Woofer and tweeter matching, modeling - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 23 Old 05-06-2012, 11:24 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Is there a program similar to WinISD Pro that models regular speakers?

I want to build floor standing speakers with the following:

Tweeter
Woofer
Woofer
Woofer

The woofers are 2-ohm each, so will be wired in series to get to 6-ohm.
Does the tweeter have to be the same impedance? What about sensitivity? The woofer is 85 db and the tweeter 89 db.

Does it really matter the volume of the box and port as much as it does for a DIY subwoofer? Thanks!
Subjga is offline  
Sponsored Links
Advertisement
 
post #2 of 23 Old 05-07-2012, 12:01 AM
Advanced Member
 
cookieattk's Avatar
 
Join Date: Jun 2011
Posts: 522
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 56
Quote:
Originally Posted by Subjga View Post

Is there a program similar to WinISD Pro that models regular speakers?

I want to build floor standing speakers with the following:

Tweeter
Woofer
Woofer
Woofer

The woofers are 2-ohm each, so will be wired in series to get to 6-ohm.
Does the tweeter have to be the same impedance? What about sensitivity? The woofer is 85 db and the tweeter 89 db.

Does it really matter the volume of the box and port as much as it does for a DIY subwoofer? Thanks!

u need to read much much more before starting, winisd models any driver that u can buy assuming they give the parameters. plz stick to someones design for the time being.
cookieattk is offline  
post #3 of 23 Old 05-07-2012, 02:21 AM
AVS Special Member
 
Drew Eckhardt's Avatar
 
Join Date: May 2001
Location: Sunnyvale, CA USA
Posts: 2,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Subjga View Post

Is there a program similar to WinISD Pro that models regular speakers?

I want to build floor standing speakers with the following:

Tweeter
Woofer
Woofer
Woofer

You don't want to do that because it will make for a lumpy vertical polar response which results in unnatural sounding timbre due to the ceiling and floor first reflection spectra.

Quote:


The woofers are 2-ohm each, so will be wired in series to get to 6-ohm.
Does the tweeter have to be the same impedance? What about sensitivity? The woofer is 85 db and the tweeter 89 db.

You don't want to do that either. Although you can pad down the tweeter to match after applying baffle step compensation you'll be clipping amplifiers with just a few hundred Watts on acoustic music at pleasant listening levels.

Quote:


Does it really matter the volume of the box and port as much as it does for a DIY subwoofer? Thanks!

Yes. Ported system misalignment causes serious frequency response issues.
Drew Eckhardt is offline  
post #4 of 23 Old 05-07-2012, 05:47 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,229
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1174
Quote:
Originally Posted by Subjga View Post

Is there a program similar to WinISD Pro that models regular speakers?

What is a 'regular speaker'?
WinISD will model any driver for which specs are available. But it, and all box programs, is only accurate within the region of pure pistonic function, roughly to two octaves above Fs. And as tweeters typically are not even used below an octave above Fs they aren't modeled at all.

Quote:


Does it really matter the volume of the box and port as much as it does for a DIY subwoofer?

You need to spend a few weeks, if not months, studying here before considering trying to design your own speaker:
http://techtalk.parts-express.com/sh...d.php?t=219617

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #5 of 23 Old 05-07-2012, 08:30 AM
AVS Special Member
 
pgwalsh's Avatar
 
Join Date: Feb 2008
Location: Colorado Springs
Posts: 1,317
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 42
Quote:
Originally Posted by Subjga View Post

Is there a program similar to WinISD Pro that models regular speakers?

I want to build floor standing speakers with the following:

Tweeter
Woofer
Woofer
Woofer

The woofers are 2-ohm each, so will be wired in series to get to 6-ohm.
Does the tweeter have to be the same impedance? What about sensitivity? The woofer is 85 db and the tweeter 89 db.

Does it really matter the volume of the box and port as much as it does for a DIY subwoofer? Thanks!

