[Gordy]

From what I read the high inductance choke is good for CD/DVD/transport and low inductance choke is good for power amp, did I got it right?

Thanks

Here's where you're getting it mixed up Sam, we're really just looking for high amperage capability for the amplifiers, low inductance is just a somewhat unfortunate reality with the 1820's etc.   You will still get excellent results!

[BradJudy]

FYI: It looks like we're down to $7/board with the volume we're at now. 

[mgalusha]

FYI: It looks like we're down to $7/board with the volume we're at now. 

Schweet!

[Gordy]

FYI: It looks like we're down to $7/board with the volume we're at now. 

Schweet!

Bogart I presume?   

[BradJudy]

The MKP 338 sets are turning out more popular than I thought, so it's likely the prices on those will go down as well. 

[kyrill]

JW Miller does offer some higher inductance models which includes a 36mH 2.9A model (8117) which I could put on the list in place of the 8110, but it runs $9 instead of $7.  It looks like Newark stocks them. 

as the Coilcraft  combines common and differential mode filtering in a single component but with its 25mH  is it a lesser choice than the 8117-RC - 36mH 2.9A  even when the Miller is not a diff. mode filter?

[whubbard]

Hi,

Could someone explain the difference between the P3717-A and the 8117-RC?
I think that the 8117-RC would be better because of the 36mh of inductance vs the 25mh of the P3717-A, however the coilcraft has the differencial filter as well. Over all, which is better?

Also, why did we not go with the 8116-RC? Was the .45 DC resistance too high?

Thanks

[BradJudy]

I do not know if the JW Miller or CoilCraft items will provide better filtering.  While I have both here, I don't have the proper equipment to test that. 

Also, why did we not go with the 8116-RC? Was the .45 DC resistance too high?

For simplicity, I was picking 3/5/10A options.  You're welcome to try other options, but I had to limit the choices to make a group buy feasible. 

[kyrill]

I do not know if the JW Miller or CoilCraft items will provide better filtering.  While I have both here, I don't have the proper equipment to test that. 
Your ears Brad, your ears? 

[whubbard]

http://www.coilcraft.com/pdfs/comoco.pdf

This series of chokes is intended for use in AC line filters
for switching power supplies. They combine common
and differential mode filtering in a single component.
By using these parts, designers can eliminate two extra
filter chokes compared to a standard common mode
choke. The unique combination of special windings and
materials provides much better filtering performance
than either a common mode choke or a single winding
inductor alone.
The differential filtering frequency response has been
designed to provide filtering at higher frequencies while
still allowing the AC line power to pass through without
loss. This characteristic is demonstrated in the graph of
Differential Mode Attenuation.

I guess the big question is: do we believe them?
I wonder if the sacrifice of inductance is worth the gain in the differencial filtering.

I feel that it will come down to wether or not the specific person has a lot of high frequency interference in their lines. If they do, then maybe these will be better, if they don't then I would assume the Miller one with higher inductance to be better.

http://www.interferencetechnology.com/ArchivedArticles/ferrites/I95art03.htm?regid=

In many cases the common-mode filter is used alone, as it can often eliminate as much as 90% of the unwanted noise.
...
Optimum materials are not readily identified according to the usual defining parameters such as permeability and loss factors. Selection is best made by winding cores of different materials, plotting impedance and permeability versus frequency, then selecting the material which provides the broadest range attenuation.

I'm going to do more reading on the article, however, it appears as thought the common choke will never remove all the noise, and we need the differencial stage as well. I believe this is also stated in his conclution, that the best choke will be the one that covers the broadest range, again, which would be the one with the added differencial stage.

I'm going to keep looking into this and I'll report back.

EDIT: I sent an email to both CoilCraft and Miller...lets see what they say.

[poseidonsvoice]

http://www.coilcraft.com/pdfs/comoco.pdf

This series of chokes is intended for use in AC line filters
for switching power supplies. They combine common
and differential mode filtering in a single component.
By using these parts, designers can eliminate two extra
filter chokes compared to a standard common mode
choke. The unique combination of special windings and
materials provides much better filtering performance
than either a common mode choke or a single winding
inductor alone.
The differential filtering frequency response has been
designed to provide filtering at higher frequencies while
still allowing the AC line power to pass through without
loss. This characteristic is demonstrated in the graph of
Differential Mode Attenuation.

