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Learning how to use psud2

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Posted on February 5, 2017 at 16:43:59
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 I am just starting to learn the various nuances of correctly inputting the values necessary to get an accurate prediction from psud2 and would appreciate some guidance. I have run a sim with my components but there are a couple of areas where i am unsure of how to proceed.
My power supply is power trans 300-0-300, 28 ohm secondary imp. 5ar4 rectified. filter is 12 uf x 6H 50dcr x 100uf x 6H 60dcr x 100uf. tubes will be 2 x kt120 SE with 6sn7 driver. B+ for the driver will be from RC off the final 100uf cap of 3.3K and 40uf.
I inputted the power supply components up to the 100uf cap and i am not sure about what to input after that. You can choose between a resistive or constant current load. When do you use one or the other? Also should the additional RC section be tacked on the sim to account for the driver tube requirements? Thank you for the help. Dak

 

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RE: Learning how to use psud2, posted on February 5, 2017 at 17:44:43
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 what plate current will your kt120s be running and what will be the total current draw of your drivers?

when you say 28 ohms is that end to end or one end to CT?


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Learning how to use psud2, posted on February 5, 2017 at 17:54:57
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 Hi tre, the 120s will be running at 110ma each. the drivers at 12ma . The 28 ohm is end to end. It is a big mofo.

 

RE: Learning how to use psud2, posted on February 5, 2017 at 17:58:07
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 drivers at 12ma. each or total?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: 12ma each nt, posted on February 5, 2017 at 18:33:32
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 .

 

I assumed 24ma. for the driver stages total., posted on February 5, 2017 at 18:08:11
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002


321.68 volts for the output tubes with less than 1mv ripple peak to peak and 261.64 volts for the drivers at less than 1/10 of 1mv ripple peak to peak.

Edit, I messed up. I entered 50 ohms instead of 60 ohms for the second choke. Both voltages went down by 2 volts, the ripple is the same.

The current tap of 220ma is loaded by right clicking on the filter parts after the spot where you want it and choosing "insert" then "Current tap".

Now right click on the current tap and chose "edit" to change it's value.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

How do you expand the graph to show the small increments?, posted on February 5, 2017 at 18:43:57
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 I can make a box around the graph by clicking and dragging but how do you get the box to stay when you take your finger off the mouse?

 

RE: How do you expand the graph to show the small increments?, posted on February 5, 2017 at 18:47:52
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 You don't. Click and drag and it "zooms in". but no box. but it should stay zoomed in.


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE:when i zoom in the graph goes off screen, posted on February 5, 2017 at 18:55:53
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 I have not found away to get to the graph. the plot goes from 0 to 160 and i can't see the rest

 

RE:when i zoom in the graph goes off screen, posted on February 5, 2017 at 18:57:17
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 Click the buttons at the top right of the graph and see what they do.


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Ok i got to expand just the graph, posted on February 5, 2017 at 19:10:34
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 I clicked the zoom all and then highlighted the curves with the click and drag box. then when released it showed what was in the box.
Although, i still did not get your graph.
Anyways, is there anything wrong showing up on the graph? I find that the power supply while very dynamic tends to have too much energy around t,s, f sounds. Just a wee bit more than i like, although my wife who has much better ears than me did not find it annoying until i pointed it out. But, she liked the overall sound from the amp. I like the dynamic punch which is probably the best of any of the amps i have.

 

RE: Ok i got to expand just the graph, posted on February 5, 2017 at 19:20:42
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 "Anyways, is there anything wrong showing up on the graph?"

Yes, you are "pounding" on the rectifier tube. What does that sound like? I don't know but it can't be good.

The tube is rated for .75 amps peak current.

The peak current is hitting over 1 amp 120 times a second (60 times a second for each diode).

Un-check all the boxes to the left. Now check the I(D1) (current first diode)

Zoom around until you see what I see in the post linked below.


Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"

 

click the zoom buttons until you can see it all then click and drag., posted on February 5, 2017 at 19:00:12
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

There is a problem, posted on February 5, 2017 at 18:37:41
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002



The max peak repetitive current for the 5ar4 of .75 amps is being exceeded.

It's over 1 amp. For the total current draw, the voltage and the DCR of the power transformer....C1 is too large.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: if i add ss rectifiers aka Graetz bridge...., posted on February 5, 2017 at 19:53:09
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 that seems to get pass the error message. If i do that would the start up current be ok for the 5ar4 and keeping everything the same?

 

RE: if i add ss rectifiers aka Graetz bridge...., posted on February 5, 2017 at 20:07:30
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 It's not the error message. It's the peak diode current that occurs every half cycle the whole time the power in on.

If you have found a way to reduce that current to within spec then that's good.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE:what about a 5u4gb ?, posted on February 5, 2017 at 21:21:17
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 I knew that the 5ar4 would be really close and i would rather have done a twin 5ar4 but my PT did not have enough 5v filament current, only 3A. I suppose i could add another fil trans and do twin 5ar4. i will check into that.

 

RE:what about a 5u4gb ?, posted on February 5, 2017 at 21:12:23
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 Is that tough enough?

 

RE:what about a 5u4gb ?, posted on February 6, 2017 at 07:42:18
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 The 5u4gb is good for an amp.


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

I had to reduce C1 to 3.9uf to get within spec., posted on February 5, 2017 at 18:45:53
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 Your voltages went down to 260 and 200 and the ripple went way up.


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Ok, i am going to input the values and see if i can match u nt., posted on February 5, 2017 at 18:36:01
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 .

 

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