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Old 27th Jul 2018, 12:03 pm   #1
victor54
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Default My valve PSU dilemma

Hi,
I am upgrading my Anzai SRPP preamplifier starting from the PSU.
As I intend to do an all valve PSU I intend to use the attached schematic with EZ80 rectifier and ECL82 regulater.
My dilema is:
EZ80 has limit Vac 350-0-350 so I think after clc filtering the Vdc has to be no more than 400-410v.
As I need 350Vdc regulated to supply the Anzai, some 60v drop on the serial element of the ECL82 shall be enough?
Perhaps some one more practic with spice programe can simulate and give me some real help.

Thanks in advance.
Victor
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Old 27th Jul 2018, 12:47 pm   #2
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Default Re: My valve PSU dilemma

My first thoughts are that if you supply 350 0 350 volts to an EZ80 the output will be just above 350V DC not 420V, so your voltage drop would be 10V to 20V.


The maximum current for the preamp would have to be no more than 35mA which is the maximum the tetrode part of the valve will pass.

I think you'll be running this valve too hard.
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Old 27th Jul 2018, 1:12 pm   #3
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Default Re: My valve PSU dilemma

Here you are a sim made by one of my friends, more or less similar with my schematics. He says ecl82 can draw more than 60 mA upon his calculations.
I am only a humble Diyer...
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Old 27th Jul 2018, 1:16 pm   #4
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Default Re: My valve PSU dilemma

Turning to the EZ80 supplyed with 350-0-350v it seams (watching the datasheet) that at 40mA goes to some 400Vdc, or I am interpreting wrong the info?
Or I can force The EZ80 to 400-0-400Vac?
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Old 27th Jul 2018, 1:36 pm   #5
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Default Re: My valve PSU dilemma

This is the original regulater proposed at the beginning of that project....I dislike the SS insert... but the Vdc drop over the regulater is also some 90-100v.
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Old 27th Jul 2018, 1:46 pm   #6
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Default Re: My valve PSU dilemma

The Philips valve data gives the maximum cathode current as 50mA and the maximum anode dissipation as 7 Watts.

What is the pre-amplifiers total current draw at your specified 350 Volts supply?

Lawrence.
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Old 27th Jul 2018, 1:54 pm   #7
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Default Re: My valve PSU dilemma

Replace ECL82 with ECL86 if you wish the valve to run cooler.
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Old 27th Jul 2018, 2:22 pm   #8
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Default Re: My valve PSU dilemma

Or 2 x ECL82 in parallel?

Aub
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Old 27th Jul 2018, 2:56 pm   #9
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Default Re: My valve PSU dilemma

Quote:
Originally Posted by ms660 View Post
The Philips valve data gives the maximum cathode current as 50mA and the maximum anode dissipation as 7 Watts.

What is the pre-amplifiers total current draw at your specified 350 Volts supply?
Total SRPP consumption is less than 16mA
We have 2xecc82@ 4mA and 4xecc83 @ less than 2mA
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Old 27th Jul 2018, 2:59 pm   #10
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Default Re: My valve PSU dilemma

That should be no problem for the ECL82.

Lawrence.
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Old 27th Jul 2018, 3:02 pm   #11
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Default Re: My valve PSU dilemma

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Originally Posted by Aub View Post
Or 2 x ECL82 in parallel?
I can splitt the psu for chR and chL with two ecl82 separate regulators.
My concern is ez80 ...how can I draw 420Vdc in order to have a 80-90v drop over the penthode? Shall I use more than 350Vac on its plates?
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Old 27th Jul 2018, 3:37 pm   #12
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Default Re: My valve PSU dilemma

Quote:
I can splitt the psu for chR and chL with two ecl82 separate regulaters.
My concern is ez80 ...how can I draw 420Vdc in order to have a 80-90v drop over the penthode? Shall I use more than 350Vac on its plates?
No the maximum voltage is 350V, if you want higher, use a GZ34 which operates up 500V

Why do you need 350V for a pre-amp? The maximum voltage on the ECC83 is 250V. Are you proposing to drop 100V on the anode load resistors?
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Old 27th Jul 2018, 6:03 pm   #13
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Default Re: My valve PSU dilemma

Mine is SRPP, first stage(RIAA) 310V and output buffer 350V
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Old 27th Jul 2018, 6:07 pm   #14
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Default Re: My valve PSU dilemma

The OP says the current draw of the pre-amp is 16mA, if you look at the rectifiers output curves here:

http://www.r-type.org/pdfs/ez80-1.pdf

For 350 volts AC input the DC output should be somewhere near 450 volts with a 50uF reservoir for a 16mA load, the ECL82 should be able to regulate that down to 350 volts no problem.

