Loudspeakers and room as a system

[Etienne88]

Originally posted by graaf
yes I can see them
can You post a schematic drawing of Your current setup - how exactly the loudspeakers are positioned?
best,
graaf

I never attached a file before, just hope it will work...!

The ceiling is at 2,4 m and the LS are 35 cm deep. They are lifted above the ground by pieces of wood so that the driver is around 40 cm above the floor.

Regards,
Etienne

[Colin]

Hi Earl

Agree about lack of facts in audio.

The material on Ted's site is somewhat simplified. I thought the polar responses are on the pages for the individual drivers but my mistake. Much of what he has researched has appeared in Wireless World over the years and I think I must be recalling some of those articles, which include more measurements. I'm hoping we'll be able to get reprints of the material onto his website in the next year or so.

Anyway, getting off the topic slightly.

[Etienne88]

Originally posted by gedlee

Not many speakers are flat 45° off axis.

That's THE problem of the set up described by Graaf. In his case (mine as well for the moment being) the drivers should be flat off axis up to almost 180º... If you've seen a driver like this, please tell me!
In our current set ups, the higher the frequency, the less direct sound we get. It is done in a quite progressive way so that it doesn't feel that wrong. Then if you read Briggs's book: Loudspeakers, at that time they recommended to have the medium and tweeter facing upward in order to achieve more spaciousness. The best tweeters of that time went up to 12kHz, maybe 15kHz... I wonder when LS started to have forward firing drivers???

Looking at this link, we can see that the FE167E (my current driver) is not that bad on axis but omnidirectional only up to 2kHz.
I will try to lift my LS up so that I can see them behind the couches. This could improve the situation since I will get more direct sound. But it could as well worsen it since i will be listening more and more off axis...

Any experience about multiple drivers in this set up?
I have the feeling that it should not be a problem below around 200Hz (where the room modes start to be discrete) but my concern is with the mid high transition. I guess the delay caused by the distance between the 2 drivers will be audible. So that coaxial speaker would be a better choice. Just guessing, any thoughts?

Regards,
Etienne

[gedlee]

Originally posted by Etienne88

Looking at this link, we can see that the FE167E (my current driver) is not that bad on axis but omnidirectional only up to 2kHz.

Any experience about multiple drivers in this set up?
I have the feeling that it should not be a problem below around 200Hz (where the room modes start to be discrete) but my concern is with the mid high transition. I guess the delay caused by the distance between the 2 drivers will be audible. So that coaxial speaker would be a better choice. Just guessing, any thoughts?

Thanks for the post to that believable data. This is the kind of response curves that I typically see when I measure loudspeakers - they are terrible.

I never use multiple drivers, I don't think that it is a good idea.

[Etienne88]

Originally posted by gedlee

I never use multiple drivers, I don't think that it is a good idea.

Earl, with multiple drivers I meant a boomer, a midrange and a tweeter. I am not sure my message was clear since I know you use subwoofers! If I understand you well, you use one single driver per channel to cover 150-200Hz to 20kHz. Is that right? That is 7 octaves, it is huge and I think I know what I'm talking about since I use a full range driver.
Do you manage to get flat response from 0º to 45º on 7 octaves with your horn design?

Regards,
Etienne

[gedlee]

Originally posted by Etienne88


Earl, with multiple drivers I meant a boomer, a midrange and a tweeter. I am not sure my message was clear since I know you use subwoofers! If I understand you well, you use one single driver per channel to cover 150-200Hz to 20kHz. Is that right? That is 7 octaves, it is huge and I think I know what I'm talking about since I use a full range driver.
Do you manage to get flat response from 0º to 45º on 7 octaves with your horn design?

Regards,
Etienne

I use subs below about 150 Hz. The mains have large woofers operating from about 50 Hz through about 900 Hz. The waveguide take over from there. The woofers are large so that they have narrowed their directivity down to that of the waveguide at the crossover frequency. The waveguides are completly CD above 1 kHz where they match the woofer - thats about 4 octaves, not seven. The need for directivty drops below 1 kHz for psychoacoustic reasons (thank god because it wouldn't be very easy to do). The 4" driver is never CD, except when its omni. But omni is a disaster in a small room with wall reflections (again unless these are below about 500 Hz.)

[Colin]

A light breaks in distant window ... when I was referring to Ted's drivers earlier, I shouldn't have been bandying about phrases like CD. His articles talk about directivity and the advantages of cone drivers over domes.

[graaf]

Originally posted by gedlee

Have you read my book?

No I haven't, neither I have read EJJ's book

therefore I was just asking and quoting adding the word "allegedly"

Have You read EJJ's book?

best,
graaf

[graaf]

Originally posted by Etienne88

I never attached a file before, just hope it will work...!
The ceiling is at 2,4 m and the LS are 35 cm deep. They are lifted above the ground by pieces of wood so that the driver is around 40 cm above the floor.

now I see, thanks fo the image

nice room, I think that those couches can take away the highs

perhaps You can use some kind of passive or active equalization instead of elevating the loudspeaker higher?

best,
graaf

[el`Ol]

Originally posted by Etienne88

Any experience about multiple drivers in this set up?
I have the feeling that it should not be a problem below around 200Hz (where the room modes start to be discrete) but my concern is with the mid high transition. I guess the delay caused by the distance between the 2 drivers will be audible. So that coaxial speaker would be a better choice. Just guessing, any thoughts?

Regards,
Etienne

You have to make sure that the midrange has still an omnidirectional radiation pattern at the crossover point. Otherwise the direct sound will have a hole in the FR in a critical region. My trial in the multi-way direction will be a narrow-beam CD-horn radiating hardly any sound in the listener´s direction, combined with either front-firing or ceiling-firing midrange.