Unity horn with 2 x Eminence Alpha 6 drivers - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 75 Old 04-25-2012, 08:26 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I finally decided to throw my Unity horn hat into the ring! I hope to add a bit to the knowledge base by documenting with measurements what happens with each sequential change to the horn. My design targets are -3db at around 200 to 220 hz for high pass, and -3db at >1000hz for low pass. 115 db+ in 4pi space. As you can see, lots of "oopsies"... nothing bondo can't handle! Since these things will hide behind speaker cloth, I really don't care. I will use a minidsp for crossover/eq. More to come...
LL
LL
LL
LL
LL
johnbomb is offline  
Sponsored Links
Advertisement
 
post #2 of 75 Old 04-25-2012, 08:26 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Attached is the google sketchup for the horn, as well as the Hornresp model. I had to learn sketchup from scratch, but I figured out what I needed in about an hour. I used the program's measuring tools (including the protractor- key for the angles) to figure out the cuts. Unfortunately, I don't have CNC machinery to cut the panels- only a bandsaw and Festool gear. Therefore, some amount of error got built into the horn.

Here's a link to an inspirational project at diyaudio:

http://www.diyaudio.com/forums/multi...ve-x-over.html

 

alpha6-1.txt 0.39453125k . file

 

rectangle unity with markup.zip 15.9287109375k . file
Attached Files
File Type: zip rectangle unity with markup.zip (15.9 KB, 30 views)
File Type: txt alpha6-1.txt (404 Bytes, 24 views)
johnbomb is offline  
post #3 of 75 Old 04-25-2012, 08:27 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
All measurements taken with a radioshack SPL meter through room eq wizard. Levels not calibrated for volume, only relative performance.

The first pic shows a ground plane measurement of the horn with 1 vs 2 drivers connected. I wanted to see if the FR trend would change when the second driver was added.... the passband of interest didn't- it only got louder.

The second pic shows the response of the raw Eminence Alpha 6 divers, measured while held in my hand, close mic'ed at about 1 inch. At first, I couldn't figure out that dip at 630hz in the first pic- I thought it was related to some diffraction or high order mode cancellation within the horn. Turns out it was just the drivers... whew! Hopefully, I can tame that with little EQ.

The third pic shows how the top end of the FR got pushed out to around 900hz after routing the frustrums into the ports. I used a plunge router with a chamfer bit after drilling 5/8" holes. This is compared to the first ground plane measurement with no frustrums.

The fourth pic shows a bump in the low end of the FR after sealing the back of both drivers with blue masking tape- It acutally worked! However, the volume is too low for what I want, making the boost too high with too much roll off below. I'll need to seal the drivers in PVC or wood boxes. Interestingly, the top end of the FR got pushed out a bit as well- didn't count on that one.

Also, note that plugging the <1 inch hole back of the horn where the CD will mount really didn't affect measurements much- can't explain that one.
LL
LL
LL
LL
johnbomb is offline  
post #4 of 75 Old 04-25-2012, 08:41 PM
Advanced Member
 
bwaslo's Avatar
 
Join Date: Jul 2006
Posts: 800
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 59
JB, looks good. Similar construction to what I've been wanting to do (if I ever get time in the garage) - I have dimensions and angles figured, but no sawdust yet

How did you make the tapered port holes for the drivers?
bwaslo is online now  
post #5 of 75 Old 04-25-2012, 09:03 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I've also orded some BMS 4550 compression drivers, recommended by the man himself, Tom Danley, when discussing these horns on the diyaudio thread linked above. Once I have them, I'll fab up a mount and see what happens.
johnbomb is offline  
post #6 of 75 Old 04-25-2012, 09:13 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
Nice work johnbomb, I'll like to see yours turns out.
mtg90 is offline  
post #7 of 75 Old 04-25-2012, 10:52 PM
Advanced Member
 
bwaslo's Avatar
 
Join Date: Jul 2006
Posts: 800
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 59
JohnBomb, another question -- when you taper the holes for the ports, do you know how that models in Hornresponse? HR wants the area of the port and the length, and the area and volume of the compression chamber - do you make the area the average area of the port, or do you keep the area value set to the smallest opening where it meets the horn? And do you increase the compression chamber volume to account for the added volume from the tapered port?

If my HornResponse model is to be believed, the results seem to be pretty sensitive to what I do with the port length and diameter.

Thanks, Bill
bwaslo is online now  
post #8 of 75 Old 04-26-2012, 06:06 AM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by bwaslo View Post

JohnBomb, another question -- when you taper the holes for the ports, do you know how that models in Hornresponse? HR wants the area of the port and the length, and the area and volume of the compression chamber - do you make the area the average area of the port, or do you keep the area value set to the smallest opening where it meets the horn? And do you increase the compression chamber volume to account for the added volume from the tapered port?

If my HornResponse model is to be believed, the results seem to be pretty sensitive to what I do with the port length and diameter.

Thanks, Bill

Hey Bill,

I made the assumption that the port area is fixed at the entry into the horn and that the effective length of the port decreases when the frustrum, or cone, is added. I believe that adding frustums also increases the volume of the compression chamber a bit.

I may rout wider frustrums- I haven't decided yet. Since this isn't a fine woodworking project for me, I can always go back and add bondo, then try something else. I'll be sure to take measurements along the way.

John

edit- Bill, I forgot to directly answer your first question. I first drilled 5/8 holes. I then used a plunge router with a chamfer bit to create the frustrums.
johnbomb is offline  
post #9 of 75 Old 04-27-2012, 07:16 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I sealed the backs of both Alpha 6s with thick cardboard and HVAC metal tape. I took groundplane measurements today, ranging from on axis to 40-50 degrees. I also took a 2.83v groundplane measurement at 1 meter... not too bad at 103.5 db.

After playing w/ hornresp, adjusting driver and chamber parameters to match my FR, I don't think I can get much more out of a 2 segment horn with these drivers without significantly changing the overall horn size. Looks like I'm getting a fairly flat response from around 300hz to 1.1khz off axis, which is not too bad. I would have preferred 200-1000hz, but I think I can make up for it with a well designed bass horn that covers around 60-350hz... we'll see.

Unless you folks give me some other ideas, I think I'll press on with this current horn design and mount up the BMS 4550 when it gets here.

John
LL
LL
LL
LL
johnbomb is offline  
post #10 of 75 Old 04-27-2012, 07:18 PM
Member
 
moosifee's Avatar
 
Join Date: Mar 2010
Posts: 86
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 19
A La Scala bottom would give you just what you're looking for.
moosifee is offline  
post #11 of 75 Old 04-27-2012, 07:21 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
johnbomb is offline  
post #12 of 75 Old 04-27-2012, 08:00 PM
Member
 
moosifee's Avatar
 
Join Date: Mar 2010
Posts: 86
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 19
Maybe, it's basically a cube 2' on a side, open in the front, with a V pointing right at you. There is a bigger PA bin that some think of as the W box. It's the bottom two thirds of this:


moosifee is offline  
post #13 of 75 Old 04-28-2012, 10:53 AM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I need some advice. Please look at this graph and tell me if this dip at 630 hz will go away with speaker burn in. As you can see, it's in the raw driver response. How do you guys burn in your drivers?

John
LL
johnbomb is offline  
post #14 of 75 Old 04-28-2012, 03:27 PM
AVS Special Member
 
Ivan Beaver's Avatar
 
Join Date: Dec 2005
Posts: 1,627
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 38
Quote:
Originally Posted by johnbomb View Post

I need some advice. Please look at this graph and tell me if this dip at 630 hz will go away with speaker burn in. As you can see, it's in the raw driver response. How do you guys burn in your drivers?

John

Since there is also a phase shift at that freq-my first guess would be that the dip is due to the reflection from the mouth of the horn-mixing in with the origional signal and causing a cancellation.

This is part of the "Magic" in the Synergy horn-proper positioning of the midrange holes so that there is no cancellation.

There are a lot of "little things" that go into the WHOLE package in the Synergy horn-not just a couple of basic simple ideas.

Sometimes you "get lucky" other times not so lucky

Danley Sound Labs

Physics-not fads
Ivan Beaver is offline  
post #15 of 75 Old 04-28-2012, 03:43 PM
Member
 
Maxjr's Avatar
 
Join Date: Dec 2010
Posts: 179
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
What exactly constitutes a horn to be a unity or synergy horn? Is it just the summation of 2 or more drivers in the same horn?

Im intrigued by these current DIY builds. I think my next build will be a unity/synergy build.
Maxjr is offline  
post #16 of 75 Old 04-28-2012, 03:58 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 johnbomb View Post

I need some advice. Please look at this graph and tell me if this dip at 630 hz will go away with speaker burn in. As you can see, it's in the raw driver response. How do you guys burn in your drivers?
John

Quote:
Originally Posted by Ivan Beaver View Post

Since there is also a phase shift at that freq-my first guess would be that the dip is due to the reflection from the mouth of the horn-mixing in with the origional signal and causing a cancellation.

If it's in the raw driver response, it is not not caused by the horn, but that graph does not look like the raw driver response of the alpha 6, it looks like another from in the horn are you sure you have the right graph? I see one in post #3, 2nd picture that looks more like a raw driver response with the 630hz dip as well.

My guess is some wierd cone breakup issue.

To break in the driver go into REW then go to linear sweep under generator run it 10-200 hz 5s and loop it.

