Beyond the Ariel - Page 397 - 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 June 2008, 07:52 AM   #3961
Variac is offline Variac  United States
diyAudio Editor
 
Variac's Avatar
 
Join Date: Dec 2001
Location: San Francisco, USA
And a 21" woofer! If it is good who wouldn't want one!-and it looks like it's pretty darned good!
  Reply With Quote
Old 15th June 2008, 09:02 AM   #3962
diyAudio Member
 
Graham Maynard's Avatar
 
Join Date: Dec 2003
Location: UK
That 21" Beyma is more for enclosure mounting with its suspension stiffness.

Two 15" could give same area with twice sensitivity, though with a dedicated amp must be impressive.

Cheers ........ Graham.
  Reply With Quote
Old 15th June 2008, 01:24 PM   #3963
Banned
 
Join Date: Feb 2004
Location: Portal 2012
Quote:
Originally posted by Graham Maynard
That 21" Beyma is more for enclosure mounting with its suspension stiffness.

Two 15" could give same area with twice sensitivity, though with a dedicated amp must be impressive.

Cheers ........ Graham.
It does a heck of a job - This 21" has a serious Xmax and a fairly high QTS and decent sensitivity at 40 cycles mounted on a board without EQ - It may seem strange but I used a 21 to make the system more compact over other systems that would require many more woofers to move this much air this low. It goes easily an octave lower than the five tens in less space, two 15's would have had to be folded (I don't like) to be this compact. This has no wings or folds- less coloration IMO


I will build your T circuit if I dig up a big enough transformer Thanks!
  Reply With Quote
Old 15th June 2008, 02:48 PM   #3964
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Default Re: Re: Re: Re: Good Articles

Quote:
Originally posted by nickmckinney



In non ferrofluid drivers the low Qms is coming from an aluminum voice coil former of which I never heard or measured a difference. Very little of the suspension comes into play for the Qms (actually the correct spec for this effect is the Rms)

Don't think so - the material of the former isn't responsible for LOW / HIGH Qms – at least if proper implemented by the speaker manufacturer.

Its suspension and surround losses that mainly cause low Qms / high rms.




The Vifa 10BG with aluminium former versus the Vifa XT18WO09-08 with Kapton former are a good example:


the VIVA XT18WO09-08 with Kapton former:
http://www.tymphany.com/files/produc...T18WO09-08.pdf
Qms = 5,87
Rms = 0,49 kg/s


VIFA 10BG120 with aluminium former:
Qms = 4,6
Rms = 0.36 kg/s (which is even LOWER )
http://www.lautsprechershop.de/pdf/v...er/10bg120.pdf


Obviously eddy currents in an aluminium former can be handled down to negligible amounts.


Greetings
  Reply With Quote
Old 15th June 2008, 05:02 PM   #3965
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Quote:
Originally posted by mige0


Its suspension and surround losses that mainly cause low Qms / high rms.

And of course the losses due to pressure air flow through the tight voice coil gap caused by the membrane-dust-cap-air-pump.

? How could I forget ?

These mechanical losses should increase with bigger voice coils as the "piston" area = dust cap area increases and thus the air volume pushed through the gap.
This model assumes ventilation holes behind the VC or an open suspension and does not apply in exactly the same way to ancient designs where the spider usually is completely sealed as is the magnet not vented and almost no air circulation happens .

All in all it depends on how the manufacturer balances between mechanical losses and extended and program dependant membrane-dust-cap-air-pump-VC-cooling





Quote:
Originally posted by mige0


The benefits of doing AC rather than DC is that you can use a simple soundcard with its very good resolution by simply replacing the mic by the shunt – symmetric inputs assumed.

We would like to inject a well defined power for a well defined time– so you will have to calculate the output voltage by measuring the speakers impedance - at ambient temperature - at 10kHz / 100Hz first.

No cabinet, no baffle, speaker positioned vertical in a room.
Doors and windows closed

Any – its not just to do a fun competition (burning down VC's would serve that better) – its for having data available to compare.
I would hold against a two decade old 12" Dynaudio 30W54 having an outer magnet and 54mm VC and a Dynaudio 17W75 having an inner magnet and a 75mm VC.
Both speakers are well documented and represent the top engineering at their time.

Lets see how much progress was made in the meantime.
nickmckinney - still interested in the thermal response competition I suggested ??

To make it a little bit more juicy for you I bet a bottle of Champaign that whatever you measure from your current designs against one of the two Dymaudios I mentioned

- DONT be better / lower twice = in terms of 1kWs resistance difference
- DONT be better / quicker twice = in terms of temperature decay




Greetings
Michael
  Reply With Quote
Old 15th June 2008, 06:13 PM   #3966
diyAudio Member
 
Join Date: May 2003
Location: Colorado
Default Re: Re: Re: Re: Re: Good Articles

Quote:
Originally posted by mige0
Don't think so - the material of the former isn't responsible for LOW / HIGH Qms – at least if proper implemented by the speaker manufacturer.

Its suspension and surround losses that mainly cause low Qms / high rms.
Sorry, but when you try arguing with a guy who has building drivers for many years, you are going to lose most of the time.

When a voice coil former is made from metal (a conductor), it will act as a shorted turn (unless there is a deliberate gap made in the former). This shorted turn provides mechanical damping to motion of the cone and will thereby affect the Qms.

When the voice coil former is not acting like a shorted turn, then you are correct that suspension and surround losses are the dominant factor.
  Reply With Quote
Old 15th June 2008, 07:59 PM   #3967
diyAudio Member
 
Join Date: May 2008
Default Re: Re: Re: Re: Re: Re: Good Articles

Quote:
Originally posted by mige0
Don't think so - the material of the former isn't responsible for LOW / HIGH Qms – at least if proper implemented by the speaker manufacturer.

