Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

Well I suppose the shallow vs. steep argument will just go on and on
Well I suppose the shallow vs. steep argument will just go on and on
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 10th November 2017, 07:04 AM   #151
marco_gea is offline marco_gea  Italy
diyAudio Member
 
Join Date: Apr 2005
Location: London, UK
Quote:
Originally Posted by system7
Now you try to poo poo my idea that above 3kHz, there isn't much information.
Quote:
Originally Posted by gedlee
Yes if your tweeter only covers 3 kHz and above it isn't a big contributor
Actually, to me it seems as if on this particular point there is good agreement.

The disagreement - instead - is on whether it's a good idea to cross over at 3kHz in the first place.

Honestly, based on my own experience, I tend to side with Dr. Geddes on this latter point. And sorry, but just because "most of us here" do it, doesn't make it the best idea.

After all, "most people" are happy listening to music on their PC speakers and crappy earpods - by the same logic, does that entail that one shouldn't argue that there are better ways to do it?

Sorry, system7, I often like your posts, but this one in particular came across as unnecessarily defensive to me.

Marco
  Reply With Quote
Old 10th November 2017, 07:41 AM   #152
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
TBH, I don't care where you crossover. The Universe seems to know you are doing it.

It's the Quantum Theory. Exemplified by one of my Physics heroes, Dick Feynman. Below. Now, TBH, it's quite hard to find Planck's constant in loudspeakers. But the diffraction maths seems to apply anyway.

Let's get back to this extraordinary Manger speaker by Joachim Gerhard:

Click the image to open in full size.

I have really no idea what exactly Joachim was doing here. But I've never heard a speaker like it. Why did he add sideways facing drivers to the narrow-directivity Manger idea? Obviously, taking the bass load out of the equation was a sensible idea. Excursion equals distortion. Because speakers are non-linear in the end.

This, BTW, is a £25,000 speaker. No compromise. I couldn't afford it myself. But my friends can. And you have to listen to it exactly on-axis, where it resembles headphones. Joachim Gerhard is a tremendously bright guy, IMO.
Attached Images
File Type: jpg Dick_Feynman_LOL.jpg (37.9 KB, 276 views)
__________________
Best Regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 10th November 2017, 08:54 AM   #153
marco_gea is offline marco_gea  Italy
diyAudio Member
 
Join Date: Apr 2005
Location: London, UK
Quote:
Originally Posted by system7 View Post
TBH, I don't care where you crossover. The Universe seems to know you are doing it.

It's the Quantum Theory. Exemplified by one of my Physics heroes, Dick Feynman. Below. Now, TBH, it's quite hard to find Planck's constant in loudspeakers. But the diffraction maths seems to apply anyway.
TBH, you lost me there.
I fail to see how Quantum Theory has anything to do to where to best crossover a woofer and a tweeter, from a psychoacoustics perspective.
(And incidentally, it's not just because the words "quantum theory" scare me. I studied a fair bit of it myself, as I happen to have a PhD in chemical sciences)

Quote:
Originally Posted by system7 View Post
Excursion equals distortion. Because speakers are non-linear in the end.
100% agreed there. :-)

Marco
  Reply With Quote
Old 10th November 2017, 10:32 AM   #154
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
TBH, the Quantum Theory is a bit beyond my own abilities too.

But I still enjoy it, because it is provably right over the classical theory. I think this is down to Sidney Coleman: YouTube.

Not quite Dick Feynman in my estimation, but a leading light. Sorry about the poor quality, BTW.

Interestingly, Sidney Coleman was interested in the idea of M + jT and M - jT. I am using the engineer's j version of the complex number i here. We do this to distinguish it from I which is current in engineering.

This is an ideas thread. We all need a good idea. I got interested in whether j actually represents 90 degree phase or 90 degree physical direction.

Click the image to open in full size.

Maybe it's debatable. IMO, 180 degrees phase might mean you point one of the drivers backwards. And it might sound much the same once it's bounced off the wall. I really don't know. I assume NOTHING about the Universe.
__________________
Best Regards from Steve in Portsmouth, UK.

