- How many watts can give an 807 in single ended output stages?
- I've read somewhere that can be used instead of 6L6 'rewiring plates'
is this practice useful?
In class AB1 (push pull) the 807 will give up to 75 watts
(at 750 volts). In class AB2 it will give up to 120 watts (at 750
are at ICAS ratings, for CCS at 600 volts up to 55 watts AB1 and 90
> Just a couple:
> - How many watts can give an 807 in single ended output stages?
It doesn't do class A exceptionally well. In triode connection, Va 300v,
about 3 watts, maybe a bit more. As a tetrode, Va 500v, Vg2 250v, about
Where it really shines is in push-pull class AB2 where you can get about
70 watts out of a pair, or even approaching 100 watts in class B (Va
750v, Vg2 300v).
> - I've read somewhere that can be used instead of 6L6 'rewiring plates'
> is this practice useful?
Yes, it's very similar to the 6L6GC in many ways. It doesn't like screen
voltages higher than about 300 though, so I'm not sure how well it would
do in ultralinear mode. Other than that, you can pretty much convert
between the two types with only minor biasing changes.
Fred [whose handle on an electronics forum is "807"]
| Music: http://www3.telus.net/dogstarmusic/ |
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An 807 IS pretty much a 6L6 with a plate cap and 5-pin base (if it has
an octal base, it's a 6BG6...) The plate cap allows higher plate
voltages, making it better for transmitter use. With higher voltages,
you should be able to get 50-60W in push-pull AB - but not in
ultralinear (screen tap on transformer), since the screen voltage
limit is lower. Class A single ended is about 6W in pentode and maybe
2.5 in triode.
"Fred Nachbaur" <fnac...@netscape.net> wrote in message
shorter life (very short I would assume..)
"Daniele" <prot...@XXXXXXXlibero.it> wrote in message
300B and 6L6 are entirely different tubes, hell one is a triode and one is a
pentode. one has a cathode, one is directly heated.
bottom line is, the audiophools made most directly heated power triodes way
(some of the neat transmitting DHTs are still quite economical, probably
more fun too..)
6BG6 is essentially an 807 repackaged for TV horizontal output use. The
only real difference is the octal socket instead of the 5-pin. (Many but
not all 807's also had a shield around the wires leading out from the
bottom, below the lower mica insulator, which was omitted on the 6BG6.)
If your 6L6GC design uses a screen voltage over 300-350 or so, I
wouldn't suggest using a 6BG6 or 807. Otherwise - have at it.
6L6, 6L6G, GA, GB all have essentially the same ratings as you pointed
out. 6L6GC really should have been given a new name, it would have
caused a lot of confusion over the years had they done so. It's a
different tube entirely; more like the 807 as has been pointed out. So
if a 6L6, G, GA, GB is used in a design meant to take advantage of the
GC's higher ratings, it won't live long. However, you can with impunity
use a GC (or 807) in any design intended for 6L6, G, GA, GB.
If you REALLY want to impress them, look up a pair of 833A in Class B
push pull. Their directly heated filaments light up very brightly and
you can run them with plates as red as a beat at full volume at about
1650 watts (CCS) or 1900 watts (ICAS) if you've the plate supply and a
good modulation....er, ah....output transformer...(c; Used to run a
pair of 833A modulating a pair of 833A on a 1KW AM daytimer. Makes a
great phono oscillator for the neighborhood, too! I seem to remember
we operated them at 3000V and about 220 ma to get 500 watts out of
them to plate modulate the 1KW transmitter to...er, ah....99%
modulation. (You always put the stronger tube in the right socket so
you could fudge on positive modulation for a little more ERP, too.)
1650 watts will drive most any speaker system. Put them in a cabinet
with a big window towards the audience so they can watch the plates
light up on loud music cherry red with a big VU meter and plate
current meter above them on a nice sloping panel.....(c; They idle at
about 150 watts per tube and that keeps the plates just barely glowing
with 100 ma of idle current for triode linearity. You'll need a -70V
bias supply, but no finicky screen supply.
Man, with a pair of 833A you can damage a BUILDING!!
Here's the spec sheet. Cheap to build. Use hose clamps to connect to
the big pins. Blow some air over the filament seals to protect them.
