Front or rear ported monitors in very small room...

[Palladium]

Not very much though. Rule of thumb is about 1 port diameter worth of distance, so generally no more than a few inches.

My Diamond 12.2 manual recommends at least a massive distance of...50mm from the wall.

 

[MMoodyB]

Here's the graph showing a 3 run pass average for both of book stands+foam vs foam.

Light blue is book stands+foam, and red'ish is foam only.

 

[james57]

My Diamond 12.2 manual recommends at least a massive distance of...50mm from the wall.

Wall distance is an interesting topic and should be seen two ways, ie the cone effect of the 90 deg walls and the impact of the wall on the port for either the excursion or the return of the driver. Wall effect will boost your bass by providing a natural gain and usually can be corrected by eq or provide a desirable effect depending on you case or taste. Impact on the port should be very small as long as you don’t stick it. The port act both ways, air speed act two ways in very different ways. Vacuum speed is usually a tenth of nominal at a distance of the diameter of the port. Exiting speed is on the other hand a tenth at ten times the diameter. So as long as you are at a few port diameter from wall the breath argument does not hold. Personally I am way more concerned about the wall boost but I am no expert just my 2 ct. I wouldn’t worry about front, rear or even base ported.

 

[Thomas_A]

There are speakers designed to be near wall for bass boost. With respect to port distance, it seems to be a lot of speculation of large distances to make the speaker "breathe". It is not so. Genelec recommends min 5 cm.

 

[james57]

There are speakers designed to be near wall for bass boost. With respect to port distance, it seems to be a lot of speculation of large distances to make the speaker "breathe". It is not so. Genelec recommends min 5 cm.

Yes but they are generally design for zero boost, ie flat and provide some kind of attenuation -10db if they are stuck to the wall. Design by assuming you would always have it would be a questionable approach.

 

[Thomas_A]

Yes but they are generally design for zero boost, ie flat and provide some kind of attenuation -10db if they are stuck to the wall. Design by assuming you would always have it would be a questionable approach.

I don't think it a questionable approach as long as it is stated by the manufacturer how the speaker is going to be used. I know several that specifies speaker placement. Genelec, actives, have options for adjusting bass for placement. Passives don't generally, and may thus be designed for one or the other, near-wall or off-wall.