Thanks Andy, no I didn't, simply I connected the Rod reg. and adjusted the voltage filament to 1,35VDC. My electronis skills are very very low like my English, could you elaborate how to select the proper operating point.
Choose the current you want. Like if you use a LL1660/20mA choose 20mA.
Choose the voltage anode to cathode. Like say 140v
Look at curves. 20mA and 140v gives you -10v bias. So voltage at top of resistor is 10v. Voltage at anode is 150v, since you also add the 10v bias.
Resistor value is voltage over current. Filament current is about 600mA for a 4P1L, then add the current through tube = 20mA. So resistor is 10/.62 = about 16R.
Voltage out of Coleman reg is 12v (10v plus 2v for filament). Voltage in is 18v to 19v.
Choose the voltage anode to cathode. Like say 140v
Look at curves. 20mA and 140v gives you -10v bias. So voltage at top of resistor is 10v. Voltage at anode is 150v, since you also add the 10v bias.
Resistor value is voltage over current. Filament current is about 600mA for a 4P1L, then add the current through tube = 20mA. So resistor is 10/.62 = about 16R.
Voltage out of Coleman reg is 12v (10v plus 2v for filament). Voltage in is 18v to 19v.
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Thanks you very much Andy, you explaint very well and easy to understand for a newbie and a non very good English speaker, one more question: how do you know Filament current for 4P1L is about 600mA?
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Read the data sheet and read Ale's accounts of starving the filaments for less microphonics. So decrease datasheet current/voltage by 5 to 15% depending on taste.
Thanks, Ale schematics is 1,65VDC?
I have other schematic with 1,8VDC, attached pic.
I want to use the same LL1660 4:5:1 Alt Q that used in my #26 preamp, is possible?
I have other schematic with 1,8VDC, attached pic.
I want to use the same LL1660 4:5:1 Alt Q that used in my #26 preamp, is possible?
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I only got this datasheet and is so small that I can't read it.
http://www.diyaudio.com/forums/tubes-valves/164494-russian-english-translation-4p1l-datasheet.html
http://www.diyaudio.com/forums/tubes-valves/164494-russian-english-translation-4p1l-datasheet.html
Hard for me to translate technical terms. Searching Google search.
Golden Middle: datasheets of NOS vacuum tubes
Next-Tube. Vacuum tubes and cores datasheets
Russian Tube Tester Files - Instrumental Curves and more
4P1L | Bartola Valves | Page 2
Golden Middle: datasheets of NOS vacuum tubes
Next-Tube. Vacuum tubes and cores datasheets
Russian Tube Tester Files - Instrumental Curves and more
4P1L | Bartola Valves | Page 2
Look at the specifications for your LL1660. What is the gap in milliamps? is it 5mA, 10mA, 18mA.......
the 4P1L will not be happy at under 15mA, it will be better at 18mA, it will be really good at 25mA and possibly better still at 30mA.
So if your LL1660 is less than 15mA forget it and buy a new transformer - it will sound fine with a 26 but not with a 4P1L which only starts to sound acceptable at 15mA. If you buy a new transformer, look for a gap around 25mA or at least 20mA. All single ended transformers have a current rating.
Hello Charm and all,
thanks for all those links to datasheets of 4p1l. As they are not written in
english and i unfortunately can´t read russian, there are three questions left:
So pin 5 is a screen. What does it screen? Connect is to ground?
What is the recommended triode-Connection? There can be found different
versions looking at all those circuits in the i-net. So a/G3/G2 or a/G2 and
G3/k-connection? Which version is the right one?
Greetings
Ulf
thanks for all those links to datasheets of 4p1l. As they are not written in
english and i unfortunately can´t read russian, there are three questions left:
So pin 5 is a screen. What does it screen? Connect is to ground?
What is the recommended triode-Connection? There can be found different
versions looking at all those circuits in the i-net. So a/G3/G2 or a/G2 and
G3/k-connection? Which version is the right one?
Greetings
Ulf
4P1L pinout in triode:
Anode connection - pins 2+3+4
Grid - pin 6
Filament - 8, 1+7 (parallel) 1.9v, 600mA or stated 2.1v, 650mA
Anode connection - pins 2+3+4
Grid - pin 6
Filament - 8, 1+7 (parallel) 1.9v, 600mA or stated 2.1v, 650mA
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Felipe,
You have an interstage transformer that is set for 18mA. Indeed, you can use it like it is written in the schematic. AndyJ is an experienced user. His advise is to use the 4P1L hotter. That means with more current. The reason is in the acoustics. He has found out listening for results over a long time. Now his ears have turned blue 😱
Go ahead with what you have. If you like it, you can buy another LL1660 that is set for 30mA and enjoy this little tube even a little more.
An externally hosted image should be here but it was not working when we last tested it.
Well, the truth is that I only have two LL1660/18mA which is what I use - I just happened to have them. They sound alright. It's Ale who says 4P1Ls sound better at 25mA - I haven't heard that in the input section. I use the 4P1L at over 30mA in the output of my PSE amp, of course. So yes, Filipe - go ahead.