Phoo, graphite or nickel ? I just put them away again in their safe box so that they can sleep some more years. They were black, that's all I know. Never have done anything with them. There is only this schematic with the 6384 ( I have them as well ) that keeps coming to mind. The Guided Missile Amp it is called.
I have the chassis but with tube amps I am just a lazy guy.
Never liked the hardwiring and the chassis-drilling etc.
I have the chassis but with tube amps I am just a lazy guy.
Never liked the hardwiring and the chassis-drilling etc.
Extract:
http://www.fnrf.science.cmu.ac.th/theory/klystron/How%20A%20Vacuum%20Tube%20Works.html
And, the hot graphite plate will tend to react with, and absorb, any free oxygen in the tube. The Svetlana SV572 series and 572B use graphite plates coated with purified titanium, a combination which gives excellent gettering action. A graphite plate is much more expensive to make than a metal plate of the same size, so it is only used when maximum power capability is needed.
http://www.fnrf.science.cmu.ac.th/theory/klystron/How%20A%20Vacuum%20Tube%20Works.html
And, the hot graphite plate will tend to react with, and absorb, any free oxygen in the tube. The Svetlana SV572 series and 572B use graphite plates coated with purified titanium, a combination which gives excellent gettering action. A graphite plate is much more expensive to make than a metal plate of the same size, so it is only used when maximum power capability is needed.
Jean-Paul,
Actually, I once heard that barium getters were only effective against oxygen.
I don't know if that's true, but many externally gassed tubes do glow blue at first.
Frank,
What is the 2nd function of the getter that you were intimating?
What I've been getting at is WHY, if you can make an effective graphite getter, would you go to the expense of a baruim getter as well?
Actually, I once heard that barium getters were only effective against oxygen.
I don't know if that's true, but many externally gassed tubes do glow blue at first.
Frank,
What is the 2nd function of the getter that you were intimating?
What I've been getting at is WHY, if you can make an effective graphite getter, would you go to the expense of a baruim getter as well?
Re: FALSE MODESTY?
Most of the SE Pentode EL84 amps i have (that indicate the primary impedance -- all German) have 7-10k primaries.
I plan on using a 6N1P (a buck each from Gintaris) as a starter driver tube when i get around to building a from the ground up SE EL84.
I used my SEP EL84 dumpster amp (4W) for some time on my 91 dB/1W speakers. It was mostly fine, but was definetly straining when i wanted to push the volume (my room is 24'x36'x10' ceilings (ave).
dave
fdegrove said:
Most of the SE Pentode EL84 amps i have (that indicate the primary impedance -- all German) have 7-10k primaries.
I plan on using a 6N1P (a buck each from Gintaris) as a starter driver tube when i get around to building a from the ground up SE EL84.
I used my SEP EL84 dumpster amp (4W) for some time on my 91 dB/1W speakers. It was mostly fine, but was definetly straining when i wanted to push the volume (my room is 24'x36'x10' ceilings (ave).
dave
I've noticed that dave. Most of the american designs I've looked at use a 5K primary and the european designs used the higher 7- 8K
primaries. I wonder where the sweet spot is. By that I mean the best trade off between damping and power transfer. BTW that is a large room to try to fill with sound with a 4 watt amp driving 91dB speakers. I'll bet the little guy was sweating.
I'll change the caps to .1 uF Joel. Thanks. Do you think that the 5687 will do the job? I only need a gain of about 5 or so.
G
primaries. I wonder where the sweet spot is. By that I mean the best trade off between damping and power transfer. BTW that is a large room to try to fill with sound with a 4 watt amp driving 91dB speakers. I'll bet the little guy was sweating.
I'll change the caps to .1 uF Joel. Thanks. Do you think that the 5687 will do the job? I only need a gain of about 5 or so.
G
GETTERS.
Hi,
Other than the usual tube manuals,this is a nice read:
Svetlana doc.
So other than burning off gaseous content the getter has a very important function:
It keeps the vacuum at the correct level.
There is more to say about this but I'll stop barking for today.
Cheers,
Hi,
Other than the usual tube manuals,this is a nice read:
Svetlana doc.
So other than burning off gaseous content the getter has a very important function:
It keeps the vacuum at the correct level.
There is more to say about this but I'll stop barking for today.
Cheers,
G said:
You will need more than that for most of the cd's I've ever run across. Yes, test CD's, etc, will put out 2V RMS, but that is unusual for a commercial music CD. I get arguments about this all the time from various forum people, but it's a very simple task to play some CD's and measure the output! I have done that.
Figure on needing a gain of 15 or more, to be safe.
Splitting hairs..
Well Frank, one follows from the other. In that case the getter also stops the heater from burning out Etc
I can't remember what vacuum we used to pump them to, but metal gas emission was a serious problem - so much so that it was necessary to ramp up the filament voltage as the vacuum got harder, to warm the gun. That was in addition to taking the whole assembly to a high temperature in an oven.
The best part was firing the getter with the RF heater
No graphite in CRT guns Maybe that's why they don't sound so good.
Well Frank, one follows from the other.
In that case the getter also stops the heater from burning out EtcI can't remember what vacuum we used to pump them to, but metal gas emission was a serious problem - so much so that it was necessary to ramp up the filament voltage as the vacuum got harder, to warm the gun. That was in addition to taking the whole assembly to a high temperature in an oven.
The best part was firing the getter with the RF heater
No graphite in CRT guns
Maybe that's why they don't sound so good.
G said:
Most of them are fairly modest in size, but i have one set from an East German hifi that are larger than the Dyna Mk III OPTs i have.
BTW that is a large room to try to fill with sound with a 4 watt amp driving 91dB speakers. I'll bet the little guy was sweating.
That would be a good description. It was a little less strained when i was running the sub with the extra 2x70 of sand power. My speakers are bipoles so i'm going to double my power by using 4 amps (and eventually more efficient speakers).
dave
5 Watts?
Hi G,
Did you ever determine if/how the el 84 yields 5w like the Zen Decware?
Also, if I understand the data sheets for this tube, the screen is to be connected to the plate to config as triode (the suppressor is internally tied to the cathode). However, the literature on pentodes suggest exactly this same configuration--so, how is this reconciled? That is, data sheet says screen tied to plate, suppressor tied to cathode = triode mode. Literature says the same config but it is in pentode mode.
Can you help me understand this?
Thank you,
Rick
Hi G,
Did you ever determine if/how the el 84 yields 5w like the Zen Decware?
Also, if I understand the data sheets for this tube, the screen is to be connected to the plate to config as triode (the suppressor is internally tied to the cathode). However, the literature on pentodes suggest exactly this same configuration--so, how is this reconciled? That is, data sheet says screen tied to plate, suppressor tied to cathode = triode mode. Literature says the same config but it is in pentode mode.
Can you help me understand this?
Thank you,
Rick
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