Thought I'd just say this sounds wonderful - 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 15th April 2004, 09:42 PM   #1
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Default Thought I'd just say this sounds wonderful

Tried going OB because the sealed mid was not cutting it, sounded too forward.

Obviously this was a test so was quick, non pretty MDF with no driver rebates but that doesnt matter.

The change from sealed to OB was not as massive as I had thought it would be but the more you listen to it the more you realise how free OB sounds when compared to boxes!

The biggest difference that was easily noticable was human speech from the TV, it sounds much more natural.

Either way ill continue to soak in sonic bliss. Now all I want to do is try it MTM....... why those excels so expensive!

Bass is XLS10 tweet a scan97.
Attached Images
File Type: jpg obmyspeak.jpg (32.3 KB, 1089 views)
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 15th April 2004, 09:56 PM   #2
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Wow, that looks a lot like what I'm planning on trying with my setup. I have a 12" woofer in a sealed enclosure, and will be adding a midrange and tweeter on top. That's encouraging to know that it sounds good

What did you do for the crossovers (active/passive, frequencies, slopes)? How did you decide on the baffle dimensions and the driver placement?
  Reply With Quote
Old 15th April 2004, 10:02 PM   #3
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
I've commented on your post just now, if you read this first its not good news im affraid

I have mentioned excursion as a limiting factor. These W15CY's have 4mm one way linear and are the limiting factor quite considerably when it comes to SPL, this is not a power issue, the driver simply runs out of excursion.

Well the crossover is active which makes dipole EQ easy. I had used some much smaller sealed boxes for the mid/tweet before. How did I come up with baffle dimensions? Simple make it the same width as the bass box! and then make the height just right for tweeter axis on ears! Driver placement? just thought id try offset tweeters.

I then simply measured the whole lot to set EQ levels correctly and to alter the xover.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 15th April 2004, 10:07 PM   #4
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Looks like we're posting to two threads in parallel Thanks for your advice, I'll see how things go. If OB doesn't work then I'll try a sealed box and place the horn tweeter on top.

I just made shorter speaker stands to accomodate this baffle-on-top idea, and now I'm thinking I might have to make them even shorter. Or put the tweeter on the bottom and the midrange on top.
  Reply With Quote
Old 15th April 2004, 11:21 PM   #5
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
I see you mention what frequencies, well the bass mid is about 150, the mid tweet about 3k. The mid is at 2500hz 3rd order butterworth and the tweet is a 3rd order linkwitz at 3000hz.

Due to the phase of the two drivers mounted how they are nothing standard had a good reverse null.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 16th April 2004, 12:29 AM   #6
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Quote:
These W15CY's have 4mm one way linear and are the limiting factor quite considerably when it comes to SPL
Could the dipole mid arrangement be rolling off your lower mid output around 150 Hz?

The Sd, (cone area) of the Seas W15CY is 75 sq cm. If the cone excursion is +/- 4 mm, that comes to about 1.9 cu inches.

According to Small's chart, 112 dB at 150 Hz requires about 3 cu inches. Since you will be crossing over at 150 Hz, the output should be 3 dB down or so.

All in all, it would seem that you have enough output down to 150 Hz for a system SPL of 110 dB or more. That ought to be loud.

Is it possible you are getting cancellation at the lowest frequencies of the dipole section?

Volume Displacement For SPL Chart
__________________
"A friend will help you move. A really good friend will help you move a body."
-Anonymous
  Reply With Quote
Old 16th April 2004, 01:40 AM   #7
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Hmmm interesting you should say that.

I made the dipole EQ following how linkwitz did it with the pheonix. And all I can say is that with music I run out of excursion. Thing is even though I might be able to achieve 110dB output at 150hz, there is considerable output below 150hz which causes the cone to obviously move more. I think perhaps that the increase in cone excursion at these frequencies is greater than the amount of attenuation a 2nd order electrical xover can provide. Also if I was getting any cancelation surely that would just affect the audible loudness and not the cone displacement?

