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How To Rack A 4Pro

Discussion in 'Amps and Cabs [BG]' started by Frank Orlando, Aug 7, 2007.

  1. Frank Orlando

    Frank Orlando

    Dec 21, 2002
    Fort Myers
    I recently was looking at some older posts on how to best rack an Ampeg 4Pro. As you may know, several brands of "plastic" racks completely block off the cooling vents on the amp. It mostly happens on the smaller size units like 4 space units (the 4Pro takes up 3 spaces). I attached some pictures of how I resolved the problem. Oh, and those people that say they have theirs in a 4 space with no added openings to their rack and don't have a problem.... two words... "Russian Roulette"


  2. tlwaps


    Feb 13, 2006
    I put mine in a RoadReady 10 space rack. I purposely bought a larger rack to make sure I had enough air flow. I started out with a 6 space rack, but after I added a compressor the last space was taken up and I decided to get a larger rack.

    Power Conditioner
    2 Spaces
  3. Ryan L.

    Ryan L. Moderator Staff Member Supporting Member

    Aug 7, 2000
    West Fargo, ND
    Russian roulette??? Well, I must be damn lucky then, because mine was in a 6 space SKB rack, with no open spaces, and I never had a single problem with it overheating. I ran it mono-bridged into a 4 ohm load, 2-4 gigs per week. And it performed flawlessly for 4-5 years this way.
  4. Frank Orlando

    Frank Orlando

    Dec 21, 2002
    Fort Myers
    Dear Damn Lucky,

    the fact that yours is a 6 space may be what saved you. You can read that my "russian roulette" reference was aimed at the 4 space variety. Several 4 space rack manufacturers (who will remain nameless) have a square plastic handle support inside the case exactly where the vents are located. The sides of the 4Pro sit hard up against this support and it blocks the air vents almost 100%. But the 6 space (and larger) has the handle support about 3 inches higher than the 4 space due to the greater height of the case and the vents are partially cleared letting in enough air to prevent a problem. Anyone with a 4 space knows what I am referring to. The Road Ready case has plently of side clearance so no problem there. I have one also. It's the "plastic" cases like in my pictures that is a problem. Before I drilled out my 4 space rack the front face of the amp (which is a heat sink for further cooling the amp) got real hot... not warm...hot. It doesn't anymore. I'm just passing along my own experience hoping to save someone a melt down.
  5. Ryan L.

    Ryan L. Moderator Staff Member Supporting Member

    Aug 7, 2000
    West Fargo, ND
    That's entirely possible, and I should have read the OP more closely. Mine never resided in a 4 space rack, so what you mentioned may very well be true, and could be the reason I never had a problem.

    I've just read a ton of threads about how 4Pros shouldn't be racked, so I figured I'd throw in my 2 cents.;)
  6. LOL!
  7. Frank Orlando

    Frank Orlando

    Dec 21, 2002
    Fort Myers
    Yeah, I think that the larger rack eliminates the problem. I am moving my stuff into an 8 space SKB because I ran out of space when I went wireless (XDR95) and it looks like I won't have to add any air vents in the rack. I will still keep an empty slot over the 4Pro for insurance. I have a vented blank that I added an Ampeg logo to personalize it. I'll be moving that to the 8 space rack too.

  8. Bryan316

    Bryan316 Banned

    Dec 20, 2006
    I bought a wider rack.

    If you check out the SKB U.S. Roto Racks, you'll notice that the way the rack body is molded, there's much more internal room around the body of the amp. Allows for more air flow. Far superior to the standard SKB racks with aluminum joints.

    Also, in the past I had two 4" computer chassis fans mounted directly to the rear rack rails. Handy how those screw holes were on the same spacing! I had space on top and on bottom of the amp, so I could have a grill 1U spacer in front, and the two amps blew air from the back out the front. Lots of air flow.

    Now my current amp's a smaller chassis with even more physical room on the sides, and it's quite convenient. Two weekends ago, I did an outdoor gig at 90 degrees, directly in the sun. I run my amp at 2 ohms, and the whole stack was sitting in the sun for 1-1/2 hours before I wired up and started to play. No thermal problems whatsoever.

  9. Jeff Scott

    Jeff Scott Rickenbacker guru.......... Supporting Member

    Apr 11, 2006
    Why amp manufacturers design their cooling to vent INTO a rack is beyond my understanding. I tried an Ashdown MK500 for a short while; I found that the two fans on the back of the amp sucked air into the chassis, not out of the chassis meaning that the exhaust was through the vents in the side of the amp, blowing into the rack. Many other amps are guilty of this, such as Ampeg and SWR among others. I like that my Markbass LM II sucks the cooling air into the chassis from the side and blows it out the back of the amp and OUT of the rack!

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