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What's your favorite brand of filter choke and why?

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Posted on December 10, 2014 at 18:03:49
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 Starting to put a parts list together for building the 91A amp and I am going to need 10H and 5H filter chokes for the power supply . First question is do I have to use the max mA that psduII shows for the choke rating or should I use the mean?
Then, what is your favorite brand of cost effective filter choke?

 

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RE: What's your favorite brand of filter choke and why?, posted on December 10, 2014 at 18:40:20
lovetube
Dealer

Posts: 3008
Location: Melbourne Australia
Joined: June 8, 2003
 I like Lundahl , i use them and sell them. quality is second to non and price is very competitive.

 

RE: What's your favorite brand of filter choke and why?, posted on December 10, 2014 at 19:04:42
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 I spec the choke HY value and use the lowest DCR Hammond choke I can find in their product line and load it approximately 65-75% of rated capacity to ensure Lcit.

Hammonds chokes are inexpensive.

 

Custom?, posted on December 10, 2014 at 19:45:21
RC Daniel
Audiophile

Posts: 1922
Location: Brisbane
Joined: November 3, 2002
 Maybe not what you need, but I am getting custom winds from a local guy - Lucas at Black Art Audio. Not cheap, but excellent quality 7Hy/10 Ohm or 1Hy/2 Ohm C-cores can't be... still, they are more cost-effective than purchasing Lundahl here down under.

I guess my suggestion is to check out custom winds; you might be able to get better than what you think for the $.

Good luck.

"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

Also, how do you determine what mA rating to use?, posted on December 11, 2014 at 03:26:40
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 See OP

 

Chokes are simply problem solvers, not tweaks, posted on December 11, 2014 at 05:14:07
Chip647
Audiophile

Posts: 2651
Location: The South
Joined: December 24, 2012
 Look at the total demand downstream of the choke to determine the minimum rating. If you have a 100mA going though your output tube, 20 through the drivers, a 5mA bleeder resistor and some winding losses in the output transformer, that channel would need a minimum of 130mA.

Now, running a choke rated for 130mA at 130mA is almost guarantee of hum from the choke itself. If the choke was feeding 2 channels, that is 260Ma minimum rating. I have found that 50% above minimum or more has the best shot at making the choke quiet.

See the link below to Henry Pasternack's post on chokes.

For me, if the choke has the inductance and is quiet, it will work. "Low DCR" chokes simply mean they are either non-critical (very low inductance) or massively overrated for current.

 

The first and most important thing about any choke to finals is...., posted on December 11, 2014 at 08:13:03
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 It MUST be 20 Ohms DCR or less. You take it from there !!!

In 2014, I've arrived, ( since 1982 when I first experimented with ALL of this ), at under ten Ohms, under 2.2 HY, and under 2.2 pounds in size.

'Also arrived at L1/C1/L2/C2 as the BEST topology to the finals.

Unbeatable, the best there ever is and was in my experience. YMMV.

Have fun learning !!

Jeff Medwin

 

RE: What's your favorite brand of filter choke and why?, posted on December 11, 2014 at 12:59:26
JKT
Audiophile

Posts: 612
Location: Midwest
Joined: November 26, 2002
 Lundahl: two coils on a C core gives you more options. Can be connected series for more inductance or parallel for more current. Also possible is a common mode connection that I use where one coil is in series with the positive leg on the bridge and one is in series with the negative leg. I experience blacker backgrounds with this type of choke input supply.


"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln

 

RE: Also, how do you determine what mA rating to use?, posted on December 11, 2014 at 13:07:17
rage
Audiophile

Posts: 793
Joined: December 17, 2010
 Hammond chokes are pretty much rated for cap input.

Look for examples of what other people have used. I know Hammond has a 5H in the 50 ohm range, but its tough to say weather or not it will buzz.

A small cap, up to about .68uf in front of the choke input will help alleviate buzz... once the voltage starts to climb though, you're running a cap input...

 

RE: Also, how do you determine what mA rating to use?, posted on December 11, 2014 at 13:58:55
Al Noakes
 Hammond chokes (the clamp-mount ones) have the advantage of being cheap and readily available . The inductance tends to fall off as current increases . DCR also seems high and the cores are nothing special . The same applies to Triad . I have used both Hammond and Triad , both get the job done . You get what you pay for . I don't know what the more pricey Hammonds are like but the cores are still standard lams by the looks of things . I now get my chokes custom built in batches of at least 10 with M6 lams and over-rate by about 50% over modelled peak current . I would recommend inmates here doing the same and splitting a batch in a group buy .

