Extended and Efficient midrange: what do we have here? - Page 3 - 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 29th November 2012, 11:09 PM   #21
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Perhaps you should talk to the person who will be doing the xover work for you so that they can help advise you on driver choices. There is nothing wrong with using notches anywhere in a design if they are needed. It seems as if you're introducing severely limiting criteria without understanding exactly what they mean or understanding if they are necessary or could potentially, even with the perfect drivers, actually make things worse.

If you want a very sensitive midrange, that will extend low and high, then you need a big driver. The B&W is a case in point. It doesn't go low enough for you, the only way around this is to increase the surface area, which will mean an even poorer off axis response and the potential for an even worse case of breakup. Yet you also want to use a minimal crossover for probably no more reason then 'simple is better', which in reality isn't really true.

If you really want to have true 1st order acoustic crossovers then talk to your xover designer about what drivers you should pick. As an example the scan ring dome, 10f and a suitable 8" would probably be about as good as it gets, but it will still have compromises and will most likely need an xover at least as complicated as other higher order designs to work properly.
  Reply With Quote
Old 29th November 2012, 11:36 PM   #22
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
I'm not against notches, but problems in the 1-3k range are the most sensitive ones. I know because I had to fix one.
The compromise between poor off-axis response and cone size I think my choice is clear, although two 6" with powerful magnet may work decently.

I surely will ask for advice from the xo designer but I need to have all cards on the table before I commission the work (and I have 3-4 months ahead to define better the project specs).

About 1st order acoustic xo, I'm not inflexible at all, and it is not to KIS, but to have a phase response pretty linear at one side and not too many passive components in front of the speakers. The b&w driver requires more than a second order xo at 250hz, that could be a problem not only for a few caps and inductors on the signal but for lack of spl at those frequencies. This i learnt from direct experience with the last speakers I built (with digital xo so I could learn and tweak endlessly), so it's not just plain stubbornness.
A compromise I do not want to make is to cross within the voice range (250-3500 at the very minimum).

In the next weeks, I'll try to find a suitable driver from PHL, then a little more for other input, then I'll present a list of options to my designer.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 30th November 2012, 12:10 AM   #23
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
You probably wont need more then 2nd order electrical. Once inside a normal sized cabinet the fs will rise, putting it closer to 250Hz, yes this will be relatively high Q, but combine this with a suitable 2nd order electrical xover and you will end up with a 4th order acoustic. This the driver can just about handle, but you will most likely require a notch filter to flatten the impedance peak, due to fs, otherwise the 2nd order filter wont do what you'd expect. Any mid crossing close to fs will most likely require this anyway.

The reason I say talk with your xover designer is because if you tell them some of your priorities they will be able to advise you as to which drivers to use and to drivers they are happy working with.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 30th November 2012, 08:47 AM   #24
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
I didn't consider the ATC dome mid because I thought it was low efficiency, but I found out that is 94db. Yes like all small drivers, it doesn't go as low as I want, and costs probably more than the budget I set. But it would be the best to cross at 4khz.
Food for thought.

Btw, I also remembered that I had speakers with 380hz xo and it was a disaster to multiamp unless both amps were the same or had the same timbre. This solution (anything higher than 250hz) would force me to go 4-way, adding some 8-10" woofer to cover this area, maybe enlarged even more to something like 150-400hz.

Unless I fall in love with the ATC or the B&W mid, this will not happen for this project -it has to stay a 3-way with the xo points I defined.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938

Last edited by Telstar; 30th November 2012 at 08:57 AM. Reason: Added more thoughts
  Reply With Quote
Old 30th November 2012, 09:48 AM   #25
diyAudio Member
 
Join Date: Apr 2007
As you're from Italy, I believe you can easily get this fine piece: Faital M5N12-80

I measured one piece of them just yesterday, see attached graphs.

Measurement conditions: anechoic room, baffle 60x50 cm open (that's where the drop at 900 Hz comes from), measurement distance 50 cm (level corrected). The levels are real! So these graphs are really at 90 dB and 110 dB! Because of the open baffle, there's a little gain between 300 and 600 Hz, so the distortion are a little lower than in a closed box.

