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Discussion Starter · #1 ·
Hi all,

I recently bought a Yamaha R-S700 receiver to use with a set of PSB Image B5 speakers that I had been using with a 2ch TV setup. The PSB's are better than the speakers I current have in the listening room but don't have much for lows so I wanted to get a sub.

If the Yamaha manual says that the sub out starts attenuating at 90hz and the speakers don't dig deeper than 50hz, am I dealing with an overlap or a gap when the sub's LPF is set at 50?

Basically, is a sub a good option with these speakers? The listening environment is set up well for bookshelves and a sub and I don't really have space for towers. My plan is to eventually upgrade the bookshelves and move these back to the TV.

If it does make sense, does it also make sense to bi-wire the speakers? I want the fullest sound possible, but I've read the benefit can be negligible.

Any info or links would be much appreciated. I'm sure this one gets asked a lot, but I'm having a hard time figuring out how the sub works with a hard cutoff at 90. Thanks!
 

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First of all, the benefits of bi-wiring aren't negligible, they're non-existent. ;)

I'm a bit confused by your sub comments - what sub are you getting that only goes to 90hz, and why would you set the LPF at 50hz??

Typically, a sub can reach much higher than 90hz, and your LPF would be set (in the AVR) at 120hz. If your bookshelves can reach down to 50hz, you would be more than fine using the standard crossover of 80hz.
 

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Set the subs low-pass filter to something in the 80 - 100 Hz range, not 50 as you seem to suggest.
 

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StVitus said:
If the Yamaha manual says that the sub out starts attenuating at 90hz and the speakers don't dig deeper than 50hz, am I dealing with an overlap or a gap when the sub's LPF is set at 50?
You're looking at a gap. Set the LPF on the sub to ~90Hz.

--Edit--
I can't find anything in the manual about the receiver having an LPF, and according to this HomeTheaterHiFi review the sub out is likely full range. In which case, simply adjust the LPF on the sub until you get the best blending with the mains.

Basically, is a sub a good option with these speakers? The listening environment is set up well for bookshelves and a sub ...
I would say 'yes'. :)

... does it also make sense to bi-wire the speakers?
No, but it also costs next to nothing to experiment. If bi-wire sounds better, go with it; otherwise, don't.
 

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Discussion Starter · #5 ·
Thanks all for the insight.

I'm a bit confused by your sub comments - what sub are you getting that only goes to 90hz, and why would you set the LPF at 50hz??
I was sort of fishing for an understanding of the LPF. I was just looking at the matching PSB 10" that runs from 50 to at least 120. So you're saying that if the receiver begins passing signals at 90hz, there's no point in setting it lower than 80-90? I thought that was the case, but was entirely unsure about it.

I can't find anything in the manual about the receiver having an LPF, and according to this HomeTheaterHiFi review the sub out is likely full range. In which case, simply adjust the LPF on the sub until you get the best blending with the mains.
The manual is partly the source of my confusion. The physical copy out of the box has the following (and only the following) regarding the Sub out. "The Subwoofer OUT Jack attenuates signals over 90hz." I had actually read the review you linked in my earlier research and the review and the line in the manual were what led me to believe it was fixed at 90 (even though the guy says its probably full range. duh). After you mentioned this, I downloaded the version currently at the Yamaha site and it doesn't have that line. I also found this FAQ (LFE/Small/large speaker settings) there that looks like it might be semi-helpful. Not as helpful as you all have been :). I think I'm probably on the right track now.

Thanks again
 

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A couple of quick notes:

- That FAQ appears to be for A/V receivers, not for your stereo receiver. IIRC (I had only a quick look at the manual yesterday), the option of a LARGE/SMALL setting for your speakers does not apply.

- *If* it did and if you set your speakers to "SMALL" and if the crossover in the receiver was fixed at 90Hz, setting the LPF on the sub to 50Hz would result in a frequency gap between the speakers (playing down to 90Hz) and the sub (play up to 50Hz).

- So - again, IIRC - it appears that your speakers will always run full-range. In which case their output will trail off naturally as the frequency decreases. So if they do play down to ~50Hz:
a) set your sub's LPF to ~50Hz for starters and see how that sounds; then,
b) try different (higher) LPF settings and see how they sound; and, finally,
c) go with the setting that sounds best to you.

- As for the sub out on the receiver, it's now irrelevant whether or not it runs full-range or has an LPF fixed at 90Hz, given that:
a) you're going to be blending your sub to your full-range mains using the LPF on the sub; and
b) you're likely not going to set it as high as 90Hz anyway.
 

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Discussion Starter · #7 ·
A couple of quick notes:

- That FAQ appears to be for A/V receivers, not for your stereo receiver. IIRC (I had only a quick look at the manual yesterday), the option of a LARGE/SMALL setting for your speakers does not apply.

- *If* it did and if you set your speakers to "SMALL" and if the crossover in the receiver was fixed at 90Hz, setting the LPF on the sub to 50Hz would result in a frequency gap between the speakers (playing down to 90Hz) and the sub (play up to 50Hz).

- So - again, IIRC - it appears that your speakers will always run full-range. In which case their output will trail off naturally as the frequency decreases. So if they do play down to ~50Hz:
a) set your sub's LPF to ~50Hz for starters and see how that sounds; then,
b) try different (higher) LPF settings and see how they sound; and, finally,
c) go with the setting that sounds best to you.

- As for the sub out on the receiver, it's now irrelevant whether or not it runs full-range or has an LPF fixed at 90Hz, given that:
a) you're going to be blending your sub to your full-range mains using the LPF on the sub; and
b) you're likely not going to set it as high as 90Hz anyway.
Thanks again Eljay. I just need to get hands on with the equipment because I'm still pretty lost.

To try and wrap my head around it; Hypothetically, when I start the sub at ~50Hz, will it be getting too much signal or not enough?
 

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Think of it this way (if it helps):
- Let's say the receiver sends 20Hz - 20kHz signals to both the speakers and to the sub (via their respective outputs / connections).


- Your speakers start off quiet at the very highest frequencies, adequately play all the frequencies from, say, 15kHz down to ~50Hz, getting progressively quieter as the frequency decreases.


- Your sub starts off quiet at the very lowest frequencies, adequately plays all the frequencies from, say, 20 or 25Hz up to whatever you set its LPF* to, getting progressively quieter as the frequency increases.


(*If it helps, you can think of a low-pass filter as a high-cut filter. You use it to determine which range of frequencies you want to pass to the sub (say, ~50Hz and below) and which range you want cut from the sub / not have it play (say, ~50Hz and above).)


- If you set the sub's LPF to ~50Hz, it will "roll off" above ~50Hz. Meanwhile, your speakers will roll off below ~50Hz. There may be enough "overlap" at ~50Hz so that the overall frequency response (FR) remains flat across that point, but there may not and you may get a "null" or dip in the FR at around that point.


- If you set your LPF to ~60Hz, the speakers will still roll off at ~50Hz but now the sub will play "more strongly" up until ~60Hz before it starts rolling off. This gives you better overlap and reduces the likelihood of a null/dip.


- Try with 70Hz and 80Hz and see if the overall sound is any better. (Google for test tone sweeps, download one that cover the 20Hz-20kHz range and play it. If the sound level remains fairly consistent throughout the sweep - and through the point where your sub blends with your mains - you're good to go.)
 
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