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[Rafi Singer]

So, I'm thinking of switching to a pair of QSC 3402's for my tops and a Crown Macrotech 3600vz for my subs. Weight-wise, it makes the most sense to put the Crown at the bottom of the rack. However, I have heard of issues with this type of set up, seeing as Crowns vent front-to-back and the QSC's vent back-to-front, meaning that the exhaust heat of the Crown will be sucked into the QSC's.

What are your thoughts and experiences on this?

[Art Welter]

So, I'm thinking of switching to a pair of QSC 3402's for my tops and a Crown Macrotech 3600vz for my subs. Weight-wise, it makes the most sense to put the Crown at the bottom of the rack. However, I have heard of issues with this type of set up, seeing as Crowns vent front-to-back and the QSC's vent back-to-front, meaning that the exhaust heat of the Crown will be sucked into the QSC's.

What are your thoughts and experiences on this?

The hot air exhaust from the bottom amp will partially be sucked in to the top amp either way.
I'd put the heavy amp at the bottom.

[Mac Kerr]

The hot air exhaust from the bottom amp will partially be sucked in to the top amp either way.
I'd put the heavy amp at the bottom.

Or use amps that all vent on the same side.

Mac

[Josh Duke]

If you already have the amps, put the Macrotech on the bottom (assuming it is the heaviest) and the QSCs on the top, but racked facing the opposite way.  Use a patch panel to get the connections all on the same side.

If you have yet to buy the amps, do what Mac said and get amps that all vent the same way.

[Chris Carpenter]

Can someone fill me in why companies don't just agree on a flow direction? I never understood that.

[Elliot Thompson]

Can someone fill me in why companies don't just agree on a flow direction? I never understood that.

Internally, both amplifiers are designed different.

The Crown Macrotech 3600vz and below offer its heat sinks on the sides whereas the QSC PLX series offers the heat sinks in the middle. The Macrotech 3600vz and below, exhaust heat from the sides. Only The Macrotech 5000/02vz exhaust heat to wards the back.

Crown used to sell a kit that would reverse the fan blades for the Macrotech (3600vz and below) to change the direction of airflow on the amplifier. However, such a modification may not be available for the 3600vz due to being 20 years old.

Having the Crown Macrotechs and QSCs together in one rack is not an issue. Such a combination has been common for decades with these amplifiers.

Having the heaviest amplifiers at the bottom also decreases the rack from warping due to having lopsided weight during transit.

Best Regards, 

[David Morison]

Can someone fill me in why companies don't just agree on a flow direction? I never understood that.

Hi Chris,
They probably don't think that making it easier to use competitors' products alongside theirs will give them more sales.
Most bigger PA companies want to standardise on amps as much as possible anyway (for reasons of operator familiarity, consistency of performance, ability to swap out a malfunctioning unit, crossrentability etc) so for those sales it doesn't really matter.
It tends to only be smaller to medium sized rigs that are often grown up with piecemeal purchases where there is much mixing of brands.
Cheers,
David.

[Bob Lee]

It took the audio industry decades to decide that pin 2 is hot, so there's not going to be unanimity on direction of cooling air flow.

I don't believe it would be a problem. You could try putting a couple rack spaces of other equipment in between them, if you want.

[Rex Ray]

It took the audio industry decades to decide that pin 2 is hot, so there's not going to be unanimity on direction of cooling air flow.

I don't believe it would be a problem. You could try putting a couple rack spaces of other equipment in between them, if you want.

You can still get the reverse air flow fan kit from Crown,AFIK. We get QSC and Crowns to play together no problem (QSC 9.0/MA 3600VZ).
Rex Ray
Sr. Engineer,Clair Nashville

[John Roberts {JR}]

Can someone fill me in why companies don't just agree on a flow direction? I never understood that.

Sure, just tell me who gets to pick which direction becomes the standard? 

Don't they make racks with rails on front and back... just rack them all up so air flows in the same direction... 

Seems more useful to me than keeping wire dress consistent.

JR

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