What are you experiences with imaging and sweet spots? - 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 26th February 2007, 10:55 AM   #1
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
Default What are you experiences with imaging and sweet spots?

I recently heard a horn system which made me question what is it that makes for good imaging and a broad sweet spot?

The speaker in question has a CD in a large 200 Hz horn on top of a vented 15" pro driver. I'd call the sound "direct." I've heard it said that wide dispersion puts the musicians in the room and narrow dispersion gives a window to the musicians. I think that would describe what I heard.

So I'd like to hear what you guys have experienced - what speakers you have heard and what kind of imaging and sound stage they created as well as the sweet spot.

This is what I've experienced:

* Tannoy - fairly recent dual concentric with 6.5" midbass drivers (vented bookshelf)

Imaging appeared to be good, despite the room being much like a garage with carpet and a couch acoustically.

* My mains - MTM with dome tweeter and 6.5" midbass

They can image quite well as previously mentioned. The sweet spot is such that you can sit off centre without the image collapsing into one speaker - a centre speaker isn't needed for home theatre.

* My mains on an open baffle panel

Noticeably bigger sweet spot, which was welcomed. The sound stage was bigger and the overall sound more appealing. When I put the drivers back in their boxes again, the sound stage was suddenly smaller.

From memory I'm not sure if the imaging is better or not as I didn't pay specific attention to that aspect, but the sound was more transparent, creating a more real illusion of the musician being in the room.

* Adire HE10 (coax 10")

Imaging did appear to be good but the treble harshness made it hard for me to really evaluate.

* CD horn

See previous comment at start

I've heard a great deal many more speakers, but these are the ones where I paid some attention. I've heard some omnis and I can't say their imaging was actually any different to conventional hifi speakers from memory. It was a surprise at the time, as I felt an omni was the worst possible design from an imaging point of view.

A more theoretical question:
How does one achieve a large sweet spot?

I'd like to experiment with horns and dipoles quite soon as an upgrade, I just wonder if I will be happy with the sweet spot and imaging of horns and if I should design any horns to have dispersion as wide as possible. One of my current ideas is a 3 way with a large mid horn (either CD or cone mid driven), concentric supertweeter and 12" pro mid on open baffle.
  Reply With Quote
Old 26th February 2007, 11:57 AM   #2
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
How does one achieve a large sweet spot?
IME, a rather large room and omnidirectional radiators.
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 26th February 2007, 12:33 PM   #3
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
what is it that makes for good imaging
Sy, good answer!

A short answer and leaving out driver qualities and filter requirements for the moment:
A speaker stereo (?) or multi-channel set-up that minimizes phantom localisation errors, vertical and horizontal together with a physical layout that maximizes phantom sharpness, minimises time/intensity trading smear/blur effects by either layout of the physical drivers if using minimal baffles and/or smoothing them out buy intelligent choice of baffle layouts.

b
  Reply With Quote
Old 26th February 2007, 12:55 PM   #4
medum is offline medum  Denmark
diyAudio Member
 
medum's Avatar
 
Join Date: Dec 2003
Location: Jutland, Denmark
Quote:
Originally posted by SY


IME, a rather large room and omnidirectional radiators.

I rather agree with SY, ..... BUT:

In my opinion you will always have a "problem", if you don't have the same distance to your speakers - no matter what kind of speakers - because you will have a phase problem. Almost all sounds from your stereo comes from two points, and unless you have the same distance to these points (speakers), the sound are out of phase, right?
So stick to your sweet spot for serious listening
  Reply With Quote
Old 26th February 2007, 01:14 PM   #5
diyAudio Member
 
paulspencer's Avatar
 
Join Date: Sep 2003
Location: Melbourne, Australia
I plan on sticking to the sweet spot, but I'm interested in how to make it bigger! So at least 2 people can sit in the sweet spot. Enjoying audio isn't always a solitary affair!
  Reply With Quote
Old 26th February 2007, 01:14 PM   #6
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
So stick to your sweet spot for serious listening
Medum, No contradiction at all but a sharpen up the general requirements of the thread owners wish: broad sweet spot and entering the lower level where imaging can be discussed?

