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Choke Filter for power supply

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Posted on August 28, 2015 at 15:36:07
onthethreshold1
Audiophile

Posts: 53
Location: OH
Joined: November 7, 2014
 I want to add a choke to quiet the hum at idle . . My question is does a two wire choke have an input or output to it and if I add a capacitor before I run it to ground do I use an electrolytic and if so does positive or negative go to ground .Thanks in advance .
Donald

 

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RE: Choke Filter for power supply, posted on August 28, 2015 at 16:11:50
xaudiomanx
Audiophile

Posts: 3647
Joined: August 16, 2004
 Boy it's a good thing you asked first(I hope) before wiring in the choke.

A choke is wired in series with the circuit used for where as the caps that isolate the choke goes to ground. If the caps are polarized then the negative goes to ground but if not polarized then it doesn't matter although many might challenge that.

You also have to use the proper value choke and current handling.

 

RE: Choke Filter for power supply, posted on August 28, 2015 at 16:20:57
onthethreshold1
Audiophile

Posts: 53
Location: OH
Joined: November 7, 2014
 So I can wire it to the 40 MFD power supply from the grounded end in series . I need sesame street directions as I am real new to all this .Can you walk me through it in simple terms ? Thank you
Donald

 

RE: Choke Filter for power supply, posted on August 28, 2015 at 16:45:17
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 You are setting up a CLC, AKA П (pi) section filter.


Eli D.

 

RE: Choke Filter for power supply, posted on August 28, 2015 at 16:52:41
danlaudionut
Audiophile

Posts: 5480
Location: Schenectady
Joined: June 6, 2002

A CLC or Pi filter is like the above schematic.
You need a cap before and after the choke.
First one so that the B+ stays about the same.
Second is to make the PS a voltage source.
If you post me off-board I can take you through it.
I will also need to model it in PSUD
to get the "right" choke for your amp.

DanL



 

RE: Choke Filter for power supply, posted on August 28, 2015 at 19:45:26
Garg0yle
Audiophile

Posts: 859
Joined: December 1, 2014
 "post me off-board"
That is not in the spirit of the forum.

Usually when somebody says that, they want to talk you into doing some ridiculous things without the scrutiny of the collective.

I'm not saying dalaudionut is going to talk you into $100 purple Chinese power cords to "wake up" your amp, but he did have my (and others) posts deleted for questioning his claims that it works on specific amplifiers.

Eli on the other hand seems to be a pretty stand up guy. If I were you, I would continue correspondence with this individual.

Ultimately do as you wish, I just would hate to see your brain get filled with mumbo jumbo while trying to learn some of the fundamental aspects of high voltage circuits.

Download PSUD yourself and experiment, it's fun and not really hard.
At the very least empowering.

Cheers




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RE: Choke Filter for power supply, posted on August 28, 2015 at 19:57:18
danlaudionut
Audiophile

Posts: 5480
Location: Schenectady
Joined: June 6, 2002
 I have tutored many people on the asylum
long before you were ever here.
I don't know what your problem is but
your posts have been mostly negative.
Take a chill pill and relax.

DanL



 

RE: Choke Filter for power supply, posted on August 28, 2015 at 20:32:57
Garg0yle
Audiophile

Posts: 859
Joined: December 1, 2014
 At the risk of going off topic, you were the one who attacked me first by saying "WOW Your lack of knowledge is showing." when I suggested that one does not need to worry much about any practical transformer break in.

You then went on to claim that solder and wire insulation also needs to break in, then out of thin air tried start a SS vs Tube debate in a thread about transformers.
Remember that?

Negativity is in the eye of the beholder.

It's a good thing for you the Audio Illuminati does not exist. △


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RE: Choke Filter for power supply, posted on August 28, 2015 at 22:03:37
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Can you post the schematic that you're interested in modifying?

How do you know that you have hum from the power supply, and not ground loop hum (or something else design/layout related)?

 

Serious Hoakum, posted on August 28, 2015 at 23:48:40
Triode_Kingdom
Audiophile

Posts: 10049
Location: Central Texas
Joined: September 24, 2006
 "Type LE2-10 AC Power Cord improves the sound of amplifiers, receivers, CD players and CD transports, and makes a big difference in the picture quality, detail resolution and color balance of any kind of TV set, video projector, or DVD player."

That's just too funny.



 

RE: Choke Filter for power supply, posted on August 29, 2015 at 04:41:02
onthethreshold1
Audiophile

Posts: 53
Location: OH
Joined: November 7, 2014
 http://www.audioasylum.com/cgi/vt.mpl?f=tubediy&m=219476 This is the circuit I wish to modify
Donald

 

RE: One you might want to look at, posted on August 29, 2015 at 10:50:52
Russ57
Audiophile

Posts: 3754
Location: South Florida
Joined: November 16, 2001
 I'm not one for snake oil either.

Take a look at Eupen power cords. I think you will agree how it "might" make a difference in some cases. If only in the sense that noise from other crap might be kept out of audio equipment.

 

RE: One you might want to look at, posted on August 29, 2015 at 12:19:09
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 You hit a nail squarely. If a power cord really improves things, it's by keeping EMI/RFI and garbage riding on the mains out of the HIFI circuitry. IMO/IME, there are less expensive ways of doing the same thing, without resort to an expensive voodoo power cord.

An outside possibility for real help from a power cord is when large wires carry current into a unit whose PSU lacks sufficient current reserves. That, in this poster's opinion, is bad design.

FWIW, I am most definitely not a fan of IEC connectors. They are another set of mechanical connections that can make trouble.


Eli D.

 

The Circuit, posted on August 29, 2015 at 16:10:22
Triode_Kingdom
Audiophile

Posts: 10049
Location: Central Texas
Joined: September 24, 2006
 That circuit should be very quiet just as it is. Is this a new problem that's developed over time? If so, you might check the electrolytics and tubes (mismatched tubes can create hum). How sensitive are your speakers?

 

RE: Choke Filter for power supply, posted on August 29, 2015 at 17:12:58
onthethreshold1
Audiophile

Posts: 53
Location: OH
Joined: November 7, 2014
 Could someone please answer the original post
Donald

 

Sure thing..., posted on August 29, 2015 at 21:37:42
Triode_Kingdom
Audiophile

Posts: 10049
Location: Central Texas
Joined: September 24, 2006
 "does a two wire choke have an input or output to it"

No, the two leads are interchangeable.

"if I add a capacitor before I run it to ground do I use an electrolytic and if so does positive or negative go to ground."

I thought some of the other members had answered this with diagrams. Anyway, capacitors in the power supply can be various types, depending on the value of the capacitor. The negative lead goes to ground if it's a polarized capacitor.

You know, I have to advise a lot of caution when someone asks me which lead of a high voltage cap goes to ground. :(



 

RE: Choke Filter for power supply, posted on August 29, 2015 at 21:51:24
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 If your amps are monoblocks as in the schematic then you should measure the actual B+ that is going to the trans CT. Putting in a choke will reduce your B+ even more so you need to know what your actual B+ is. If your actual B+ is close to stock you won't have much leeway for a choke. regards, Dak
PS someone suggested your problem may lie elsewhere, and I would agree. You should probably rebuild the amp if it is stock or troubleshoot a possible problem if it was just rebuilt.

 

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