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 29th January 2009, 08:59 PM   #21
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hello,

Quote:
Originally posted by CLS
I think the major 'problems' of guitar drivers are those not-so-controlled (or specifically controlled) cone breakups in the mid-high frequencies. With the not-low-enough voice coil inductance, rising impedance, and the cone full of breakups, the sound in this frenquency range is almost produced by cone breakups and not properly driven by motor!
Regardless of the shortcomings, it sounds like you are having a lot of fun with those drivers, and that's of course the most important thing above all

What was your cross-over freq and slope again for that driver?

I was intending to stay below about 1.5kHz to avoid the worst breakups, and use active crossing 4th order slope. For that freq range I'd like to believe there can be a reasonable low price high efficiency driver available, I don't mind if somebody call it a guitar driver

I think the reason for poor behaviour is partly because of the straight cone profile of guitar drivers. Interesting to compare the cone profile to any 8" and bigger full range hifi drivers which almost all have curved profiles. Clearly they do straight cones intentionally for their own interests (damn them ).

- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 30th January 2009, 12:08 AM   #22
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
Quote:
Originally posted by Elias
Click the image to open in full size.

I just love that looks

http://www.eminence.com/pdf/legend-1028k.pdf

10dB mid peak is evil for HiFi though
  Reply With Quote
Old 30th January 2009, 02:06 AM   #23
CLS is offline CLS  Taiwan
diyAudio Member
 
Join Date: Jun 2005
Location: Taiwan
Fun? Yes, of course!

The afore-mentioned Legend 125 was used as center channel for a while. Back then the driver was not treated by any means, so that midhigh breakup was clearly audible. Those ts~ ch~ z~ voices and picks of strings in concert DVD were emphasized, which can be intrusive sometimes (depends on your mood...).

Now the drivers have been modded and the breakups are largely damped. So I didn't avoid that frequency range on xover and still use them up to 3kHz (12dB/oct). This is quite high for a 12"er by any standard. And they sing beautifully! Mr. Oistrakh is playing Beethoven's Sonata in my living room right now The sound is very lively and vivid. For a pair of cheap 'guitar' drivers, it's just amazing! Compared with other 'normal' drivers, I think it's overall performance in this application is still very good.

The straight cone prolfile might be a double sided sword. I like its directness and dynamics. However the breakups must be controlled for hi-fi use. The corrugated press might help a little. And my later PVA glue treatment and phase plug give furthur improvement. (which can be proved by impedance scan and RTA measurement)

In my application, I don't worry about the Xmax at all. 12" midrange is just so loud with so little moves. With the help of 160Hz high pass, I think I won't have any chance to use up the 0.5mm Xmax.

By this I also found an interesting thing when I cut the dust cap -- I have to push the cone forward (from the back) by about 3~4mm to see the voice coil protruding the pole piece. From the thickness of top plate, it's impossible to be an under hung motor (and by that large of travel). I'm wondering whether the voice coil is un-aligned or the center pole piece is higher than the top plate. I can not disassemble the whole driver to examine this.

A similar condition appears on my 18" woofer of the same brand. The voice coil protrudes the pole piece by only about 1mm. And the published datasheet shows 6mm of Xmax. I can't tell whether it's bad alignment or the long pole.

------------------

Here are some pictures for your reference:


The modded driver:
Click the image to open in full size.

Click the image to open in full size.


The cuts on paper surround:
Click the image to open in full size.
These cuts brought the fs from 110Hz down to 90Hz. But the Q was barely affected. The overall stiffness of suspension is soften somewhat (tested by hand) but still sort of stiff... And the midbass leaks from these slots so I need about +3dB EQ in the range of 200~350Hz. I'll work on this area in the near future....


The very crude initial setup, just tucked on the original baffle hole for 8" from the back. So the outer area was covered and a cavity was formed, just like a 'compression chamber', haha....
Click the image to open in full size.

Click the image to open in full size.


The 'improved' version of baffle cut -- enlarged to proper size and chamfered.
Click the image to open in full size.


Overall view now.
Click the image to open in full size.

Any comments are welcome.
  Reply With Quote
Old 30th January 2009, 09:01 AM   #24
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hello,

Quote:
Originally posted by Geek
10dB mid peak is evil for HiFi though
How about now?

100-200Hz peak is used for dipole compensation.

- Elias
Attached Images
File Type: jpg legend 102_edit.jpg (58.3 KB, 349 views)
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 30th January 2009, 10:09 AM   #25
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
Quote:
Originally posted by Elias
How about now?
Click the image to open in full size.