They don't need fancy chimneys and aircooled sockets. Fils are 10V x
10A...100W. It'll light up a whole room with two tubes!! You can get
the tubes for free at any broadcast station that uses them. They'll
have a few hundred thousand hours on them, just barely broken in good!
Here's our old girl, a Gates BC1E....(c;
I used to stand at the contactor switches during major lightning
storms. Nature would knock it in the head, then I'd press the buttons
and she'd pop right back online every time....
Geez, that's over 3KW in a stereo! You don't HAVE to run them at full
power, ya know!!
Larry....we'll be listening for ya...way over here!!
>If you REALLY want to impress them, look up a pair of 833A in Class B
>push pull. Their directly heated filaments light up very brightly and
Cool! Here's an audiophile amp with a single 833A and 100W output....
I'll be it has the "warmest" smooth freq response.....(c;
Extremely intelligent life must exist in the universe.
You can tell because they never tried to contact us.
Good questions. There are a few factors involved; the first is that
807's and 6L6's were made in vast quantities for the war effort, and
afterwards for radio gear and audio equipment. The 300B, on the other
hand, was mainly made by Western Electric specifically for telephone
repeaters and similar "in house" applications. As a result, the 300B is
quite scarce nowadays, whereas the 807 and 6L6 are still quite plentiful.
The 300B is indeed a lovely valve. Look at its curves, and draw a load
line through them. It's about as linear a triode as you'll find
anywhere. That being said, while the 300B is about 50 times as expensive
as an 807, it's certainly not "50 times as good." I think the average
listener, even the average audiophile, would find it difficult to tell
the difference between a well-designed 300B amp and a well-designed 807
>On Thu, 19 Dec 2002 06:16:22 GMT, no...@home.com (That Larry) wrote:
>>If you REALLY want to impress them, look up a pair of 833A in Class B
>>push pull. Their directly heated filaments light up very brightly and
>Cool! Here's an audiophile amp with a single 833A and 100W output....
>I'll be it has the "warmest" smooth freq response.....(c;
I found you a dealer! http://www.tmhaudio.com/
He wants $47,000 EACH......almost $100K for a stereo with 200W of
PT Barnum was WRONG.....It's every 8 seconds!
Larry....Can we sell you a $10,000 Usher 12" speaker to go with that?
The 6L6G, GA and GB have the same parameters as the 807, 1625, and 6BG6G
The 6L6GC has higher screen dissapation, and a higher max screen voltage
But note that ANY of the 6L6 family tubes CAN be used with up to 400v or so
on the screen IF THE SCREEN IS CONNECTED TO A TAP ON THE OUTPUT
TRANSFORMER (Ultra Linear mode).
The 6L6G has an ST16 bulb, the GA has an ST14 bulb, the GB and GC have
The 807, 1625 and 6BG6G have ST14 bulbs, the GA has a T14 bulb. Otherwise
these tubes are all similar, but note that the interelectrode
capacitance is higher on the
6BG6's due to the lack of a shield on the bottom and top of the bulb
present on the 807 and 1625 tubes. Also not that some 807's and 1625's
spacers mounting the plate to the mica wafers. (some 6BG6G's had them
807's lacked them.
The 6L6GC is a heavy duty version of the 6L6 (G,GA,and GB), but few amps
so hard that you couldn't sub an older 6L6 for it. Actually the 6L6GC
is similar to the
7027A which is probably the number the 6L6GC should have been given
(maybe the 7027
was going to be called the 6L6GD?)
The 300B was actually used in theatre amplifiers, I didn't think it was a
telephone repeater bulb. WE 300B's may be scarce, but there are plenty
of new manufacture 300B's being made in Asia that are of very good quality.
Obviously if you push it hard a lower rated tube would decay. Or, would
you get to distortion faster, satisfying the proper distortion or "tone" the
player wants without the higher volume needed to push it to that point
"Fred Nachbaur" <fnac...@netscape.net> wrote in message
sounded fine, but the plate was a little orange (gee.. I wonder why)
I still need to try something with my 807s, I've got no darn 5pin sockets
"Mark Oppat" <mop...@flash.net> wrote in message