DIY Fan Mod for a Quieter Yamaha PX Series Amplifier

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Intro

The recent addition of my Yamaha PX series amplifier to my AV rack has brought an unexpected challenge, noise. This is due to the two chassis fans. Positioned just 3 meters (9ft) behind my sitting area, the constant hum and whir of the fans have become noticeable and distracting when watching content, even with the rack’s doors closed. Relocating the rack to another room is not an option for me, so I needed a creative solution to tackle this noise issue.

Is This Even Possible?

Replacing the fans with quieter ones should be a straightforward task, but it depends on how Yamaha has integrated the existing fans into the amplifiers. Although fan modifications are common for other amplifiers, I could not find any instances of this being done with the PX series during my research. So, it was time to open one up and see if it was possible for these amps.

To my surprise, the designers of the PX series made this a semi user-friendly process. Upon opening the chassis, I found the left fan easily accessible, screwed into the side of the case, and connected with a 3-pin JST connector. The right fan is a bit trickier to see in the image as it is located beneath the air shroud that funnels air over the components. However, it is mounted and wired the same way as the left side. The air shroud will just need to be removed and replaced.

I also noticed that the fans were screwed in from the inside of the chassis, and there appeared to be little room to fit a screwdriver to remove the screws. This is likely because the fans were one of the first components installed in the box. This means it will be a little harder to get the screws out, but it is not a showstopper.

Now that I know it is possible, it is time to decide which fans I will use to replace the stock ones.

What Fans?

Luckily, I already knew which company I would choose for fans if this were possible: Noctua. Noctua makes some of the best and quietest performing fans in the electronics space. They are most well-known for their CPU coolers, which also utilize their discreet fans, but they also sell fans for all kinds of electronic uses.

After a bit of research and reading some forum posts about people doing similar things to other amps, I chose to go with the Noctua NF-R8 redux-1800 High Performance Cooling Fan. Although not the quietest fan they make in this size, it is the closest one that matches the original airflow of 69 m³/h. The new fan is a little bit lower at 53.3 m³/h, but it should be close enough to not cause concern. However, the main benefit of the Noctua fan is that it is 17 dB quieter, which means that it is subjectively less than half as loud as the stock fans.

One downside is that the Noctua fans use a different 3-pin connector than what Yamaha uses for their stock fans. This is not a showstopper either, but it does make the process a little more complicated, as the Noctua fans will have to be converted to match the pinout and style of the Yamaha fan output.

Replacing the Fans

Procedure:

Step 1: Disassembly

1. Remove the handle
2. Remove the top cover

Step 2: Remove the Air Shroud

If your unit has a large air shroud then it is time to remove it. Note: different versions of the PX series have different air shrouds, so yours may look different than the pictures and may have to be taken out in a different order.

1. Remove ribbon cable from air shroud
2. Carefully pop out plastic rivets from top of air shroud
3. Remove shroud (you will put it back in after the new fans are installed)

Step 3: Remove Sheet Metal Divider

To make removing the left fan easier, it is advised to remove one more piece: the metal divider on the left side of the case.

• Cut the wire tie from the round ferrule near the back
• Unplug the 2-wire bundle that is attached to the divider
• Unscrew the 5 screws that hold in the divider

Step 4: Removing Stock Fans

Now it is time to remove the original fans from the case.

• Unplug the fan wires from the board
• Unscrew the 4 screws per fan
  • If you cannot fit a screwdriver in the space, you can use pliers to slowly rotate the screws out.

Step 5: Remove the Front Plate

Remove the front plate if you plan on using the rubber screws, as you will need to get behind the front plate.

1. Remove the menu selector knob from the front
2. Remove the 7 screws holding in the front plate

Step 6: Rewiring the Fans

The easiest way I found to accomplish this is to remove the connector from the end of the Noctua fan, then solder the JST extender cables to the wires of the Noctua fan.

1. Remove connector from the end of the Noctua Fan
2. Cut back black wire on the JST cable extension (it is not needed as the PX series only runs off 2 wires)
3. Solder the Noctua Fan to the JST cable extensions
   • Red Noctua → Yellow JST
   • Black Noctua → Red JST
   • Yellow Noctua → Cover

Step 7: Mounting New Fans

Now it is time to install the new fans into the chassis.

1. Using either the original screws or the rubber screws, mount the new fans into their original positions
   • If using the rubber screws, make sure you trim them back after to ensure they do not interfere with anything inside the chassis or the front plate.
2. Plug the newly made wires into the correct spot on the board: left fan to the left side and right fan to the right side
3. Cable manage the remaining wires so they are not in the direct path of airflow and are not resting on any major components
4. Reinstall sheet metal divider back into the case (make sure that you resecure any wire bundle that was wire tied)

Step 8: Replace Air Shroud

1. Reattach the air shroud, making sure that all attachment points are in their original locations
   • Note: Different versions of the PX series have different air shrouds, so yours may look different than the pictures.
2. Route the ribbon cable back through the shroud

Step 9: Finishing Up

Reinstall the top cover and handle. Before installing the unit back into the rack, power it on and ensure that the fans turn on. They should activate about 10 seconds after powering on.

After ensuring that the fans do in fact work, everything should be good to go to enjoy quiet operation.

Results

Note the image on the right does not have the air shroud put back on so that the right fan can be seen.

In Action

Now it is time to see if this was really worth it. Did I actually help my situation or not? I wired the amps back into my rack and turned them on. The first thing I noticed was the lack of noise. Yes, success! Even with my rack doors open, I could no longer hear the fans, and they are now below the natural noise floor of my room.

Was it Worth it?

Since I do not have the ability to put my rack in another room, I need to keep it as quiet as possible to not raise the noise floor of my theater. Doing this fan modification, allowed me to take very audible fans and make them dead silent. For me, the joy of not hearing the fans anymore is well worth the couple of hours and $30 per amp spent on upgrading the fans.

Thank you for reading. If you are into home theater, do not forget to check out our Display and Audio Calibration Guides to maximize your experience.