My HT60 blew a fuse at a practice a few days ago, and after replacing it it worked again for a while but at a recording session it started making these annoying crackling noises. I troubleshot it and narrowed it down to the amp.
Now, according to some googling I did this would normally be the sign that it is time to change the power tubes. However I just changed them less than 2 years ago (April of 2015 to be exact), which was two years after I bought the amp. From what I've heard a good set of power tubes is supposed to last 10 years, 6 or 7 if you gig a lot, which to be fair I do. I tour relentlessly with my band, but if my amp is eating through power tubes this quickly I'm wondering if it might be an issue with my amp. I really don't like paying for a new set of tubes this often. Should I try replacing the other fuse first?
HT60 blowing fuses and making crackling noises.
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thephantum
- Posts: 1160
- Joined: Wed Jan 29, 2014 7:42 pm
- Location: Virginia, United States
Crackling is a sure sign that electricity is finding a path to ground inside the amp that it should not have (i.e. - a short). Blowing a fuse (or fuses) is the amps defense mechanism to protect itself from said short. Replacing said fuse and trying again is like spinning the barrel of the gun when playing russian roulette...it's only a matter of time until your luck runs out.
Most likely cause is a bad power tube. Not sure where you read 10 years but, on a amp that is used at gig levels regularly, it's usually recommended to change the tubes every 2 to 3 years. That's not to say they can't last longer but, when tubes are pushed hard, they tend to run a higher risk of catastrophic failure. So putting fresh tubes in prior to that is usually a good idea.
There are things you can do to help preserve tube life. The first (and biggest) is to make sure the amp is properly biased whenever the power tubes are replaced. That doesn't mean "set bias to xyz". Despite what people say, there is no set number for any amp. You need to measure the plate voltage, calculate bias current, adjust bias and repeat until it's dialed in. You can literally double the life of your tubes by biasing an amp properly.
The second biggest thing is to never move the amp while it's still hot. Always let the amp (and tubes) cool for at least 30 minutes prior to moving it. You can extend the life of the tubes by at least 50% when you follow this rule.
Most likely cause is a bad power tube. Not sure where you read 10 years but, on a amp that is used at gig levels regularly, it's usually recommended to change the tubes every 2 to 3 years. That's not to say they can't last longer but, when tubes are pushed hard, they tend to run a higher risk of catastrophic failure. So putting fresh tubes in prior to that is usually a good idea.
There are things you can do to help preserve tube life. The first (and biggest) is to make sure the amp is properly biased whenever the power tubes are replaced. That doesn't mean "set bias to xyz". Despite what people say, there is no set number for any amp. You need to measure the plate voltage, calculate bias current, adjust bias and repeat until it's dialed in. You can literally double the life of your tubes by biasing an amp properly.
The second biggest thing is to never move the amp while it's still hot. Always let the amp (and tubes) cool for at least 30 minutes prior to moving it. You can extend the life of the tubes by at least 50% when you follow this rule.
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Mattocaster
- Posts: 15
- Joined: Sun Feb 08, 2015 8:35 pm
Get your tech to check the opamps, mine was doing the same thing.
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