Yet another query re TMM vs.MTM (using DEQX) - Page 2 - 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 20th April 2013, 01:57 AM   #11
terry j is offline terry j  Australia
diyAudio Member
 
Join Date: Aug 2006
more than happy to help if I can with the subs. If I don't respond then PM me...hopefully I have 'email notice' as I might miss a post...find I am less and less checking forums.

guess that is the trouble with an IB...once they're in and you are less than impressed it is damned hard to do anything about it! At least placement wise.

If in your shoes I think I'd be pretty happy with whichever layout you went with. Tho personally not a real fan of MTM I find it hard to imagine that the diff between the two is so great that regret (if you magically went to the other) would be a word you'd use.

Still, if you are like me and curiosity bites real hard, with a bit of forethought building a box with interchangeable baffles (which can be permanently fixed later) is not a hard thing to do.

Then you can let us all know what you found for yourself! Finding out for yourself (rather than relying on posts like mine...ie someone else's opinion) is gold.

good luck
  Reply With Quote
Old 20th April 2013, 11:04 AM   #12
DEQXter is offline DEQXter  United States
diyAudio Member
 
Join Date: Mar 2013
Location: ABQ, NM
Send a message via Yahoo to DEQXter
Quote:
Originally Posted by terry j View Post
more than happy to help if I can with the subs. If I don't respond then PM me...hopefully I have 'email notice' as I might miss a post...find I am less and less checking forums.

guess that is the trouble with an IB...once they're in and you are less than impressed it is damned hard to do anything about it! At least placement wise.


good luck
Ha. Had to chuckle on that. Not only hard to move but hard to fix the nearly 2 x 2 hole you just put into the floor of you great room.
Attached Images
File Type: jpg P1010028.JPG (217.1 KB, 149 views)
File Type: jpg P1010031.JPG (206.3 KB, 146 views)
File Type: jpg P1010034.JPG (188.9 KB, 142 views)
  Reply With Quote
Old 20th April 2013, 11:11 AM   #13
DEQXter is offline DEQXter  United States
diyAudio Member
 
Join Date: Mar 2013
Location: ABQ, NM
Send a message via Yahoo to DEQXter
Quote:
Originally Posted by terry j View Post
more than happy to help if I can with the subs. If I don't respond then PM me...hopefully I have 'email notice' as I might miss a post...find I am less and less checking forums.

guess that is the trouble with an IB...once they're in and you are less than impressed it is damned hard to do anything about it! At least placement wise.


good luck
Ha. Had to chuckle on that. Not only hard to move but hard to fix the nearly 2 x 2 hole you just put into the floor of you great room.
  Reply With Quote
Old 21st April 2013, 01:32 AM   #14
DEQXter is offline DEQXter  United States
diyAudio Member
 
Join Date: Mar 2013
Location: ABQ, NM
Send a message via Yahoo to DEQXter
Quote:
Originally Posted by LineSource View Post
Consider a modular (MT) W design, perhaps with the goal of designing one high'ish efficiency woofer with two different MT tops as time and money allows. AMT planars are typically expensive, and mated to higher quality ~95db/watt midbass like the Lambda TD10M or Beyma 8P300. There are several good DIY Usher 8948a + dome tweeter MT designs that can go above a woofer.

There are several well written, and well reviewed papers on M-T-M spacing with equations plus measurements for both the M-T and M-M spacings required to avoid lobing. These papers prove that an MTM using 7" midbass speakers with any Xover over ~700Hz will have noticable lobing.

Biro Technology

Vertically Symmetric Two-Way Loudspeaker Arrays Reconsidered
---------

If you are set on usin effects.g just the four Ushers, then a 2.5 way (TM)M would be a good choice, where the low frequency M can have the Xover frequency and height adjusted for baffle step and floor bounce

Don't forget rounded edges for diffraction control.
LS,
I just wanted to thank you for taking the time to respond to my thread re MTM vs TMM. The article you pointed me to was very helpful in making a decision not to do an MTM. In fact I felt major league stupid for not seeing the problems inherent to a system that advances and retards arrival time simultaneously with movements along the y axis and provides no fill from the tweeter.

