woofer phase

sucks2beme

I had a problem where after changing speakers in my two channel rig, I couldn't get the woofer to sound in sync.
I'm going from a preamp into the sub, then back out to the power amp and speakers. The bass sounded quite mushy. Setting the woofer to a higher pass-thru setting helped a bit. I tryed both 0 and 180 settings. Finally, I pulled the sub out of the circuit, and
the sound is great. I will most likely not need the sub(the Paradigm 11se's have 10" drivers) but was wondering if others had problems with this. I suspect that if my sub was ajustable instead of just 0 and 180, it would of worked ok .

MaxxuM

The phase problem may be due to your mains playing into the subs domain. Are you using bass management? If not try doing so cutting off your mains at 40-60Hz and your subwoofer to roughly the same point and see if your phase problem goes away. I have a feeling it will.

sucks2beme

With 2 channel, the signal path was from the pre-amp through the sub via rca interconnects, then back out to the power amp.
This arrangement worked ok before with a different set of speakers. The sub in this arrangement controlled what was passed on to the power amp. The sub blended in transparently with the tower speakers for music. The description of the current
speakers states" The speakers are electrically time aligned".
I suspect this feature is throwing off the phase somewhat.
Some subs have a varible phase instead of 0'/180'. I think this style of plate amp would of worked. The current speakers have enough grunt to do music without a sub. I am still thinking of building a 12" sealed enclosure sub with a variable phase plate amp with some serious power. This is rig is music only. Fast and accurate is the name of the game.

RuSsMaN

Don't make me come over there and set that **** up for you.

So which Canadian speaker do you like best?

dorokusai

Originally posted by MaxxuM
The phase problem may be due to your mains playing into the subs domain. Are you using bass management? If not try doing so cutting off your mains at 40-60Hz and your subwoofer to roughly the same point and see if your phase problem goes away. I have a feeling it will.

Why would you cut your subwoofer AND your AVR?

MaxxuM

Originally posted by dorokusai
Why would you cut your subwoofer AND your AVR?

Hi-pass with the main speakers (on AVR) and Lo-pass on the sub; the new sub may be adding too much bass (dB) which can cause phase problems. If he is using a splitter with a photo jack then it may be adding a premature +3dB too (which I forgot to mention) – so another thing he can try (if it is setup this way) is to just hook up to the left input. This seems to be a sub problem; so just start with freq and dB and go from there.

dorokusai

Negative. You should never double filter.

You mentioned the subwoofer may be causing phase problems....why would it do that exactly? Why would you say it's a phase issue as opposed to a subwoofer volume issue? Have you heard of room gain?

The subwoofer input is the same unless you add a splitter, and that can be manufacturer dependent.

You should never use a subwoofer with a phono, or "photo" output, period. Where did that even come from exactly? The thread starter didn't mention it to my knowledge....

In order to incorporate a subwoofer best, in a 2CH, you can't use line level inputs in most cases. The "most case" scenario being that most non-5.1 pre-amps don't care about a subwoofer, and it's dependent on another set of outputs.

I use an outboard subwoofer, via secondary outputs from my pre-amp. The blend is perfect, BUT I BARELY have the subwoofer turned up, one click....just enough to round everything out.

RuSsMaN

Whats a photo jack?

I was with ya right up to that point.

Seriously, even if he was overloading at a certain freq, or had overlap - it wouldn't matter unless either the mains (in either setup) or the sub (amp) was inverting phase.

I doubt either set of speakers is in absolute phase (both 8ohm nominal), but a 0/180 flip should make short order of most phase issues with adding a sub into the mix.

Try inverting speaker phase, regardless of what the sub 'says' the phase is set at. We don't care if the woofers move in or out first, as long as they both do the same thing.

Cheers,
Russ

sucks2beme

The Preamp L & R out goes to the sub low level line in. The sub low level line out L& R go to the power amp line in. The docs for the sub say the low level line out will be cut off at freq. below the sub xover setting. So the signals sent to the power amp should be above 80-150 htz.(per the knob setting ). The only issue at that point is if the sub is in phase with the speaker. If it truly works like documented, then the phase switch should be the only
variable. The sub worked with the Polk RTI6's and PSB's just fine.
The Paradigm was a different story. At this point, it doesn't matter
The Paradigm's sound great without a sub.

