Crossover Frequency - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 16th June 2008, 05:14 PM   #1
diyAudio Member
 
Join Date: Dec 2007
Default Crossover Frequency

Hi, I got interested in diy audio a few months ago but kind of dropped it because of some confusion I had about choosing a xo frequency. My interest was sparked again when I came across a pair of older (90's) Polk Audio bookshelf speakers for $4 at a local thrift store. Turned out that one woofer was completely useless and the other was near its end. I decided to remove all the old components and use the enclosures to build my own custom computer speakers. My problem is that I want to choose the right frequency to crossover at. I have read that I should crossover 1 to 2 octaves above the Fs of my tweeter which in my case is 3,000 Hz. I'm not sure how to determine that value correctly. Should the xo frequency be 6,000 Hz?

Here are the drivers I plan to use.
Tweeter: http://www.partsexpress.com/pe/showd...number=276-025
Woofer: http://www.partsexpress.com/pe/showd...number=264-817

I don't want buy a kit so please don't recommend that option. I feel that building a kit would be the same as simply tearing apart and reassembling a pair of speakers.
  Reply With Quote
Old 16th June 2008, 05:59 PM   #2
diyAudio Moderator Emeritus
 
Iain McNeill's Avatar
 
Join Date: Oct 2007
Location: Santa Cruz, California
Are you using these speakers because they fit in the existing baffle or are you going to cut a new baffle to suit?

Reason I ask is the tweeter you have chosen will be hard to design a crossover for. The natural response is a 2nd order at 3KHz and so as you say, you need to crossover above this point.

You could add a cap at 3KHz (to protect tweeter from LF) and make it a 3rd order acoustic and design woofer hi pass to match.

Then again, the Tang Band is a really nice speaker. I have some W3-1364's which are great as full range albeit no bass below 80-100Hz.

My recommendation? just use the TB's in you're thrift store cabs with new baffles and then add a sub down the road.
  Reply With Quote
Old 16th June 2008, 07:30 PM   #3
diyAudio Member
 
Join Date: Dec 2007
Quote:
Originally posted by Iain McNeill
Are you using these speakers because they fit in the existing baffle or are you going to cut a new baffle to suit?
No they will not fit, I will be making a new baffle regardless of what drivers I end up with in the end.

Quote:
Reason I ask is the tweeter you have chosen will be hard to design a crossover for. The natural response is a 2nd order at 3KHz and so as you say, you need to crossover above this point.

You could add a cap at 3KHz (to protect tweeter from LF) and make it a 3rd order acoustic and design woofer hi pass to match.
I chose that tweeter mainly because of price and looks, but if there is another that would work better I wouldn't mind switching.

Quote:
Then again, the Tang Band is a really nice speaker. I have some W3-1364's which are great as full range albeit no bass below 80-100Hz.
My enclosures are .162 cu. ft. And the woofer selection chart on partsexpress.com indicates the my selected woofer would be at F3=77 at .15 cu.ft. ported. I'm thinking this will be fine for computer speakers especially if I add some damping material. Like you said, I could add a sub later on. I have seen other tang band and Hi-Vi full range drivers that reach 20,000 Hz, Would it be better to just use one or 2 full range drivers? Or is that more complicated?

Quote:
My recommendation? just use the TB's in you're thrift store cabs with new baffles and then add a sub down the road.
Are you recommending to leave out the tweeter and just use the TB's. I would do that but I'm not sure if I would need any type of xo or if it would just be straight wired?

Sorry for so many questions.
  Reply With Quote
Old 16th June 2008, 08:00 PM   #4
diyAudio Moderator Emeritus
 
Iain McNeill's Avatar
 
Join Date: Oct 2007
Location: Santa Cruz, California
exactly. Just use the TB's full range straight wired to the amp. No fuss, no muss, no darned XO to mess things up.

Do a search of the W4's on the full-range forum, I think you'll get a lot of hits.

