The filament of a CV4038 takes 0.95 A at 6.3 V, producing 6 Watt of heat. TS specified in post #7 that the tube he/she is looking for should be able to run at 60/100V and at 60 mA. With these numbers the plate would be dissipating an additional 3.6 to 6 Watt.
Personally I would not want a tube inside a chassis that is radiating so much heat, even if the plate dissipation would be lower than 3.6 Watt.
Personally I would not want a tube inside a chassis that is radiating so much heat, even if the plate dissipation would be lower than 3.6 Watt.
Thank you all for information.
List of octal tubes:
6L6 = 6P3S (rus) 0.9A
6S19P (rus) 9pin 1A
6Y6 pentode 1.2A
E235L pentode 1.2A
6CK4 1.25A
6BX7 double 1.5A
S11E12 tetrode 1.6A
6N5S (rus) double 2.5A
6N13S (rus) 2.5A
List of octal tubes:
6L6 = 6P3S (rus) 0.9A
6S19P (rus) 9pin 1A
6Y6 pentode 1.2A
E235L pentode 1.2A
6CK4 1.25A
6BX7 double 1.5A
S11E12 tetrode 1.6A
6N5S (rus) double 2.5A
6N13S (rus) 2.5A
I have quite a few of them running, absolutely perfect and original GEC mil spec quality.
Have you seen the size/quality of glass?
They are designed to dissipate 15W steady, for decades, which is well in excess of what any 6V6 or EL84 can manage.
I am running them at a steady 30-40mA with 125V but they have at bursts to deliver another 60ma, so dead easy 10-12W + the 6W of heater.
It's no worse than a small car light bulb or map light!
As for the S11E12, (STC), I have few of those.
Never was that impressed and TBQH, as an output valve it's really rubbish.
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oh, I can assure you, squeezing in a mini tag board c/w series stab triode, with a partridge choke in behind it is peanuts compared with wiring up triple triode compactrons...
I realised point to point involving 12 pin valves involved thinking in layers, and it takes some skill to work out how on earth to squeeze all those bits into one of the most compact dual 100W amps ever made, especially as it involves totally changing the original design conception of the amp from A-Z!
But there again, that particular amp is becoming rare now, there are none apart from these in Europe, and once sorted sound really like nothing else.
Simply magic, with giant power output.
I realised point to point involving 12 pin valves involved thinking in layers, and it takes some skill to work out how on earth to squeeze all those bits into one of the most compact dual 100W amps ever made, especially as it involves totally changing the original design conception of the amp from A-Z!
But there again, that particular amp is becoming rare now, there are none apart from these in Europe, and once sorted sound really like nothing else.
Simply magic, with giant power output.
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50W Amp with in Chassis Screen Regulator
This one is PP 6550s or PP KT88s. The B+ is about 500V, the screens regulated at 380-400V. The screen regulator losser is both sections of a 7AU7, the error amp a 6AU6 & the reference a 991 Neon Regulator.
The 7AU7 heater is parallel connected for 3.5V operation thru a dropping resistor from the 5V rectifier winding. The HV rectifier is a 5AR4.
The 6AU6 error amp is visible inside, behind the center of the front panel. It & the 7AU7 are on a brass plate with some of the regulator components.
The iron is mostly Hammond from the mid-50s. This I built circa 1956.🙂
This one is PP 6550s or PP KT88s. The B+ is about 500V, the screens regulated at 380-400V. The screen regulator losser is both sections of a 7AU7, the error amp a 6AU6 & the reference a 991 Neon Regulator.
The 7AU7 heater is parallel connected for 3.5V operation thru a dropping resistor from the 5V rectifier winding. The HV rectifier is a 5AR4.
The 6AU6 error amp is visible inside, behind the center of the front panel. It & the 7AU7 are on a brass plate with some of the regulator components.
The iron is mostly Hammond from the mid-50s. This I built circa 1956.🙂
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Perhaps add the 6AU5GT in triode. Triode curves for 6AU5
E235L is by far the best choice, i think. combining low internal resistance with a slightly higher mu than the double triodes. Its a adaptation of the EL36 without a topcap. it has the Ri of a 6C19 but higher dissipation.
If magnoval is acceptable, the PL508/EL508 could also work i think.
For series stabilizer, current source load a EF184 and you will have a very high gain error amplifier.
It's the heat that is radiated by the CV4038 pass tube when situated inside the chassis that doesn't appeal to me, especially whith many other parts squeezed in there too. That is why in post #21: "...that is radiating so much heat".
Appealing to who?
Have you actually tried it?
I have, and that Bogen amp originally had a full OCTET of 8417 running at 25W idle (that's 200W!!).
It's unneccessary and stupid to run more than 2 pairs,and doesn't affect either output power or longevity/
so:-
When you have instead 4 x 35W BT upstairs at 650V, (with 25W+ each Pa at idle + 10W per heater) + a couple of compactrons and a 350VA transformer....
6W under the chassis is absolute peanuts compared with the flaring off of of all that above chassis power.
When you have a large complete dual channel amp running at somewhere around 50-60C I literally no longer care about a few lost watts under the chassis, it's barely 8-10% of the total, and that is what matters.
Have you actually tried it?
I have, and that Bogen amp originally had a full OCTET of 8417 running at 25W idle (that's 200W!!).
It's unneccessary and stupid to run more than 2 pairs,and doesn't affect either output power or longevity/
so:-
When you have instead 4 x 35W BT upstairs at 650V, (with 25W+ each Pa at idle + 10W per heater) + a couple of compactrons and a 350VA transformer....
6W under the chassis is absolute peanuts compared with the flaring off of of all that above chassis power.
When you have a large complete dual channel amp running at somewhere around 50-60C I literally no longer care about a few lost watts under the chassis, it's barely 8-10% of the total, and that is what matters.
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Well, atleast you finally seem to (want to) understand what I meant in post #21, so that's something. Only the numbers don't add up yet: the CV4038 produces more heat than the 6 Watt you mention now.
Fine with me that you build like you do.
Probably this is one of your psychological experiments again (like the one in the "Power dissipation in tubes" thread) so I'm out of this thread.
Fine with me that you build like you do.
Probably this is one of your psychological experiments again (like the one in the "Power dissipation in tubes" thread) so I'm out of this thread.
Not bothered at all.
It's up to me what I choose to do with my 55yr old amplifier to make it better.
I was merely making suggestions to the Russian guy "Bigwolf" here.
They have a lot of smart people on Russian forums, and some of the valves they made in the USSR are unequalled in the west.
It's up to me what I choose to do with my 55yr old amplifier to make it better.
I was merely making suggestions to the Russian guy "Bigwolf" here.
They have a lot of smart people on Russian forums, and some of the valves they made in the USSR are unequalled in the west.