Active crossover/preamp? - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 4th September 2012, 11:35 PM   #1
diyAudio Member
 
Join Date: Sep 2012
Default Active crossover/preamp?

I've had a bug for a while to build a modern boombox. In my research I stumbled across this forum. I plan to start with the amp and speakers, and then move on to "source" and maybe use an embedded PC to run media portal. But until then, I'll just use an MP3 player or something.

Anyway, on to my problem. I plan on having a tweeter/woofer combo up top, and then a dual voice coil sub on the bottom... probably ported. I'm not apposed to having passive crossovers between the tweeters/woofers but the sub I deffinately want on a discrete channel. I think that, tops, I want 50watts per channel. With the sub running at 100 or so.

I've found many amplifiers that would suit my needs based on the Class-T chips that seem to be relatively popular in this forum. But I can not find an active crossover to split the sub off from the rest of the signal. I'd be really interested in getting a 6 channel amp and running all of the channels discretely. But again, this crossover issues in the way. Everything I've found has been very expensive and very large. I need someone relatively small, with adjustable thresholds, preferably in circuit board form. I've no need for a case.

Does anyone have any suggestions?

Thanks!
  Reply With Quote
Old 4th September 2012, 11:38 PM   #2
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
You could used a Passive Line Level crossover (PLLXO) in front of each amp channel if you don't need to go past 2nd order. Or you could build it into the feedback loop of the amp itself.
__________________
Big Altec Moving Sale!
  Reply With Quote
Old 4th September 2012, 11:43 PM   #3
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Electronic Kit - 2-Way Active Crossover | eBay
  Reply With Quote
Old 5th September 2012, 12:06 AM   #4
diyAudio Member
 
Join Date: Sep 2012
Quote:
Originally Posted by Saturnus View Post

Thanks! That's the sort of thing I was looking for... but it's mono. I'd need 4 of them at $30/each and I'd have to solder it myself. :-/
I searched for 3 way crossover kits and I don't see any.

I guess I could get a car audio crossover like THIS but it just doesn't seem right to me... lol
  Reply With Quote
Old 5th September 2012, 12:09 AM   #5
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
A car crossover - why not? That one looks big, but otherwise should do what you want it to.
__________________
Big Altec Moving Sale!
  Reply With Quote
Old 5th September 2012, 12:20 AM   #6
diyAudio Member
 
Join Date: Sep 2012
Quote:
Originally Posted by Pano View Post
A car crossover - why not? That one looks big, but otherwise should do what you want it to.
Well, I do want it to run off of a 12v battery. hmmm....

I was looking at line level passives and the only ones I could find were low-pass filters for subs... and they were very expensive and not adjustable.
  Reply With Quote
Old 5th September 2012, 08:59 AM   #7
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Note that car audio x-o's usually are intended to much higher input/output voltages than are used in mobile audio. 8Vp-p is not uncommon on the output. Such voltages would fry almost all amplifier intended for small signals instantly. Also note that the typical output of an mp3 player of down to 1Vp-p wouldn't be enough to drive most car audio x-o's above noise level.

Btw, why are you saying you'd need 4 of them? You implied that you'd use passive filtering on the top section between midrange and tweeter and only need the filter for the sub. If you want something more sophisticated then just buy a miniDSP (or 2) instead. Problem solved.

Last edited by Saturnus; 5th September 2012 at 09:02 AM.
  Reply With Quote
Old 10th September 2012, 12:10 PM   #8
diyAudio Member
 
Join Date: May 2010
google for minidsp, minidsp 8 in 8 out should do it.
  Reply With Quote
Old 11th September 2012, 03:52 PM   #9
diyAudio Member
 
Join Date: Feb 2009
Quote:
Originally Posted by Saturnus View Post
Note that car audio x-o's usually are intended to much higher input/output voltages than are used in mobile audio. 8Vp-p is not uncommon on the output. Such voltages would fry almost all amplifier intended for small signals instantly. Also note that the typical output of an mp3 player of down to 1Vp-p wouldn't be enough to drive most car audio x-o's above noise level.

Btw, why are you saying you'd need 4 of them? You implied that you'd use passive filtering on the top section between midrange and tweeter and only need the filter for the sub. If you want something more sophisticated then just buy a miniDSP (or 2) instead. Problem solved.
and the input/output voltage is relative how? it do not put out more then it gets in anyways
  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
Passive crossover into active crossover hahfran Multi-Way 16 10th February 2008 07:16 PM
Diy preamp/active crossover JaRoD Analog Line Level 7 11th August 2006 12:15 PM
Active CrossOver Toast_Master Subwoofers 4 26th April 2006 08:39 AM
Help with active crossover sunil Multi-Way 3 8th March 2004 11:44 AM
XVR1 active crossover, discrete active stage promitheus Pass Labs 18 22nd July 2002 02:29 AM


New To Site? Need Help?

All times are GMT. The time now is 08:59 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