Liang D4 niose!!! Help!

|kbn| · 11-13-2004, 07:05 AM

Ive had a liang (DD) D4 pump for about 6 months now, and the high pitched hum is really, very annoying.

Is there ANY way atall to stop this noise? it is the one thing in my pc that is ruining the silence.

I have tryed running it at lower voltage, by putting a few 1n5401 diodes in line, but it makes hardly any difference to the niose, just lowers the pitch... and they get v hot so I cant leave it running like that, so I use 12v instead.

The pump is great in every other way..just the niose!!!

bobkoure · 11-13-2004, 08:07 AM

Does it make the same noise when running but held in your hand? If so, some of what's annoying you is being transmitted to your case, which is then working like a speaker diaphragm. If this turns out to be the case, try sitting the pump on foam.
If you are using vinyl tubing, that can be transmitting audio power as well - put your hand on the tubing and see if the noise goes down - if so, think about using something lots softer, like silicone.
I've heard (but don't know) that these pumps make a bit less noise if you sit them on their "tail", so you could try that.
The noise that comes out of a pump is not distributed evenly - and you may have pointed one of the high output "lobes" either at yourself, or, more likely, at a reflective surface, like a case wall (which is also picking up some audio energy and re-radiating it on the outside (again, like a speaker diaphragm). Try turning the pump and try lining any hard interior surfaces with sound absorptive foam (the best stuff is for lining speaker cabinets and has a "limp wall" built into it - so in cross-section it looks like two layers of foam with vinyl between). You could build a separate box for the pump - remembering that it needs some airflow.
Finally, here's an off-beat one: you could try increasing the weight of the motor housing to bring the resonant frequency down (this works like putting a capacitor in a circuit, but you're working with mechanical energy and inertia). It was very common, years ago, to fill the ends of motorcycle handlebars with lead so they wouldn't vibrate so badly - particularly Velocette handlebars which, otherwise, had a tendency to "grow" in your hands.
Finally, if the noise is still driving you crazy, you might think about the Swiftech 650 - or a new one from DD as they're supposed to be quieter now.

Ruiner · 11-13-2004, 11:06 AM

Bah. I had a muffled d4...even at 7v it whined, til it burned out its channel on my fanbus (that took about a minute).
I lined my case with roofers tape (the heavy peel and stick stuff)...still loud.

I went back to my eheim 1048 and my temps didn't change any. Reading the preview to cathar's new article makes me feel dumb for buying the D4 in the first place.

|kbn| · 11-13-2004, 05:58 PM

bobkoure thanks for that, Idont think it will help with the pump though, but Ive saved your post for future, incase have any annoying compnents that need quieting

The problem I think is inside the motor, I think cathar explained it as being caused by the square wave which powers the motor, much like cheap PWM on fan controlers. I dont know if anything can be done to quieten it except run at lower voltage...

I am tempted to get another pump and sell this, I wonder how quiet the c-systems ones are...

bobkoure · 11-13-2004, 06:04 PM

Quote:

Originally Posted by |kbn|

... caused by the square wave which powers the motor...

right. That was the point of the "weight the housing" suggestion. Increased mass should reduce the amplitude of the vibration.
I would guess that the other thing you could do is to add a capacitor to the square wave generation circuit - just like reducing PWM noise in fans. I am not the person to ask for circuit advice, though - unless you are looking for a better reason to replace the pump (i.e. dead)

|kbn| · 11-13-2004, 06:19 PM

heh

Problem with weight of the housing, the motor is encloded, much like all pumps. I suppose I could bolt on some fairly heavy pieces of steel to it. Sounds like agreat idea acctually, Ill give it a think.

Cant fiddle with the circuit

its inside the motors housing. Also adding a capacitor to PWM doesnt work, as the capacitor would just draw more current when the pulse is on, resutling in enough to keep the fan running asif there was no PWM. Maybe it would work if the cap was very small, infact that would probably be perfect, but as I cantfiddle with it

azuras · 11-14-2004, 10:49 PM

Having the same problem. Bought a "muffled" swiftech 650 with manf. date of 07/04 and the whining noise is driving me nuts. Have it mounted on the supplied foam pad, no hose vibrations. I'm ready to look for a new pump.

