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Old 16th May 2013, 02:51 PM   #31
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Those are offloaded voltages, and will be high since they are unloaded. No need to disconnect the CT. When the amp is drawing current, the voltages will be a little lower (as you have already noticed).

37R seems reasonable.

What value caps are you using for C4 & C5?

The 560V "normal hookup" is with the amp idling with all of the tubes in place, correct?

Last edited by boywonder; 16th May 2013 at 02:54 PM.
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Old 16th May 2013, 03:20 PM   #32
ffejgo is offline ffejgo  United States
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C4 is 22uf

C5 is 150uf with a 80mdf Motor Run Cap in parallel

The 560v "Normal" is with the amp on and all tubes in place


Refering back to a previous question you had about changing to a 300b setup:
I think with the voltage problems I'm having with the 45's once I/we (Thank you for doing this) get it solved I'm sticking with the 45's. I can always just roll 45's. Plus the WAF is running lower. She expected Plug & Play...
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Old 16th May 2013, 03:39 PM   #33
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Here is a PSUDII model.

78ma=27ma each 45 and 12ma each 5842
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File Type: png Tubelab SE 45 PSUD.png (164.2 KB, 109 views)
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Old 16th May 2013, 03:45 PM   #34
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Lowering C4 to around 2.2uf gets B+ down to about 287V using the existing triad choke and about 280V using the Hammond 158M.....

Do you have a load resistor connected across the speaker terminals when taking the voltage measurements?
Attached Images
File Type: png Tubelab SE 45 PSUD (2.2uf C4).png (163.2 KB, 103 views)
File Type: png Tubelab SE 45 PSUD (2.2uf C4+Hammond 158M).png (166.3 KB, 102 views)

Last edited by boywonder; 16th May 2013 at 04:00 PM.
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Old 16th May 2013, 04:57 PM   #35
ffejgo is offline ffejgo  United States
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No seperate load resistor... But the speakers are connected. 8 ohm (Klipsch Forte II).

I have to admit I don't know what the "ma" numbers mean? I did attempt the PSUDII program but couldn't figure it out.

A 287v R30 with the exsiting Triad would be great. I know that if I switch the Mullard 5AR4 out with a "New" store purchased rectifier or the other one I have on hand the 287v will drop by 10v or so. It's an option??? With the numbers you gave me I'll be able to save the $23.00 on the Hammond and not have to worry about taxing my system. The PT did hum louder and get 10 degrees hotter with those 2 x 50ohm resistors in series. Although there was no hum through the speakers. I did order 2.2uf caps Just have to wait for them to arrive.

I can't begin to express how very helpfull you have been. Thank you!
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Old 16th May 2013, 05:29 PM   #36
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Quote:
Originally Posted by ffejgo View Post
I have to admit I don't know what the "ma" numbers mean? I did attempt the PSUDII program but couldn't figure it out.

A 287v R30 with the exsiting Triad would be great. I know that if I switch the Mullard 5AR4 out with a "New" store purchased rectifier or the other one I have on hand the 287v will drop by 10v or so. It's an option??? With the numbers you gave me I'll be able to save the $23.00 on the Hammond and not have to worry about taxing my system. The PT did hum louder and get 10 degrees hotter with those 2 x 50ohm resistors in series. Although there was no hum through the speakers. I did order 2.2uf caps Just have to wait for them to arrive.
The load is a constant current (instead of the default resistive load in PSUD) the total current draw is:

27 ma for each 45 x 2=54 milliamps

12 ma for each 5842 x 2 = 24 milliamps

so 78ma total.

One advantage of the Hammond 158M is more henries, which will give you less hum, but if the hum is acceptable now, no worries.

Tubes have B+ "guidelines", so 270V-300V B+ is fine. The end result is the tube current times the B+ voltage roughly equals power dissipated as heat out of the tube. That's why Tubelab recommends backing off the idle current a bit when using higher B+ voltages. If you crank up the B+ and the current (within specs for the tube) the tube life will be shorter.

It's interesting that almost doubling the resistance of the choke only drops the B+ about 7V. That's because the current draw is relatively low.
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Old 17th May 2013, 07:47 AM   #37
gmonno is offline gmonno  Italy
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Hi, first of all excuse me if this is not the correct thread, but here you're talking about supply, chokes, B+, so I try to present my question.

I've just built a TSE with 300B, as choke input I used a 200mA 7H 130 Ohm.

I understand that a higher resistance will have an impact in lowering B+, and that the power (200mA) must be correctly defined to match the tube's draw.

What I don't understand clearly is how a bigger or smaller Henries will affect.

I mean, for example, what would be the difference on B+ between these two :
Hammond 193L 5H 300mA 57 Ohm
Hammond 193M 10H 300mA 63 Ohm

Many thanks
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Old 17th May 2013, 02:40 PM   #38
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Quote:
Originally Posted by gmonno View Post
Hi, first of all excuse me if this is not the correct thread, but here you're talking about supply, chokes, B+, so I try to present my question.

I've just built a TSE with 300B, as choke input I used a 200mA 7H 130 Ohm.

I understand that a higher resistance will have an impact in lowering B+, and that the power (200mA) must be correctly defined to match the tube's draw.

What I don't understand clearly is how a bigger or smaller Henries will affect.

I mean, for example, what would be the difference on B+ between these two :
Hammond 193L 5H 300mA 57 Ohm
Hammond 193M 10H 300mA 63 Ohm

Many thanks
Hi: The choke current rating does not necessarily need to match the tube's draw; it needs to equal or exceed the current draw. No harm in using a higher current rated choke other than size and $$.

Using PSUD, the difference between 5H and 10H in a typical TubelabSE 300B PS is about 30mv of B+ ripple (60mv vs 30mv). The B+ voltage difference is less than a volt due to the 57 to 63 ohm DCR of the chokes.

To get the B+ ripple voltage, just take the difference between the max and min voltages in the table at the left. Note I used a 4 second delay to get on the steady-state part of the B+ curve so that the voltage has settled out.
Attached Images
File Type: png Tubelab 5H.png (185.0 KB, 86 views)
File Type: png Tubelab 10H.png (149.9 KB, 70 views)

Last edited by boywonder; 17th May 2013 at 02:43 PM.
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Old 18th May 2013, 08:59 AM   #39
gmonno is offline gmonno  Italy
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OK, understood, nearly no difference from the B+ point of view.
I change the question, what criteria will make one decide to use a 5H vs a 10H choke?
This point have never been clear even trying to read on books.

Thanks
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Old 18th May 2013, 02:42 PM   #40
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Quote:
Originally Posted by gmonno View Post
I change the question, what criteria will make one decide to use a 5H vs a 10H choke?
Thanks
The PSRR (power supply rejection ratio) of the amp circuit. Circuits with high PSRR are more immune to B+ voltage ripple; ie they are less sensitive to the ripple voltage with respect to hum at the outputs (speaker terminals)......and of course $$ spent on the choke.
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