Psw250 Noise! Need Help!

DONZE · November 2003

Hi, i'm a newbie of this fantastic world and i have a great problem with my new home theatre system. I hope that someone helps me to solve it!
My system is:
Amp: Yamaha rxv640 rds
4 rti 28
1 csi 30 center
1 sub psw250
I put the sub in the corner on the opposite side of the room (5x6,5 mt.). To do this i used a high quality shielded rca cable(10 mt. long), from the sub out (mono) of the amp to the sub. Then, usin a y-RCAcable i connect it to the 2 line in of the SUB.
The problem is that powerin on the sub, some deep noise comes from it and there's no way to eliminate it.If i listen to music at mid-high level volume, there's no problem, but if i keep system volume low,i can hear this deep noise and it is fastidious. The sub's level volume is set at 50%. If i higher it, the noise increases too much.
If i lower it, the noise goes away, but the subs perform not enough bass to cover the range of the room.
I've tried another shielded sub-cable, but the problem persist.
What to do?
In attach: my system' position.
Thanks very much for any suggestion!
Donze (Italy)

Tour2ma · November 2003

First, welcome to the Ciub... Always a treat when an international member joins. Will look forward to chatting, but first let's see what we can do about your issue...

The noise is almost certainly RF from power wiring. In the long run down your side wall you may well be paralleling power wiring in the wall. This is probably enough to induce a current in your long line level feed... especially considering your power supply is 220V.

Simplest thing to try is with the sub making noise, simply pull the sub cable as far from the wall as you can and see if the noise level changes. If it does, a different cable routing or sub location may be the solution.

If the above does not help, we need to hunt a ground loop issue...

Also a thought on your sub calibration. Somewhere around 11:00 position is normal for subs, so your 50% is already pretty high and you menion going higher... Have you calibrated your system using a test disc and an SPL meter?

Chiao....

DONZE · November 2003

Thank You very much for replying (and for your welcome). For what you say, the problem may be the paralleling way of the line cable and the power cable to the sub. This is not my case, because the sub is powered from the wall directly on its back, while the line cable comes from the other side of the room. I've also tried (for experimentation) to let the line cable free to cross the room directly (not paralleling the wall), but the noise persist!(oh damn!!!!!!). What can i do?

- About the sub level, i agree that a 11:00 position is normal (and would lower considerably the deep noise), but it isn't enough to garuantee a good room coverage of the bass!
The amp's speaker level configuration is set in this way:
Front speakers: -8db (range: - 20 to 0)
center speaker: -7db (-10 to 0)
rear spkeakers: 0db (-10 to +10)
subwoofer: 0db (-10 to 0)
as you can see, i've configured the output level of the sub out at maximum (0db),keeping lower level of the other speakers, in the way to let psw250 perform at maximum of its capacities, but the minimum position of the sub level that let me appreciate good bass coverage is still at 50% (12-13.00)! (crossover at 100hz - fase switched to "rev").

- Unfortunately i haven't a SPL meter....sigh!
Thanks very much for advice.
Ciao!

Tour2ma · November 2003

Donze,

First... I can't believe I mispelled "ciao"... :rolleyes:

Sorry, I was not referring to the power cord to the sub.The AC power wiring I was concerned about may be in or on the wall. I know that often in Europe home wiring is in conduit run along the baseboards. Try pulling the middle of the Sub cable away from the wall.

Ciao

DONZE · November 2003

dear tour2ma,..dont'worry for your wrong "ciao"!
as i said, i've yet tried to pull the line cable away from the wall, but it seems that nothin' changes..
maybe a 10mt cable is too long for a sub connection?
Do ya think is the case to try putting the sub near the amp (at the right side, see my map in the first post)? By doing this i would use a 2mt only long line cable.. perhaps i would obtain a slighty decrease of the noise...?!
-my apprehension is that doing in this way,(that is)placing the sub in front-right of the listener position (and not in a corner) i would lose too much bass response from the sub, forcing me to upper the sub's volume level higher more (approx. at 75%..)..
....what a maze....ohi ohi....

