Audio Asylum Thread Printer

Get a view of an entire thread on one page

FAQ / News / Events

Tubes Asylum

RE: What size choke are you .. .

76.90.100.230

Tre'

In Reply to: RE: What size choke are you .. . posted by John PA on May 15, 2023 at 11:59:32

The input choke is 70mH. Critical inductance with the load the 300b filament is drawing (1.2 amps) is only 11mH

Choke value in Henrys = ((voltage/current) + dcr of choke)/1000

FYI Critical inductance is the amount of inductance that it takes, for a particular circuit, to keep the diodes on, each in turn, for their entire half cycle. That keeps the charging currents to the first cap (and the load) just a little bit higher than the load current. With a cap input filter the charging currents can be many many times the load current because the diodes are only on for a short time and those current spikes cause (according to Lynn Olson) RF to be generated and then it's just everywhere. You can't filter is out, you have to try to shield it.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

choke I use (Open in New Window)

Follow Ups:

So what you are saying is. . . - John PA 12:20:31 05/17/23 (1)
To get the current just above what is needed to not have the issue with RF?

iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.
- RE: So what you are saying is. . . - Tre' 15:32:29 05/17/23 (0)
  No, you keep the diodes on for their entire half cycle so that current is always flowing to the filter so the charging currents will remain low.
  With a cap input supply filter the diodes are off most of the time and only on for a very short time. The same amount of "power" has to be delivered to the filter (so it can be delivered to the load circuit) so the power supply has to deliver a huge amount of current in that short amount of on time (to make up for the longer time when no current is being delivered).
  Tre'
  Have Fun and Enjoy the Music
  "Still Working the Problem"
  
  Edits: 05/17/23

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

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