I also stumbled across a comment of yours on some Beyma thead which contained more wisdom in a paragraph than most books on the subject of audio re the pros of dipole, sealed box, horns etc which ought to be engraved somewhere. Likely could have saved a 100 bucks on a couple of almost useless books. And in retrospect I wish I had trusted my instincts a few months back when i wanted to get some pro audio midbass units like a PHP or Beyma--that sense of startling immediacy is what I crave. But inadvertently I got that right as the AMT will be outboard, the woofers underneath it all, and can swap out mids in a NY minute and have all the XOs available at the touch of the keyboard.

But really just wanted to say thanks for the outreach to the noobs.
JohnS
  Reply With Quote
Old 21st April 2013, 01:58 AM   #15
terry j is offline terry j  Australia
diyAudio Member
 
Join Date: Aug 2006
well there ya go john, 'we are moving closer' albeit unplanned.

I use pro drivers everywhere 'cept tweet, PHL 6.5's, PHL 10's and PHL 18's (the subs are not pro...pro's don't worry about anything under thirty I guess) so use maelstrom 18's there.

Startling slam and jump factor, a real kick in the chest when it is in the music, ability to play loud without strain, minimum sensitivity about 96 db (none of this audiophile 90 db stuff)...all active (as yours will be)

The one common comment from all who hear it is 'well, THAT ain't your normal stereo'. Whether it is preferred or not is of course a personal thing, but all seem to recognise it is not a 'sound' you have heard before.
  Reply With Quote
Old 22nd April 2013, 02:57 AM   #16
diyAudio Member
 
LineSource's Avatar
 
Join Date: Sep 2003
Location: SiliconValley
Quote:
Originally Posted by DEQXter View Post
the AMT will be outboard, the woofers underneath it all, and can swap out mids in a NY minute
The MAX 3-way speaker picture that I posted earlier (TPL150H + 8"midbass above separate woofer) was designed by an engineer who understood how important it was to BUTT the TPL150H to the midbass with the smallest possible gap. No separate boxes with their >1" wood separation that risks lobing. Let's assume a TM 1600Hz Xover. 13550 / 1600Hz = 8.4" wavelength. Ideally you want your TM speakers separated by 1/4 this wavelength, but 1/2 is often accepted as the worst acceptable gap. Approaching even a 1/2 Lambda T-M separation is only possible when the M is butted next to the T, no extra box wood.

A free, easy to use program call xdir provides basic graphical lpolar data for M-T spacing vs Xover frequency. Life gets harder with the more you learn... Pizza quickly becomes a temptation of the Devil vs. a snack with College friends.

Tolvan Data
  Reply With Quote
Old 23rd April 2013, 03:56 AM   #17
DEQXter is offline DEQXter  United States
diyAudio Member
 
Join Date: Mar 2013
Location: ABQ, NM
Send a message via Yahoo to DEQXter
Quote:
Originally Posted by LineSource View Post
The MAX 3-way speaker picture that I posted earlier (TPL150H + 8"midbass above separate woofer) was designed by an engineer who understood how important it was to BUTT the TPL150H to the midbass with the smallest possible gap. No separate boxes with their >1" wood separation that risks lobing. Let's assume a TM 1600Hz Xover. 13550 / 1600Hz = 8.4" wavelength. Ideally you want your TM speakers separated by 1/4 this wavelength, but 1/2 is often accepted as the worst acceptable gap. Approaching even a 1/2 Lambda T-M separation is only possible when the M is butted next to the T, no extra box wood.

A free, easy to use program call xdir provides basic graphical lpolar data for M-T spacing vs Xover frequency. Life gets harder with the more you learn... Pizza quickly becomes a temptation of the Devil vs. a snack with College friends.

