Fender champ speaker ohm question

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Just picked up a 70s fender champ which sounds insanely good. It has an upgraded warehouse G8C speaker in it. The speaker is an 8 ohm but the amp is 4 ohm. Will this give me any problems or is it a safe mismatch? 
Thanks 
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Comments

  • munckeemunckee Frets: 12255
    Can't help but I've got a 79 with a 4 ohm G8C in it and sounds amazing.  There is one for sale on here for not very much at all.  I would be tempted to buy it and sell yours.
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  • munckee said:
    Can't help but I've got a 79 with a 4 ohm G8C in it and sounds amazing.  There is one for sale on here for not very much at all.  I would be tempted to buy it and sell yours.
    Can you link me to it? 
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  • ICBMICBM Frets: 71960
    8 ohms is not a safe mismatch for a Champ, no. Technically it's outside the usually-safe 2:1 mismatch range since the amp output is actually 3.2 ohm, not 4. I have seen a couple of Champs with blown OTs which also had 8-ohm speakers fitted, and I don't think this is a coincidence.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • ICBM said:
    8 ohms is not a safe mismatch for a Champ, no. Technically it's outside the usually-safe 2:1 mismatch range since the amp output is actually 3.2 ohm, not 4. I have seen a couple of Champs with blown OTs which also had 8-ohm speakers fitted, and I don't think this is a coincidence.
    Thanks for this. Looking on eBay there only £45 to buy so might be worth just buying another and selling this one 
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  • munckee said:
    Just snagged that speaker so thanks a lot for that mate really appreciate it. 
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  • munckeemunckee Frets: 12255
    munckee said:
    Just snagged that speaker so thanks a lot for that mate really appreciate it. 
    Nice one, glad to help.  I think you'll like the speaker.  What year is the champ out of interest?
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  • munckee said:
    munckee said:
    Just snagged that speaker so thanks a lot for that mate really appreciate it. 
    Nice one, glad to help.  I think you'll like the speaker.  What year is the champ out of interest?
    It’s a 1979, got it from the original owner. He advertised it for £500, I offered £325 and he accepted so well happy. . Sounds fantastic. Just got to find a replacement back panel as the original one was removed and he can’t find it. 
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  • munckeemunckee Frets: 12255
    Wow the two on the bay are both at £700+, won't sell for that I wouldn't think but you have a proper bargain there.
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  • Now I know why people remove the rear panel on these amps, they run pretty dam hot 
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  • munckee said:
    Can't help but I've got a 79 with a 4 ohm G8C in it and sounds amazing.  There is one for sale on here for not very much at all.  I would be tempted to buy it and sell yours.
    Do the output tubes in your amp run very hot? Mine seems crazy hot almost instantly. This amp sounds amazing but I think I’m going to take it to a tech to get it checked over just for peace of mind. 
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  • munckeemunckee Frets: 12255
    Mine doesn’t run particularly hot. I would get it looked at!
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  • munckee said:
    Mine doesn’t run particularly hot. I would get it looked at!
    Ye I think it would be silly not to, it’s such a great little amp it’s worth it. Cheers mate 
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  • ICBMICBM Frets: 71960

    Do the output tubes in your amp run very hot? Mine seems crazy hot almost instantly. This amp sounds amazing but I think I’m going to take it to a tech to get it checked over just for peace of mind. 
    Yes, make sure the cathode bypass cap hasn’t failed - they quite often do because they run right on the limit of their 25V rating or even over it. I always replace it with a 50V one.

    It’s worth checking the valve dissipation as well, it may be necessary to increase the resistor value slightly. 16W is about the maximum before redplating sets in normally.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Just want to say a big thanks to everyone for there advice and especially ICBM for always sharing all of his knowledge with us mere mortals. I have changed the speaker to a 4ohm (purchased from this forum) and also replaced a power tube and it now sounds stunning. Thanks again 
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  • sratosrato Frets: 24
    Is it safe to use a 4 ohm attenuator for a Vibro Champ with a 3.2 ohm speaker output?
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  • dindudedindude Frets: 8534
    srato said:
    Is it safe to use a 4 ohm attenuator for a Vibro Champ with a 3.2 ohm speaker output?
    Ditto, I have the vary same question
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  • Winny_PoohWinny_Pooh Frets: 7732
    It should be, I use a 4 ohm speaker with mine with no issues. 
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  • ICBMICBM Frets: 71960
    Yes. There's really not much difference between 3.2 and 4 - it's just 8 ohms or above that you need to avoid.

    So do make sure that the attenuator is a proper 4-ohm one or has a switch to select that, and not a 'universal' one that's claimed to be 4-16 ohms, as these are in fact 8 ohm but rely on a 2:1 mismatch being safe.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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