I was in the same boat no more than a month or two ago and I ended up taking people's advice and am building a professionals MTM design. Doing a subwoofer is fairly simple, but a full range is not. I'm also looking into another build that's completely different using waveguides.

Eqpmt: Denon AVR-4520CI, EP 4000's, Sony BDP-S5100, Old Rear Projection DLP. 

Builds: Maelstrom 21 Ottoman Build, Dual Opposed MFW's x 2, Statements, SEOS-12/TD12M x 5. 

On Deck: TD6M's/SEOS Surrounds x 6, Finalists (maybe)

pgwalsh is offline  
post #6 of 23 Old 05-07-2012, 09:25 AM
AVS Special Member
 
fbov's Avatar
 
Join Date: Nov 2006
Location: Bushnell's Basin, NY
Posts: 1,014
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 28
Quote:
Originally Posted by Subjga View Post

Is there a program similar to WinISD Pro that models regular speakers? I want to build floor standing speakers with the following:...

Yes, but the input data is far more complex, and you need to know how to design driver crossovers to use the available tools.

As Bill suggests, ask on PE's TechTalk forum for a wider range of responses. The universally good advice will be what pgwalsh found - build a proven design. I've only built one speaker of my own design, but lots of proven designs. They sound better.

If you really, really want to create a speaker design using drivers of your choosing, read this (links on right side, "Getting Started in DIY Speakers" and the FAQs):
http://sites.google.com/site/undefinition/diy
And if you're not yet disabused of the notion, read this to find out what steps are involved (link at top to "Using FRD Tools to Design a Speaker"):
http://www.pvconsultants.com/audio/frdhow.htm

I'm pointing at links so you see what other info is available. I've followed Roman's process for a commercial kit I bought, and confirmed the design so I knew I was ready to "roll my own" XO. (Note that not all tool links at FRD are still live) I would also suggest one of the speaker building books, unless you have a strong EE background.

Have fun,
Frank
fbov is offline  
post #7 of 23 Old 05-07-2012, 12:37 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanks everyone. Guess there's a lot more to it than I thought.
fbov, I'm going to check out those links.

Here is the woofer I was thinking of:
http://www.parts-express.com/pe/show...number=299-289
I can't find a ready-made design for it.
Subjga is offline  
post #8 of 23 Old 05-07-2012, 01:27 PM
Advanced Member
 
mtg90's Avatar
 
Join Date: Aug 2011
Location: Millbrook, IL
Posts: 754
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 118
I used that woofer before, made a small set of monitors for my brother with them and powered by the lepai 2.1 amp.
Just about as far as you can get from a tower though.




The tweeter I used was this: Nuance TW5-073LR 1/2" Mylar Tweeter You really don't know what you are getting with those,
they are all over the place as far as their Fs/rolloff/SPL go. 4 of the 8 I have are almost unusable, but when you get good ones they are quite nice.



A frequency response graph of the finished speaker, ignore it below 200hz as it gets messy from room interaction, they rolloff around 100hz.




I know its not the floor standing speaker you wanted but let me know if you interested I could dig up the crossover / enclosure specs for you.
mtg90 is offline  
post #9 of 23 Old 05-07-2012, 08:55 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by mtg90 View Post

I used that woofer before, made a small set of monitors for my brother with them and powered by the lepai 2.1 amp.
Just about as far as you can get from a tower though.

The tweeter I used was this: Nuance TW5-073LR 1/2" Mylar Tweeter You really don't know what you are getting with those,
they are all over the place as far as their Fs/rolloff/SPL go. 4 of the 8 I have are almost unusable, but when you get good ones they are quite nice.

Those look really nice! Did you come up with the design yourself? What would be wrong with doing something like this, but tripling-up on the woofers to get to 6-ohm?

Also, is it the woofer or the tweeter that have a 50% unusable rate?
Subjga is offline  
post #10 of 23 Old 05-07-2012, 09:04 PM
AVS Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia; now run by adults.
Posts: 5,150
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Liked: 41
Quote:
Originally Posted by Subjga View Post

What would be wrong with doing something like this, but tripling-up on the woofers to get to 6-ohm?

