-A830 sub-out (subout #2) through a Y splitter into the upper (label?) *Power-In* L/R inputs. These connect directly to the AVRs power amp section bypassing the pre-amp section.
3) Then connect speaker wire to the set of amps/speaker outputs these two *Power-In *inputs support and you are done.

If you want to use the pre-amp section: 
a) Don't remove the jumpers. You will only need one set of connections; i.e. subout #1 into the L input of your choice (i.e. VCR 1) and subout #2 into R input of the same set (i.e. VCR 1). 
b) Then select an "all channel stereo" mode (assuming the VSX-D1S has one) to force the AVR to output the sub-signal to two sets of AVR amplifiers (i.e. L/R Front and Surround L/R). 
c) Connect speaker wires to these speaker outputs.

Post or PM if I have left these waters too muddy 

Cheers,
Shamu


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## XEagleDriver (Apr 15, 2010)

P.S. The old reviews I found online for the VSX-D1S spoke very highly of its power amps and it should be able to power your passive sub quite well.


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## maverick_goose (Feb 10, 2014)

Sorry for the late response, but hey thanks Shamu for the crystal clear explanation. I will definitely be trying this out. Yeah the VSX-D1S was regarded highly when I bought it. I paid well over 1k for it 20 years ago.

I think I will be trying option #1 using directly the amp. If I understand the difference, it means that the VSX-D1S will only be used as an amp and volume will be controlled by the new receiver (Denon avr-x4000).

Do you have an opinion on the lack of a HPF for the subs?


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## XEagleDriver (Apr 15, 2010)

maverick_goose said:


> Sorry for the late response, but hey thanks Shamu for the crystal clear explanation. I will definitely be trying this out. Yeah the VSX-D1S was regarded highly when I bought it. I paid well over 1k for it 20 years ago.
> 
> 1). I think I will be trying option #1 using directly the amp. If I understand the difference, it means that the VSX-D1S will only be used as an amp and volume will be controlled by the new receiver (Denon avr-x4000).
> 
> 2). Do you have an opinion on the lack of a HPF for the subs?


M-G,
1). Yes, volume will be controlled by the Denon.
2). Should not be a problem since you are using the Denon's subwoofer output. Therefore, the Denon will already have applied signal filtering/bass management IAW the crossover and other instructions you program into the Denon. However, like any new setup, I would begin with low volume, ensure all sounds OK, before a full-up test using your favorite bass track or action flick.

Shamu


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## maverick_goose (Feb 10, 2014)

XEagleDriver said:


> M-G,
> 1). Yes, volume will be controlled by the Denon.
> 2). Should not be a problem since you are using the Denon's subwoofer output. Therefore, the Denon will already have applied signal filtering/bass management IAW the crossover and other instructions you program into the Denon. However, like any new setup, I would begin with low volume, ensure all sounds OK, before a full-up test using your favorite bass track or action flick.
> 
> Shamu


Thank you again Shamu. Exactly what I was looking for:T. 

I will report the results here when it's all set up. The divisions and electrical are done. I'm currently in the process of installing the backer boxes for the in-walls and passing the low voltage wiring.


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## maverick_goose (Feb 10, 2014)

Well the the sheet rock is up and I couldn't resist a test run and I'm happy to report that the setup passed the test with flying colors. I went with option #1, bypass pre-amp, so everything is controlled by the new AVR. I needed to increase DB output on the the new AVR sub control to get satisfying sub output.

Thanks again for the help.


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## XEagleDriver (Apr 15, 2010)

maverick_goose said:


> Well the the sheet rock is up and I couldn't resist a test run and I'm happy to report that the setup passed the test with flying colors. I went with option #1, bypass pre-amp, so everything is controlled by the new AVR. I needed to increase DB output on the the new AVR sub control to get satisfying sub output.
> 
> Thanks again for the help.


Glad to hear (pun intended) you are pleased with the results!
Cheers,
XEagleDriver


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