low pass filter - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 12th October 2006, 12:04 PM   #1
diyAudio Member
 
Join Date: Oct 2006
Question low pass filter

Hey guys, I have just entered in this forum and it seems it's great.
Well first of all I had a question about preamp filtering:
I've got a 200w car amplifier(phonocar) briged and a 12" boschman sub. my problem is that my amp has got no preamp filtering. just full pass.Listening to music in that way is terrible, believe me.
I was wandering if I can construct a low pass preamplifier filter which allows frequencies under 80Hz and goes at 18 or 24 db/octave. It doesn't matter to me if it is a passive or active filter.
  Reply With Quote
Old 12th October 2006, 12:09 PM   #2
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
You need an active filter. Search here and Google for "sallen-key filter" it's pretty easy.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 12th October 2006, 01:46 PM   #3
diyAudio Member
 
Join Date: Oct 2006
Yeah it is really simple but I don't understand what kind of operational amplifier should I use. Any identifying code will be a great help.

Here is the link if u need to have a glance

http://www.ecircuitcenter.com/Circui.../opsalkey1.htm
  Reply With Quote
Old 12th October 2006, 02:27 PM   #4
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
It's really not that critical TL071 is a good place to start.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 13th October 2006, 06:19 AM   #5
diyAudio Member
 
Join Date: Oct 2006
OK I will try that. I hope it helps.
I just had a look at the google and there is something i don't understand in that Operational Amplifier. (I might admit it, I am not at all experienced in making up electronic circuits)
What do I connect to
OFFSET N1, OFFSET N2, and NC pins. Well I imagine NC is connected to ground but I can't figure it out what to connect to the other 2 pins.
I really need that help.

If u need to chek that out the link below might be usefull
http://focus.ti.com/lit/ds/symlink/tl071.pdf
  Reply With Quote
Old 13th October 2006, 08:12 AM   #6
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Do NOT connect NC to ground, it's "Not Connected".

Offset 1 and 2 are for nulling out DC offset, leave them unconnected or whatever the manufacturer tells you to do in the data sheet.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 13th October 2006, 08:49 AM   #7
diyAudio Member
 
Join Date: Oct 2006
Woow what a terrible mistake i have done. . .
I told u that I was unexperienced in circuit building.

Now I see... NC stands for "not connected".
Well does it matter if I don't connect the offset terminals at all. Will it affect the results I expect?

Did I thanked you for the help?I guess i haven't. well, thanks a lot. I really appreciate your advices. I'm glad I am part of this forum now.
  Reply With Quote
Old 17th October 2006, 11:38 AM   #8
Dan2 is offline Dan2  South Africa
diyAudio Member
 
Join Date: Sep 2005
don't connect the offset terminals to anything - the opamp is running at unity gain so it won't make a noticable difference
  Reply With Quote
Old 17th October 2006, 11:53 AM   #9
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Just read the datasheet of the op-amp chip you intend to use.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 20th October 2006, 09:19 AM   #10
diyAudio Member
 
Join Date: Oct 2006
I just made up the low pass circuit based on TL072 op amp. Well let me say that the result was great. but.... after a few minutes working in music a terrible noise came out of the sub and I immediately disconnected the amp from power source. Then I removed the filter and the amp was completely OK. connected again the filter but the noise was again present. I think i have blown up the op amp of the filter cause i supplied it at +18 -18 volts dual voltage of the amplifier. may this have caused the problem? If so then at what voltage should I supply the TL072 op amp? specifications from the producer say from +/-5 to +/-18 volts. can u help me please?
  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
need help with low pass filter prezden Multi-Way 11 12th January 2009 08:04 AM
Low pass filter help ifrythings Subwoofers 1 24th February 2006 09:45 AM
NO low pass filter? jmar Digital Source 7 19th January 2006 12:53 PM
low pass filter crazyant Car Audio 3 15th September 2005 06:15 PM


New To Site? Need Help?

All times are GMT. The time now is 07:35 AM.


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