Subwoofer Out VS Subwoofer Crossover

I'd look at the 701's manual and see what the sub out is doing and whether or not it has a built in high pass for your mains, or a low pass for the sub.

Neither is better, but with luck the 701 includes a high pass filter for your mains that will assist you in getting the most out of your speakers.

I'll look closer. I saw some info that said the amp (yamaha 701) crosses the sub at 90hz, I understand crosses. Is this what is called a low pass filter?

And thank you for your response.

Manual states cut off freq at 100. so if i use the sub out, what shall i do with the subs onboard crossover dial/setting? 

Giving both the amp and the mains a break, not trying to amplify low bass is what you want.

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Stereo Pair of Self Powered Subs, line in/line out (minus low bass back to amp.)

1. self powered

2. front firing

3. no port, if so, front firing. maker should provide an optional port plug, i.e. avoid distribution to corners/rear/side walls.

4. line in, sub's crossover, line out without low bass back to the amp. Amp now does not need/try to make low bass, thus a lower powered amp can be used.

4a. Of course an external crossover can be used to separate the low bass from the amp instead of the sub’s crossover. Personally, todays technology, a sub’s crossover does a great job.

5. Most Advantageous using tube amp as a lower powered amp can be used successfully when not trying to amplify low bass. 

The easiest way to try lower powered tube amps. More tube amp models available, thus: lower competitive prices, lower weight, lower heat, increased location options (consider remote control signals).

6. Single Sub: works to add enough lower bass that the smaller mains do not sound small.

7. Stereo Pair of Subs. Located adjacent to Front Left and Front Right. Thus earlier front firing recommendation.

Very low bass sound waves are wide enough to be experienced as Mono in the listening space. HOWEVER, each/any frequency has overtones, i.e. fundamental 36hz: overtones 72, 144, 288, 560 …: present while progressively reduced in volume. It is these overtones that become narrow enough to become directional, thus Stereo Bass, blended with the front mains.

Stereo Imaging/Location of a Bass Source: Cannon/Jazz/Chamber/Rock …., is definitely achievable. (assuming proper mic locations/recording/mixing, the excellent engineering we seek).

You can still set the sun low pass filter lower than 100 Hz if you want.

You can use your sub with the 701 the same as with your other integrated or you can use the RCA sub connection to the sub setting the crossover point on the sub to best compliment your speakers and run speaker wires to your main speakers. With the RCA approach you would be running the main speakers full range. Using your sub the way you have been you are removing low bass frequency from the mains. I would try it both ways and see which approach best serves.

How low do your main speakers go down to? A sub is for 'sub' low bass that the main speaker can't achieve. If your main speaker has good lower ranger woofers I would let them do what they were designed for. They can add punch and dynamics that you will eliminate if you cross over too high. I run main speakers full range and set the sub crossover to 40hz.  Connection goes from amp high level output to speakers then to sub high level input. This way you pick up the same characteristic tonality and dynamics of the amp.

...I run main speakers full range and set the sub crossover to 40hz. Connection goes from amp high level output to speakers then to sub high level input. This way you pick up the same characteristic tonality and dynamics of the amp.

This is how my sub is set up also....the sub's low pass set at the lowest possible setting, and just enough gain to be barely audible on bass heavy passages.  I don't "feature" the sub.   Every room and situation is unique, so YMMV, but my main speakers go pretty low, and I just use to sub to help augment the output of the bottom octave or so in a large room. I also prefer not to run the mains through the sub’s high pass filter.

Your post omits a lot of relevant information.  The Yamaha Sub output frequency and slope is not specified in their spec sheet or in the manual, although some online say it is 100Hz, others say 90Hz.  [In the past (before digital bass management) Yamaha always had the sub out at 140Hz, 12dB/Oct].  You neglect to identify your subwoofer, except to say it has speaker wire in and out.  Some subs put an electrolytic cap in series with the speaker output affording 6dB/Oct. High Pass attenuation to the attached speakers, others don't (and whether an audiophile wants a cheap electrolytic in series is also a question).  You also don't say what your speakers are, and whether your system's subwoofer implementation up to now has been satisfactory to your taste.  Your new amp has no preamp in/out connections, so a real crossover cannot be used.  My advice is probably to continue using it as you have been, but filling in the missing details might make me revise that opinion.

I disagree with some.

1.  Bass is the bigger power user from your amp. I would plan on 200W unless subs are very efficient.  Powered subs.are fine.

Splitting the signal is fine.  I don't run full range through my mains.  IM distortion is in mains when you use them with out a sub.  Making your mains sound better with better bass is the goal.

I have an external crossover.  I adjust gain.  Crossover set at 100.  A good crossover is $600 on up.  I have Marchand and I just read about another one, can't remember the name. 

Two subs are better than one.  Mine are streo but can be summed to mono.  Multiple ones are easier to integrate.  I feel my subs and mains become invisible. 

Isolate your subs from the floor.  I used springs but there are many options.  

Thank you all for chipping in. I never realized how little I know now that I’ve acquired this integrated amp that is a bit more "stout" then anything I’ve ever owned. So my first question was yes, a little lite on info. This stuff is probably beginner level stuff. I’ve always wanted to own a system with a good solid punch. So, I found myself grabbing the yamaha integrated amp, 2 polk speakers, and a powered sub.

The amp is a Yamaha A-S701 (manual). It maintains a single RCA out for the sub. It also maintains an impedance selector.

I’m running 2 Polk Monitor XT70s (manual).

I have a 100W Sony sub with speaker in and outs, as well as a single RCA in, and an adjustable cross over dial.

My thoughts were to remove 80 or so and down from the speakers, and allowing my sub to take care of 80 and under, aprox. My understanding is that this keeps the amp from having to pull a lot of low freq weight. As well as free up the speakers for a bit more volume headroom, in order to play loudly, safely.

I’m also new to the impedance setting. The speakers specs/manual shows they run at 4ohm. I’m not perfectly sure if I’m to set to high or low on the impedance filter. I'll be simply playing 2 speakers out of A.

Thank you again. I’m excited at what appears to be a nice leap up in home audio experience. 2.0 that is.

@whitneyhengesbach

Points to consider... Your amp is very capable of powering the mid-base drivers of the main speakers no problem. 220 watts into 4 ohm. Plenty loud.

The Polk XT70’s are capable of going down to 35hz/40hz. Why buy speakers that can go this low if your not going to let them? 2-61/2" mid base drivers with 2 8" passives and then cut them off at 80hz and then hand it off to ONE weak 100 watt subwoofer?? Why do that? Huge mistake IMO. The XT70’s are very capable of adding LOTS of punch and dynamics far better than one, weak 100 watt subwoofer can.

An upgrade you might consider is splurge on a pair of better powered subs like SVS or REL and set them up in stereo and then cross them at 40hz to blend properly with your speakers.

Or...

If you don’t add new subs I’d probably set this system up using the speakers full range and leave that sub out altogether. I bet you’ll be very impressed with the bass extension of the XT70’s all on their own. 35hz IS VERY DEEP BASS! No sub needed. Especially not that sub. No offense but you’ll probably make it sound far worse by adding that sub.

Good luck!

Given the new information I agree with @gdaddy1. I would set the system up without the subwoofer running the speakers full range.

If you use the system for video also you could try the subwoofer via the RCA input when doing so. Value of this approach would depend on how low one can set the subwoofer crossover.  Set the crossover to lowest setting. You would likely find yourself sub turning the subwoofer off for music, maybe not using it at all..  

Interesting. No sub. I'll definable try that.

Any input on the Low or Hi impedance setting per these 4ohm?

After looking at this chart, I'm pretty sure it's LOW.