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best fan placement.

Discussion in 'Amps and Cabs [BG]' started by dereksilloway, Jun 30, 2007.

  1. I have a GK head (the backline 200) that has problems overheating. I was thinking about buying this fan http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=305-200
    and putting it on the head to cool it down. Where is the optimal fan placement. I was thinking on the back mounted to the slots for the convection heating system. Any suggestions.
  2. Get the air right into the vents and you'll be all set. Interesting find BTW>
  3. anderbass


    Dec 20, 2005
    Phoenix. Az.
    Oh... From the title, I thought this thread was possibly referring to band groupies...:smug:
  4. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Do you mean the Backline 250 head? Does it have vent holes directly above the power amp heat sink, like on the Backline 600 head? If so, I would get a regular muffin fan and have it blow down directly onto the heat sink, because that's how the BL600 is structured. The air is sucked in the top, and blows out the front and back. And my only reason for suggesting this arrangement is that it's already a proven concept on the BL600.

    Some pics, with the covers on and off, would be extremely helpful for advising your best options.
  5. Picture419jjj.gif



    muffin fan? what is that?
    Hope these pictures help.
  6. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    The pictures help a lot. Indeed, your amp is structured just like the Backline 600 head, with vents above and behind the power amp module. It could be the same amp circuit with slightly different component choices.

    A muffin fan is like the typical fan that's inside a PC. This is the typical size and shape:



    I would bet that practically any fan of this genre would work. It could simply be mounted below the upper vent blowing down, or in the rear vent blowing in. Now, the next issue is where you are going to come up with 12 Volts at 0.3 or 0.15 Amps, respectively, inside your amp. I figure your options are to do some sleuthing and find the power supply voltage running the preamp. If that voltage is 15 Volts, you can drop it down with a handful of silicon diodes in series -- roughly 0.7 Volts per diode.

    If you are not comfortable with that level of digging, then you could mount the fan on the outside of the amp, in back, blowing in. Power it with a 12 V wall wart, and you are in business. I have to guess that many are the bass amps that have received an external fan at some point in their lives, especially with rack mounting.

    Upgrading to the Backline 600 head nails the problem dead.
  7. BbbyBld


    Oct 13, 2005
    Meridian, MS
    4 CFM??

    That's not a lot of air flow at all! There must be a typo!

    You can't always go adding fans to an amp that was designed to run without a fan. Sometimes it can cause the amp to not bias the power transistors correctly.
  8. theshadow2001


    Jun 17, 2004
    The GK was probably designed not to overheat which would lead me to ask the question whats causing it to overheat? Also that its worth dealing with this problem than the extra heat that results from this problem.
  9. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    I remember when researching the BL600, that there was at least one review on Harmony Central about overheating issues on the BL250 head. One person reported success with adding a fan.

    But the words of caution are justified and welcome. And I did not look closely enough at those CFM ratings.
  10. You can get muffin fans that operate on 120VAC, like http://www.weisd.com/store2/SRCACFAN-6P.html, which will save you looking for a 12vdc supply. I can't tell for sure but it looks like you could mount a fan inside the case on top of the heat sink.

  11. I see that those muffin fans are relatively cheap, but part of the reason i wanted to go with the fan i provided in the first link is because it comes with a power supply http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=305-305.
    Im not really too good with electronics and am not comfortable jabbing around inside to figure how to wire up the fan so ill probably just go with the fan in the first link with that ac adapter. and because of the adapter i think im going to place it outside of the back vent.

    ive read a few reviews that say the this head has trouble with overheating and ive also read that a fan helped it out. this is my only complaint about this head (and the single speaker out) but im going to be fixing that problem by purchasing a BL 600 head shortly.
  12. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    Feb 26, 2021

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