6L6 Tubes

jimipage · Post by **jimipage** » Tue 08/22/06 3:32 pm

kd wrote:Anyone tried the JJ's?

Ken

yep, I dig 'em. Svetlanas are pretty killer, too.

marshman · Post by **marshman** » Tue 08/22/06 5:54 pm

I'm hardly an expert, and I've never actually heard NOS RCA blackplates, but I recall reading somewhere that the 'new GT reissues' cost as much as the NOS anywho, at least when they were new to the market.

In my very limited experience, I've enjoyed all the JJ 6L6GC I've used.\\

Happy hunting!

billv · Post by **billv** » Tue 08/22/06 6:24 pm

About those RCAs - I have a pair from an old organ. Look to be original, and the organ was from the late '50s. However, they have gray plates. Clear top, dual D side getters/flashing. How do these compare to the black plate RCAs?

The power section (when new) supplied 400v to the center tap of the OT. Can't read the schem clearly, but it looks like 390v or so on the plates. 310v on the screens. High? Low? About average?

Just wondering if these are worth building an amp around.

kd · Post by kd » Tue 08/22/06 7:05 pm

About those RCAs - I have a pair from an old organ. Look to be original, and the organ was from the late '50s

The tubes I'm using in the amp now are also RCA's. They are coke bottle shaped and came from an old Baldwin made in the late 50"s. They sound good to me, but I've only been running them at lower volumes. They are marked 6L6G on the tube. They look much like the photo attached.

Post by **markh** » Tue 08/22/06 8:07 pm

6L6G tubes are an older type and have a bit lower rating than the 6L6GC we know and love.

6L6G -- 360/270v plate/screen max, 19w max diss.
6L6GC -- 500/500v plate/screen max, 30w max diss.

--mark h

kd · Post by kd » Tue 08/22/06 8:24 pm

6L6G -- 360/270v plate/screen max, 19w max diss.
6L6GC -- 500/500v plate/screen max, 30w max diss.

Thanks Mark,

Going by those specs, I'm really torturing my 6L6G's, I've got 425 volts on the plates and I haven't checked the screens. Looks like it's time to get 'em out of there and put in some 6L6GC's.

kd · Post by kd » Sun 08/27/06 8:42 pm

Thanks to all that replied, much appreciated

Ken

mr_coffee · Post by **mr_coffee** » Mon 09/04/06 4:21 pm

markh wrote:6L6G tubes are an older type and have a bit lower rating than the 6L6GC we know and love.

6L6G -- 360/270v plate/screen max, 19w max diss.
6L6GC -- 500/500v plate/screen max, 30w max diss.

--mark h

Is that spec applicable across the board, or is there some variance from manufacturer to manufacturer?

Do you know the ratings on any of the other 6L6/5881 variants?

-m

Post by **markh** » Mon 09/04/06 9:53 pm

Certainly this varies from mfr. to mfr., and I would hope these are the worst-case specs for new units, at least matching what the old tube manuals say.

--mark h

Post by **rjgtr** » Mon 09/04/06 10:38 pm

The TAD 6L6GC is a very impressive sounding tube. They touch a bit of the old RCA magic. I also like the SEDs (or Winged C - true non-New Sensor Svetlanas) because they have a fat tone. But NOS RCAs and GEs are still the best sounding for an old school tone.

Post by **zaphod_phil** » Tue 09/05/06 5:35 am

kd wrote:Going by those specs, I'm really torturing my 6L6G's, I've got 425 volts on the plates and I haven't checked the screens...

If they're not arcing inside, then they're probably doing fine in your amp. Just check the dissipation and bias. Over-dissipation is what wears out tubes, not over-voltage.

mr_coffee · Post by **mr_coffee** » Tue 09/05/06 9:33 am

zaphod_phil wrote:If they're not arcing inside, then they're probably doing fine in your amp. Just check the dissipation and bias. Over-dissipation is what wears out tubes, not over-voltage.

Is this to say, then, that if I'm running plate voltages in excess of a tube's "ratings", that provided my dissipation and bias are tweaked appropriately, the tubes should be okay?

