[JN] CLC Filter Choke Choice

Guido Tent Guido at Tentlabs.com
Tue Jun 4 09:06:43 CDT 2019


I was working on an SE 300b amp yesterday. It has local filtering, 4H+22uF

Yes, that resonates around 27Hz where the HT showed max modulation :-)  The low frequency playback must suffer from that, I id not perform a listening test yet, will do.


> On May, 30, 2019, at 23:10, Joseph Levy via Sound <sound at soundlist.org> wrote:
> Greetings,
> I have several transformers and chokes on hand that were stripped off a collection of somewhat crudely built (by someone else) DIY 300B amps. They include a pair of Tango Permalloy SET OPTs and a pair of Tamura Permalloy PP OPTs.
> I also have several pairs of vintage filter chokes that meet or exceed the minimum specs for the designs I'm working from. The chokes have specs of:
> 10Hy @ 200mA, DCR = 90 ohms
> 8Hy @ 300mA, DCR = 80 ohms
> 5Hy @ 400mA, DCR = 45 ohms
> The rectifier is a 5AR4 / GZ34 followed by a 40uF cap, a choke, and then a higher value cap.
> Some time ago, one of my local audio buddies told me that a lower DCR is preferred in an SET design rather than a PP where it's not as critical, but I don't recall him explaining why. If I were to use one of those chokes with either the SET or PP designs, is there a preferred combination?
> Thanks!
> JL
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Guido Tent
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