b
  Reply With Quote
Old 26th February 2007, 01:29 PM   #7
medum is offline medum  Denmark
diyAudio Member
 
medum's Avatar
 
Join Date: Dec 2003
Location: Jutland, Denmark
Quote:
Originally posted by bjorno


Medum, No contradiction at all but a sharpen up the general requirements of the thread owners wish: broad sweet spot and entering the lower level where imaging can be discussed?

b

of course - If you want a broader "sweet spot" - go for the reflections from the walls. My Marin Logan Clarity speakers have a rear mounted tweeter, that can be activated for "party-listening" - maybe that could be a solution. But I must say that it is not really a sweet spot. Unless you have the same distance to the speakers, you are not in the sweet spot.
  Reply With Quote
Old 26th February 2007, 01:54 PM   #8
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
If you want a broader "sweet spot" - go for the reflections from the walls.
No offence Jrn, but now the subject is expanding into including room effects and I find it hard to stay focused at the original question.

There is no indication that the room effects should be counted as I can see. Im hesitating to further follow this thread because the risk that this matter is divergating too much for my taste.

But maybe this picture can be used as good starting point if a discussion of pros and cons of the sweet spot; sweet spot area is essential for the thread owner?

Look at:Post#2

Aww Jeez, another moronic post (pls forgive me but)...


b
  Reply With Quote
Old 26th February 2007, 02:10 PM   #9
diyAudio Member
 
Join Date: May 2002
Location: Switzerland
Quote:
you will have a phase problem
Primarily you generate a delay problem but this will lead to a phase problem as well of course.
But the delay part is the one that spoils imaging.
The phase problem will lead to frequency-response aberrations.

Regards

Charles
  Reply With Quote
Old 26th February 2007, 02:11 PM   #10
diyAudio Member
 
Join Date: Jan 2006
Location: Indiana
FWIW, my experience has been similar. My first DIY's were an MTM. They sounded good, had good imaging, but the soundstage was not particulary big and was sort of flat front to back, nor were they forgiving of listener position.

My second major DIY was the NaO Mini, open baffle MTM. The soundstage was much bigger and deeper. The imaging was still very good and more forgiving of listener position. You get a real sense of 3d space around them.

My latest project is a hybrid omnidirectional design. Each speaker has a downfiring 12" sub for 100hz down, an up and down firing midwoofer covering from about 100hz up to 1450hz. Then there is a front firing tweeter that covers from 1450 up to 21khz or so. It has a much bigger and deeper soundstage than even the NaO and for the first time, I seem to be able to hear the size of the recording venue, for example one recording sounds like you are in a small nightclub and another sounds like the soundstage is well outside the walls of the room you are in. Instruments can sound like they are way behind the speakers. However, I think becuse of the direct firing tweeter, they still have good imaging and are very forgiving of listener position, IMO. YMMV.

When I was building and testing the omni prototype, I was able to compare a single speakers sound from each of these types. It was eye opening to me, but sort of hard to describe. Here is the best way I came up with to describe it. You know how a single box MTM sounds so much smaller than a pair of stereo boxes? I could describe the single box MTM as having about 1/4 of the soundstage as two of the box MTM's in stereo. Compared to the box MTM, a single open baffle NaO mini could be described as having 1/3 of the sound of the pair of NaO's. Compared to the others, the hybrid omni had more like 1/2 the sound of the pair of omni's. A single omni almost sounded like it could be as big 3/4 of the soundstage as the two boxes. Here is a photo of the hybird omni:

Click the image to open in full size.
__________________
Dan N.
  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
Price / performance sweet spots preiter Solid State 0 9th January 2007 08:23 AM
Tubes and their sweet spots. ak_47_boy Tubes / Valves 38 15th December 2006 03:42 AM
ESL imaging, soundstage, sweet spot ??? michaelpage26 Planars & Exotics 6 6th December 2004 09:42 PM


New To Site? Need Help?

All times are GMT. The time now is 01:33 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