Tolvan Data
Linesource,
Very informative link and I see exactly what you mean re avoiding too much interdriver distance--makes perfect sense to me now why faceplates get carved up. Maybe you can help me with one question re XDir: The distance one specifies I assume is center to center from tweet to woofer. But nowhere does it ask what the distance between woofers is and yet displays TWW config data which in a few cases shows some strong lobing at +/- 60 degrees or so which I figure would result in nasty ceiling (and floor) reflections. I am a little worried at this point as I doubt I can get the distance to less than 4.6" to the lower edge of the Heil and another 3 to the center. But am I correct in thinking that the XDir assumes 2pi radiation and so maybe the result is not as bad, ie the 4.6" distance obtains, not the 7.6".
With heroic lengths I could contrive to knock almost an inch off the distance by doing a slightly stepped baffle where I bury the bottom part of the Heil faceplate underneath the flange of the woofer. But besides a PITA, have no idea what adverse effects on performance may have in addition to obvious detrimental impact on aesthetics. BTW leaning toward the Aurum cantus aerostriction 30130 at this point as it looks like 1100 to 1200Hz might be doable. But always that gocha-can't be used dipole--at least according to the PE guy.
  Reply With Quote
Old 23rd April 2013, 04:05 AM   #18
DEQXter is offline DEQXter  United States
diyAudio Member
 
Join Date: Mar 2013
Location: ABQ, NM
Send a message via Yahoo to DEQXter
Quote:
Originally Posted by terry j View Post
well there ya go john, 'we are moving closer' albeit unplanned.

I use pro drivers everywhere 'cept tweet, PHL 6.5's, PHL 10's and PHL 18's (the subs are not pro...pro's don't worry about anything under thirty I guess) so use maelstrom 18's there.

Startling slam and jump factor, a real kick in the chest when it is in the music, ability to play loud without strain, minimum sensitivity about 96 db (none of this audiophile 90 db stuff)...all active (as yours will be)

The one common comment from all who hear it is 'well, THAT ain't your normal stereo'. Whether it is preferred or not is of course a personal thing, but all seem to recognise it is not a 'sound' you have heard before.
Sounds like a lot of fun. I think running pro drivers does makes a big diff, better yet if you like horns. Most of the DEQXed systems I have heard (where the measurements and implementation were done right) also have some of that snap and alacrity--just by getting the phases of the divers all in a ro--tho I have no proof and indeed have read umpteen references to the inaudibility to say nothing of the futility of a phase coherent full way speaker(s).

Last edited by DEQXter; 23rd April 2013 at 04:06 AM. Reason: typo
  Reply With Quote
Old 10th February 2014, 05:10 AM   #19
frangus is offline frangus  Australia
diyAudio Member
 
Join Date: Dec 2013
I'll resurrect this one just to ask:

Can the DEQX do 2.5 way using 3 amps, instead of using an inductor?

I mean does the software "wizard" have an option to create a 2.5 way design or is some manual trickery involved?
  Reply With Quote
Old 11th February 2014, 03:07 AM   #20
diyAudio Member
 
Join Date: Jun 2003
Location: Tennessee
I don't think that the DEQX has that configuration as one of its capabilities. Usually a 2.5 way configuration is a passive crossover artifact that uses an inductor to achieve a 6 dB per octave slope on one of the two mid-range drivers that would otherwise cover the same frequency band. Essentially you can adapt this arrangement to achieve 6 dB baffle step compensation.

With its ability to calibrate amplitude, phase and time you have considerable capability built-in to the DEQX unit. This includes equalization and high order linear phase crossover slope capabilities, so the DEQX takes compensation to a new level. Typical slopes are 48 dB/octave or greater. I do not believe that the DEQX has the capability to separately calibrate over two overlapped frequency bands. I would just use a two-way DEQX configuration. You can set the amplitude EQ limits range to easily adjust the amplitude response so that you attain flat amplitude response so that a 2.5 way configuration is not needed. Bottom line is that you have race horse capable DSP so don't limit it to solving donkey era problems.

Last edited by Jim Griffin; 11th February 2014 at 03:12 AM. Reason: correction
  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
MTM or TMM LaraBingleHo Multi-Way 7 29th March 2010 08:24 AM
MTM -vs- TMM Coenlaf Multi-Way 10 18th March 2009 06:47 AM
Why MTM? Why not TMM? valnar Multi-Way 27 17th May 2008 12:30 AM
TMM vs. MTM............. Gavinator68 Multi-Way 3 10th December 2005 09:20 PM
tmm vs. mtm ermes Multi-Way 0 11th August 2005 08:51 AM


New To Site? Need Help?

All times are GMT. The time now is 03:59 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