New version of Martin King's MathCad Worksheets is coming soon! - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 December 2005, 01:01 AM   #11
Jorge is offline Jorge  Brazil
diyAudio Member
 
Join Date: Apr 2001
Location: Brazil
My experience shows Martin knows what he's doing...

Hot stuff ahead!
  Reply With Quote
Old 15th December 2005, 01:21 AM   #12
Tweeker is offline Tweeker  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Cincinnati, Ohio
You sir, are a horrible tease.
__________________
Be sure your foil hat has a good low impedance ground.
  Reply With Quote
Old 15th December 2005, 01:31 AM   #13
MJK is offline MJK  United States
Account disabled at member's request
 
Join Date: Feb 2002
Location: Clifton Park, NY
Looks like Scott has been having some fun. Wow! I have to thank Scott for being patient, it took a couple of weeks for me to find a bug that prevented the new version from running with the free Explorer program. It appears as if MathCad changed the way a function worked between version 8 and 2000 and this had me stumped for a while. It ran fine on my machines but not on Scott's PC.

Some answers to the questions.

Quote:
1. Does it take into acount driver size and Xmax effect on low frequency drive capability? I beleive the original worksheets just told you how much excursion would occur regardless of the Xmax limits.
It takes into account driver size but displacement is treated as linear. I have added the ability to specify the input power and the displacement curve will be calculaetd based on this value. There are no non-linear terms in the displacement calculation.

Quote:
2. Does it take into acount Bl variation?
No. What would you do if it did? How would you establish a BL vs displacement curve? I think that is beyond most DIY speaker designers, myself included.

Quote:
3. Does it take into acount listening distance?
Yes. Listening distance and angle off of the driver center axis are user specified. I could probably add an elevation angle to be completely general.

Quote:
4. Which resonance directions in box resonancd are calculated?
Same as the current TL worksheets, the long dimension of the enclosure. I have a 3D version of the Closed Box and Ported Box worksheets I wrote a tear ago but it has a couple of bugs that need fixing. So a 3D set of standing waves in the box is in the future.

Quote:
5. Can you just input non-standard design shape data fron CAD programs like the Alibre? Smooth horns are understood to react differently from piecewise straight curves.
No. All geometry is represented as sections of exponential expansion just like in the current versions. If you use enough sections then the shape will approach a cmoother curve.

Quote:
However a question re in-room response. I'm currently building a three-way where the bass is really a sub- ie 100 Hz or so- but the driver faces the wall. Can it do this? ( the other drivers face front)
Quote:
I guess it would be similar to where the driver faces the floor.
Quote:
The same question also would apply to side mounted drivers.
The geometry of the enclosure needs to be rectangular with the driver on the front baffle and the open end or port on the front or back, nothing exotic. This should cover most of the DIY designs people build. The next upgrade will be to go to a trapazoidal baffle so that my ML TQWT design can be modeled. That will come later.

Quote:
Will this program cover line source and line array speakers?
Not yet, but it could at some point. I will be adding an open baffle worksheet which is new to my site.

Quote:
Will this program cover putting speakers up against the wall? Putting speakers into the wall?
I think it will handle this but I need to check to make sure.

Quote:
Flat panels hanging on the wall are changing many room layouts, and putting the speakers against the wall is demanded by many interior designers.
Shoot, next thing you know the interior designer won't let me run my gear with wires all over the floor and the top off. No more surplus amps stacked in the corner or boxes of Lowthers behind the couch. Sorry, could not resist.

Thanks for the positive comments and thanks to Scott and Bob for giving the worksheet a work out and providing constructive feedback.
  Reply With Quote
Old 15th December 2005, 01:39 AM   #14
maxro is offline maxro  Canada
diyAudio Member
 
maxro's Avatar
 
Join Date: Dec 2004
Location: Survey says: Least happiest city in Canada
Wow, those are a lot of new features. Martin is going to have to start charging money for his work.

Just a few questions:

How about modelling two drivers as seperate points?

Bipoles?

Floor firing ports?

Hope I'm not asking for too much, as it is already an awesome tool.

Max
  Reply With Quote
Old 15th December 2005, 02:42 AM   #15
MJK is offline MJK  United States
Account disabled at member's request
 
Join Date: Feb 2002
Location: Clifton Park, NY
Quote:
Wow, those are a lot of new features. Martin is going to have to start charging money for his work.
I am going to ask for a modest donation for the use of the worksheets. If this works out the worksheets will continue to advance. If this does not work then things stay put for a few years like the last set have since 2003. People are using the current worksheets to make money. The cost of the latest MathCad and Maple upgrades is pushing $300+ each. Blah blah blah ... I hope people understand.

Quote:
How about modelling two drivers as seperate points?
That is something I get asked about and believe it can be done. It will be coming if things work out.

Quote:
Bipoles?
Can be done.

Quote:
Floor firing ports?
Not sure how to model that at the moment.

Quote:
Hope I'm not asking for too much, as it is already an awesome tool.
There are so many things that can be added relatively easily. I have been stalled for 2 years trying to figure a way not to give my work out for free and then have people turn around and make money. If I collect a small fee then I can't complain if they are used for profit. If this system works there will be a continual stream of new worksheets and improvements to worksheets.
  Reply With Quote
Old 15th December 2005, 04:58 AM   #16
maxro is offline maxro  Canada
diyAudio Member
 
maxro's Avatar
 
Join Date: Dec 2004
Location: Survey says: Least happiest city in Canada
Quote:
Originally posted by MJK


I am going to ask for a modest donation for the use of the worksheets.
Good for you.