Approx. anode dissipation for the above would be 1.6 watts, well within the valves maximum limits. Even adding a few mA's for the triode section etc of the regulator it's still no problem.

So far as I can make out.

Lawrence.
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Old 27th Jul 2018, 7:26 pm   #15
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Default Re: My valve PSU dilemma

Hi, In your series regulator you need to take into consideration that you are not exceeding whatever the maximum heater to cathode voltage rating for the valve is.

May I ask why have you decided to use a voltage stabilised power supply to feed your pre-amp.

An EF86 or an ECC81/82 or ECC83 would be a more obvious choice for a pre-amp and would run quite happily at a few to 10 milliamps which could easily be drawn from the power amplifier's own supply; it would only need a dropper resistor and a few microfarads of decoupling. I can't see the necessity for providing a stabilised power supply for a pre-amp.

Ross
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Old 27th Jul 2018, 7:48 pm   #16
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Default Re: My valve PSU dilemma

Quote:
Originally Posted by n_r_muir View Post
... May I ask why have you decided to use a voltage stabilised power supply to feed your pre-amp ...
Since it's an RIAA pre-amp it will have to handle very small signals (very small signals indeed if the cartridge is moving coil) so perhaps the OP is looking to minimise HT rail noise ? If so then he might want to consider putting a capacitor across the stack of Zeners used as the voltage reference. They can be hissy little chaps.

Cheers,

GJ
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Old 27th Jul 2018, 8:08 pm   #17
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Default Re: My valve PSU dilemma

Yes indeed, and I shall choose a 5w zener as I heard is less noisy.
The problem now is to calculate some how if the values of the components(resistors) are the right ones. The original schematics belongs to AN 2 and was designed for 350Vdc in and 260Vdc out (same current more or less)
That's why I was asking for some one more parctical with spice program.
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Old 27th Jul 2018, 8:16 pm   #18
victor54
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Default Re: My valve PSU dilemma

Quote:
Originally Posted by n_r_muir View Post
Hi, In your series regulator you need to take into consideration that you are not exceeding whatever the maximum heater to cathode voltage rating for the valve is.

May I ask why have you decided to use a voltage stabilised power supply to feed your pre-amp.

An EF86 or an ECC81/82 or ECC83 would be a more obvious choice for a pre-amp and would run quite happily at a few to 10 milliamps which could easily be drawn from the power amplifier's own supply; it would only need a dropper resistor and a few microfarads of decoupling. I can't see the necessity for providing a stabilised power supply for a pre-amp.

Ross
I use Anzai SRPP config as preamplifier and two OTL monoblocs.
So the main reason is the distance from pre to the monoblocs.
Nevertheless more important reason was listening the first srpp some 30 years ago using a ss recyifier and CLC filtering then making with my friends some refurbishing and we find out that tube rectifier was better and then a regulator SS or valve one improoved the sound and the ripple.
I am a good listener and I rely on my live music experience since I was a kid.
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Old 27th Jul 2018, 8:19 pm   #19
victor54
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Default Re: My valve PSU dilemma

Quote:
Originally Posted by ms660 View Post
The OP says the current draw of the pre-amp is 16mA, if you look at the rectifiers output curves here:

http://www.r-type.org/pdfs/ez80-1.pdf

For 350 volts AC input the DC output should be somewhere near 450 volts with a 50uF reservoir for a 16mA load, the ECL82 should be able to regulate that down to 350 volts no problem.

Approx. anode dissipation for the above would be 1.6 watts, well within the valves maximum limits. Even adding a few mA's for the triode section etc of the regulator it's still no problem.

So far as I can make out.

Lawrence.
This is encuraging, so I shall go further. But the problem is calculating the right values of the regulator components (resistors) as I dont have the expertise.
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Old 31st Jul 2018, 7:04 pm   #20
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Default Re: My valve PSU dilemma

This is Ok, after testing, the ez80 draw on the fist cap some 445Vdc and after the shocke 440Vdc, so no problem on the regulater. If someboady more experienced can simulate the voltages around the ecl82 I'll be gratefull.

Regards,
Victor
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