Hi - I recently got an old (68-69) Teisco guitaramp.
Works great but I like to be prepared and have a set of
spare output tubes.

The amp has two 6L6 RCA tubes.
I have looked at Harma tubes at watfordvalves.com as
replacement however it seems 6L6 comes in different
variations of which I like the description of 6L6GC.

Not knowing if this choice is good or they will fit the amp
it seems wise to ask the groups opinion before ordering.

I also look for spare tubes for my main amp which currently
has 4 EL34 Mullard tubes.
Again I look at Harma and again I don't know if it's the right
choice.

Thanks for reading

Steen

Steen wrote:
Hi - I recently got an old (68-69) Teisco guitaramp.
Works great but I like to be prepared and have a set of
spare output tubes.

The amp has two 6L6 RCA tubes.
I have looked at Harma tubes at watfordvalves.com as
replacement however it seems 6L6 comes in different
variations of which I like the description of 6L6GC.

Not knowing if this choice is good or they will fit the amp
it seems wise to ask the groups opinion before ordering.

I also look for spare tubes for my main amp which currently
has 4 EL34 Mullard tubes.
Again I look at Harma and again I don't know if it's the right
choice.

Thanks for reading

Steen

Yes, the 6L6 family is one of the most successful lines of tubes ever
made. And you're right, a great many different variants have been
manufactured over the years.

The 6L6, 6L6G, 6L6GA and 6L6GB are all basically interchangeable. The
difference is mainly in the "bottle," 6L6 was in the straight-sided
metal bottle, the G variant was a glass ST ("coke-bottle") style, and
GA/GB were in straight-sided glass envelopes.

The 6L6GC is actually a *different* device, sporting a considerably
higher maximum power rating than its predecessors. You can therefore use
a 6L6GC in any 6L6 design. However, note that putting a 6L6GC in an
amplifier designed for 6L6 will generally *not* increase the amp's
output power! That's more dependant on the power supply and output
transformers.

As to the Harma brand - you have to understand that this is simply a
Watford branding. What is it really? Well, they're very quick to say
that "it's not Chinese," but they never do say what it *is*. Might be
any of a number of Russian or Yugoslav manufacturers, all of which are
just fine. (In all fairness, even the Chinese ones can be "just fine",
but tend to be somewhat less rugged.)

The original metal 6L6 is still quite readily available as "new
old-stock", and its price is quite reasonable (probably at least partly
because of its rather plain appearance). For instance, Antique
Electronics http://www.tubesandmore.com/ has them for USD $17.95. This
would actually be my choice for use in a guitar amp, especially if it's
going to spend much time on the road. Others will have very different
opinions, it seems that every guitarist has his own favourite that
stands head-and-shoulders above the rest.

The EL34 is functionally very similar to the 6L6 family, though again
there will be those who consider such a statement heretical. And again,
any of the reputable Russian or Yugoslav brands (JJ/Tesla, Svetlana,
Sovtek, etc.) should be fine.

Cheers,
Fred
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
| http://www.dogstar.dantimax.dk |
+--------------------------------------------+

Nothing beats 6P3S commerade ;-)

Give them a whirl.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*

Steen wrote:

Hi - I recently got an old (68-69) Teisco guitaramp.
Works great but I like to be prepared and have a set of
spare output tubes.

The amp has two 6L6 RCA tubes.

Are they labelled 6L6 only? Look on the tubes themselves - not on the
chassis.

If they are indeed RCA 6L6 tubes they are black metal tubes.

6L6 tubes can be replaced by any type of 6L6 tubes you can get. The
Russian 6L6GB equivalent (sometimes called 6L6GT) should work well, as
will the 6L6GC tubes from Sovtek, Svetlana or JJ. Have a look at
http://triodeel.com/ for good service and prices.

Best regards,

Mikkel C. Simonsen