Russ, the Paradigm's are definately keepers! I'm gonna have to have a speaker clearance sale to get my closet cleared out.

MaxxuM

Originally posted by dorokusai
Negative. You should never double filter.

You mentioned the subwoofer may be causing phase problems....why would it do that exactly? Why would you say it's a phase issue as opposed to a subwoofer volume issue? Have you heard of room gain?

The subwoofer input is the same unless you add a splitter, and that can be manufacturer dependent.

You should never use a subwoofer with a phono, or "photo" output, period. Where did that even come from exactly? The thread starter didn't mention it to my knowledge....

In order to incorporate a subwoofer best, in a 2CH, you can't use line level inputs in most cases. The "most case" scenario being that most non-5.1 pre-amps don't care about a subwoofer, and it's dependent on another set of outputs.

I use an outboard subwoofer, via secondary outputs from my pre-amp. The blend is perfect, BUT I BARELY have the subwoofer turned up, one click....just enough to round everything out.

My concern was looking for the problem before looking for the solution(s) – and I was not saying he should double filter. I didn’t know how exactly he was wired so I was just adding another option. And yes, I know this is a two channel situation but these days with the advent of .1 there are a growing number of sub users now which logically will begin to intrude or mesh with surround sound techniques and pitfalls. I was also assuming the user knew the difference between electrical phase and acoustical phase and it was the latter I was speaking off. I’m sure he can see if his speakers are wired right so I never thought to mention it.


And I’m sorry, I’ll try harder not to make any more typos… Geezzzzz.

MaxxuM

Originally posted by sucks2beme
The Preamp L & R out goes to the sub low level line in. The sub low level line out L& R go to the power amp line in. The docs for the sub say the low level line out will be cut off at freq. below the sub xover setting. So the signals sent to the power amp should be above 80-150 htz.(per the knob setting ). The only issue at that point is if the sub is in phase with the speaker. If it truly works like documented, then the phase switch should be the only
variable. The sub worked with the Polk RTI6's and PSB's just fine.
The Paradigm was a different story. At this point, it doesn't matter
The Paradigm's sound great without a sub.

Russ, the Paradigm's are definately keepers! I'm gonna have to have a speaker clearance sale to get my closet cleared out.

By your post I assumed you think you are having an acoustical phase problem (mushy sound) and I agree. You’ve added a lot more bass to your system I’m guessing (w/o looking up the speaker stats) so you may be having spikes or dips in your freq ranges that your ears are picking up as ‘mushy’ sound. Switching the phase helping led me to think that btw since I am assuming all your wires and electronics are working fine. If you take a testing cd like Rives and do tone tests from say 20Hz to 120Hz you might find that where the new speakers and sub mesh (or cross slopes) is where your problem my be (the mushyness). If in fact a problem in this region and it is in fact causing your problem you can try by fiddling with the distance setup in the receiver to see if it helps (w/ sub). I know all receivers do not have this function so you might also use an EQ or changing the placing of your sub too (but after using the test cd).

As doro also mentioned or prodded, room gain could be an issue – but again, I do not think it is mere volume (dB) is the issue – more, it is the actual frequencies below or at 120Hz this is causing the problem along with placement and acoustics.

Heck, I may be completely off on it being acoustical phasing, but still, using the test cd will result in a flatter better response level and I’m sure you can appreciate that.

sucks2beme

It's a Nad 917 tuner/preamp. There is no distance setting for front speakers. That's part of the problem trying to run a sub with this system. There's a limited number of setup options. With a HT receiver, you have a lot of tweaks available. The Nad does have a
sub out, but it still sends the full output to the speakers. The result is a lot of bass. There is just not enough adjustment with this sub/preamp combo to set the sub frequency low enough or adjust around the problem. The best fix is to lose the sub, and keep things simple. Thanks everyone for your imput.

MaxxuM

Sorry... and NP