biasing electrolytics in speaker crossovers? - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 5th August 2002, 08:33 AM   #1
diyAudio Member
 
Join Date: Feb 2002
Location: Germany
Default biasing electrolytics in speaker crossovers?

I know there has been plenty of discussion about biasing electrolytics and film in DC blocking apps.

However, a search for crossover AND electrolytic AND bias drew a blank.

Wouldn't it make sense to replace the large bipolar electrolytics in speaker crossovers with two polar ones of twice the capacity and bias them, e.g. with a 1 k resitors to the positive or negative rail of the power amp?
  Reply With Quote
Old 5th August 2002, 10:24 AM   #2
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Default biasing electrolytics etc

Hi capslock,

You're right, electrolytics behaver differently depending on the signal polarity. The applications of 'lytics in xovers I have seen/used always had either bi-polar 'lytics or back-to-back "normal" 'lytics. Any particular reason for you to use a polarised set-up (or just wondering)?

Cheers, Jan Didden
  Reply With Quote
Old 5th August 2002, 10:50 AM   #3
diyAudio Member
 
Join Date: Feb 2002
Location: Germany
Jan,

go to the "electrolytic decoupling ..." thread in this forum and look at the Jung/Marsh article which is the first or second link provided by H.H.

Fig. 3 gives two 6u8 caps back to back with 680 R load in a DC blocking (high pass) configuration with no bias (C), and 5, 10, 15 V bias (D, E, F).

Occured to me that that might be a neat way to fix the large crossover capacitors that aren't readily replaced by film devices.

In my speakers, I have already replaced all the series capacitors, but the shunts in the woofer branch were simply too big. Conventional wisdom has it that it does not really matter what happens in the shunted branch (see e.g. Harry's shunted volume control). I am not really convinced because the shunt impedance is after all part of a voltage divider and will have some influence on what passes through...

Eric
  Reply With Quote
Old 5th August 2002, 11:23 AM   #4
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally posted by capslock
Jan,

[snip]
Conventional wisdom has it that it does not really matter what happens in the shunted branch (see e.g. Harry's shunted volume control). I am not really convinced because the shunt impedance is after all part of a voltage divider and will have some influence on what passes through...

Eric
Eric, OK I'll check the Jung/Marsch article. Should have it in my lab library, but its from waaay back when.

On the above quote, I am strongly convinced that whatever you do in (a) shunt DOES influence the resuls! As you say, the shunt is as much part of the circuit as the series arm. Consider a node that has three leads connected: the input from a series circuit (let's call it the source), a shunt to ground and a wire to the input of an amplifier. Thevenin has it that the sum of currents into a node is zero, so whatever goes to the input of the amp is the sum of the current from the source + the shunt. QED.

Cheers, Jan Didden
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
70's speaker drivers and crossovers worth reusing? Dejavous Multi-Way 10 29th April 2008 05:40 AM
Speaker connectors for use with external crossovers luvdunhill Multi-Way 6 2nd April 2008 12:58 AM
Loud Speaker Crossovers and power amp placement JRKO Multi-Way 20 1st August 2004 11:07 AM
static bias for electrolytics in speaker crossover? capslock Multi-Way 2 6th August 2002 01:58 PM


New To Site? Need Help?

All times are GMT. The time now is 02:30 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2