This driver has 94 dB/W efficiency (8 Ohm), and I would not cross lower than 300 Hz, if you want high SPL 400 Hz.
Attached Images
File Type: png Faital_M5N120_90dB.png (28.0 KB, 287 views)
File Type: png faital_M5N120_110dB.png (33.8 KB, 283 views)
  Reply With Quote
Old 30th November 2012, 10:01 AM   #26
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Quote:
Originally Posted by Baseballbat View Post
As you're from Italy, I believe you can easily get this fine piece: Faital M5N12-80
Yes, I am.
It looks good from 270hz to 4k (i dont need super-high SPL, let's say 105dB for the transients).
One more to add to the list of small good drivers to cross higher than ideal.

Just a note:
http://www.faitalpro.com/products/sc...p?id=101010100
to show how the real sensitivity is often much lower than the declared one. You lost a couple db in your OB baffle, but the behaviour across FR is pretty similar to your measurements, the peak at 5k is less pronounced. No way this driver is 99db, though.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938

Last edited by Telstar; 30th November 2012 at 10:06 AM.
  Reply With Quote
Old 30th November 2012, 10:27 AM   #27
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
PS: I also found the ATD Veravox units, googling around, but I believe ATD exist no more.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  Reply With Quote
Old 30th November 2012, 02:08 PM   #28
diyAudio Member
 
Join Date: Apr 2007
Quote:
Originally Posted by Telstar View Post
Just a note:
FaitalPRO - Professional Loudspeakers Made in Italy
to show how the real sensitivity is often much lower than the declared one. You lost a couple db in your OB baffle, but the behaviour across FR is pretty similar to your measurements, the peak at 5k is less pronounced. No way this driver is 99db, though.
I confirmed the 94 dB/W with a TSP measurement. Haven't compared the parameters in detail, so I don't know what causes the difference. The measured efficiency is still very good. Even more as this driver has a quite high impedance (I measured Re=7.5 Ohm, Faital gives 7.2 Ohm).
  Reply With Quote
Old 30th November 2012, 02:13 PM   #29
Account disabled at member's request
 
Join Date: Mar 2011
Location: Somewhere in Quebec
Quote:
Originally Posted by Telstar View Post
I didn't consider the ATC dome mid because I thought it was low efficiency, but I found out that is 94db. Yes like all small drivers, it doesn't go as low as I want, and costs probably more than the budget I set. But it would be the best to cross at 4khz.
Food for thought.

Btw, I also remembered that I had speakers with 380hz xo and it was a disaster to multiamp unless both amps were the same or had the same timbre. This solution (anything higher than 250hz) would force me to go 4-way, adding some 8-10" woofer to cover this area, maybe enlarged even more to something like 150-400hz.

Unless I fall in love with the ATC or the B&W mid, this will not happen for this project -it has to stay a 3-way with the xo points I defined.
can you elaborate a bit about the 250 hertz cross over.
Im planning on crossing my FR at 300 hz, but you seem to think its not ideal...
  Reply With Quote
Old 30th November 2012, 02:17 PM   #30
Telstar is offline Telstar  Italy
diyAudio Member
 
Join Date: Dec 2007
Location: Italy
Quote:
Originally Posted by Baseballbat View Post
I confirmed the 94 dB/W with a TSP measurement. Haven't compared the parameters in detail, so I don't know what causes the difference. The measured efficiency is still very good. Even more as this driver has a quite high impedance (I measured Re=7.5 Ohm, Faital gives 7.2 Ohm).
I meant that published specs are usually too optimistics, very few manufacturers provide realistic data. Moreover, production tolerance (and burn-in!) has to be considered.
__________________
"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938
  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
"Best" extended midrange driver below $200 ? youyoung21147 Full Range 48 6th May 2011 03:22 PM
What is meant by 'Extended Cut-off'? Alastair E Tubes / Valves 5 5th May 2005 02:18 PM
1 efficient 12" or 2 (far) less efficient 10"s? beady Car Audio 4 8th August 2004 04:55 AM
high efficient low midrange driver maik Multi-Way 3 27th May 2003 03:27 PM


New To Site? Need Help?

All times are GMT. The time now is 08:31 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