GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Upperbass horns – tone vs. distance

Post Subject: There is no such a thing as optimal distancePosted by Romy the Cat on: 7/26/2012

haralanov wrote:
I think it is very interesting subject and I’m looking for first hand opinions by people, using properly sounding upper bass horns in their listening rooms. I’m not interested in theoretical opinions – only by opinions, coming from personal listening experience.

Everybody knows there is no such thing as "sound of a driver" or "sound of a horn" – the sound varies depending on how the channel is being used – distance, angle, positioning in a room and many other factors. So if we take a given properly made upperbass horn channel, placing it in a big room away from the walls, then how does the sound change with distance? What I’m interested to know is there any optimal distance from the mouth of the horn (I’m talking about tractrix horn of let say 90cm diameter – the size of Romy’s UB horn), where the tone develops its maximum value. How does the tone changes when we listen to the horn at 1m, then at 2,5m and then at let say 6m away from it? Another important thing that deserves to be discussed is how does the type of sound presentation change with distance – I’m talking about the size and shape of the sound. Any deeper analyses of the subject are welcomed.

Of cause there is no such a thing as optimal distance. The “propagation of tone” with distance is to a great degree the acoustic properly of given listening space and I do not think that it is possible to generalize anything in it.

The bass horns do not sound good from short distance and do not sound good when they pointed to listener. Then we need to define what “bass horns” are. I would say that anything under 200Hz is benefited by indirect sound.

The “distance where tone develops its maximum value” is a bit slippery concept. I feel that instead of thinking about the “distance of max tone” we need to think the “distance of proper integration”. The upper/mid bass horns are complicated animal themselves and I do not see that it is practically possible to evaluate the “tone distance” alone. The upper/mid bass horns are narrow bandwidth devises and this tone is hugely moderated by the associated channels. You can’t just slide the upper/mid bass horns a few feet closer and further. Moving of an upperbass horn for a few feet in most of cases means a complete change of installation topology. I just do not see how it might be done from practical perspective. I think the topology of installation is chosen in respect of the configuration of the given listening space and the objectives of the listeners. This sets the upper/mid bass horns at the very specific distance and considering the obligatory need for time-alignment I do not see any flexibility in it.

So, from a theoretical point of view for sure would be nice to talk about the preferable distance to let tone to be developed and I would advocate for relatively large distance and indirect sound. However, I do not think that it makes any practical sense. I feel to change the drivers in the horns is more practical and more effective way to find optimum tone then to move the horn.

It is good idea however to use (or at least to think of using) the impediments within the bass horn’s direct sound. I did illustrate it before but I am not sure if the “impediments” directly affect “tone”. You see, by fracturing the directly output of bass horn we change the gain output of the horn. If we add let say 1dB to the upperbass horn at let say 80Hz and it changed the balance between the upperbass and MF horns then what we did was “Tone” or “Volume”? I do not have an answer to this question and in practical terms I do not think that anyone does.

Rgs,
Romy the Cat

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