Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Tweakers' Asylum ]

---

[ Alert Moderator ]

---

Please re-read my post, and share my views with your friend.

Posted by Al Sekela (A) on May 16, 2007 at 08:41:53

In Reply to: Are we talking about the same thing??? posted by cheap-Jack on May 16, 2007 at 08:21:25:

The choke has a steel core. Steel cores have limited frequency response, so the choke only acts as an inductor up to the frequency limit imposed by the core. Above this limit it acts like a low impedance (with residual inductance and parasitic capacitance, as well as frequency-dependent resistance caused by the skin effect).

If you doubt this, try measuring the output voltage of a power transformer as you sweep the input frequency. You will find that the output voltage drops off rapidly above some frequency in the range of 5 KHz to 100 KHz. Every model of power transformer has a different cutoff frequency. Each was designed for 60 Hz, and works well at that frequency, but each steel core has its own high frequency limit.

A similar measurement with a Hammond choke would be easy: just put a non-inductive resistor in series with the choke and measure the voltage drops across the choke and resistor as the frequency is swept. I don't know when I will get one of the 193L chokes to play with, but I will do the measurment and report when I have one.

Protection is always important. Keep in mind that the choke is built with the same technology as power transformers, and the insulation in the 193L is rated for 800 volts DC. The core frequency response limit will make the choke a good short-circuit for power line voltage spikes, so the choke's insulation will not be stressed by spikes as much as capacitor filters would be. A fuse is a good idea, but a fuse will have audible consequences on how well the choke works in this application. Some experimentation with different fuse types and fuse holder designs would be useful for this board.

I'm going to be away for the rest of the month, so I will not be able to carry on this discussion.

This post is made possible by the generous support of people like you and our sponsors:

Parts Connexion

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---