I guess the big question is: do we believe them?
I wonder if the sacrifice of inductance is worth the gain in the differencial filtering.

I feel that it will come down to wether or not the specific person has a lot of high frequency interference in their lines. If they do, then maybe these will be better, if they don't then I would assume the Miller one with higher inductance to be better.

http://www.interferencetechnology.com/ArchivedArticles/ferrites/I95art03.htm?regid=

In many cases the common-mode filter is used alone, as it can often eliminate as much as 90% of the unwanted noise.
...
Optimum materials are not readily identified according to the usual defining parameters such as permeability and loss factors. Selection is best made by winding cores of different materials, plotting impedance and permeability versus frequency, then selecting the material which provides the broadest range attenuation.

I'm going to do more reading on the article, however, it appears as thought the common choke will never remove all the noise, and we need the differencial stage as well. I believe this is also stated in his conclution, that the best choke will be the one that covers the broadest range, again, which would be the one with the added differencial stage.

I'm going to keep looking into this and I'll report back.

EDIT: I sent an email to both CoilCraft and Miller...lets see what they say.

Hi.

Thanks for stepping up and working on this. I had the same question as well. I had always thought that one should try to get the highest inductance possible for a given current load.

Anand.

[whubbard]

I am currently in a converstion via email with a very helpful engineer over at coilcraft. He says that the differtial mode will only really matter in certain situations, so I have explained ours (audio  ) and I am awaiting a reply.

Here are two PDF which you all might find useful that he forwarded to me. I'm reading them right now.
http://www.coilcraft.com/pdfs/doc191_CMFiltDesign.pdf
http://www.coilcraft.com/pdfs/doc200_CMFiltAnalysis.pdf

I'll continue updating

[BradJudy]

Thanks for looking into this whubbard.  I'm pretty crazy busy in the evenings as it is (prepping the house to go on the market, etc) so I haven't even tried to ask the questions. 

[BradJudy]

The good news is I think we might also squeeze a bit more discount out of the 8117 and 8118 JW Miller CMC's.  The bad news is that only two people were interested in the 8113 and they only accounted for a handful, so unless others want those, their cost will go up. (my original post in the thread noted both of these possibilities)

I'll send notes to the two who wanted 8113's and see if they want to stick or switch. 

I the end, I hope everyone ends up pleasantly surprised by their total costs. 

BTW: If you don't want boards and just want to order cap/CMC sets with a bit of a discount, I'm okay with that too. Just remember that there aren't any CoilCraft discounts, so there isn't any point in buying those through me if you aren't getting boards.   

[TomS]

I'm still trying to figure out what I want but have been busy too.  I'll do my best to sneak in before the 14th passes me by.  Tom

[kyrill]

I thank you again Brad
Now for the extra logistics, you know, administrating all those different addresses and finance, making all those different packages, finding out shipping and bring the whole lot to the post office...
pfff a lot of work for mostly love  of the audio community
thx

[Christopher Witmer]

I'll be thinking warm thoughts about Brad every time I power on my equipment, knowing that they are better protected thanks to his generous efforts on our behalf.

-- Chris Witmer
(Currently trying to recover from a few hours of lugging around and working with a 120lb. isolation transformer -- my achin' back!)

[rajacat]

I'm still trying to decide between the Coilcraft P3727 3A and the JW Miller 8117-BC 2.9A . I will be using these for a SB3, dac and preamp. Could one be better for a specific component like the SB3 but the other be more suited for the dac or preamp?

-Roy

[rajacat]

I'm still trying to decide between the Coilcraft P3727 3A and the JW Miller 8117-BC 2.9A . I will be using these for a SB3, dac and preamp. Could one be better for a specific component like the SB3 but the other be more suited for the dac or preamp?

-Roy

Well .... since they're not that expensive, perhaps I'll buy a mix of the two and decide for myself. 

[kyrill]

the SB3 is easy
it is very digital and then the Coilcraft design principles do play a role. Especially in the 5V line, between pws and SB3