[Bill310]

We are moving and I am having a wooden rack constructed to hold the gear at the new house.

The rack will be open on all 4 sides and the shelves will be  2" thick hardwood

How much air space should there be around  pair of Bryston 7 ST mono blocks?

I figure once that once I get the spacing set for the Amps everything else will fall into place.

Thanks in advance

[James Tanner]

We are moving and I am having a wooden rack constructed to hold the gear at the new house.

The rack will be open on all 4 sides and the shelves will be  2" thick hardwood

How much air space should there be around  pair of Bryston 7 ST mono blocks?

I figure once that once I get the spacing set for the Amps everything else will fall into place.

Thanks in advance

Hi Bill

Generally 1 rack-space  (1 3/4 inches) will be sufficient.

james

[Bill310]

Thanks James.

[srb]

Generally 1 rack-space  (1 3/4 inches) will be sufficient.

Does the current model 7BSST² amplifier differ from the 7BST in that regard?

The manual for the 7BSST² says "Allow 3.5" (2u) to 5.25” (3u) inches of space above and to the sides of this amplifier"

The manuals for the 3BSST²/4BSST² say "Allow at least 3.5 inches (2 rack units of 1.75" each) of space above and 1" to either side of this amplifier"

[95Dyna]

Hi Bill,

My 7BSST2's are now six years old and I can tell you do not skimp on the vertical dimension.  The heat sinks are convectional and draw cooler air into the bottom of the sinks to replace the warm/hot air rising up from the amp.  I have 8" of space above my 7's and would not want to cut it any closer.  Remember the more heat an amp endures the shorter its life expectancy.

Bill (also  )

[KeithA]

Hi Bill,

My 7BSST2's are now six years old and I can tell you do not skimp on the vertical dimension.  The heat sinks are convectional and draw cooler air into the bottom of the sinks to replace the warm/hot air rising up from the amp.  I have 8" of space above my 7's and would not want to cut it any closer.  Remember the more heat an amp endures the shorter its life expectancy.

Bill (also  )

Hmmm...wouldn't the dominant cooling on a 7B or 14B SST be thermal conductive? I would suspect that the transistors are backing onto the protruded heat sinks out of the side of the amplifiers with residual heat escaping from the chassis interior? So, I would think it would be more important to have better exposure and airflow for the external heat sinks....but you wouldn't want to choke off the top obviously.

I could be wrong in what I've said, though !

[Big Red Machine]

Heatsinks are most efficient when air FLOWS though the fins. That means air has a chance to get into the space below it and can escape from the space above it. This creates a current of air as the delta temps move it along.

I personally like to raise the bottom of the amps up and give the sinks more air to draw from or hog out the shelf under the sink for a reservoir of air instead.

[James Tanner]

Heatsinks are most efficient when air FLOWS though the fins. That means air has a chance to get into the space below it and can escape from the space above it. This creates a current of air as the delta temps move it along.

I personally like to raise the bottom of the amps up and give the sinks more air to draw from or hog out the shelf under the sink for a reservoir of air instead.

Hi Big Red

Yes the heatsinks are in fact small chimneys - the hot air moves in a convection type manner from the bottom of the fins to the top. The efficiency of that air movement is affected by the space between each pair of fins and also the colour. We found that a small difference of even a few millimetres in the gap between the fins affects the heat flow significantly.  Also black is the most efficient colour as well.

james

[KeithA]

Hi Big Red

Yes the heatsinks are in fact small chimneys - the hot air moves in a convection type manner from the bottom of the fins to the top. The efficiency of that air movement is affected by the space between each pair of fins and also the colour. We found that a small difference of even a few millimetres in the gap between the fins affects the heat flow significantly.  Also black is the most efficient colour as well.

james

Neat, so it's both conductivity and convection. It's cool (no pun intended) that the colour actually makes a difference as well....especially black.

[95Dyna]

Neat, so it's both conductivity and convection. It's cool (no pun intended) that the colour actually makes a difference as well....especially black.

That is correct.  The heat generated internally is conducted (transferred from one solid to another of a different temperature). out to the heat sink.   It's what happens to the heat once it is conducted to the outside of the amp that is important for rack design/configuration. In this case the hot air accumulates between the fins of the heat sink and rises  creating a vacuum of sorts (which nature abhors) into which ambient cooler air flows.  Air flow created by differential temperatures is the definition of convection which requires ample space above and to a lesser degree below the amp.

[srb]

We found that a small difference of even a few millimetres in the gap between the fins affects the heat flow significantly.

And apparently the surface can also affect efficiency.  Heat sink fins that have striations exposing more surface area vs. a completely smooth surface are supposed to work better in a convection application.  In fan-cooled applications it can be argued that a smooth surface has better, less turbulent airflow.

There are some amplifier models that have/had horizontal finned heat sinks (Music Hall, Musical Fidelity, Odyssey, Sim Audio, etc.) which seems to fly in the face of convention - and convection.

Steve

[Grit]

You'd be surprised what an incredibly low-flow fan can do to improve cooling! As long as you're custom designing the cabinetry, you might consider some nearly silent forced air flow too.