Tour2ma · November 2003

Next I would try moving the sub, or at least the source of its power...

If you have a wall outlet in the room that is in a different house circuit than the outlet into which the sub is currently plugged, that would be ideal. If you do not, perhaps you have a heavy extension cord you could run from another room, if need be... just for testing.

Appliances, fluorescent lighting, and other household items on the same circuit as audio gear can contribute noise. Sometimes just having amps and other audio components on the same circuit causes issues through the ground wiring.

Hope this helps...

DONZE · November 2003

ok, i'll try and then let you know...let's hope!
Thanks VERY MUCH!

PolkThug · November 2003

Hello Donze,

There is one piece of cable you can get rid of. You don't need a y-splitter going into the sub. Just plug your cable into the left or right input, and you will have the same outcome.

Regards,
PolkThug

dorokusai · November 2003

I believe that Dr. Spec mentioned that the Y-splitter adds 3db gain to the signal, which is a good thing. Can anyone confirm that?

Tour2ma · November 2003

yup... adds 3 dB.

rs159 · November 2003

So does turning up the volume....

rs159 · November 2003

Also, can I ask why you care if the whole room is getting bass?

There are things called standing waves that make bass response wildly variable throughout the room.

In my experience, the least bass is usually in the center of the room.

If you listen only where you drew the sofa, then place sub where the best sound is in that position. Forget about the rest of the room.

DONZE · November 2003

Right, sorry for my bad english. What i ment (bass coverage of the room) to say, was that while sittin' on the sofa, i can hear well defined bass (as you can see i like very much them...i play bass guitar in my band..!),i don't care about the situation in the opposite side of the room.
Makin some different placing experiment,i realized that the place on the corner at the right of the hearing position, is the best performing for the sub,but the noise is present usin low level of the Amp.

Instead..i discovered that movin the sub away from the corner (and the wall), and placing it for example near the sofa (at its right side), the noise noticeably DECREASEs!
...but even the sub's performance isn't the same..sigh! bass are less deep and defined.
What to do?

Please don't tell me that i've chosen the wrong sub...i'm startin' to think in this way...oh no!!!!

Tour2ma · November 2003

Donze,
Your english is fine...

I think the decrease in noise and performance as you move out of the corner are unrelated. The performance decline is understandable as in most rooms the maximum room gain is found in the corners.

Something near that corner, possibly even on the opposite side of the walls, is generating RF that the sub's amp is picking up.

DONZE · November 2003

Ok, i decided to re-try many different positions and find the best compromise...
My wife (i'm just married...3month ago!) isn't really happy to see the living room continuosly "on testing" with cable and speakers everywhere....
...but i think this is a PRIMARY step in the set-up of the living room's furniture...(instead of thinking at paintings, tables an so on...uff!).Do ya think so???
Thanks to all, you fantastic guys, see you again in this pages!
Ciao.
Donze

Dr. Spec · November 2003

Originally posted by rs159
So does turning up the volume....

More accurately, your response should have read: So does turning up the 'subwoofer level control'.

A Y splitter does indeed double the voltage input to the sub, which in turn provides a 3 dB increase in sub level, all other things being equal.

The only thing a Y splitter is good for is keeping a "sleepy" sub "awake" if you have a lazy auto-on circuit that tends to shut off the sub during extended quiet passages.

"Chiao...."

BOTTLEDZ28 · February 2005

bringing this post back from the dead...... search feature sure does work. I had a question posted in the hookups dept petaining to this Y splitter thing. I have the PSW250 and I use a Y splitter from my SUB OUT to the L and R inputs on the sub. I DO NOT HAVE MY MAINS HOOKED UP TO THE SUB!!! Is this bad? I ask because the manual stated I should be hooking my mains up to the back of the sub. whats the deal here.

Psw250 Noise! Need Help!

Comments