|
Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
|
Thread Tools |
27th Jul 2018, 12:03 pm | #1 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
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 |
27th Jul 2018, 12:47 pm | #2 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
|
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. |
27th Jul 2018, 1:12 pm | #3 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
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... |
27th Jul 2018, 1:16 pm | #4 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
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? |
27th Jul 2018, 1:36 pm | #5 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
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.
|
27th Jul 2018, 1:46 pm | #6 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
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. |
27th Jul 2018, 1:54 pm | #7 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
|
Re: My valve PSU dilemma
Replace ECL82 with ECL86 if you wish the valve to run cooler.
|
27th Jul 2018, 2:22 pm | #8 |
Nonode
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 2,039
|
Re: My valve PSU dilemma
Or 2 x ECL82 in parallel?
Aub
__________________
Life's a long song, but the tune ends too soon for us all. |
27th Jul 2018, 2:56 pm | #9 | |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
Re: My valve PSU dilemma
Quote:
We have 2xecc82@ 4mA and 4xecc83 @ less than 2mA |
|
27th Jul 2018, 2:59 pm | #10 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
Re: My valve PSU dilemma
That should be no problem for the ECL82.
Lawrence. |
27th Jul 2018, 3:02 pm | #11 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
Re: My valve PSU dilemma
|
27th Jul 2018, 3:37 pm | #12 | |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
|
Re: My valve PSU dilemma
Quote:
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? |
|
27th Jul 2018, 6:03 pm | #13 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
Re: My valve PSU dilemma
Mine is SRPP, first stage(RIAA) 310V and output buffer 350V
|
27th Jul 2018, 6:07 pm | #14 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
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. |
27th Jul 2018, 7:26 pm | #15 |
Hexode
Join Date: Jul 2007
Location: Edinburgh, UK.
Posts: 344
|
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 |
27th Jul 2018, 7:48 pm | #16 | |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
|
Re: My valve PSU dilemma
Quote:
Cheers, GJ
__________________
http://www.ampregen.com |
|
27th Jul 2018, 8:08 pm | #17 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
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. |
27th Jul 2018, 8:16 pm | #18 | |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
Re: My valve PSU dilemma
Quote:
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. |
|
27th Jul 2018, 8:19 pm | #19 | |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
Re: My valve PSU dilemma
Quote:
|
|
31st Jul 2018, 7:04 pm | #20 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
|
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 |