11-13-2004, 07:05 AM	#1
\|kbn\| Cooling Savant Join Date: Feb 2004 Location: W. Sussex, UK Posts: 329	Liang D4 niose!!! Help! Ive had a liang (DD) D4 pump for about 6 months now, and the high pitched hum is really, very annoying. Is there ANY way atall to stop this noise? it is the one thing in my pc that is ruining the silence. I have tryed running it at lower voltage, by putting a few 1n5401 diodes in line, but it makes hardly any difference to the niose, just lowers the pitch... and they get v hot so I cant leave it running like that, so I use 12v instead. The pump is great in every other way..just the niose!!! __________________ Waterblocks

11-13-2004, 05:58 PM	#4
\|kbn\| Cooling Savant Join Date: Feb 2004 Location: W. Sussex, UK Posts: 329	bobkoure thanks for that, Idont think it will help with the pump though, but Ive saved your post for future, incase have any annoying compnents that need quieting The problem I think is inside the motor, I think cathar explained it as being caused by the square wave which powers the motor, much like cheap PWM on fan controlers. I dont know if anything can be done to quieten it except run at lower voltage... I am tempted to get another pump and sell this, I wonder how quiet the c-systems ones are... __________________ Waterblocks

11-13-2004, 06:19 PM	#6
\|kbn\| Cooling Savant Join Date: Feb 2004 Location: W. Sussex, UK Posts: 329	heh Problem with weight of the housing, the motor is encloded, much like all pumps. I suppose I could bolt on some fairly heavy pieces of steel to it. Sounds like agreat idea acctually, Ill give it a think. Cant fiddle with the circuit its inside the motors housing. Also adding a capacitor to PWM doesnt work, as the capacitor would just draw more current when the pulse is on, resutling in enough to keep the fan running asif there was no PWM. Maybe it would work if the cap was very small, infact that would probably be perfect, but as I cantfiddle with it __________________ Waterblocks

11-13-2004, 08:07 AM	#2
bobkoure Cooling Savant Join Date: Feb 2003 Location: USA - Boston area Posts: 798	Does it make the same noise when running but held in your hand? If so, some of what's annoying you is being transmitted to your case, which is then working like a speaker diaphragm. If this turns out to be the case, try sitting the pump on foam. If you are using vinyl tubing, that can be transmitting audio power as well - put your hand on the tubing and see if the noise goes down - if so, think about using something lots softer, like silicone. I've heard (but don't know) that these pumps make a bit less noise if you sit them on their "tail", so you could try that. The noise that comes out of a pump is not distributed evenly - and you may have pointed one of the high output "lobes" either at yourself, or, more likely, at a reflective surface, like a case wall (which is also picking up some audio energy and re-radiating it on the outside (again, like a speaker diaphragm). Try turning the pump and try lining any hard interior surfaces with sound absorptive foam (the best stuff is for lining speaker cabinets and has a "limp wall" built into it - so in cross-section it looks like two layers of foam with vinyl between). You could build a separate box for the pump - remembering that it needs some airflow. Finally, here's an off-beat one: you could try increasing the weight of the motor housing to bring the resonant frequency down (this works like putting a capacitor in a circuit, but you're working with mechanical energy and inertia). It was very common, years ago, to fill the ends of motorcycle handlebars with lead so they wouldn't vibrate so badly - particularly Velocette handlebars which, otherwise, had a tendency to "grow" in your hands. Finally, if the noise is still driving you crazy, you might think about the Swiftech 650 - or a new one from DD as they're supposed to be quieter now.

11-13-2004, 11:06 AM	#3
Ruiner Cooling Savant Join Date: May 2003 Location: New Smyrna, FL Posts: 258	Bah. I had a muffled d4...even at 7v it whined, til it burned out its channel on my fanbus (that took about a minute). I lined my case with roofers tape (the heavy peel and stick stuff)...still loud. I went back to my eheim 1048 and my temps didn't change any. Reading the preview to cathar's new article makes me feel dumb for buying the D4 in the first place.

11-14-2004, 10:49 PM	#7
azuras Cooling Neophyte Join Date: Feb 2004 Location: Tucson AZ Posts: 1	Having the same problem. Bought a "muffled" swiftech 650 with manf. date of 07/04 and the whining noise is driving me nuts. Have it mounted on the supplied foam pad, no hose vibrations. I'm ready to look for a new pump.

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