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Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


    Gold Lion KT-88 Issues?

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    Guest
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    Gold Lion KT-88 Issues? Empty Gold Lion KT-88 Issues?

    Post by Guest on Tue Apr 14, 2020 8:56 pm

    I heard some people are having problems with the Gold Lion tubes. The other day my speakers made a strange noise, so I shut the ST-120 amp down, and there was an odor, I removed the cover which was very hot on one side, then I touched the tubes, one was extremely hot compared to the other 3. I removed the base to see if anything was damaged, I noticed a two resistors burnt, and one actually fell off from the heat. I was told a bad tube can do this, is this true?
    LeGrace
    LeGrace

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    Post by LeGrace on Tue Apr 14, 2020 9:58 pm

    Prior to installing AB control boards in my M125's I lost a GL KT88 from overheating so severe the glass cracked. Another time I lost two resistors. But ever since adding the AB's no more issues. They constantly regulate bias preventing drift to high side which can cause a tube to cook.
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    wildiowa

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    Post by wildiowa on Tue Apr 14, 2020 11:15 pm

    Not sure any specific known weakness with Gold Lions, I use them as McShane and Sachs etc.have recommended them and they seem to be some of the best available in this new generation of tube manufacturing.  Unlikely you will find the quality of any new tube as you would with the old Gold Lions made in the UK or other old-school European manufacturers.  I have had two Gold Lions crap out in recent years but hard to tell if it was the tube or other factor that caused the failure.
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    Jim McShane

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    Post by Jim McShane on Wed Apr 15, 2020 5:32 pm

    For what it's worth - the Genalex KT-88s are one of the most reliable power tubes I carry. The failure rate is well below 1% and has been for a good long while.

    Poor socket to tube pin contact can often be the cause of failures. Be sure you clean the sockets thoroughly to ensure good contact, If you want to know more about tube related issues check my FAQ post here:

    https://www.audioasylum.com/messages/tubes/253369/quot-tube-problems-quot-that-aren-t-tube-problems

    Finally - it's wise to replace the power tubes before they fail. Once cathode emission drops too far the tube sometimes can run away and damage itself (or your amp!). I know power tubes aren't necessarily cheap - but in many cases you can save having additional damage (and expense) by replacing the tubes before they are too far gone. A number of amp makers make the same recommendation.
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    wildiowa

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    Post by wildiowa on Wed Apr 15, 2020 7:06 pm

    I had very high line voltage and since adding a Variac have had no failures. I have always believed this high voltage caused the red plate events and have had no issues since I brought it down to 120 v.
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    monkuboy

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    Gold Lion KT-88 Issues? Empty Re: Gold Lion KT-88 Issues?

    Post by monkuboy on Sun Nov 01, 2020 12:42 am

    Jim McShane wrote:For what it's worth - the Genalex KT-88s are one of the most reliable power tubes I carry. The failure rate is well below 1% and has been for a good long while.

    Poor socket to tube pin contact can often be the cause of failures. Be sure you clean the sockets thoroughly to ensure good contact, If you want to know more about tube related issues check my FAQ post here:

    https://www.audioasylum.com/messages/tubes/253369/quot-tube-problems-quot-that-aren-t-tube-problems

    Finally - it's wise to replace the power tubes before they fail. Once cathode emission drops too far the tube sometimes can run away and damage itself (or your amp!). I know power tubes aren't necessarily cheap - but in many cases you can save having additional damage (and expense) by replacing the tubes before they are too far gone. A number of amp makers make the same recommendation.

    Are there any warning signs to indicate the power tubes should be changed? Or if by use, number of hours?
    peterh
    peterh

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    Gold Lion KT-88 Issues? Empty Re: Gold Lion KT-88 Issues?

    Post by peterh on Sun Nov 01, 2020 3:20 am

    monkuboy wrote:
    Jim McShane wrote:For what it's worth - the Genalex KT-88s are one of the most reliable power tubes I carry. The failure rate is well below 1% and has been for a good long while.

    Poor socket to tube pin contact can often be the cause of failures. Be sure you clean the sockets thoroughly to ensure good contact, If you want to know more about tube related issues check my FAQ post here:

    https://www.audioasylum.com/messages/tubes/253369/quot-tube-problems-quot-that-aren-t-tube-problems

    Finally - it's wise to replace the power tubes before they fail. Once cathode emission drops too far the tube sometimes can run away and damage itself (or your amp!). I know power tubes aren't necessarily cheap - but in many cases you can save having additional damage (and expense) by replacing the tubes before they are too far gone. A number of amp makers make the same recommendation.

    Are there any warning signs to indicate the power tubes should be changed?  Or if by use, number of hours?

    4000 - 5000h might be considered a liftime for powertubes.

    monkuboy likes this post


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