If that is established, would it then be feasible or even advisable to tweak certain value components to allow for a greater range of adjustment to the bias supply if necessary to avoid destroying tubes?

BTW, I just want to say this is a great site and a great forum. I've been lurking for a couple weeks now, and I admire the friendly atmosphere, the support offered, the wisdom shared.

-m

Post by **markh** » Tue 09/05/06 1:53 pm

Yep, it's too much current that normally kills tubes (at least at the voltages we use), particularly the screen grid.

I'd only tweak the bias parts if I was planning to use an off-the-wall tube. One minor problem that pops up is if you make a relatively wide range bias control, is that it gets increasingly difficult to dial in one certain value (unless you use a 10-turn pot, in which case it's still a pain). The best way is to switch between two smaller ranges like the ever-popular 6L6-EL34 switch found in many commercial amps.

--mark h

Post by **zaphod_phil** » Tue 09/05/06 2:08 pm

mr_coffee wrote:Is this to say, then, that if I'm running plate voltages in excess of a tube's "ratings", that provided my dissipation and bias are tweaked appropriately, the tubes should be okay?

If you haven't heard or seen any sparks inside your tubes, and they're biased correctly, then they'll be fine.

mr_coffee wrote:BTW, I just want to say this is a great site and a great forum. I've been lurking for a couple weeks now, and I admire the friendly atmosphere, the support offered, the wisdom shared.

Nah, it's lousy and full of losers with stupid names!

justinm · Post by **justinm** » Tue 09/05/06 4:13 pm

I have a set of JJs in a silvertone twin twelve and it is the loudest rip-snorin' distorted 1484 i've ever played. it's actually a force to be reconed with on stage. though around the same time i added the JJs i also added a weber c12Q copy and a ceramic silver bell, so they are part of the new sound this amp now has.

I've been testing Ruby 6L6GCMSTRs in other amps and I'm very happy with them. They have a well rounded sound. I havn't tried them in a vintage amp yet though. I also like how Magic Parts is setup as far as testing and their 6 month guarantee. They do a very good job testing and labeling everything.

j

Post by **zaphod_phil** » Tue 09/05/06 4:35 pm

They also did a heck of a good job sueing Paul Ruby for using his own name for his amp hobby and web site.

kd · Post by kd » Tue 09/05/06 4:53 pm

I finally ended up buying a pair of Shuguang 6L6 WGC tubes. They're blackplate, shortbottle tubes. One of the distributors is TAD und the number TAD6L6 WGC STR. These are nice sounding tubes with a nice rounded overall sound, no harshness at all. From the reviews I've read, they are well regarded for their sound and durability.

Ken

dartanion · Post by **dartanion** » Tue 09/05/06 5:14 pm

My second guitarist keeps buying Ruby Tubes 6L6GCMSTRs and they literally last about 8-9 months before they are cooked. They sound ok, but nothing to go ape-**** over.

I haven't tried a 6L6 that I like better than the true RCA Blackplates. Nothing compares. I am still playing on the original set in my '69 SFTR!!! Mighty impressive longevity and tone.

Post by **markh** » Tue 09/05/06 6:10 pm

justinm wrote:...it's actually a force to be reconed with...

I'm sure you meant "reckoned with", but I like the typo better.

--mark h

dotfret · Post by **dotfret** » Thu 09/07/06 11:33 pm

Me myself I recently got desperate and substituted a pair of 807s instead - I just thought they might work. They look like coke bottles with nipples, they sound like NOTHING ON EARTH and if you see them cheap and your B+ is in the right range, buy them. They are supposed to be RF amp valves - they handle AF with coloration that Charlie Watkins could only imagine. Fiddle with your tail resistor values, muck about with the feeds - they precede the classics and transcend them. My present no1 has EF806S x 2 into a 12AX7 and the 2 x 807 vicious stage, and it bites ladies legs until they dance! I hesitate to substitute the ECC83 in case it is too much for human ears. Thats all I'm saying - but that's a plenty.

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