Last edited by system7; 10th November 2017 at 10:34 AM.
  Reply With Quote
Old 10th November 2017, 11:07 AM   #155
Juhazi is offline Juhazi  Finland
diyAudio Member
 
Juhazi's Avatar
 
Join Date: Mar 2007
Location: Jyväskylä, Finland
Quote:
Originally Posted by system7 View Post
--

This is an ideas thread. We all need a good idea. I got interested in whether j actually represents 90 degree phase or 90 degree physical direction.

Click the image to open in full size.

Maybe it's debatable. IMO, 180 degrees phase might mean you point one of the drivers backwards. And it might sound much the same once it's bounced off the wall. I really don't know. I assume NOTHING about the Universe.
Front wall reflection is totally different, it has delay.

180 phase shift means that you have to rotate the "upper" driver, or more likely to wire it in negative polarity. This thinking is a bit complicated, because at crossover region both upper and lower driver have phase shift in opposite directions. They sum flat SPL, but phase gradually turns 180¤ This can be measued if we compare phase angle before LP and after HP begin to have an effect. This means 2 octaves apart with LR2!


An example from Troels OBL11
Click the image to open in full size.
Click the image to open in full size.
__________________
AINOgradient speaker project

Last edited by Juhazi; 10th November 2017 at 11:17 AM.
  Reply With Quote
Old 10th November 2017, 04:07 PM   #156
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by system7 View Post
Earl, you are tremendously aggressive. First you try to lure me into saying that RCL filters are non-linear, which of course they aren't. The whole topic is LINEAR signal processing.

Now you try to poo poo my idea that above 3kHz, there isn't much information. I don't care what YOU do in your esoteric horn designs. It's what most of us here do that matters.
Yes, I will aggressively go after false or misleading statements, like yours about filters being nonlinear. All you have to say is "Sorry, I misspoke, I did not mean to imply that they are nonlinear."

I misspeak all the time and when called out I try to clear things up. No one never makes mistakes and it's important to keep the record factual. Otherwise audio will continue to wander into the never-never land of audiofoolery.

And you must not have read what I said because I agree that if all your tweeter does is > 3kHz then its not so important, but many people don't do things that way.

Keep to the facts and stay away from subjective based hypothesizing (and maybe irrelevant references to quantum mechanics) and we'll be just fine.
__________________
Earl Geddes Gedlee Website

Last edited by gedlee; 10th November 2017 at 04:11 PM.
  Reply With Quote
Old 12th November 2017, 05:38 AM   #157
Fernando R is offline Fernando R  United States
diyAudio Member
 
Join Date: May 2017
Location: Charlotte NC
As someone who has been in this hobby for 50 years now, and stopped to get an electrical engineering degree somewhere along the way, I am greatly amused by some of the arguments on these boards and those who believe that engineering is actually ruled by inviolable concepts and theories. The absolute best definition of engineering I have ever come across is “the art of figuring out which parameters can be safely ignored.”On another thread someone wrote something to the effect that those who crossed over at or above 3 KHz ignoring the directivity index were fools who had no idea what they were doing.
That comment made me draw up a short list of fools who did not know what they were doing and whose speakers must have had terrible midrange.
  • The entire BBC team who thought 8” drivers could be crossed over at 3 KHz in their monitors.
  • Spendor, from the original BC1 (8”) to the current D7 (7”) crossing at 3 KHz
  • Harbeth who still think you can cross 8” woofers at 3 KHz.
  • Bowers and Wilkins who still think you can cross 6” drivers at 4 KHz in their flagship 800 series.
  • Aerial Acoustics who take an SB 5” Papyrus mid to 3KHz in their 7T
  • Sony with their SS-AR1 who think that they can take a Scan 15M Revelator from 400 to 4 KHz
  • The biggest fool had to be Peter Walker of Quad who thought you could take a wide flat panel to 7 KHz before crossing to a narrow strip
These people were either fools or they figured out that gains could be made in other areas by compromising some directivity. They succeeded in creating great products becausethey figured out what and how much could be safely ignored.
Lighten up guys. None of us have absolute answers.
I apologize to any other fools I neglected to mention.
__________________
He uses numbers and statistics like a drunk uses a lamp post; for support rather than illumination.
  Reply With Quote
Old 12th November 2017, 06:32 AM   #158
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
Juhazi, I think my idea that 90 or 180 degrees has a physical as well as a phase interpretation is just terribly clever. But not actually original because Roy Allison did this stuff years back, see below.