Try some sweeps on another speaker to rule out any issues with the messurement system as well, just to make sure.
mtg90 is offline  
post #17 of 75 Old 04-29-2012, 07:14 AM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by mtg90 View Post

If it's in the raw driver response, it is not not caused by the horn, but that graph does not look like the raw driver response of the alpha 6, it looks like another from in the horn are you sure you have the right graph? I see one in post #3, 2nd picture that looks more like a raw driver response with the 630hz dip as well.

My guess is some wierd cone breakup issue.

To break in the driver go into REW then go to linear sweep under generator run it 10-200 hz 5s and loop it.

Try some sweeps on another speaker to rule out any issues with the messurement system as well, just to make sure.

Thanks for the time, guys. I've included another graph, showing the raw response of both Alpha 6 drivers superimposed (blue/red), as well as the horn response (purple). Note that the Alpha 6s are not baffle mounted for these raw response graphs, only hand held and close mic'd at about 1 inch from cone center. Those dips are in the raw response, and I don't see how they can be horn related.

You're right, mtg90, that dip isn't present in the Alpha 6 published graph, shown here:

http://www.eminence.com/pdf/Alpha_6A.pdf (I posted a close up of the FR)

Thanks,

John
LL
LL
johnbomb is offline  
post #18 of 75 Old 04-29-2012, 07:33 AM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Here is a comparison of the raw Alpha 6 response to that of an Elemental designs 160v.2 15" sub. Again, neither driver was baffle mounted, and both were close mic'd at about 1 inch from cone center. Phase response also shown.

My money's on cone breakup, as both drivers show a similar dip: alpha 6 at 625 hz, ED sub at 418 hz. Those peak/dip waveforms resemble one another quite a bit to my eye, although why a midrange speaker (Alpha 6) would have cone breakup smack dab in the midrange doesn't make much sense...
LL
LL
johnbomb is offline  
post #19 of 75 Old 04-29-2012, 08:07 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,213
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1173
Quote:
Originally Posted by johnbomb View Post

Thanks for the time, guys. I've included another graph, showing the raw response of both Alpha 6 drivers superimposed (blue/red), as well as the horn response (purple). Note that the Alpha 6s are not baffle mounted for these raw response graphs, only hand held and close mic'd at about 1 inch from cone center. Those dips are in the raw response, and I don't see how they can be horn related.

The dips are very much horn related, though you shouldn't drive yourself nuts measuring with too high a resolution. 1/6 octave is all you can perceive. This is an Alpha 6 woofer only in one of my Wedgehorn 6 cabs, half-space 1/6 octave smoothed.


Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #20 of 75 Old 04-29-2012, 09:20 AM
Member
 
JackNC's Avatar
 
Join Date: Aug 2011
Posts: 167
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 13
re' the dip
Per D'Appolito, close mic is good only up to Fmax = 4311/DriverDiaInInches. 718 hz for a dia of 6". That dip you measured is close to that limit, which estimates the frequency at which various reflections start to show up in the nearfield response. Try a gated impulse response measurement at 1M or more and see if the dip goes away
JackNC is offline  
post #21 of 75 Old 04-29-2012, 11:50 AM
AVS Special Member
 
Ivan Beaver's Avatar
 
Join Date: Dec 2005
Posts: 1,627
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 38
There are actually THREE different responses in play here.

1: The response of the totally raw driver.

2: the response of the modify driver with the sealed back

3: The response on the horn.

So when you add the 2 variables of the sealing and the horn-things start to change.

Danley Sound Labs

Physics-not fads
Ivan Beaver is offline  
post #22 of 75 Old 04-29-2012, 11:53 AM
AVS Special Member
 
Ivan Beaver's Avatar
 
Join Date: Dec 2005
Posts: 1,627
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 38
Quote:
Originally Posted by Bill Fitzmaurice View Post

The dips are very much horn related, though you shouldn't drive yourself nuts measuring with too high a resolution. 1/6 octave is all you can perceive. This is an Alpha 6 woofer only in one of my Wedgehorn 6 cabs, half-space 1/6 octave smoothed.


THe amount of resolution in the measurement (display of the measurement) can change all kinds of things.

If we looked at unsmoother measurements (and the display unsmoothed) taken with a high quality system-the dips a peaks would be driving us crazy.

Agreed a certain amount of smoothing is needed to see the "useful" response.

But some people use way to much smoothing-so the result looks much better than it actually is.

Danley Sound Labs

Physics-not fads
Ivan Beaver is offline  
post #23 of 75 Old 04-29-2012, 01:51 PM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,213
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1173
Quote:
Originally Posted by Ivan Beaver View Post

But some people use way to much smoothing-so the result looks much better than it actually is.