Because the lower two LF drivers will have too large a centre to centre distance with the HF driver (and probably top to bottom LF drivers) and will cause combing.
A9X-308 is offline  
post #11 of 23 Old 05-07-2012, 09:15 PM
AVS Special Member
 
Drew Eckhardt's Avatar
 
Join Date: May 2001
Location: Sunnyvale, CA USA
Posts: 2,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Subjga View Post

Those look really nice! Did you come up with the design yourself? What would be wrong with doing something like this, but tripling-up on the woofers to get to 6-ohm?

Vertical polar response.

If you have your heart set on those drivers to pair with any amplifier make an MTM (preferably with a small flange tweeter), cross 3rd order Butterworth, and live with the 4 Ohm impedance.

The worst that should happen with a receiver that's not "4 Ohm compatible" with the volume cranked up too loud is thermal shutdown until things cool off; although you're unlikely to get there with music due to the dynamic range that keeps the average level down for given peaks and distortion resulting from the low xmax should keep you from turning it up too loud.

Or use the $27 Lepai amp from Parts Express like mtg90 did to accommodate the 2 Ohm impedance. If your receiver lacks preamp outputs and isn't using a full bridge amplifier it's trivial to make speaker to line level converters. Connect a 1K 1W resistor in series with a 100 Ohm resistor; connect black speaker wire to the non-common 100 Ohm resistor lead; connect the red speaker wire to the unused 1K resistor lead; take the RCA ground connection off the black wire; and use the common terminal for the RCA signal conductor.

Or just try it. Many amplifiers are stable into 2 Ohms but aren't rated to work that way because it would look bad (the FTC stereo and mono amplifier rating scheme requires "preconditioning" at 1/3 of the rated output where power dissipation is worse than with a steady sine wave so the number would be necessarily low). I've used Adcom 545ii and 555ii amps with 2.5 Ohm woofer loads.
Drew Eckhardt is offline  
post #12 of 23 Old 05-07-2012, 09:20 PM
Advanced Member
 
mtg90's Avatar
 
Join Date: Aug 2011
Location: Millbrook, IL
Posts: 754
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 118
Did the design myself, the biggest problem with trippling the woofers is the comb filtering you get when there are multiple drivers all covering the same passband, you get peaks and nulls in your response. (looks like Drew and A9X-308 got to it first) Those woofers just are not going to work for a design that has 3 or 4 of them in a two way unless you can cross your tweeter real low < 1000hz. A three way would be possible WWWMT or WWMTW, but then finding a design using them like that would be a challenge.

Sorry for the confusion, the tweeters are the ones that have a QC problem, though I did buy four of those woofers and one was bad, voice coil rub, PE sent out another no charge and I was able to fix the other by repositioning the foam surround.
mtg90 is offline  
post #13 of 23 Old 05-07-2012, 09:32 PM
AVS Special Member
 
Drew Eckhardt's Avatar
 
Join Date: May 2001
Location: Sunnyvale, CA USA
Posts: 2,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by mtg90 View Post

Did the design myself, the biggest problem with trippling the woofers is the comb filtering you get when there are multiple drivers all covering the same passband, you get peaks and nulls in your response. (looks like Drew and A9X-308 got to it first) Those woofers just are not going to work for a design that has 3 or 4 of them in a two way unless you can cross your tweeter real low < 1000hz. A three way would be possible WWWMT or WWMTW, but then finding a design using them like that would be a challenge.

The Aura NSW2 2" "full range" driver makes a lovely mid-tweeter (250Hz Fs, 3mm xmax, 13.2cm^2 Sd) for moderate listening levels (84dB sensitivity) although at $23 each a pair will cost double mtg90's amplifier and will take design work.
Drew Eckhardt is offline  
post #14 of 23 Old 05-07-2012, 10:20 PM
Advanced Member
 
mtg90's Avatar
 
Join Date: Aug 2011
Location: Millbrook, IL
Posts: 754
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 118
Quote:
Originally Posted by Drew Eckhardt View Post

Or just try it. Many amplifiers are stable into 2 Ohms but aren't rated to work that way because it would look bad (the FTC stereo and mono amplifier rating scheme requires "preconditioning" at 1/3 of the rated output where power dissipation is worse than with a steady sine wave so the number would be necessarily low). I've used Adcom 545ii and 555ii amps with 2.5 Ohm woofer loads.

+1

I ran those speakers off my Yamaha HTR-5440 without any problem, it was quite comfortable running them up to where the woofer reached its mechanical limits.
mtg90 is offline  
post #15 of 23 Old 05-07-2012, 10:49 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Yup, sounds like this is complicated. Maybe I'll stick to proven designs, buy commercial, or maybe get a tritrix from PE. Still, I'm going to look into comb filtering, and whatever else I can find, because I find it all fascinating!
Subjga is offline  
post #16 of 23 Old 05-08-2012, 08:22 AM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Ok, still trying. Please tell me what you think.

This 8" woofer
http://www.parts-express.com/pe/show...number=292-428
With this tweeter
http://www.parts-express.com/pe/show...number=297-416
And this crossover
http://www.parts-express.com/pe/show...number=260-142

I can use winISD to figure out the box size, ported, for the woofer.

Are there any caveats that I'm missing?
Subjga is offline  
post #17 of 23 Old 05-08-2012, 08:30 AM
AVS Special Member
 
tuxedocivic's Avatar
 
Join Date: Feb 2010
Location: Ladysmith, BC
Posts: 4,267
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 109 Post(s)
Liked: 401
Still a bad idea. Sorry.

That woofer won't mate very well with that tweeter. And it's generally not a good idea to use those pre-built cross overs. They don't work as advertised.

Try this: http://gonecatfishin.net/Cabrini.pdf

If you're not sure how to assemble the cross over, I can help.
tuxedocivic is online now  
post #18 of 23 Old 05-08-2012, 08:31 AM
AVS Special Member
 
tuxedocivic's Avatar
 
Join Date: Feb 2010
Location: Ladysmith, BC
Posts: 4,267
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 109 Post(s)
Liked: 401
What's your budget??
tuxedocivic is online now  
post #19 of 23 Old 05-08-2012, 11:37 AM
AVS Special Member
 
Drew Eckhardt's Avatar
 
Join Date: May 2001
Location: Sunnyvale, CA USA
Posts: 2,674
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
Originally Posted by Subjga View Post

Ok, still trying. Please tell me what you think.

This 8" woofer
http://www.parts-express.com/pe/show...number=292-428
With this tweeter
http://www.parts-express.com/pe/show...number=297-416
And this crossover
http://www.parts-express.com/pe/show...number=260-142

I can use winISD to figure out the box size, ported, for the woofer.

Are there any caveats that I'm missing?

Speaker building can be very easy especially with basic rectangular painted cabinets and a little proficiency using power tools.

Speaker design is much more involved and lots of people make bad to mediocre DIY speakers even when using very expensive drivers.

Read _Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms_ by Floyd Toole. It's a short (500 pages) summary on what we know about how speakers and rooms work with psychoacoustics ending with the latest research that lets us predict speaker preference using a formula taking into account things like on-axis flatness, off-axis smoothenss, and bass extension.

After reading it you should have a good idea of what's more and less likely to make excellent speakers.

Then read _The Loudspeaker Design Cookbook_ by Vance Dickason. It's a practical guide on how to implement speakers (things like "here's how to get your cross-over to sum flat on-axis") but is short on what's important (for instance you'll just get a rule of thumb on drivers 45 degree -6dB and -3dB frequencies with a suggestion to cross over before the previous and ideally before the later; although with first side-wall reflections around 70 degrees off axis that's not ideal).