Click the image to open in full size.

And it's not inconceivable that Joachim Gerhard, who knows a thing or two about BW3, might have been doing something like it here, because sideways facing drivers can fill a crossover power hole in a room even if you don't hear them directly:

Click the image to open in full size.

And don't forget that a speaker is usually a dipole, which is a game changer to the thought experiment.

But, thankyou, Fernando. I too have a great time crossing an 8" to a 2" at 3kHz, but TBH, I am increasingly preferring steeper filters with this slightly difficult combination:

Click the image to open in full size.

It took me years to understand why it is actually very BBC and all done 50 years ago with engineers with slide rules (logarithms) and Smith charts (circle preserving conformal transformations) to do the computing: Rogers Loudspeakers › LS5/9

Negative polarity on a bass unit with terrible time-alignment problems! Makes it all work! And we know (because I showed you...) that group delay on the musical information is not affected by polarity. That plus the currently almost ignored BW3 90 degree phase idea which fills the power hole (in the room acoustic) of a (modern...) 6db crossover phase-aligned LR2 or LR4 crossover.

IMO, I very rarely talk nonsense. I do simplify on occasion for brevity. Nobody reads the long posts.

Increasing, as an old timer in this game, I just shoot the breeze and trust my muse. And I have definite opinions of what works well and I test them, because, Earl, a point in every direction is no point at all. We should beware of being negative and critical. It's a VERY BAD THING! For all I know, your speakers may just be blowing smoke-rings. Prove to me they are not! The Four States of Mind

I'll shut up now. But do keep the ideas coming. I want to hear yours!
Attached Images
File Type: png snoopy.PNG (29.9 KB, 41 views)
File Type: jpg The_Point.JPG (35.3 KB, 14 views)
File Type: jpg Slide_rule.JPG (51.3 KB, 16 views)
File Type: jpg Smith_chart.jpg (169.8 KB, 20 views)
File Type: jpg Smoke Ring Machine.JPG (20.6 KB, 31 views)
File Type: jpg Allison_Model_6_Le_Cube.JPG (39.3 KB, 27 views)
__________________
Best Regards from Steve in Portsmouth, UK.

Last edited by system7; 12th November 2017 at 06:48 AM.
  Reply With Quote
Old 12th November 2017, 08:24 AM   #159
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
Ok, I can measure (very crudely) the power response dip at 125Hz in my LR4 xover, or can I with a mic? All OB BTW, but I can't hear it, is that because I'm also in the room and not down the hall or is there another reason?
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 12th November 2017, 03:39 PM   #160
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by system7 View Post
And I have definite opinions of what works well and I test them, because, Earl, a point in every direction is no point at all. We should beware of being negative and critical. It's a VERY BAD THING! For all I know, your speakers may just be blowing smoke-rings. Prove to me they are not!
Steve

None of my comments to you have been about my speakers or how I designed them. They were simply pointing out errors or serious limitations in your comments. This is not a contest of speaker designs.

That said. I have always offered proof of what I claim in the form of a database of extensive polar measurements on dozens of loudspeakers of a variety of designs so that people could look and judge for themselves.

As you may or may not know I no longer make speakers, I don't do any acoustic designs of any kind anymore so I have no "dog in this race" so to speak. I do have 50+ years of education, research and experience in this area however and I will always use that to try and bring some sanity into audio.
__________________
Earl Geddes Gedlee Website
  Reply With Quote

Reply


Well I suppose the shallow vs. steep argument will just go on and onHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
2 + 1, variable state bi-amping VS steep low pass subwoofer emosms Analog Line Level 0 16th February 2016 06:50 PM
Shallow mid-range enclosure inside a 3-way?? too shallow?? Kooshball Multi-Way 8 3rd November 2012 11:40 PM
Suppose I should have introduced myself first. J_Starner Introductions 2 19th May 2006 01:41 PM
pc xo : steep crossover slopes advantages and drawbacks Nemophyle Multi-Way 2 14th September 2005 12:25 AM
Inexpensive 8" driver with steep top-end roll-off The Paulinator Multi-Way 1 6th June 2003 07:25 AM


New To Site? Need Help?

All times are GMT. The time now is 10:05 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki