Waveguides and horns - Page 113 - diyAudio
Go Back   Home > Forums > Commercial Sector > Group Buys

Group Buys Members group buys

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 13th May 2012, 11:43 AM   #1121
sendler is offline sendler  United States
diyAudio Member
 
Join Date: Aug 2004
Location: ny
Quote:
Originally Posted by jzagaja View Post
Seven please
No drum kit in that song. Maybe track eight.
__________________
Scott
  Reply With Quote
Old 13th May 2012, 11:54 AM   #1122
jzagaja is offline jzagaja  Poland
diyAudio Member
 
Join Date: Jun 2004
Location: Szczecin
Send a message via Skype™ to jzagaja
Haha see Silbatone

Btw: other presentations sound very good, strong resolving highs no boom.
__________________
Visit us at http://www.horns.pl/
The SEOS™ Project http://www.avsforum.com/t/1291022/he...-rallying-here
  Reply With Quote
Old 14th May 2012, 04:33 PM   #1123
diyAudio Member
 
Join Date: Apr 2005
Location: London, UK
Quote:
Originally Posted by ra7 View Post
Jean,
My biggest concern in designing a passive crossover is accounting for the delay in HF arrival with respect to the woofer acoustic center.
TAD tackled this in their TSM series (aka 2401/2402) monitors by employing an asymmetric crossover, which I have recently reverse-engineered, based on the published schematics and frequency-response graphs.

Such crossover appears to work as follows:

Crossover frequency Fx = 650Hz

LF) 6th order electrical Low Pass > 6th order Linkwitz-Riley target @ Fx; normal polarity connection (+); phase @ Fx = -6*45=-270º

HF) 2nd order electrical High Pass > 3rd order Butterworth target @ Fx; inverted polarity connection (-); phase @ Fx = 3*45º-180º=-45º; level = -1dB

LF-HF offset set for phase match at Fx = (270-45)º = 225º = (5/8)*c/Fx = 5/8*34400/650 = 33cm

In attachment: (i) a technical drawing of the TSM-1 (2401) monitor, (ii) the filtered Woofer LP response, (iii) the filtered Compression Driver + Horn HP response, (iv) the passive crosssover schematic.

I actually plan to make a three-way crossover for my own high efficiency system soon, based on this design (by adding a super-tweeter and second crossover point at Fx2 = 10*Fx).

Cheers,

Marco
Attached Images
File Type: jpg tad_2401.jpg (82.7 KB, 819 views)
File Type: gif LF.GIF (35.2 KB, 793 views)
File Type: gif HF.GIF (32.3 KB, 778 views)
File Type: gif x-o.GIF (22.1 KB, 875 views)
  Reply With Quote
Old 14th May 2012, 05:37 PM   #1124
ra7 is offline ra7  United States
diyAudio Member
 
Join Date: Feb 2009
Blog Entries: 1
OMG! Thank you so much for this post. This is like goldust for me.

Will get back to you with some questions.
  Reply With Quote
Old 16th May 2012, 01:02 PM   #1125
Jmmlc is offline Jmmlc  France
R.I.P.
 
Join Date: Oct 2005
Hello,

What you describe is only phase match but that does not means that this crossover + offset between loudspeakers is in anyway able to achieve linear phase linear phase which is needed for a constant group delay and optimal impulse response.

If we imagine to obtain the time delay required to compensate an offset around 33 centimeters through the crossover, we need a low-pass (Bessel for example) of a very degree (17 to 20 degree) with the cut-off frequency you indicated.

I guess that in the TAD monitor the goal was only to obtain a phase match and a smootgh variation of the lobing with frequency, not an optimal Impulse Response.

Best regards from Paris, France

Jean-Michel Le Cléac'h

Quote:
Originally Posted by marco_gea View Post
TAD tackled this in their TSM series (aka 2401/2402) monitors by employing an asymmetric crossover, which I have recently reverse-engineered, based on the published schematics and frequency-response graphs.

Such crossover appears to work as follows:

Crossover frequency Fx = 650Hz

LF) 6th order electrical Low Pass > 6th order Linkwitz-Riley target @ Fx; normal polarity connection (+); phase @ Fx = -6*45=-270º

HF) 2nd order electrical High Pass > 3rd order Butterworth target @ Fx; inverted polarity connection (-); phase @ Fx = 3*45º-180º=-45º; level = -1dB

LF-HF offset set for phase match at Fx = (270-45)º = 225º = (5/8)*c/Fx = 5/8*34400/650 = 33cm

In attachment: (i) a technical drawing of the TSM-1 (2401) monitor, (ii) the filtered Woofer LP response, (iii) the filtered Compression Driver + Horn HP response, (iv) the passive crosssover schematic.

I actually plan to make a three-way crossover for my own high efficiency system soon, based on this design (by adding a super-tweeter and second crossover point at Fx2 = 10*Fx).

Cheers,

Marco
  Reply With Quote
Old 16th May 2012, 05:51 PM   #1126
diyAudio Member
 
Join Date: Apr 2005
Location: London, UK
Quote:
Originally Posted by Jmmlc View Post
Hello,

What you describe is only phase match but that does not means that this crossover + offset between loudspeakers is in anyway able to achieve linear phase linear phase which is needed for a constant group delay and optimal impulse response.

If we imagine to obtain the time delay required to compensate an offset around 33 centimeters through the crossover, we need a low-pass (Bessel for example) of a very degree (17 to 20 degree) with the cut-off frequency you indicated.

I guess that in the TAD monitor the goal was only to obtain a phase match and a smootgh variation of the lobing with frequency, not an optimal Impulse Response.

Best regards from Paris, France

Jean-Michel Le Cléac'h
Dear Jean-Michel,

thank you for your contribution.

In a nutshell, yes, I agree completely.

The TAD crossover does not fully compensate for the physical offset between the woofer and compression driver. Moreover, by employing a L-R low pass instead of a Bessel one, the group delay (GD) of the woofer is not constant below Fx.

Ideally, one would like to achieve GD(LP)-GD(HP) = physical offset, with a constant GD for both crossover branches at and in the vicinity of Fx. That, and of course a quasi-flat summation and good phase match.

Still, the TAD crossover may be regarded as a reasonably good compromise, given that it does produce a flat summation and good phase match, despite the rather large 33cm offset dictated by the physical dimensions of the TH-4001 horn.

I am personally still investigating alternatives.

One such alternative which I have found to work quite nicely, at least in theory, is a 6th order Bessel LP + 2nd order Butterworth HP, both set so they are -6dB at Fx, with reversed polarity on the HP and an offset = 0.4*c/Fx.
For the same Fx = 650Hz as the TAD monitors, one gets offset = 22cm (good but not quite as much as with the TAD crossover, so the horn would have to sit forward with respect to how it is deployed in the TSM monitors).
One further potential problem, though, is that it is sometimes hard to achieve a true acoustical 2nd order HP with a typical horn...
On the positive side, this alternative crossover does meet the GD(LP)-GD(HP) = physical offset condition, and still sums flat.

I'll keep simulating other alternatives. For example, one could use an even steeper Bessel LP (e.g. 8th order - beyond that the insertion losses would be a major drawback, I guess), paired with some reasonable HP (2nd or 3rd order), to try and increase the offset while still achieving a flat summation, good phase match at Fx and ~constant GD difference.

Cheers,

Marco
  Reply With Quote
Old 21st May 2012, 05:02 PM   #1127
Tytte71 is offline Tytte71  Norway
diyAudio Member
 
Join Date: Oct 2010
So far I have been very happy with the SEOS waveguides - in addition to IMO measuring, integrating and sounding very well, they are beatifully made. However, I feel the potential of the largest ones could have been even better released if allowed for larger drivers than the 1"-ers.

I would therefore suggest a little race to see how many that could be interested in the SEOS 15, 18 or 21 with 1,4" and/or 1,5" throats. If the interest is large enough I feel quite confident Jzagaja would make a mold or two

Personally I would love to have the SEOS 18 and 15 with 1,4" throat (Radian 951Be / 0º exit ). If possible I would also like to have the SEOS 18 for 1.5" JBL 2447 (unfortunately I don't know the exit angle).

Cheers
  Reply With Quote
Old 24th May 2012, 07:57 AM   #1128
Tytte71 is offline Tytte71  Norway
diyAudio Member
 
Join Date: Oct 2010
Hmm.. only me that would like to have SEOS with larger throat?
  Reply With Quote
Old 27th May 2012, 11:26 PM   #1129
jzagaja is offline jzagaja  Poland
diyAudio Member
 
Join Date: Jun 2004
Location: Szczecin
Send a message via Skype™ to jzagaja
Dr. Geddes style phase plug design stages. Optimized means all channels have OS curvature.
Attached Images
File Type: png Dr. Geddes phase plug.png (95.7 KB, 589 views)
__________________
Visit us at http://www.horns.pl/
The SEOS™ Project http://www.avsforum.com/t/1291022/he...-rallying-here
  Reply With Quote
Old 28th May 2012, 12:02 AM   #1130
diyAudio Member
 
Join Date: Mar 2005
Location: MI
Quote:
Originally Posted by Tytte71 View Post
Hmm.. only me that would like to have SEOS with larger throat?
I've got a few 1.4" and 2" throad compression drivers, but I'll count myself as one of those not interested in a larger diameter throat SEOS.
  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
smith horns and using compression horns for a Karlson party speaker project bikehorn Multi-Way 14 30th January 2013 06:20 PM
Horns inside of horns open foe discussion oilcanracer Multi-Way 3 15th February 2010 04:42 AM
Compression drivers in horns or waveguides 454Casull Multi-Way 6 1st December 2008 01:41 PM
Phase plug necessity in horns/waveguides 454Casull Multi-Way 3 18th September 2005 08:36 PM
Horns: Vibrations and resonances in metal horns Rocky Multi-Way 10 28th July 2004 02:38 AM


New To Site? Need Help?

All times are GMT. The time now is 09:02 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