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How can I test my tubes?


Joe

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Posted

I recently replaced tubes in my Peavy Delta Blues 1X15. This time I used Groove Tubes but after reading some recent posts, I think I may invest in a more expensive set next time.I was wondering if anyone here tests their tubes and replaces only the bad ones. The way I do it now is when the amp starts to buzz or hum I replace the whole set. Not a huge deal if your using less expensive tubes but is it wise to replace only the bad ones with a more expesive set? Thanks for any input.

Posted

I think KBP810 will know the answer to your question. There was recently a thread regarding the pencil test. That may have been about whether or not the tubes are microphonic.

Posted

I think KBP810 will know the answer to your question. There was recently a thread regarding the pencil test. That may have been about whether or not the tubes are microphonic.

I did see the thread describing the pencil test.I was thinking more along the lines of testing resistance. If resistance is the proper test. I was hoping KBP810 would offer some insite.

Posted

I did see the thread describing the pencil test.I was thinking more along the lines of testing resistance. If resistance is the proper test. I was hoping KBP810 would offer some insite.

Aside from microphonic tap tests, there's not a lot more you can do test wise, sans a tube tester itself.

 

You can't really measure resistance on a tube, or in essence the pins would/should all read open with the exception of the heater pins.

 

Most errors can be detected by your ears - amp gets noisy, bad hums, loss of power, etc... usually if you can see or smell the problem, somethings has likely gone terribly wrong!

 

If you start to hear a buzz or hum, it's best to start at the preamps and do a little trial and error by swapping one out at a time with a known good tube until you find the culprit (after a tap test of course, as that would likely be the tell)... usually, it's only one, but if two or more have gone south the above process could get a little frustrating :wacko:

Posted

I remember the days of taking a bunch of tubes to the local Radio Shack (which had a tester for free) to test out the tubes. Always trying to keep straight what each one measured...

Posted

A local second hand shop around here has a tube tester. Its meant to test his stock of old tubes he has lying around, but I'm sure he wouldn't have a problem allowing you to use it for your own tubes.

Posted

I remember the days of taking a bunch of tubes to the local Radio Shack (which had a tester for free) to test out the tubes. Always trying to keep straight what each one measured...

I remember seeing those in drug stores.That was a long time ago.

Posted

A local second hand shop around here has a tube tester. Its meant to test his stock of old tubes he has lying around, but I'm sure he wouldn't have a problem allowing you to use it for your own tubes.

Where is that store?

Posted

Aside from microphonic tap tests, there's not a lot more you can do test wise, sans a tube tester itself.

 

You can't really measure resistance on a tube, or in essence the pins would/should all read open with the exception of the heater pins.

 

Most errors can be detected by your ears - amp gets noisy, bad hums, loss of power, etc... usually if you can see or smell the problem, somethings has likely gone terribly wrong!

 

If you start to hear a buzz or hum, it's best to start at the preamps and do a little trial and error by swapping one out at a time with a known good tube until you find the culprit (after a tap test of course, as that would likely be the tell)... usually, it's only one, but if two or more have gone south the above process could get a little frustrating :wacko:

Thanks KBP. I guess I'm trying to make my world to perfect in these penny pinching times.

Guest HRB853370
Posted

I think KBP810 will know the answer to your question. There was recently a thread regarding the pencil test. That may have been about whether or not the tubes are microphonic.

 

I thought the pencil test was for cleavage!

Posted

Where is that store?

I believe he was referring to Blues Airman, it's on Ford Rd near Merriman in Garden City, MI

 

There's usually not much to look at there, but every now and then they get some neat stuff in - they usually have a box or two of used but working tubes for $5 a piece. I actually found a couple of old GE 12ax7's in there once that turned out to be solid tubes.

Posted

I believe he was referring to Blues Airman, it's on Ford Rd near Merriman in Garden City, MI

 

There's usually not much to look at there, but every now and then they get some neat stuff in - they usually have a box or two of used but working tubes for $5 a piece. I actually found a couple of old GE 12ax7's in there once that turned out to be solid tubes.

Thanks for the info. I've only been in there once but I'll definetly take my last set of tubes in there.Should be interesting.

Posted

There are usually a few vintage tube testers on eBay at any given time. Worth the investment?

Posted

There are usually a few vintage tube testers on eBay at any given time. Worth the investment?

I've been wondering about that myself.I saw testers on a tube website. I think they were about $190.00.

Posted

Hey, Nice Truss Rod Cover in your picture!

 

Stiener and KBP810 found a place that makes them. I wasn't sure they be able to fix Detroit Blues in script on it, but I'm so glad they could! Can't wait to put it on my H-140. Its the final piece that makes that guitar uniquely mine.

Posted

There are usually a few vintage tube testers on eBay at any given time. Worth the investment?

In my opinion... unless you are buying/selling a lot of tubes, it probably isn't

 

The best test equipment for a tube is always an amp and a pair of ears

 

A tester can tell if a tube is good and should work, but it's not going to do much in the way of telling you it's going to sound good... and it's also not really going to tell you if it's noisey and/or microphonic either.

 

The only other best purpose I can think of is if you have a whole bunch of single power tubes that you want to pair up/match; but otherwise, I'd say you can probably easily live life without one.

 

Just my one and a half cents on the matter :)

Posted

Just got back from Bluesairmen. Two power tubes from that set were bad.Got some good advice on tubes from the guys there.

Posted

Just got back from Bluesairmen. Two power tubes from that set were bad.Got some good advice on tubes from the guys there.

 

Hopefully it was the owner and not that kid he has working for him.

Posted

Hopefully it was the owner and not that kid he has working for him.

Yes it was the owner and thanks for the tip about him testing tubes. I found out what I needed to know.

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