TAD tubes

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TAD tubes

Postby cedarchoper58 on Sun Oct 28, 2012 8:42 pm

I have been using TAD 6L6 tubes in my fender pro reverb for seveal years and never can get more than 40 gigs out of a pair. I dont get it. I did a show last night and my amp sounded strange and i checked the bias today and one of the tubes had droped 10ma. The last set one blew and took out the fuse around 40 gigs. I have gone back to Grove Tube 6L6 GE's today. I have always gotten 60+ gigs out of them and they just get weak never blow. Any one elses have problems like this with TAD tubes. I love the way the small bottle TAD tubes sound in my 67 BF pro reveb but the dependility and mismaching is horrible
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Re: TAD tubes

Postby PeterS on Mon Oct 29, 2012 12:38 am

Maybe that's just the way new production tubes are. As an experiment it might be worth buying some good tubes--- if they cost twice as much but last 10x longer it's better value. I only use old pulls and they last for years and years.
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Re: TAD tubes

Postby cedarchoper58 on Mon Oct 29, 2012 1:19 am

How hard is it to get a matched pair of old tubes and how do you know how good they are without a tube tester
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Re: TAD tubes

Postby Unit_1 on Mon Oct 29, 2012 1:55 am

http://www.kcanostubes.com

nos and new tubes

you might get better deals on ebay, but caveat emptor applies there
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Re: TAD tubes

Postby PeterS on Mon Oct 29, 2012 12:55 pm

how do you know how good they are without a tube tester


I don't find a tester all that useful for power tubes. I put them in an amp and measure the current. If they bias to a reasonable current at a reasonable grid voltage, they're good. Match them by selection from a pile...
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Re: TAD tubes

Postby cedarchoper58 on Mon Oct 29, 2012 1:56 pm

I gig with my amp so I dont want to wear out the socket puting hundreds of tubes in and out
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Re: TAD tubes

Postby PeterS on Mon Oct 29, 2012 3:27 pm

How many decades do you expect to be doing this? Buy a dozen quality 6L6GCs. Measure the current for all 12. Toss the weakest 4, rank the remaining 8 into order, you've got 4 pairs, enough to last til you're old and grey.
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Re: TAD tubes

Postby jcs on Mon Oct 29, 2012 11:30 pm

Thru the years, i always test my tubes in a B&K 600 & Hickok533a first and then measure current draw with a Bias Rite for at least 15 minutes.

If you are biasing at 70% you might want to bias a bit cooler, say 55-60%.....tubes will last longer generally.
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Re: TAD tubes

Postby cedarchoper58 on Tue Oct 30, 2012 2:54 pm

I bias at 36ma @ 480v which is around 60-65%
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Re: TAD tubes

Postby dtw576 on Tue Oct 30, 2012 3:13 pm

I also use/used a Bias Rite for years to match tubes and it works well for that purpose. Along with my Hickok 600A to test for shorts and transconductance, i was set. But with all the EL34's and KT66's I have, I finally ponyed up for a MaxiMatcher to test my power tubes. It isn't the best in the world but certainly is decent enough for what I do. With over 50 vintage power tubes it made sense to invest the $600 in it. I'll probably recoup a fair portion of that whenever i decide to sell it, if I ever do. If you are an occasional tube matcher, get a BiasRite or something like that and it will do fine.
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