the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
icon

How to filter out low frequencies


Post ReplyPost New Topic
< Prev Topic Next Topic >
DYohn 
Moderator - Posts: 10,741
Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: April 22, 2003
Location: Arizona, United States
Posted: April 30, 2006 at 12:23 PM / IP Logged  

I don't want to put words into haemphyst's mouth but what I believe he is saying is polarized caps cannot be used in crossovers BY THEMSELVES in the same way non-polar caps are used.  He then goes on to say it is possible to configure polarized caps for this purpose, but that they must be used differently than non-polar ones.

I will add my 2 cents that one should NOT use polarized or electrolytic caps for audio crossovers even if electrically it is possible to do so because they simply sound bad.  Non-polar non-electrolytic caps (and for bass blockers you need them to have at least a 100 volt rating) are the best solutions, and yes some of them are very expensive indeed.  It is not unusual for a passive crossover to cost more to build than the driver it is controlling.

Support the12volt.com
haemphyst 
Platinum - Posts: 5,054
Platinum spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: April 30, 2006 at 12:38 PM / IP Logged  
stevdart wrote:

Good thing the thread came this far then. Wired in series with one cap reversed is a bit different than wired in series. Huh, haemphyst? And that latest info you gave is new to me, too. I didn't know that about overcoming the polarized issue.

"But, again, polarized caps, and unusable in this application."

Is that a typo? Because if not it makes your entire statement contradictory.

All right, all right, all right... ya caught me. What I MEANT to say was this: right out of the package, without properly connecting a second one, they will be unusable in this application... How to filter out low frequencies - Page 2 -- posted image.
sab0276 wrote:

I have some 3.5" coaxial speakers that I would like to filter out the low frequencies. Is there like a base cap or a resistor or something I can put inline? I would like some thing cheap and easy if possible. I don't really want to use a crossover or anything.

Thanks.

-Scott

And while Dyohn is absolutely correct in his statement above, I was looking for the least expensive (i.e. "cheap" - $1.69 * 4 = $6.76, as opposed to $9.99 plus freight for the lowest frequency "bass blockers"), as well as the fastest method (i.e. "easy" - trek to the local RS and walk out with 'em, as opposed to waiting a week for Parts Express) for him to reach his desired destination. While not COMPLETELY wrong, my suggested method will work, with 100% safe and satisfactory results, sometimes offering additional safety, due to the increased voltage capabilities of two caps in series, rather than a single high voltage cap. I have done it before, on MANY occasions.
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
stevdart 
Platinum - Posts: 5,816
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spaceThis member consistently provides reliable informationspace
Joined: January 24, 2004
Location: Pennsylvania, United States
Posted: April 30, 2006 at 1:25 PM / IP Logged  
...and we get a good learning thread out of the deal, too.  Can't complain about that!   How to filter out low frequencies - Page 2 -- posted image.
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
geepherder 
Platinum - Posts: 3,668
Platinum spaceThis member consistently provides reliable informationspace
Joined: October 27, 2003
Posted: April 30, 2006 at 5:32 PM / IP Logged  
Yes, that's interesting to know about polarized caps.
My ex once told me I have a perfect face for radio.
boomer_106 
Silver - Posts: 710
Silver spacespace
Joined: November 25, 2003
Location: United States
Posted: April 30, 2006 at 8:38 PM / IP Logged  

[/QUOTE]

Those frequencies are FAR too high... You still want SOME bass, right? You are just trying to filter the deepest bass to prevent "flapping", right? These are WAY more expensive, too... All those are? Expensive capacitors... The SAME as I linked for you in my original post.
sab0276 wrote:

I was only showing him an example of a bass blocker. It's up to him to choose what he wants thats  all.

sweatyogre 
Member - Posts: 15
Member spacespace
Joined: April 06, 2006
Location: United States
Posted: April 30, 2006 at 9:29 PM / IP Logged  
I'm currently using 200 Hz bass blockers on my 6x8s. Is that too high? The lowest frequency they're supposed to be able to handle is 37 Hz.
sab0276 
Copper - Posts: 61
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: April 21, 2006
Location: United States
Posted: May 01, 2006 at 10:49 AM / IP Logged  
Excellent information here. Thank you.
Just to throw another monkey wrench into the equation. The 3.5" are replacements for the 2.5" in the very back of my Yukon. After I installed them I realized that they are wired in series. They only work if both are connected. How will this effect adding a cap?
Thanks again.
-Scott
2002 GMC Yukon SLT non-Bose
Pioneer AVIC N3
DYohn 
Moderator - Posts: 10,741
Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: April 22, 2003
Location: Arizona, United States
Posted: May 01, 2006 at 11:23 AM / IP Logged  

sab0276 wrote:
Excellent information here. Thank you.
Just to throw another monkey wrench into the equation. The 3.5" are replacements for the 2.5" in the very back of my Yukon. After I installed them I realized that they are wired in series. They only work if both are connected. How will this effect adding a cap?
Thanks again.
-Scott

If both speakers are 4-ohms, then the total load in series is now 8-ohms.  This will change the crossover frequency by a factor of 2.  For example, if you use a 4uf capacitor, it will serve as a 6db/oct high-pass filter at 100Hz for a 4-ohm load, but at 50Hz for an 8-ohm load.  If you want 100Hz HP with an 8-ohm load, you want a 2uf cap.  And, since both speakers are in series, you only want to use one cap on the positive leg of the speaker closest to the amp.

Support the12volt.com
sab0276 
Copper - Posts: 61
Copper spaceThis member has made a donation to the12volt.com. Click here for more info.spacespace
Joined: April 21, 2006
Location: United States
Posted: May 01, 2006 at 11:52 AM / IP Logged  
I'm not sure which one is wired closest to the amp. Does it matter?
Also since the speakers have a range of 60Hz-28kHz and I'd like to lose as little bass as possible would the 4uf cap that high pass filters at 50Hz be ok?
Thanks.
-Scott
2002 GMC Yukon SLT non-Bose
Pioneer AVIC N3
DYohn 
Moderator - Posts: 10,741
Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: April 22, 2003
Location: Arizona, United States
Posted: May 01, 2006 at 12:04 PM / IP Logged  
Ah crap, I composed too quickly and committed the old "shifted decimal place" error.  Instead of "4" and "2" uf as I wrote above, it should read "400" and "200."  Thanks to stevdart for being my proof-reader.  How to filter out low frequencies - Page 2 -- posted image.
Support the12volt.com
Page of 3

  Printable version Printable version Post ReplyPost New Topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

  •  
Search the12volt.com
Follow the12volt.com Follow the12volt.com on Facebook
Friday, July 12, 2024 • Copyright © 1999-2024 the12volt.com, All Rights Reserved Privacy Policy & Use of Cookies
Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.

Secured by Sectigo
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
Support the12volt.com
Top
the12volt.com spacer
the12volt.com spacer