True, but if it's good enough for Danley Sound Labs it's good enough for me.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #24 of 75 Old 04-29-2012, 10:05 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Here's yet another plot. This one shows, from top to bottom:

1) horn response with 2 alpha 6 drivers, ground plane

2) multiple handheld sweeps with sealed back single alpha 6 driver, measured outdoors at about 2.5 feet.

3) original responses of raw unsealed drivers, handheld, close mic'd at about 1 inch.

4) impedance plot of sealed back driver, not horn mounted.

Again, that dip in the mid 600 range is there, in the original raw sweeps, the sealed sweeps, and represented in the impedance plot. At this point, I'll have a VERY hard time believing it is caused by the horn response. I still don't understand why a midrange driver would have that kind of breakup (or whatever it is) in the middle of the mid range, and on 2 units... very odd.

John

John
LL
johnbomb is offline  
post #25 of 75 Old 04-30-2012, 05:17 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,213
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1173
Quote:
Originally Posted by johnbomb View Post


Again, that dip in the mid 600 range is there, in the original raw sweeps, the sealed sweeps, and represented in the impedance plot. At this point, I'll have a VERY hard time believing it is caused by the horn response. I still don't understand why a midrange driver would have that kind of breakup (or whatever it is) in the middle of the mid range, and on 2 units... very odd.

A dip like that is typically sourced by an out of phase reflection, which also can show up on an impedance plot. It won't show up on HornResp. I doubt it's driver sourced.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #26 of 75 Old 04-30-2012, 05:50 AM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Bill Fitzmaurice View Post

A dip like that is typically sourced by an out of phase reflection, which also can show up on an impedance plot. It won't show up on HornResp. I doubt it's driver sourced.

That impedance plot is from the sealed driver sitting next to my computer, not horn mounted.
johnbomb is offline  
post #27 of 75 Old 04-30-2012, 02:52 PM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,213
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1173
Quote:
Originally Posted by johnbomb View Post

That impedance plot is from the sealed driver sitting next to my computer, not horn mounted.

That means the blip, and possibly the response dip as well, is sourced by whatever you sealed the driver in. The closed back version of the Alpha 6 (available as OEM only) has a 1 ohm impedance blip at 700Hz; the Alpha 8 MR has one at 900Hz.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #28 of 75 Old 04-30-2012, 03:11 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Bill Fitzmaurice View Post

That means the blip, and possibly the response dip as well, is sourced by whatever you sealed the driver in. The closed back version of the Alpha 6 (available as OEM only) has a 1 ohm impedance blip at 700Hz; the Alpha 8 MR has one at 900Hz.

That's a good point, Bill, and I had looked at the sealed back alpha 6 graph before you posted. If the blip is related to the homebrew seal job that I did, I can live with that, because I need the low end boost that it provides. I can just EQ the blip in the raw resonse with the minidsp, if I even notice it during listening. Either way, moving on...

I found out that the BMS 4550s will be here this Wednesday. My dad has a shopsmith w/ lathe capability, and hopefully I'll get to use it this weekend to make the CD mounts w/ contoured throats, ala Paul Spencer. Hopefully, more measurements to come soon!

John
johnbomb is offline  
post #29 of 75 Old 05-01-2012, 10:20 AM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Just a heads up: since I'm getting close to a minidsp based crossover, I thought I'd link some good threads related to phase and crossover design.

http://redspade-audio.blogspot.com/2...alignment.html

http://www.diyaudio.com/forums/multi...-tracking.html
johnbomb is offline  
post #30 of 75 Old 05-02-2012, 06:20 PM - Thread Starter
Senior Member
 
johnbomb's Avatar
 
Join Date: Aug 2005
Location: Nashville
Posts: 331
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
My BMS 4550s came in today... YES! Man, these things are heavy! I routed a hole through my horn so that I could hand mount the driver and get some quick measurements. No bondo shaping in the corners of the horn... yet.

I posted two graphs:

1) The first shows ground plane measurements of the driver sitting on its side on the ground (green) vs handheld against the back of the horn (red). Things look really good until about 8 khz, where the FR rolls off pretty quickly, faster than it does for the raw compression driver measurement. Also, I had hoped for lower extension from the compression driver, to make my crossover easier... Oh well. Hopefully, bondo contour shaping will help things.

2) The second graph was lifted from jmorken's unity horn project, documented here:

http://www.diyaudio.com/forums/multi...ve-x-over.html

He made this measurement before he had done final contour shaping of the horn throat. I figured this was the best benchmark for my project at this time. I'll need to fab up a mount for the compression driver, likely out of 1/2 inch wood, just to support its weight. This will probably increase the effective distance from the midrange ports to the mouth, and I expect the midrange to rolloff a bit earlier than it does now.
LL
LL
LL
LL
LL
johnbomb 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