Quote:

There are so many things that can be added relatively easily. I have been stalled for 2 years trying to figure a way not to give my work out for free and then have people turn around and make money. If I collect a small fee then I can't complain if they are used for profit. If this system works there will be a continual stream of new worksheets and improvements to worksheets.
It would be nice if you could work out a royalty deal for commercial use of your worksheets, rather than a one time pittance. I don't know how you would go about that though.

Oh, and thanks very much for the worksheets. I hope to have my first DIY speakers up and running before the new year. This dang holiday season is sucking up my free time.

Max
  Reply With Quote
Old 15th December 2005, 07:34 AM   #17
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Some great ideas and thoughts there guys -keep them coming. Many of them would be useful additional features for future tweaks. Twin or more driver positions, including bipoles and the ability to model line-sources would be a superb addition (though that latter might need a new sheet of its own, I wouldn't know) as, insofar as I know, there isn't anything out there that can accurately model them. Downward or upward firing ports could also be useful -I bet it would be a right pig to figure out though as you'd then have to take into account the levels of damping different elevations from the plinth would mean... and the fact that some people don't just elevate the speaker on spaces, but partially box it in on two or three sides etc... wince.

I'm sure Martin can do it, but we're going to be having enough to be playing with for the moment, believe me. Like I said, it's not hard to do, anyone who can use the current sheets should be able to without difficulty, so long as you step back, think logically, and don't allow yourself to be phased by the sheer quantity of data. Remember, the hard stuff has already been done for you.

Next post I'll show a graph for the Small Thor MLTLs without the hefty bass response. After that -it's going to be designs and tweaks to different enclosures for Lowther PM6Cs (and no, I can't figure out why they're not more popular either). After that... well, we'll decide that when we come to it. Something I want to experiment with, with the Lowther models is the in-room response of wide-baffle designs, and their effect on reducing the necessary values in BSC circuits.

I'll just add, before I disapear to carry on with my thesis for a few more hours, that I support Martin and his work 100% (like you hadn't already guessed that!), that has contributed so much to our knoledge and ability to design decent systems already, and that I'm going to be first in line in the queue to make whatever contribution / donation he asks us for to use, and allow him to continue developing these sheets. Unless Bob Brines beats me to it of course (bet he already has... ;-)

Best
Scott
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com
  Reply With Quote
Old 15th December 2005, 08:32 AM   #18
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5


Ready to send my money... another push to get my PC running too...

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 15th December 2005, 01:02 PM   #19
f4ier is offline f4ier  Australia
diyAudio Member
 
f4ier's Avatar
 
Join Date: Sep 2001
Location: Sydney
Quote:
I am going to ask for a modest donation for the use of the worksheets.
And so you should! Your sheets have reduced, if not eliminated, the amount of guess-work in designing TLs.

Quote:
If this does not work then things stay put for a few years like the last set have since 2003. People are using the current worksheets to make money.
Likewise, I've even had someone contact me -- asking for my programs' download pages -- so he can design and build a multi-thousand-dollar system for his client; and what do I get... zero I'm seriously considering charging money for the (coming) combined version of my programs.

May you have many appreciative users of your worksheets
__________________
Crossover/Subwoofer Simulator
  Reply With Quote
Old 15th December 2005, 02:18 PM   #20
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
And here we have Small Thor, modified to flatten out the in-room frequency response in the circumstances I described above.

Little needed to be modified. The port has been raised by 1", and reduced in diameter to 2". That's it. (At this point, I will mention that I'm always a little uneasy about using ports narrower than 3", as I wonder about port-noise. However, other people have sucessfully used them, and this has done the trick as far as the predicted response goes.)

How did I do it? As I described above. I played around with the port dimensions in Part 1 of the sheet, until the anechoic frequency response prediction indicated a gradually rising response, which I was looking to achieve, then ran down the sheet and checked the in-room response predictions. Much better. The dip that I suspect was casused by floor-reflections around 150Hz seems to have moved up in frequency, and decreased in depth. As an added bonus, the compensation required by the system is much reduced -the resistor value has dropped by 1/3, and the inductor value has also been reduced. Listening slightly off-axis, like most people do (these are just examples) would mean that these values could probably be halved again. (I'm gessing there -someone please put me straight if I'm wrong)

Overall: not bad. Time now to get back to full-range drivers though. I'm suffering from withdrawal symptoms. So I'll indulge myself and look at a Lowther. In this case, I'll use the under-rated PM6C, which according to Martin is a very good driver for the money. I don't own any Lowthers yet, but I wanted a pair of new drivers for the New Year, and it's a toss-up between these and their smaller brothers, the PM55C. Think I'll go for the larger ones though. Bigger Is Better, you know...

See you later
Scott
Attached Images
File Type: jpg small thor corrected for flatter in room response.jpg (55.7 KB, 789 views)
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com
  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
mathcad worksheets brsanko Full Range 0 15th March 2009 07:53 PM
Question on MJK's mathcad worksheets cs Multi-Way 3 3rd November 2006 05:24 PM
New versions of Martin King's MathCad worksheets Scottmoose Multi-Way 0 14th December 2005 10:05 PM


New To Site? Need Help?

All times are GMT. The time now is 09:00 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