I'll buy one!
  Reply With Quote
Old 30th January 2009, 10:36 AM   #26
tinitus is offline tinitus  Europe
diyAudio Moderator
 
Join Date: Nov 2005
There are enthusiasts who believe the benefits from the paper voice coil former of old drivers are significant

Lowther, Supravox and PHY use, and maybe others like Fertin and EMS use paper former

Notice that Eminence Legend alnico is available in a lower 20watt version with paper voice coil former

As fore the peak
Even the most popular have peaks, often much sharper and worse
And even the best driver with apparently no peaks may still need notch filter
__________________
sometimes we know very little, and sometimes we know too much
  Reply With Quote
Old 30th January 2009, 11:13 AM   #27
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
For that Vintage look...

Jensen AlNiCo series.

Click the image to open in full size.

Click the image to open in full size.
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 31st January 2009, 01:57 PM   #28
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hello,

Quote:
Originally posted by CLS
Now the drivers have been modded and the breakups are largely damped. So I didn't avoid that frequency range on xover and still use them up to 3kHz (12dB/oct). This is quite high for a 12"er by any standard. And they sing beautifully!

Mr. Oistrakh is playing Beethoven's Sonata in my living room right now The sound is very lively and vivid. For a pair of cheap 'guitar' drivers, it's just amazing! Compared with other 'normal' drivers, I think it's overall performance in this application is still very good.
I think 3kHz is quite high for any 12" driver, be it hifi, PA or guitar driver. At 3kHz many of the smaller 8" and even 6" drivers are losing it's performance. Time domain transient waveforms look horrible. It's interesting though what is the impact to the sound however. Lucky our ears are not oscilloscopes. As you say, it sounds like it is enjoyable even at 3kHz. What else is needed? When you know the cheap price of the driver it sounds even better


I didn't catch if you use active or passive cross over?

Dipoles rules! The baffle is reasonably big I think. It's bigger than I ever tried, instead I use more dipole correction in equalizer.

I see you have some tube gear on the pics. I think you are using these elements in just the way they should be used

Quote:

By this I also found an interesting thing when I cut the dust cap -- ...
I can't tell whether it's bad alignment or the long pole.
Have you tried applying DC bias on the element for experimenting of active realignment? That could be fun too, don't you think?

- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 1st February 2009, 01:56 AM   #29
CLS is offline CLS  Taiwan
diyAudio Member
 
Join Date: Jun 2005
Location: Taiwan
Hi,

According to the datasheet, the driver itself can play up to about 5kHz. As I see the FR chart, it drops like a stone after 4k, though. Well, maybe those above 1.5kHz are all rubbish anyway. I don't know.

The straight cone is pretty stiff by itself. And the PVA glue treatment made quite a lot of influence on it (much more than other 'normal drivers' I tried). From very intrusive to enjoyable, I think that is a big change. I will keep modifying this driver and see how far it can go....

A 12"er does beam when playing up to 3kHz. Off-axis performance is not as good as the 8" one I previously used. However on the dipole configuration, in room response is still pretty good. I often listen to them by my dinning table which is at the right side of the right channel. It can not be a proper listening position but the sound is still good.

DC bias to the voice coil is new to me and seems very interesting. However, before I know the exact correct alignment, it sounds like shooting in the dark.
  Reply With Quote
Old 1st February 2009, 02:22 AM   #30
CLS is offline CLS  Taiwan
diyAudio Member
 
Join Date: Jun 2005
Location: Taiwan
Oh, forgot to mention that the xover is passive 2nd order between mid and high, active 1st order between mid and low.

Pre and active xover are made as one, using 5842 and OPT for each channel (total 4 of them). Amp for mid-high is choke loaded 6J5 driver with 6H30 output, only about 1W output. Amp for woofer is now SS (cheap and good old Hafler) -- the T-bass circuit I use in bass section need low output impedance.

The old tuby stuff you saw on the bottom of equipment rack is Altec 1568 which is not used for the time being.
  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
High efficiency 12 inch midrange - recommendations? hasselbaink Multi-Way 13 8th March 2013 11:23 PM
high efficiency midrange tsmith1315 Car Audio 15 15th March 2009 11:02 PM
High efficiency 15" TomatoBangBang Multi-Way 72 11th November 2008 06:55 PM
UK source of inexpensive 3" or 4" driver - high efficiency sreten Full Range 9 23rd November 2005 03:15 PM


New To Site? Need Help?

All times are GMT. The time now is 11:02 PM.


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