PLLXO help - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 March 2012, 07:06 PM   #1
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
Default PLLXO help

OK. I'm ready to embark on a PLLXO. I ran some numbers through the spreadsheet and notice that the cap values are several orders of magnitude smaller than speaker level XO's. Questions:

1. In my ignorance, it appears that the low valued caps will have to be ceramics or styrene type bypass caps. True?

2. I have no idea what the amp Z is. I suppose that I can simply assume 100kΩ, see what happens and adjust values acordingly?

3. I intend to use a plate amp to cross the sub. I'll start with 300Hz 1st ordrfor the high-pass.

4. Using a pot for the XO resistor, what kind of frequency range can I expect for a given cap?

Thanks,
Bob
  Reply With Quote
Old 5th March 2012, 07:26 PM   #2
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Bob, is this for the Topping?

The amp Z is essentially the R to ground at the input...

For hipass, i have been using this R as the shunt element of the RC filter and just using a cap in front for 1st order... adding an additional shunt R in front decreases the net input R and degrades potential performance if you want to reach for 2nd order and also requires a larger cap.

One of the advantages of PLLXO is that it uses much smaller caps then a passive XO, allowing you to get a much better cap for your budget -- no point in using anything but good poly caps in these.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 5th March 2012, 08:12 PM   #3
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
Quote:
Originally Posted by planet10 View Post
Bob, is this for the Topping?
Yes

Quote:
The amp Z is essentially the R to ground at the input...
OK. I can do that. The Topping reads 49kΩ, and old Yami 100kΩ and my p-p tubes 87kΩ

Quote:
For hipass, i have been using this R as the shunt element of the RC filter and just using a cap in front for 1st order... adding an additional shunt R in front decreases the net input R and degrades potential performance if you want to reach for 2nd order and also requires a larger cap.
Putting 49kΩ into the spreadsheet gives 10.8nF. Unless I don't understand the units, which of course is possible, the smallest foil and film cap is 0.01μF, or 10pF and 10^3 too big. Where would you suggest that I sourse the proper caps?

Bob
  Reply With Quote
Old 5th March 2012, 08:56 PM   #4
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
0.01 is close enuff...

Solen Electronique Inc.

Solen Electronique Inc.

You can fine tune with a shunt R across the input R.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 5th March 2012, 09:19 PM   #5
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
re:'Using a pot for the XO resistor, what kind of frequency range can I expect for a given cap?' - you can use a resistor in series with the pot to set the range
__________________
Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
  Reply With Quote
Old 5th March 2012, 11:22 PM   #6
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
Quote:
Originally Posted by planet10 View Post
0.01 is close enuff...
Ah! So the units on the spreadsheet are really μF. I'll buy some parts for a patch box and see what happens.

Thanks,
Bob
  Reply With Quote
Old 6th March 2012, 11:28 AM   #7
diyAudio Member
 
Join Date: Dec 2008
Location: Knoxville, TN
Doesn't it go:
milli = 10^-3
micro -6
nano -9
pico -12

Pico being smaller than nano that is. .01 micro = 10 nano?
  Reply With Quote
Old 6th March 2012, 10:58 PM   #8
diyAudio Member
 
Join Date: Jul 2009
Default PLLXO help

Here's on online converter that may help.
Online Conversion - Electric Capacitance

eta -When I ran 49 kohms through my first order calculator @ 300hz, my result was C1 = 1.0816326530612E-8 farads, so I think you are on the right track

Last edited by Rev. Billy Bob; 6th March 2012 at 11:05 PM. Reason: ading something
  Reply With Quote
Old 7th March 2012, 02:13 AM   #9
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
Thanks, guys.

Bob
  Reply With Quote
Old 6th April 2012, 03:55 AM   #10
diyAudio Member
 
Join Date: Aug 2008
Quote:
Originally Posted by planet10 View Post
Bob, is this for the Topping?

The amp Z is essentially the R to ground at the input...

dave
Is this also true when using a volume pot. Or is the input impedance now the impedance of the volume pot
Paul
  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
Trying to build a PLLXO andb Multi-Way 15 15th January 2011 09:29 PM
pllxo w lm3886? mrkramer Chip Amps 1 5th December 2009 12:15 PM
Anybody interested in checking my PLLXO? kirk57 Analog Line Level 6 4th December 2009 02:18 AM
PLLXO implementation lbstyling Multi-Way 14 29th September 2009 12:58 PM
Calculate PLLXO audiobomber Multi-Way 5 22nd August 2007 05:34 PM


New To Site? Need Help?

All times are GMT. The time now is 05:05 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