6922 working voltage & current
Hendrik Skarpeid
I am trying to find the sweet spot on a Sovtek 6922.
I was thinking about 300V supply, with a 100k load at 1.5mA
This gives about 150VDC on the plate.
I have heard that the 6922 don't sound good at high plate voltages. Is
150VDC to high?
Any comments?
Hendrik
Dieter Wolbart
were they sound the best. I have a pre where the plate voltage is "only"
45VDC and they just sound wonderful.
- Dieter
Kevin Killebrew
caps are only rated at 63v.
KK
P. de R. L.
For a start, they are more linear there.
You do not say what the application is, but I would run a lot more current.
That way you get the gm up, thereby improving noise performance and of
course, lowering your output resistance.
The other thing with these is to watch out for UHF oscillation - grid
stoppers should be fitted - as close to the valve as possible.
paul leclercq
Hendrik Skarpeid <hendrik....@phontech.no> wrote in message
news:j_h95.20580$R7.36...@juliett.dax.net...
Darryl
You were saying......
>I agree with the others on this; run them <100V.
>
>For a start, they are more linear there.
>
>You do not say what the application is, but I would run a lot more current.
What a coincidence, I just posted elsewhere about this. Yep, I agree, run them
up around 10ma or so, with 90 on the anode.
>That way you get the gm up, thereby improving noise performance and of
>course, lowering your output resistance.
Yes, I suspect that is why so many people seem to be saying they need super low
noise versions of this family of tubes. I'd like to know for sure, but I suspect
that the designs of their equipment are such that they are running down near 1
or 2 ma like a 12AX7 or something.
Dazz
Hendrik Skarpeid
I suspect I will be using paralell 12AX7's instead, with somewhat larger
plate resistor.
I wanted to use the 6922 as a driver for a 6B4G in a loftin white circuit. I
have to have about 90Vpp drive for the 6B4G. Thats why I wanted to have
150VDC on the plate.
I wanted to use the 6922 for its low plate resistance, and I dont absolutely
need the high gain of the 12AX7's, as I already own a tube preamp quite
capable of freaking out the 12AX7.
The 6922's will probably end up in my heavily modified Pioneer CD player
(somewhat of a mod-testbed actually)
I want to use a cathode follower in the CD-player, how's the 6922 in this
position?
Otherwise I have to use transformer loading with line output transformers
7.2/1 ratio. Hmmmm, lots of decisions and lots to be learned.....
Hendrik
Frank R.
follower have a close look into Allen Wright Tube Preamp Book:
www.vacuumstate.com
...or valley and wallman 'Tube Amplifiers'.
Regards
Frank
"Hendrik Skarpeid" <hendrik....@phontech.no> schrieb im Newsbeitrag
news:Uppa5.22057$R7.39...@juliett.dax.net...
yfconan
dkl...@removethisbit.ieee.org wrote:
> What a coincidence, I just posted elsewhere about this. Yep, I agree,
run them
> up around 10ma or so, with 90 on the anode.
Do you mean each section around 10 mA or two parallel sections at 10 mA
(each triode section at 5 mA)?
Sent via Deja.com http://www.deja.com/
Before you buy.
Darryl
You were saying......
>In article <bpldmscs2ns2i8536...@4ax.com>,
> dkl...@removethisbit.ieee.org wrote:
>
>> What a coincidence, I just posted elsewhere about this. Yep, I agree,
>run them
>> up around 10ma or so, with 90 on the anode.
>
>Do you mean each section around 10 mA or two parallel sections at 10 mA
>(each triode section at 5 mA)?
Each. They are rated at 15ma each and 1.8 watts.
Dazz
Terry Demol
Darryl wrote in message ...
Be careful not to exceed the combined anode
(both anodes operating) dissipation of 2 watts.
Terry
>
>Dazz
Darryl
You were saying......
>>Each. They are rated at 15ma each and 1.8 watts.
>
>
>Be careful not to exceed the combined anode
>(both anodes operating) dissipation of 2 watts.
>
>Terry
Sorry, yes. The recommended 90 volts at 0.01 A gives 0.9 watts ea, or 1.8 watts
total, which gives a little leeway on that limit.
Just as an aside. If the tube is cooled, say with a fan, would this allow more
power to be tolerated (not that I need it... just curious).
Dazz
Ken Gilbert
> Just as an aside. If the tube is cooled, say with a fan, would this
allow more
> power to be tolerated (not that I need it... just curious).
d,
yes, in my experience you can indeed burn more power inside the
envelope if you remove it faster from the outside. just keep in mind
that max cathode current, which cannot be exceeded no matter what (at
least not without adversely affecting tube life).
kg
--
I know that the twelve notes in each octave and the varieties
of rhythm offer me opportunities that all of human genius
will never exhaust. --Igor Stravinski
Andrew Cowley
>
> > Just as an aside. If the tube is cooled, say with a fan, would this
> allow more
> > power to be tolerated (not that I need it... just curious).
>
> d,
>
> yes, in my experience you can indeed burn more power inside the
> envelope if you remove it faster from the outside. just keep in mind
> that max cathode current, which cannot be exceeded no matter what (at
> least not without adversely affecting tube life).
>
They will however tolerate up to 100mA for _short_ periods without any
discernable damage. The curves I have go up that far. They also work
as valves down to less than 6 volts, although at very low currents and,
presumably, with appalling noise. (Mullard E88CC's)
Andy Cowley
John Harper
Andrew Cowley wrote in message <39743494...@uwe.ac.uk>...
>
>They will however tolerate up to 100mA for _short_ periods without any
>discernable damage. The curves I have go up that far. They also work
>as valves down to less than 6 volts, although at very low currents and,
>presumably, with appalling noise. (Mullard E88CC's)
>
which had a faulty switch when I bought it, the effect of which was that the
input tube (an ECC85, I think) had 0V - and it worked. (The reason is that
the space charge surrounding the cathode is at about -0.6V, so actually
there is a tiny relative positive voltage on the plate). I don't see why
noise
will be appalling - although it will be higher than usual because of the low
Gm at the kind of current you'd be getting.
As far as maximum current is concerned, the cathode emission of even a
small tube is several 100 mA, you can certainly pull 100mA for a pulse
of a few uS or so since the thermal inertia of the plate will mean there is
no
significant heating. The ECC88/6DJ8 was not intended for pulse applications
so this figure was not given, but for example the 7119/E182CC - which was
intended for pulse applications and so gives this figure - is rated at 400
mA
for 10 uS - and 200 mA grid current for the same pulse!
John
John Harper
margin. The first stage of a radio receiver is working with mV level
signals at the output, so this is not an issue, but the higher signal levels
involved in audio mean that it will be clipping - under those signals
strong RF can break through and will be rectified due to the
non-linearity.
The kind of currents that you will be getting here mean that the tube is
near-enough cut off the whole time, hence cathode poisoning will happen
as much as if there was no plate voltage, or close to. However some
premium tubes were specifically designed to resist poisoning under
these circumstances (e.g. 7119) - no idea if this is the case for 6067.
John
Ugga Botha wrote in message <39756d31...@news1.c2i.net>...
><snip>
>I built a test mockup on a breadboard of some guitar overdrive circuit
>using both sections of a 6067 with 6V on the plate. Under this
>starved-plate condition different tubes gave very different sound and
>the circuit is quite noisy (sometimes it even picks up several radio
>stations simultaniously). I have thought that when I get to build it
>proper in a shielded metal box all the noise will go away, but maybe
>this low plate voltage still will give noise. I have also wondered if
>the need for a standby switch to prevent cathode poisoning reduses
>with redused plate voltage. Anyone?
>
>Ugga
>
>