How do I reverse the phase of my sub on the LSi15's?

Hyper_Lite83

An audio review mentioned reversing the phase of your sub on the LSi15 will improve the bass, but I have no idea how to do it.

Can someone shed a little light on this please?

ShinAce

Try the sub amp. Look for a knob or switch marked 'phase' or 'polarity'.

Have fun and remember where the switch was when you started, just in case you don't like the cahnges.

Face

I wouldn't advise it, but you can pull the driver and just switch the + and - cables on the woofer.

Do you have a link for this review?

Face

ShinAce wrote: »

Try the sub amp. Look for a knob or switch marked 'phase' or 'polarity'.

Have fun and remember where the switch was when you started, just in case you don't like the cahnges.

15's don't have a powered sub, the 25's do though.

Hyper_Lite83

The LSi15's have a passive subwoofer so there is no built in amp.

Here is the review:




I'd like to provide a detailed review once these speakers break in properly, but first I'd like to provide the following warning:

***IMPORTANT*** If you are using these speakers in a 5.1 or 7.1 system with a subwoofer, and notice weak bass, REVERSE THE PHASE OF YOUR SUBWOOFER.

When I had them playing in stereo mode along with my my subwoofer, the bass sounded very weak. There was no bottom and I couldn't understand it. I was so dissapointed with the sound I almost boxed them up and sent them back. Luckily, while I was tweaking, I tried reversing the phase of my sub and WOW what a difference. I was so relieved. Why? you ask.

My best guess is the woofers of the LSi15's are designed to fire inward and force the pressure wave into the enclosure and out the port at the bottom. This is reverse of most speakers that fire outward. The reversed waves of the speakers cancel out the positive waves of the sub and vica versa. It's the same concept used by noise-canceling headphones. Result: it's like someone turned off the bass.

Anyway, try it and your bass will come back. You'll be glad you did.

Strengths:
Clean. Clean. Clean! These speakers will astonish you! The closest thing I've heard to these was easily quadruple the price...and these sound better! Ghost notes on the snare come out. You can hear the vocalist breathing and fingers moving on the strings. Distorted guitar passages gain structure. You'll hear your favorite music like you've never heard it before. It's like someone took the cotton out of my ears.

They are beautiful. The finish is a deep black piano laquer. The cherry wood side panels are warm and well finished. The speakers look, feel, and sound very expensive. I cannot begin to express the value presented by these speakers.

Weaknesses:
These are nit-picks. For this price, you really can't complain.

1. The grilles are unneccesary. They extend the full height of the tower and the drivers only occupy the top 1/3rd.

2. The manual mentions nothing about reversing the phase of your sub.

3. The very bottom end is a bit weak without a subwoofer. Easily cured.

tcrossma

I'm pretty sure that review was talking about reversing the phase of their stand-alone subwoofer; not the woofer in the LSi15 itself.

Most subwoofers have a phase switch or dial, and if set out of phase with the pretty good bass the LSi15's put out they could cancel each other. Assuming you have a separate subwoofer I'd recommend just experimenting with your subwoofer placement and phase dial until you get the sound you like.

jakelm

Sounds like they are infact talking about the 15's.

This what you can try. I believe the 15's have seperate post for the sub. So, at the binding post, hook your reciever/amp in a normal fasion, then unhook the subs post, as you would do for bi-amping, and run a wire from the +tive post of the main speakers to the -tive post of the sub. Do the same with the other. This will reverse the polarity of the sub compared to the rest of the speaker.

I do not own a pair of 15's, so I apologize if am wrong in this, please chime in.

dorokusai

Do what Face said.

tcrossma

When I had them playing in stereo mode along with my my subwoofer, the bass sounded very weak. There was no bottom and I couldn't understand it. I was so dissapointed with the sound I almost boxed them up and sent them back. Luckily, while I was tweaking, I tried reversing the phase of my sub and WOW what a difference. I was so relieved.

"Playing in stereo mode along with my subwoofer" and "I tried reversing the phase of my sub".

Doesn't this just sound like changing the phase of his subwoofer, and nothing at all to do with opening up the speakers and trying a hack noone's even considered up until this point??

reeltrouble1

His result has nothing to do with the room you use your speakers in.

Do what Face Man said but dont be suprised if you do not hear any difference.

RT1

bbeacham

jakelm wrote: »

Sounds like they are infact talking about the 15's.

No, it does not sound as if they are talking about the LSi15s.

"I tried reversing the phase of my sub and WOW what a difference"

Sami

bbeacham wrote: »

No, it does not sound as if they are talking about the LSi15s.

Yes, he is definitely talking about reversing the phase on his subwoofer, not on the speakers. Reversing phase on your speaker woofer, well, just doesn't make any sense does it?

Ron Temple

Yes, it's the sub phase not the 15s and it's totally dependent on where his sub is placed in the room. Wouldn't work for everybody. It's just another thing to try to get the most out of your system.

Face

Ron Temple wrote: »

Yes, it's the sub phase not the 15s and it's totally dependent on where his sub is placed in the room. Wouldn't work for everybody. It's just another thing to try to get the most out of your system.

This is correct, he is talking about a separate sub and it heavily depends on your room, etc...

My old school Tannoys are out of phase from my newer Tannoy's, so when trying to integrate a sub with the old Tannoy's, I had to reverse the phase on my sub. For HT, I use a combination of old and new Tannoys. I had to reverse the + and - on my center because it was out of phase from my mains and sounded VERY strange, almost trippy.

unc2701

My best guess is the woofers of the LSi15's are designed to fire inward and force the pressure wave into the enclosure and out the port at the bottom. This is reverse of most speakers that fire outward. The reversed waves of the speakers cancel out the positive waves of the sub and vica versa. It's the same concept used by noise-canceling headphones. Result: it's like someone turned off the bass.

This guy has no idea what the hell he's talking about.

jakelm

The polarity of the sub on the LSi15's are probably reversed due to the opposite side fireing config. They probably work great without a sub. Reversing polarity of an external sub does make some sense.

Just try it and see. Let us know what happens.

unc2701

The polarity of the sub on the LSi15's is in the phase that it's in due to it being wired to the crossover of the LSi15, which is in turn wired to the REST of the LSi15. The Polk engineers did it that way for a reason- to get the best bass response in the crossover region from the mids to the sub. The original review was not talking about flipping the phase on the sub driver in the LSi15, nor would this be a good idea.

Flipping the phase on an external sub may very well improve bass response, depending on the room, placement and crossover point. This topic has been covered extensively elsewhere.

I would NOT recommend flipping the phase on the sub driver for the LSi15- but I'd love to see Ken S's response to that idea.

clubvikram

well, it is...and it isn't. I've had several discussions on here with some people, and without getting too deep into the physics of it all ('cause I hardly understand it myself), the switch does do a phase shift as well. It's just not in the same "time" domain that we're so used to when talking about two distant mics. But in the rest of the physics world it does. I can probably hunt down the link of the convo we had awhile back if you want.

but drummerboy for your questions, Harvey's right. It takes the parts of the wave form that goes up and makes them go down instead. And vice versa for the part of the wave that goes downwards. It can help in situations where gear may have been improperly wired (although very few people may actually realize this just by hearing it), but more importantly it may help correct where you have phase problems with your signal. This can happen anytime you use two microphones on a source. For example, using a top and bottom microphone on a snare. Using the phase/polarity button helps you listen to a quick fix of how the two sounds appear when they are played back together. Sometimes it helps, sometimes it doesn't.