Pump Decoupling Comparison – Metal vs. Neoprene vs. Eggcrate

Posted: March 2, 2011 in Pumps
Tags: , , ,

Welcome to a pump decoupling noise comparison test.  This test will focus on consistency using just one pump, the Swiftech MCP-35X and compare a direct metal contact (no decoupling), the factory neoprene pad, and a chunk of egg-crate.  I was also experimenting with microphone and sound level meter setup because I wasn’t very happy with my previous video results.  It seems having the microphone on the test bench was artificially introducing some vibration type noise into the audio recording and possibly into the sound level meter as well.  This time around I docked my Zoom H1 on top of my Canon T2i which is sitting on a tripod a couple of feet away.  I also place the sound level meter on some cushion to also decouple the sound meter from vibration.  I’m starting to notice that while fans generally have very little vibration, pumps obviously do to the point where the instruments can be affected by those vibrations if instrumental decoupling isn’t done as well.

Also doing a little work in YMEC software to take a more detailed look at frequency response.  Here are the three scenarios with the egg-crate decoupler as the baseline in the middle overlayed each of the other two so you can see the frequency spike differences.  While the neoprene pad helps, it’s not nearly as good as the thicker softer egg-crate foam.  The downside is that any sort of foam like this will trap heat, but this is just comparing some decoupling scenarios.  Decoupling AND cooling the pump base at the same time is a challenge.  I have heard of some people suspending pumps by tubing alone.

Here is that frequency response comparison at 100% PWM.  Zoom H1 microphone is approximately 2′ away mounted to camera on separate tripod.  This does seem to avoid any vibration induced noise on the microphone itself.  Of coarse this is tested in extreme silence to try and sort out any fine details.  Even with the microphone place a couple feet away, using software A-weighting I’m seeing upwards of 6dbA improvement using the neoprene pad over direct metal contact, and around a 12dbA improvement using the egg-crate as a decoupler.  This is fairly substantial and easily perceived difference in this silent testing environment.  No doubt that decoupling makes a noteworthy improvement to pump noise in silent environments.

A quick A-weighted frequency response comparison/overlay

And the video recording, zoom to the very end for just the 100% PWM sound clip comparison.

The pump used in this experiment was sponsored by Gabe from Swiftech.com, thanks!



  1. […] – The DDC/MCP350/355/PMP400 Pump Lift For Added Cooling With my recent noise decoupling test, many have noted that a problem with that is the DDC series pump and heat. In an effort to show a […]

  2. PepeLapiu says:

    How do you feel about leaving the pump suspended by the hoses? Can you see any problems from having the pump suspended in this manner?

    • Martinm210 says:

      It’s what I’m currently doing, but the effectiveness does depending the the tubing length and durometer. I think it also depends on the orientation of the tubing. Tubing is more likely to bend than stretch in length and vibrations are likely more oriented to the impeller rotation (about the axis), etc. Try to allow at least a few inches of tubing, the more the better to allow dampening.

      It’s a very good effective way to do it though and it avoids the whole insulation negative of using decoupling materials against the hot pump base.

      Works really good on the smaller DDC pumps, I even have my reservoir/35X pump suspended by tubing using the top down inlet..:)

      • PepeLapiu says:

        Durometer? LOL, you are a certified nerd dude! I had to google that.

        So, of all the tubing you’ve played with, which one would you say is the softest, and least likely to transmit vibrations?

        I’m using Koolance 1/2 ID tubing but it probably would be worth it to have the pumps ‘hung’ by a few inches of some softer tubing on both IN and OUT ports.

        And on behalf of all the wanna-be-puter-nerds-everywhere, thanx for the great info.

  3. Martinm210 says:

    Yeah I know…read too many tubing specs and reviews…eventually it rubs off on me I guess..LOL!

    I like the Danger Den / TFC tubing best of what I have tried. It stays nice and soft for years and holds it’s color really well too.

    I suppose a short piece of surgical type tubing would be even softer, but I have only used that for my manometer tubes.

  4. Ceadderman says:

    Great test but I have one question regarding direct metal contact. Since no case is that thick what is the actual dB rating from a thin piece of sheet and the residual vibration caused in the surrounding sheet metal? It’s going to be louder I would think but have nothing to prove this hypothesis. Could you try testing in a case that has some actual feet on it? Would very much appreciate it. 🙂

    • Martinm210 says:

      I thought about doing that, but I didn’t have a spare case to try it in. I also figure that every single case out there will be dramatically different since there is such a wide range of metal thicknesses, metal types, and bracing setups not to mention the location variable.

      I think this test is just a good starting point to show just how important mounting is on pumps, but I don’t think you can really find any one test method to fit the variety of conditions and cases out there.