Al

 

A Note...., posted on December 11, 2014 at 15:44:48
sony6060
Audiophile

Posts: 1465
Location: USA
Joined: August 8, 2014
 My power supplies using inexpensive Hammond chokes are used in a CLC filters- no hum issues. A choke input may need a more heavy duty choke. See Al Noakes post.

 

RE: What's your favorite brand of filter choke and why?, posted on December 11, 2014 at 20:27:34
danlaudionut
Audiophile

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

I like the One Electron chokes.
They are also plate chokes so
they perform better than most.
They also have dual windings
for more flexible use.

DanL



 

agree, posted on December 12, 2014 at 04:24:44
Jim Dowdy
Manufacturer

Posts: 1518
Location: Atlanta, GA
Joined: July 22, 2000
 The Lundahls wired in common mode are my favorite.

 

Thanks everyone!, posted on December 12, 2014 at 04:43:42
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 Lots of good suggestions to check out. I appreciate it!

 

RE: Also, how do you determine what mA rating to use?, posted on December 12, 2014 at 17:01:38
wheezer
Audiophile

Posts: 4309
Joined: January 24, 2001
 I've found Hammond chokes don't carry true to their spec'd current and core saturation occurs below their current rating.
I too have gone to custom wound chokes with M6 lams....you do get what you pay for.

 

RE: Also, how do you determine what mA rating to use?, posted on December 13, 2014 at 06:39:37
Al Noakes
 Hammonds are more intended for standard capacitor input usage , purely as smoothing chokes . However , I have used their 660mH 750mA (159Y?) chokes as cathode loads in an SE OTL amp and got good results .

Al




 

Ditto, posted on December 14, 2014 at 17:48:13
kyle
Audiophile

Posts: 1839
Location: London Ontario
Joined: September 29, 1999
 But I wouldn't spend the money for a WE 91A type amp. It's not really a hi-res design, generic parts would suffice.

 

RE: Also, how do you determine what mA rating to use?, posted on December 14, 2014 at 19:50:41
kyle
Audiophile

Posts: 1839
Location: London Ontario
Joined: September 29, 1999
 I asked Hammond (here in the great white north) and they said their chokes are good for either choke or cap input. They pointed out that their spec sheets show both options and they have been spec'd that way. I'll take them at their word as I've used them in both ways with no issue.

 

RE: What's your favorite brand of filter choke and why?, posted on December 18, 2014 at 17:21:11
Stuben
Audiophile

Posts: 669
Location: Guber Ohio
Joined: December 30, 2005
 Hey Vinnie,

Thought I'd chime in late...

I have used the Hammond offering for well over a decade mainly because I've been able to achieve my goals using them after some experience.

I typically de-rate them 100% percent to ensure lower DCR. With this said, they have been used for my prototypes.

One day I'll pay for the multi-winding C-core or R-core animals and see if there is ROI. I'm a Lundahl fan for signal service, so I will probably get around to trying their PS chokes. You have loads of choices. Implemented with some thought, most manufacture offerings (with in reason) will do the job.

Stuben

 

Absolute Nonsense, posted on December 23, 2014 at 13:07:47
Triode_Kingdom
Audiophile

Posts: 10047
Location: Central Texas
Joined: September 24, 2006
 "It MUST be 20 Ohms DCR or less."

The filter cap *after* the choke is responsible for providing the low Z path to ground. The resistance of the choke must only be sufficiently low so as not to create voltage sag under varying loads. If the average load doesn't vary, as in the case of a Class A output stage, the choke can be thousands of ohms with no ill effect.

 

RE: The first and most important thing about any choke to finals is...., posted on December 24, 2014 at 09:46:19
Al Noakes
 You are over-generalising but I agree regarding LCLC supplies . What you describe is not a 'one size fits all' . If you understand what a choke does in term of impedence , then you would realise that low DCR is a nice parameter to have but not a necessity . Besides , you use filamentary rectification which is where the majority of losses occur in your power supplies

Merry Christmas :)

Al

 

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