Your .16cuft cab is a bit small for sealed cabinet and would increase resonance / cut off some bass while reducing distortion. But ported, as you indicate, you should get quite acceptable bass with tuning (at the expense of transient response.)

I think the FR crowd may try to persuade you to go open baffle......
  Reply With Quote
Old 16th June 2008, 08:09 PM   #5
diyAudio Member
 
Join Date: Dec 2007
Great, because I was starting to change my mind and just spend my money on some brand new speakers from amazon. I was leaning toward 2 way because of bass but I may save that for another day when I feel like building enclosures and all. Also I realized that when comparing tweeters I was comparing the Fs of the audax with the wrong number in other tweeters specs. Therefore thinking the audax tweeter had the lower Fs. lol.

Thanks for the help.

edit: Still I would like to know how to measure one octave above any given frequency. If anyone would help me out there. I get confused between different things I have read. Am I correct that its just twice whatever the starting frequency is?
  Reply With Quote
Old 16th June 2008, 08:46 PM   #6
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Yes, going up an octave is the same thing as doubling the frequency.
  Reply With Quote
Old 16th June 2008, 08:57 PM   #7
diyAudio Member
 
Join Date: Nov 2004
Location: sk
Send a message via AIM to ocool_15 Send a message via Yahoo to ocool_15
Quote:
Originally posted by Ironhead


I chose that tweeter mainly because of price and looks, but if there is another that would work better I wouldn't mind switching.

I don't see alot of information available but I expect you will get a better result using a driver that can cross over lower.
Quote:


Would it be better to just use one or 2 full range drivers? Or is that more complicated?

If you are talking 2 full range drivers per side it would normally be used for a full baffle step design which isn't normally used for near field computer speakers.

For best results you will need to measure the drivers.
From the cone diameter you should crossover no higher then 4050 Hz. From the supplied frequency response graph the peak centered at 6500 Hz will likely show up as a peak F2 harmonic of 3250Hz. If its bad you should cross this driver below that point.
  Reply With Quote
Old 17th June 2008, 12:16 AM   #8
diyAudio Member
 
Join Date: Dec 2007
Ok, I'm still not totally decided on whether I want to use 1 full range driver per side or a new pair of drivers I think will work much better together. Like I said above my decision on that tweeter was due partly to my not comparing the right numbers. So, if I don't do 1 full range per side I may try this.

Tweeter: http://www.partsexpress.com/pe/showd...number=270-176
Woofer:http://www.partsexpress.com/pe/showd...number=297-429

I believe that pair would work much better. Crossed over at 2600Hz. The enclosure will still be too small I think but stuffing it would bring it up to acceptable I think. Yes, it will be ported. I may even save this pair for later and make new enclosures specifically for them. How does this look? Comments? I'm learning a lot so don't stop with the help.
  Reply With Quote
Old 17th June 2008, 08:38 AM   #9
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Stay away from Goldwood tweeters, they are rubbish.
see : http://www.zaphaudio.com/tweetermishmash/

/sreten.
  Reply With Quote
Old 17th June 2008, 03:18 PM   #10
diyAudio Moderator Emeritus
 
Iain McNeill's Avatar
 
Join Date: Oct 2007
Location: Santa Cruz, California
now this is a tweeter

http://www.partsexpress.com/pe/pshow...TOKEN=38207949

luvverly!
  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
DIY Crossover w /two frequency adjustments ? iain42 Multi-Way 1 4th January 2009 05:09 PM
How to determine crossover frequency? maurycy Multi-Way 2 7th January 2006 03:29 PM
digital crossover frequency millim Digital Source 33 19th March 2004 12:25 AM
crossover frequency Laufer Multi-Way 2 22nd October 2003 06:52 PM
crossover frequency ray Multi-Way 1 10th September 2001 06:31 AM


New To Site? Need Help?

All times are GMT. The time now is 03:33 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