Its suspension and surround losses that mainly cause low Qms / high rms.


BS - You don't think I tested Kapton only vs Kapton/Aluminum formers for my drivers? When we first started selling them we offered them both ways, low Qms and high Qms. Only difference was the former material that was in the gap.


Quote:
Originally posted by mige0
nickmckinney - still interested in the thermal response competition I suggested ??

To make it a little bit more juicy for you I bet a bottle of Champaign that whatever you measure from your current designs against one of the two Dymaudios I mentioned

- DONT be better / lower twice = in terms of 1kWs resistance difference
- DONT be better / quicker twice = in terms of temperature decay


I like mine slightly chilled, I own a set of those drivers, my first DIY design. I still use them in my office.

BTW - Like I said before again and again - someone else has to do the tests. Lynn and a few others are getting drivers shortly, they can comment on what they find.


Quote:
Originally posted by Charles Hansen
Sorry, but when you try arguing with a guy who has building drivers for many years, you are going to lose most of the time.

When a voice coil former is made from metal (a conductor), it will act as a shorted turn (unless there is a deliberate gap made in the former). This shorted turn provides mechanical damping to motion of the cone and will thereby affect the Qms.

When the voice coil former is not acting like a shorted turn, then you are correct that suspension and surround losses are the dominant factor.

Finally someone that has a grasp of what really happens inside the driver.

Only issue the former always has a gap so its not a shorted turn, in this case it would be called an "eddy brake" or similiar. This same concept is used in other damping designs outside of speakers. If you can find an old set of Rockford Fosgate with the compression rings, you can see what a solid turn will do (its like hitting a brick wall)

BTW - I started in the speaker world rebuilding drivers, about 20-40 a day with other people on a team. I rebuilt probably about 2000-4000 of other people's drivers before I designed my own. I have seen about everything (and copied the best ideas for my own)
  Reply With Quote
Old 15th June 2008, 08:13 PM   #3968
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Quote:
Originally posted by Charles Hansen


Sorry, but when you try arguing with a guy who has building drivers for many years, you are going to lose most of the time.

When a voice coil former is made from metal (a conductor), it will act as a shorted turn (unless there is a deliberate gap made in the former). This shorted turn provides mechanical damping to motion of the cone and will thereby affect the Qms.

When the voice coil former is not acting like a shorted turn, then you are correct that suspension and surround losses are the dominant factor.

Concerning gaps in metal formers to prevent from eddy currents:

Yeah, - I know– you know - Vifa knows

- but – are you sure nickmckinney knew?


Well - most certainly he did – I guess (hope) - now for sure.



Greetings
Michael
  Reply With Quote
Old 15th June 2008, 08:35 PM   #3969
mige0 is offline mige0  Austria
diyAudio Member
 
mige0's Avatar
 
Join Date: Jan 2005
Location: Austria, at a beautiful place right in the heart of the Alps.
Default Bs - Btw

Quote:
Originally posted by nickmckinney

BTW - Like I said before again and again - someone else has to do the tests. Lynn and a few others are getting driver
BS again? – ts, ts ..

BTW ...
You miss a really good chance – and a bottle Champaign.
The chance to provide hard data as the MANUFACTURER about what you claim to be the superiority of your design.

Anyway, either you don't know how to take measurements (embarrassing, embarrassing ) OR you are afraid to proof your own words.

Regarding third party measurement - I guess we both don't have any problem with delivering trustworthy data (plus / minus some tolerance) as anybody here can do a proof and display different findings.


Beside our little combating it may be a real challenge to lower thermal transient response significantly for ANY manufacturer and to put things into (measured) perspective should be worth the effort.

Not seen that much data about yet.

To some degree I guess that what Lynn has in mind about the effortless dynamic presentation from PA speakers may be based on exactly that – different thermal response due to the generally bigger VC's compared to home speakers.



Greetings
Michael

  Reply With Quote
Old 15th June 2008, 09:18 PM   #3970
diyAudio Member
 
Join Date: Jun 2004
Location: Green Bay, WI
Send a message via AIM to John_E_Janowitz Send a message via MSN to John_E_Janowitz Send a message via Yahoo to John_E_Janowitz
Default Re: Bs - Btw

Quote:
Originally posted by mige0

You miss a really good chance – and a bottle Champaign.
The chance to provide hard data as the MANUFACTURER about what you claim to be the superiority of your design.

Anyway, either you don't know how to take measurements (embarrassing, embarrassing ) OR you are afraid to proof your own words.

Regarding third party measurement - I guess we both don't have any problem with delivering trustworthy data (plus / minus some tolerance) as anybody here can do a proof and display different findings.
The problem with us providing any data is that we can't directly compare it to anything, or more realistically people in general cant' compare it to anything. Finding any other companies who have adequate data on power compression is difficult to begin with. Finding one that will give their specifications on how they come up with the numbers so someone can duplicate the measurements is impossible. We can publish our own data and state how the results are measured, but without other manufacturers measuring in the same way for comparison sake the data alone doesn't do much good. It's like saying vehicle A is 300hp and vehicle B is 600HP, which is faster? Without knowing vehicle A is a corvette and vehicle B is a dump truck you can't make a valid comparison.

We can do in house measurements of our drivers vs other manufacturers, but we can't very well publish the results of their info for comparison. Then figure in the fact that the industry is so full of marketing lies and garbage, that people can skew any tests to make the results look how they want. No matter how reliable our tests are, people won't believe them anyway. This is why an impartial 3rd party is the key to the whole thing. Not being associated with either company, the full comparison can be published and their is no "hidden agenda" so people can make reliable conclusions for the results.

John
  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



New To Site? Need Help?

All times are GMT. The time now is 04:15 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