When I say they cant go loud, I mean subjectively in comparison to a sealed cabient, they do still produce a fair bit of level.

I will look into that link you provided but now I need to sleep

Cheers Matt

P.S. if you are going to make a three way and use active xovers and and are using a mid/bass for mids DO OPEN BAFFLE, your ears will thankyou for it. You do get enough SPL out of them and they are not difficult to design.

Also when I said quite considerably I was also refering to how the woofer and tweeter were performing and that they could each go louder, the mid was the limit and not the other two.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 16th April 2004, 03:40 AM   #8
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Quote:
Originally posted by 5th element


I made the dipole EQ following how linkwitz did it with the pheonix. And all I can say is that with music I run out of excursion...Also if I was getting any cancelation surely that would just affect the audible loudness and not the cone displacement?

Well, I am no expert on dipoles. My reading on the subject is largely confined to HiFi Loudspeakers and Enclosures, written by Abraham Cohen in 1956. As I recall, he said that to prevent cancellation, the open baffle should be one half wavelength of the lowest frequency passed. Since the wavelength of 1 Hz is 13,500 inches, we have:
13,500 inches 150 = 90 in.

The wavelength of 150 Hz is 90 in. But we only need half a wavelength for our baffle. So: 90 2 = 45 inches.

However, judging by your picture with the Peerless 10 incher, your baffle is only about 12 inches wide-about 1/4 what is needed to prevent partial cancellation.

I realize that Kuei has said that the baffle width is less than what people said way back when, but still-this is only one quarter the old standard.

This would still not cause excess cone excursion by itself. It would cause a drop in SPL. But if your system is EQ'd to compensate for this loss of SPL due to partial cancellation, then definitely cone excursion needs are increased-perhaps drastically. If the SPL dropoff is 6 dB and you equalize to compensate, then your cone has to travel twice as far as if there were no cancellation.

I think that might be happening here.

As long as this is not a finished product, how about it you just temporarily attach two pieces a foot wide two feet high or so and going back at 90, sort of to follow the contour of the box sides? Just something to knock together quickly. See if that changes the situation at all. You might have to minimize the equalization to bring things back into balance-but that would be a good thing for the cone excursion.
__________________
"A friend will help you move. A really good friend will help you move a body."
-Anonymous
  Reply With Quote
Old 16th April 2004, 12:08 PM   #9
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
just note that for the open baffle :

Above the units bass resonance 12dB / octave roll-off keeps
the excursion constant for the same input at any frequency.

So with the baffle boost before 150Hz quite a lot of unecessary
low frequency excursion will be going on. I'd say you need 3rd
order electrical roll-off to give a 4th order L/R to match the bass
unit crossover, lifting 150HZ a little higher would also help.

sreten.
  Reply With Quote
Old 16th April 2004, 01:18 PM   #10
Paul W is offline Paul W  United States
diyAudio Member
 
Paul W's Avatar
 
Join Date: Oct 2003
Location: North Georgia
5th,
When I was experimenting with rough wood, I attached 6-12" baffle side panels with hinges to quickly adjust wing angle. Signal was wide-band pink noise through a P17...no EQ as I was interested only in "character". I found 90 degree panels introduced a distinct resonance. I assume the resonance could have been damped (just like a box) but decided not to mess with mother nature. (Angled wings may also help minimize diffraction effects.)

While you're experimenting, you might try hinges to see what you think.
Paul
4-way dipoles
  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
Wonderful manufacturer roberta Vendor's Bazaar 3 6th August 2008 01:36 PM
Hashimoto and the wonderful 45 kmaier Tubes / Valves 10 24th June 2008 02:46 PM
My Aleph p1.7 sounds wonderful ! zei Pass Labs 39 7th January 2007 10:25 PM


New To Site? Need Help?

All times are GMT. The time now is 07:40 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