Monsoon S2 Dual Bay D5 Reservoir

Performance

Performance testing is done with a flow meter, differential manometer and a gate valve faucet. Resistance to flow is adjusted and flow/pressure readings are taken for the plots below. For information on how to read these, check out this guide.

The first thing to look at with this reservoir in terms of performance is to find the optimal configuration. There are two options for ports when using a single loop, and two options for o-rings. If we simplify things by just considering the D5 strong then we see the differences are small but real:

The optimum performance occurs with the red o-ring and the lower ports. However it can be seen that the performance is not far off the Laing top, which isn’t bad considering that this is dual bay reservoir that has to have sharp bends as part of the design.

If we then take this optimal setting and look at the performance with a D5 Vario and compare to the cheaper XSPC unit then it can be seen that the XSPC performs ~0.05 GPM better. A small difference considering all the other factors.

However if we compare to a high performance standalone top coupled with a cylinder reservoir the difference gets closer to 0.2GPM

Noise

Monsoon did a lot of work to isolate pump noise. The pump is mounted in a full coverage housing with foam behind the cap. Direct noise propagating from the pump is therefore minimized. In addition the exterior of the reservoir is made of softer plastic material that should dampen any vibrations. Then the mounting screws themselves isolate the noise from being transmitted to the case chassis which is often where most of the audible “pump noise” really comes from.

I strongly dislike showing this noise plot because it’s very misleading. The noise measured is isolated noise when the pump is not attached to a chassis at all. It’s purely measuring whether the pump and top itself are causing any noise. Monsoon has done a ton of work to make sure any pump vibration does not get through to the chassis. As there is no chassis and no mount therefore none of this work is reflected in these numbers at all. Having said all of this the Monsoon reservoir did have an unusual flow noise signature when running a D5 Vario at setting 5. It has the highest noise reading of any D5 top at any pump speed:

Resonance with a chassis can easily raise noise numbers by 6-12dB, and so the isolation work Monsoon have done is likely to help more than this noise bump would hurt however which is why I think this plot is misleading!

Value

The S2 reservoir retails at between $80 and $100 depending on whether it comes with a pump mount or not. This D5 version therefore is a good amount more than the XSPC version which only costs $55. However it has a ton more features that create value. In comparison to the XSPC the Monsoon has dual fill ports, dual loop capability, awesome lighting, anti-microbial silver plugs, noise isolation and a higher quality finish. I think despite the cost being 80% more than the XSPC that it’s still good value for money because of this.

Summary

The Monsoon S2 is a very well thought out reservoir with some cool features. Again there are minor niggles – performance could be a bit better and the pump noise at vario setting 5 was somewhat higher than it should be. Having said that the lighting circuit is awesome, and the work to reduce chassis vibration may help a lot more.