After consuming both those you'll understand that tweeter's high resonance (1200Hz) suggests a high cross-over frequency where the 8" will have narrowing dispersion causing a directivity mismatch with unnatural timbre. Assuming you put an L pad on the tweeter to deal with the sensitivity mismatch with that cross-over you'd still have no provisions for dealing with rising response from the woofer, suppressing audible resonances, compensating for baffle step, and dealing with the complex impedances. You'll also understand that the canned cross-over also won't work well since it can't provide the asymmetric slopes and cross-over points needed to seamlessly marry the specific drivers' amplitude response, phase, and physical offset (a particular driver pair might get to a 4th order Linkwitz-Riley acoustic response with a second order electrical low-pass and third-order electrical high-pass).

If you haven't been scared off buy a calibrated measurement microphone, USB preamp, and software. As a minimum you need measurement capabilities (ARTA) after which you can do your cross-overs digitally or with line level circuits running an active bi-amp/tri-amp setup where the technology lets you put zeroes atop the drivers' poles, provide all-pass behavior to adjust for phase differences, and operate your analog realizations into purely resistive loads so text book filters work. Otherwise you'll want cross-over design software too.

Having spent a few hundred dollars on software, hardware, and books you're ready to get started in earnest.

Measure Thiele-Small parameters, build boxes (perhaps compromising with a Q of .9-1.0 for small sealed systems to give the illusion of bass), measure, perhaps repeat if your ported system ends up misaligned, pick cross-over points, test with digital cross-overs, adjust, compromise (a notch can help offset the broadening polar response after crossing to a dome tweeter), build speaker level cross-overs, and be happy until you try again.

If you don't want to do that read the books so you understand what's going on and use that knowledge to pick documented designs from experienced people that are likely to work well for your budget/output level/extension/placement requirements where the level of due diligence increases with budget.
Drew Eckhardt is offline  
post #20 of 23 Old 05-08-2012, 12:45 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Drew Eckhardt View Post

After consuming both those you'll understand that tweeter's high resonance (1200Hz) suggests a high cross-over frequency where the 8" will have narrowing dispersion causing a directivity mismatch with unnatural timbre. Assuming you put an L pad on the tweeter with that cross-over you'd still have no provisions for dealing with rising response from the woofer, suppressing audible resonances, compensating for baffle step, and dealing with the complex impedances. You'll also understand that the canned cross-over also won't work well since it can't provide the asymmetric slopes and cross-over points needed to seamlessly marry the specific drivers' amplitude response, phase, and physical offset (a particular driver pair might get to a 4th order Linkwitz-Riley acoustic response with a second order electrical low-pass and third-order electrical high-pass).

If you haven't been scared off...

Nope, you got me..
Subjga is offline  
post #21 of 23 Old 05-08-2012, 12:47 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by tuxedocivic View Post

What's your budget??

Not too much, but not too restricted either, but looking for diy. Probably the cost of the tritrix is close to max.
Subjga is offline  
post #22 of 23 Old 05-08-2012, 02:44 PM
AVS Special Member
 
tuxedocivic's Avatar
 
Join Date: Feb 2010
Location: Ladysmith, BC
Posts: 4,267
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 109 Post(s)
Liked: 401
Well, that Cabrini is $40 for the pair, so maybe you'd like something better. Johnny has put together tons of very budget friendly speakers. He's over on PE's techtalk. Goes by Johnny Richards. He might have a design for you.

There are certainly many $200 designs out there. Stick to something documented. If you want something small, I've got a little design that's easy to build.
tuxedocivic is online now  
post #23 of 23 Old 05-09-2012, 01:03 PM - Thread Starter
Senior Member
 
Subjga's Avatar
 
Join Date: Feb 2012
Posts: 207
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by tuxedocivic View Post

Well, that Cabrini is $40 for the pair, so maybe you'd like something better. Johnny has put together tons of very budget friendly speakers. He's over on PE's techtalk. Goes by Johnny Richards. He might have a design for you.

There are certainly many $200 designs out there. Stick to something documented. If you want something small, I've got a little design that's easy to build.

I'll take a look at all those projects at PE. Thanks for offering to help with X-overs.
Subjga is offline  
Reply DIY Speakers and Subs

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

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