807 tube questions

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Daniele

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Dec 18, 2002, 7:40:31 PM12/18/02
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Just a couple:

- 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?

Thanksss
^__^
Daniele


kenneth scharf

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Dec 18, 2002, 8:43:54 PM12/18/02
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Since the 807 and the 6L6 have the same plate wattage rating (25 watts) and
in single ended operation (class A) the plate rating is the limiting
factor I would
think that the 807 would give identical power output to the 6L6. OTHO
you could
operate the 807 at higher voltage which would yield a higher output
impedance
and maybe less distortion.

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
volts). These
are at ICAS ratings, for CCS at 600 volts up to 55 watts AB1 and 90
watts AB2.


Fred Nachbaur

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Dec 18, 2002, 8:49:01 PM12/18/02
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Daniele wrote:
> 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
12 watts.

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.

Cheers,
Fred [whose handle on an electronics forum is "807"]
--
+--------------------------------------------+
| Music: http://www3.telus.net/dogstarmusic/ |
| Projects, Vacuum Tubes & other stuff: |
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Tom Bavis

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Dec 18, 2002, 9:24:48 PM12/18/02
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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.

Daniele

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Dec 18, 2002, 9:33:56 PM12/18/02
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Thanks for the answers, this was because
i saw in my tube manual an output of 120w with 600V
and i was not able to explain me why so
different prices with 300b and expecially with
the 6L6 if it can be a substitute... another audiophile mania?
^__^
Daniele

Mark Oppat

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Dec 18, 2002, 10:31:36 PM12/18/02
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Is the 6BG6 a direct sub for the 6L6 in all cases, except for the
connections? I recall Mike Male selling base adapters at Elgin for those,
mostly for guitar players who wanted to keep tube costs down. Anyone on
here used them in guitar amps?
I know the 6L6, G, GA, and GB were 19W rated, the GC kicked up to 30W. So
the 6BG6 is really only a sub for the pre"GC" versions.
What happens in a git amp when the G, GA or GB are used in place of the GC?
I dont play guitar, so my "hands on" experience is nil. I sell a fair
number of tubes to local guitar players, but just usually match their old
ones.

Mark Oppat
Antique Audio


"Fred Nachbaur" <fnac...@netscape.net> wrote in message
news:3E012591...@netscape.net...

Maaaaaark

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Dec 18, 2002, 10:52:52 PM12/18/02
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> I know the 6L6, G, GA, and GB were 19W rated, the GC kicked up to 30W.
So
> the 6BG6 is really only a sub for the pre"GC" versions.
> What happens in a git amp when the G, GA or GB are used in place of the
GC?

orange plate...

shorter life (very short I would assume..)


Maaaaaark

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Dec 18, 2002, 10:55:49 PM12/18/02
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"Daniele" <prot...@XXXXXXXlibero.it> wrote in message
news:oeaM9.30423$TC5.9...@twister1.libero.it...

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
too expensive.

(some of the neat transmitting DHTs are still quite economical, probably
more fun too..)

Fred Nachbaur

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Dec 19, 2002, 1:15:44 AM12/19/02
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Mark Oppat wrote:
> Is the 6BG6 a direct sub for the 6L6 in all cases, except for the
> connections? I recall Mike Male selling base adapters at Elgin for those,
> mostly for guitar players who wanted to keep tube costs down. Anyone on
> here used them in guitar amps?
> I know the 6L6, G, GA, and GB were 19W rated, the GC kicked up to 30W. So
> the 6BG6 is really only a sub for the pre"GC" versions.
> What happens in a git amp when the G, GA or GB are used in place of the GC?
> I dont play guitar, so my "hands on" experience is nil. I sell a fair
> number of tubes to local guitar players, but just usually match their old
> ones.
>
> Mark Oppat
> Antique Audio

Hi Mark,

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.

Cheers,
Fred

That Larry

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Dec 19, 2002, 1:16:22 AM12/19/02
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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!!

http://www.tubebuilder.com/images/tubedata/833a.pdf
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!


http://www.transmitter.be/rca-bhf1a.html

Here's our old girl, a Gates BC1E....(c;
http://66.181.162.202/wa2iac/bc1e/
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!!


That Larry

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Dec 19, 2002, 1:22:48 AM12/19/02
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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....

http://www.wavac-audio.gr.jp/he833_e.html

I'll be it has the "warmest" smooth freq response.....(c;


Larry

Extremely intelligent life must exist in the universe.
You can tell because they never tried to contact us.

Fred Nachbaur

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Dec 19, 2002, 1:29:36 AM12/19/02
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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
triode-mode amp.

Best regards,

That Larry

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Dec 19, 2002, 1:34:19 AM12/19/02
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On Thu, 19 Dec 2002 06:22:48 GMT, no...@home.com (That Larry) wrote:

>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....
>
>http://www.wavac-audio.gr.jp/he833_e.html
>
>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
output!

PT Barnum was WRONG.....It's every 8 seconds!

Larry....Can we sell you a $10,000 Usher 12" speaker to go with that?

kenneth scharf

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Dec 19, 2002, 7:44:06 PM12/19/02
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The 6L6G, GA and GB have the same parameters as the 807, 1625, and 6BG6G
and GA.
The 6L6GC has higher screen dissapation, and a higher max screen voltage
rating.
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
T14 bulbs.
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
which is
present on the 807 and 1625 tubes. Also not that some 807's and 1625's
had ceramic
spacers mounting the plate to the mica wafers. (some 6BG6G's had them
too). Later
807's lacked them.

The 6L6GC is a heavy duty version of the 6L6 (G,GA,and GB), but few amps
pushed them
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?)


kenneth scharf

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Dec 19, 2002, 7:48:29 PM12/19/02
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> 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
> triode-mode amp.
>

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.

Mark Oppat

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Dec 19, 2002, 9:46:51 PM12/19/02
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Good note, Fred. However, does anyone here have experience using other
tubes (6L6 G, GA, GB, or other types) in place of the 6L6GC in a guitar or
similar amp?

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
normally?

Mark


"Fred Nachbaur" <fnac...@netscape.net> wrote in message

news:3E016412...@netscape.net...

Maaaaaark

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Dec 20, 2002, 12:04:51 AM12/20/02
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I ran a 6L6GB @ ~30w diss once.

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
though.

"Mark Oppat" <mop...@flash.net> wrote in message
news:vwvM9.1768$1j5....@newssvr16.news.prodigy.com...

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