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Home amp repair..


NHTom

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Ok, back in the 80's, I worked for a Laney dealer. When the time came for me to get a new practice amp, I gravitated toward Laney because they were all ways good quality, etc.

 

I purchased a little Laney Cub 12R. 15 or less than 1 watt inputs, All Tube, single 12", built in reverb, effects loop, etc.

LOVE it.....great little practice amp.

 

Just under a year into it, I ran into a problem where after about ten minutes of playing, the volume would cut in half and it would lose a lot of bass.

Checked the Laney forum and seems there were a couple "known problems" that they can run into....mine "should" be newer than the known issues, but I figured the easiest one was replace the stock tubes.

 

I swapped the original Ruby EL84's for a pair of JJ's and it is working great again. Played for an hour straight with no issues, no tone loss, etc.

 

The interesting thing I noticed about the tubes is that 1) the JJ's fit the tube socket tighter and 2)the JJ's are longer than the ruby's.

 

101_0136_zps77e6bd96.jpg

 

Not sure how much any of that matters, but if anything, I assume the tighter fit helps.

 

NHTom

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EL84s are fragile in the tube world, 6 months to a year if you play regularly more if you are lucky or use a standby switch properly (depending on amp design, blah, blah)

 

Learn the signs of a EL84 going bad and replace before it goes out otherwise it may damage other stuff in the amp, fuses don't always burn out on time.

 

JJ EL84s are pretty temperamental, I have seen two blow out and it ain't pretty.

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How old is "old" on a tube?

 

I used to have an old fender super that had ancient tubes in it.

 

A few factors at play here I think...

 

- They definitely don't make them like they used to! [biggrin]

 

- A lot of Fender amps don't deliver a ton of plate voltage to the tubes. By contrast Marshalls punish them pretty hard. There are exceptions on either side of course, but this generally holds true. I have some ancient tubes in some of my Fender amps as well.

 

- I certainly agree with Riffster that EL84s (modern production particularly) don't last as long as say an old RCA 6V6. Though I haven't had any JJ EL84s go bad on me as he has. I have been disappointed in the newer "Mullard" EL84s however. Tung Sols have been pretty good to me as have Electro Harmonix and the aforementioned JJs.

 

- Relatedly JJ has a new tube out - the EL844. It's a low power EL84. You can get to the sweet spot of your amp a bit more quickly. I was unsure at first, but I tried them in my 18 watt Marshall and have been quite impressed. Since you need to buy a spare set any, you might try a set of those.

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Actually got to open it up for a couple hours last night.......still not cranked, but on the high power setting.

 

Sounds great. Very pleased, no cutting out, etc.

 

Love this little amp....with my Special with the P100's it gives a great classic crunch with very good string definition.

 

NHTom

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...

JJ EL84s are pretty temperamental, I have seen two blow out and it ain't pretty.

Several months ago, I had to deal with a JJ EL34 shorting out. It grew so hot that the red script went brown and the bulb warped. Luckily it took just the fuse with it. It was the only shorting of an EL34 I experienced more than three decades.

 

...

- They definitely don't make them like they used to! [biggrin]

...

This is sad, but true. Consistency and durability aren't what they used to be. :(

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