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-   -   Type of Choke for CLC? (https://www.diyaudio.com/forums/pass-labs/316894-type-choke-clc.html)

Eric 2nd January 2018 06:40 PM

Type of Choke for CLC?
 
I've been poking around for a while and can't seem to find a good answer to this, so I'm hoping someone here can provide some insight for me.

I'm building a "First Watt" type modular power supply for F4, M2, AJ, etc. The box will contain my power transformer, rectifiers, a few caps, and a choke on each rail. This will connect to a power jack in the back for the umbilical to the amp. Each amp will have a few more caps, forming a CLC power supply.

What type of inductor is preferred in this case? Air core? Iron core (sledgehammer), or P-core? There is a big difference in price and if there is not much difference in performance, I'd rather go for the cheaper ones.

Thanks!

Zen Mod 2nd January 2018 06:48 PM

of these you listed , make compromise between price , inductivity and lowest Rdc

Jason Hubbard 2nd January 2018 07:10 PM

Inductors
 
Quote:

Originally Posted by Eric (https://www.diyaudio.com/forums/pass-labs/316894-type-choke-clc-post5295682.html#post5295682)
I've been poking around for a while and can't seem to find a good answer to this, so I'm hoping someone here can provide some insight for me.

I'm building a "First Watt" type modular power supply for F4, M2, AJ, etc. The box will contain my power transformer, rectifiers, a few caps, and a choke on each rail. This will connect to a power jack in the back for the umbilical to the amp. Each amp will have a few more caps, forming a CLC power supply.

What type of inductor is preferred in this case? Air core? Iron core (sledgehammer), or P-core? There is a big difference in price and if there is not much difference in performance, I'd rather go for the cheaper ones.

Thanks!

Hope that I'm not going to find myself swimming in shark infested waters but here goes...

Current in SE amplifiers will on average be Iq but will at any point in time be a value between zero and 2Iq - so 2Iq is the minimum current rating that you will need for your inductor. If you undersize the inductor and it has a core then the core will saturate (air core being the exception because it has no core to saturate and it's current capability is limited only by the gauge of the wire it is made from). If you have a bit of iron in your inductor then the inductance goes up (so you can make a smaller, cheaper inductor than an equivalent air core).

That's my understanding anyway....

Zen Mod 2nd January 2018 07:15 PM

have no objections

eduard 2nd January 2018 07:32 PM

Hello,
The French did use 200 or 150 my iron core chokes in some their high current class a designs.
If I would ever build one of these amps again I would use the high current rated filament chokes from Lundahl ll1694 or ll2733 depending on the current needed you can put the 2 coils in parallel. I think bbecause of higher my they would filter much better than the average air core coil.
Greetings, Eduard

Eric 2nd January 2018 08:22 PM

I started my search on PartsExpress (which tends to run a bit on the expensive side) and found these:

Erse Air Core 800w 14ga 2.2mH 0.33Rdc

Jantzen P-core 400w 15ga 2.2mH 0.15Rdc

Jantzen C-core 700w 14ga 2.2mH 0.06Rdc

Jantzen air core 500w 15ga 2.2mH 0.52Rdc

ERSE iron core 500w 16ga 2.2mH 0.154Rdc

I'm inclined to go with the P-core for $15 each.

Zen Mod 2nd January 2018 08:34 PM

Erse Iron core is best one , on the list

Eric 2nd January 2018 10:27 PM

Zen: Thanks for the input.

Eduard: The Lundhal's look nice, but they are a rather expensive option in this application.

Jason: Thanks for the link to the Amveco's on ebay - they look nice, but don't specify a Rdc and with an 8mH rating, I presume the Rdc is high.

I'll probably use these at Madisound (2.25mH, 15ga, 0.16Rdc) since I already need to place a Madisound order.

eduard 2nd January 2018 11:50 PM

Hello,
But the Lundahl are the only ones designed for this option. I have been using them in a few of my gear. With ll2733 the 2 coils in parallel you will get 100 mH THEN you are making a filter.
2,2 mH you can probably measure the result but 100 mH you will say wow. Maybe you should wait a few weeks, I brought some ll2733 for a friend in Vietnam whom is going to use them in his Nelson Pass design.
It has been discussed before.
Sincere greetings from Eduard

Eric 3rd January 2018 12:15 AM

Quote:

Originally Posted by eduard (https://www.diyaudio.com/forums/pass-labs/316894-type-choke-clc-post5295975.html#post5295975)
But the Lundahl are the only ones designed for this option. It has been discussed before.

I'm always curious to know more. The Lundahl chokes sure do look nice, but come at a heavy price penalty. I presume these are the only ones designed for this purpose because they are filament chokes. Also, do you have a link to prior discussion on this topic - I've been poking around both here and the web in general and most of what I have found is for tube amps and Class-D power supplies. Neither of which fit Class-A solid state amps very well...


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