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Post subject: bassman 100t tubes
Posted: Sun Jul 22, 2012 11:40 am
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Dear Fender-Loungers,
I recently purchased and received a new Bassman 100t amplifier and I noticed that one of the four power tubes is a bit smaller (shorter) than the other three. I'm not totally inexperienced with tube amps but I've never encountered this anytime before. Is it reasonable to expect vacuum tubes to vary slightly in size? If not, is there any reason why a tube with "less glass" would not perform up to standard? In other words, should I be thinking of replacing it based only on it's appearance?
Thanks so much for reading this.
Peas.
Chuck


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Post subject: Re: bassman 100t tubes
Posted: Sun Jul 22, 2012 12:57 pm
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:?: :?: :?: Take them out and examine/measure them.

On the bright side :) :arrow: Congratulations :!:

How does it sound? Powerful? Awesome?

What cabs are you runnin'?

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2018 Rumble Studio 40 Combo
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One day they shall name a GREAT city after me, and they shall call it LINNINGRAD


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Post subject: Re: bassman 100t tubes
Posted: Sun Jul 22, 2012 1:07 pm
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Thanks linnin,
Yes, it sounds wonderful.
Right now it's serving a Ampeg 810 Heritage.

There are some pics at this link...
http://www.talkbass.com/forum/f15/bassm ... st12938962


Thanks again.
Chuck


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Post subject: Re: bassman 100t tubes
Posted: Sun Jul 22, 2012 2:04 pm
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OK Chuck,

I took a look, and yes it definitely looks like one 6L6 is of a different manufacturer. They should all produce the same power. BUT I'd yank 'em all (and keep them) and put in Groove Tubes. Expensive, yes. Great Tone Ain't Cheap! As you well know, having just spent some $1,500+. I hope you enjoy it no matter what.

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2012 Lefty American Standard Jazz
2017 Lefty American Professional Precision
2018 Rumble Studio 40 Combo
2016 Rumble 200 Combo
One day they shall name a GREAT city after me, and they shall call it LINNINGRAD


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Post subject: Re: bassman 100t tubes
Posted: Fri Aug 31, 2012 3:00 pm
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GROOVE TUBES is a FMIC owned brand. They were a separate company until late 2008 when FMIC bought the San Fernando, CA company out, shut down USA production there, moved the business offices to Scottsdale, AZ and Ontario, CA while moving production to Mexico. In addition to producing some tubes of their own such as the 6L6GE they were contracting foreign suppliers to produce other tubes for them which may or may not have said Groove Tube on them but got a Groove Tube sticker. Tube production is a very expensive proposition these days with a much smaller market that consists primarily of musicians and audiophiles so the volume of tube production worldwide is tiny compared to 50 or 60 years ago when everything was tubey.

Fender and Groove Tube do match up pairs and quads performance wise, so regardless of any bottle size irregularity, they should all match up closely in every performance category in a new Fender amp. All Fender tube amps use Groove Tube tubes. (Try saying that 3 times fast!)

Over the history of tube use in bass amps the 60's GE 6L6GC seems to stand out as one of the standards against which all others are judged. The 60's RCA version weren't bad either, especially popular were RCA black plate 12 series preamp tubes. But for some reason more of the GE 6L6's held up better in the long run and many of them have in fact lasted till this day still preforming well.

The USA made Groove Tubes 6L6GE was actually based on the GE 6L6GC tube with a few design mods due to modern production techniques. Groove Tubes even named it the 6L6GE to reflect the GE tube origin. The bottle on the USA Groove Tube GE version was a little taller than the GE GC version for example. You can still find the old GE tubes sometimes as new old stock from amplifier parts suppliers that specialize in new old stock tubes but you can expect to pay a premium for them. Also the USA made 2008 and back NOS Groove Tube 6L6's can still be found. There is some risk in buying NOS tubes as many suppliers sell them with a no-returns policy where of course a new production tube has a better return policy if they don't work correctly. After all, they are in some cases half a century old.

Today Groove Tubes has a pretty good warranty on their new stuff when purchased through an authorized dealer. 90 days on power amp tubes and 180 days on preamp tubes. As I recall there were no tube warranties back in the 60's or 70's, but tubes seemed to last a very long time back then. And today Groove Tubes offers several different 6L6 tubes with different performance characteristics instead of just one.

As long as the amp works well, I wouldn't worry about the "runt" tube. It isn't how it looks that is really important. Far more often than not you can expect years if not decades of use from the original power tubes. When replacing power tubes bias adjustment or at least checking to see if one is needed is absolutely a requirement and that usually means an amp tech, unless you are skilled at that and have the right gear to do it yourself. Preamp tubes don't require bias checks or adjustments and you can just swap them out yourself. That is a good thing because in my experience preamp tubes fail completely (or become microphonic) much sooner than power tubes give problems these days no matter what brand they are.

Is it just me or are modern preamp tubes shorter lived than the 60's and 70's ones?


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Post subject: Re: bassman 100t tubes
Posted: Sun Sep 02, 2012 6:33 pm
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brotherdave wrote:
Is it just me or are modern preamp tubes shorter lived than the 60's and 70's ones?


Trust me, Brother Dave......it ain't you.

And the same still holds true when comparing contemporary power tubes and NOS bottles. If only those old JAN's weren't so damned expensive......

:lol:

+1 on the rest of your excellent commentary as well!

8)

Arjay

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