Transistor very hot (tweeter protection)

Discussion in 'The Projects Forum' started by mhtplsh, Aug 25, 2011.

  1. mhtplsh

    Thread Starter Member

    Jul 29, 2007
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    The transistor 2N 3055 becomes too hot.
    Can i replace with other devices like TIP 34 or some Mosfet?

    Guidance required.
     
    Last edited by a moderator: Sep 4, 2011
  2. wayneh

    Expert

    Sep 9, 2010
    12,145
    3,055
    the purpose of that circuit is to burn off power as heat, to spare the tweeter. So the problem is getting rid of that heat, not replacing the part.
     
  3. mhtplsh

    Thread Starter Member

    Jul 29, 2007
    27
    0
    Thanks wayneh.
    Yes you are right.
    Is there any other way?
    Or use two transistors in parallel.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Yes.
    Turn the volume down before you blow out your eardrums.
     
    Sparky49 likes this.
  5. mhtplsh

    Thread Starter Member

    Jul 29, 2007
    27
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    the circuit is Professional audio. So reducing the volume is not preferable many times but to save the driver is also must.
     
  6. Potato Pudding

    Well-Known Member

    Jun 11, 2010
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    92
    You are wanting to waste more power and add more clamping = clipping. That is not very professional.

    What you would rather do first is upgrade the Tweeter so that you can redirect more power to it.
    Reducing the clamping level which is what heats that transistor, might be as easy as using higher values in the bias resistors.

    For overheating I would suggest putting a thermal monitor on the transistors and when they signal spiking temperatures - turn down the volume.

    For upgrading the tweeters I suggest you expand to a bank 2x2.

    Two parallel sets of two series tweeters. You should be able to easily double the power. You need to refit the speaker cabinet for them but that might not be too hard.

    Keep in mind that you might need to upgrade other components in the crossover. The HighPass capacitor is particularly likely to stress under higher power.
     
  7. mhtplsh

    Thread Starter Member

    Jul 29, 2007
    27
    0
    I got it what is said by fellow members.
    I appreciate this.
    I today bought one chinese crossover with triac B12 600B.
    Here is the schematic of the same.
    kindly explain how it works.
    The heatsink is small so i assume it might not be that hot while operation.
    i need guidance in the matter.
     
  8. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
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    Attache a heatsink and fan!
     
  9. mhtplsh

    Thread Starter Member

    Jul 29, 2007
    27
    0
    i found a tweeter protect project pictures. I made the schematics based on it. There might be resistor value mistake. Before moving further i will like to know the views of fellow members about the circuit.
    My preference for the circuit is due to no heatsink on T3 2N 3055. T2 is 2SD 1761.
     
  10. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    How much power?

    What is the impedance of speaker?
     
  11. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Is this a continuation of your other thread?
    Transistor very hot

    If so, then I can merge them.

    Bertus
     
  12. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    I worked a few years for a PRO audio manufacturer. The expensive products had a guarantee replacement with no questions asked and no product was returned.
    But the cheap speakers frequently had their tweeters not working because the tweeters were burned out and sometimes the woofers were burned out.

    Years ago I bought two RadioShack Minimus 7 speakers rated at 40 Whats each. I played my 70W per channel stereo thru them then one failed so I bought its replacement woofer. The original woofer was stamped Korea 5W.
     
  13. mhtplsh

    Thread Starter Member

    Jul 29, 2007
    27
    0
    Respected Bertus,
    My purpose is the same but circuit is not same.
    So you can decide what you think is best.

    Last time the transistor was very hot & according to fellow members the circuit is not good to use.

    Here the circuit is totally different & there is no heatsink in the project & hence i am surprised.
     
  14. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    I merged the threads.
    This way you can find all information in this thread.
    I also changed the title.

    Bertus
     
  15. mhtplsh

    Thread Starter Member

    Jul 29, 2007
    27
    0
    The tweeter is of 40~50 watts with 3"VC. The impedance is 8 ohms.
    The DJ operator is careless when operating the system. Hence try to make safer protection system.
     
  16. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Then use a brickwall limiter in a locked box in front of the power amp, possibly multi-band. Limiting at the speaker should be a last resort in case something fails, not to compensate for stupid DJs.
     
  17. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    I still think that adding 3 more tweeters to make 2 series by 2 parallel would be your best option.

    Don't expect to get 4 times the power but you should reliably be able to deliver twice the power and reduce your clamping levels by changing the bias to the crossovers bypass transistor or triac.

    That should allow your DJ to damage peoples ears sufficiently.
     
  18. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    From the stupid joke that ended my previous post it occurs to me that the problem might be your DJ's ears.

    It is an occupational hazard for DJ's to get partial deafness.
    They lose hearing for high frequencies most often.

    He might not be careless. He might be trying to compensate for his own damaged hearing as he balances the the sound levels.

    If he is partially deaf and doesn't realize it, then he would actually be risking others peoples hearing.
    He won't know when the music is too loud. He could send customers running away from painfully screeching highs.
     
    Last edited: Sep 7, 2011
  19. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    I was going to say this yesterday.
     
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