In the bass region I can hear it clearly, peaks and nulls due to the room are evident.
Yes, this is now correct and I understand the "integration step" although I had not thought of it that way before. But it makes sense to me now.
One comment on "smooth response".
Bass does sound great in rooms, but not small rooms. A low bass instrument played live in a small room would likely not sound very good because of the large modal peaks and dips. These are a problem with small rooms, not the instrument or the listener, but the room itself. Hence for good "reproduction" we should want to smooth out the small room modes that do not occur in larger rooms where things always sound good.
And let's all remember that we are talking about only the very lowest octaves not the full bandwidth. We want to help a small room act and sound like a larger one, because that is where sound is optimum - small rooms are flawed, but we are forced to live with them.
You debugged me from my "indoor VS outdoor" logic comprehension trap
Not a easy task debugging a French
Ok, thank you very much, Earl.
So, now that you confirmed one can use L+R measurements I'm still curious what did you mean by "making mains mono and treat them as a single source"?
Does that mean a measurement of both speakers or is language barrier messing with me again?
For the purposes of setting up the subs, play the same signal through both L+R mains and treat as a single source, not two.
In practice, of course the mains will be stereo, and it's this stereo that will carry the perception of bass location from the higher frequency harmonics, even as the low bass is mostly mono.
Hi Anand,
Geddes speakers are sealed pro audio drivers so they will have a built in acoustic 12dB HP, in my experience usually around 80 / 100Hz so they will not be running 'full range' per se. He's also mentioned he sometimes uses a 1st order HP on the mains, increasing the slope to 3rd order.
To be honest I think of a 'crossover' as the point at which 1 driver hands over to another acoustically. So to me (at least!) a subwoofers acoustic -6dB point on its slope would be the subwoofers 'crossover' point. (To me using a lowpass filter on a sub is exactly the same thing as using a crossover on a sub.)
Sorry if this has caused some misunderstanding.
I'm running 15's with horns for mains here and use my DCX to roll of the mains to follow the JBL synthesis curves and am enjoying the setup.
Makes me wonder what a Geddes setup would measure like with the mains switched off (subs only). Maybe the curve looks more conventional than I'm thinking ?
Rob.
Rob
Let's be clear on what we are talking about here: a small room, not a free field. What you say might be true given a whole lot of assumptions, most of which do not fit my case. First my mains have an Fs of about 65 Hz - very high for a big speaker - but they have a Q of about .6. This means that, in a free field, they will not be <-6 dB/oct until about 45 Hz., Say 50 Hz. In a free field this would mean a very low level at about this freq.
But mine is not a free field and the mains have similar output to the subs (no EQ) at the lowest resonance of 35 Hz. Mind you it is hardly flat <150 Hz, but it's still not that limited a range and "full range" might apply.
My definition of "crossover" is the same as mine, but not a lot of people, so I stopped using it as it caused confusion. And when you have 3 subs, which -3 dB do you use?
I think that you would find the answer to your question to be:"Yea, that's looks 'conventional'". Why wouldn't it?
Let's be clear on what we are talking about here: a small room, not a free field. What you say might be true given a whole lot of assumptions, most of which do not fit my case. First my mains have an Fs of about 65 Hz - very high for a big speaker - but they have a Q of about .6. This means that, in a free field, they will not be <-6 dB/oct until about 45 Hz., Say 50 Hz. In a free field this would mean a very low level at about this freq.
But mine is not a free field and the mains have similar output to the subs (no EQ) at the lowest resonance of 35 Hz. Mind you it is hardly flat <150 Hz, but it's still not that limited a range and "full range" might apply.
My definition of "crossover" is the same as mine, but not a lot of people, so I stopped using it as it caused confusion. And when you have 3 subs, which -3 dB do you use?
I think that you would find the answer to your question to be:"Yea, that's looks 'conventional'". Why wouldn't it?
Hi Earl,
I'm assuming one of the 'My' Or 'mine' should be ''your' or 'yours' ?
wrt the 3 subs If it was me I would get the 'multi sub' setup flat across (and beyond) its working range and then apply a global low pass to the whole lot and that would give the -3dB point.
Maybe from previously reading your papers / forum discussions I have wrongly assumed when you said lots of overlap and no crossovers that your subs were running up into the bass range and going way beyond the 'conventional' ~80Hz crossover point of 'normal' sub / mains setups. If that is the case I apologise. (If it's not the case then I still don't understand ?
)Cheers,
Rob.
Hi Earl,
I'm assuming one of the 'My' Or 'mine' should be ''your' or 'yours' ?
wrt the 3 subs If it was me I would get the 'multi sub' setup flat across (and beyond) its working range and then apply a global low pass to the whole lot and that would give the -3dB point.
Maybe from previously reading your papers / forum discussions I have wrongly assumed when you said lots of overlap and no crossovers that your subs were running up into the bass range and going way beyond the 'conventional' ~80Hz crossover point of 'normal' sub / mains setups. If that is the case I apologise. (If it's not the case then I still don't understand ?
Cheers,
Rob.
Yes, "My" should be "Your"
I think that the crossover would then be more audible as the system went abruptly from subs to mains. If they overlap - all at different points - then this is not an issue.
It is the case that my subs run well above 80 Hz. Probably 120 Hz in one case.
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When adding a sub, have you found that it works well up to some frequency then goes the wrong way? I mean you find a location that is very good for lower frequencies then has an issue at some point, flipping polarity doesn't seem to change that higher frequency in a way that suggests anything beneficial. It suggests case by case.
Yes, hence the need for asymmetrical distribution. I have only one sub in the corner, the rest are interspersed. One is closer to one of the mains. Another is at a midpoint along a side wall. The last is along the wall behind the MLP. Each sub plays a part and has areas where it measures maximally flat at certain frequencies but not all. The mixture or blend of all 4 plus the mains (which has some LF extension) is what seems to work. I have very little EQ most likely due to decent LF damping/absorption as well.
Best,
Anand.
Beige,
All my subs are sealed. The only sub that has a high pass filter is my 21 inch to minimize excessive excursion below 20 Hz. All of the subs have low pass filters, all are at different frequencies and slopes vary between 2nd to 4th order (Linkwitz-Riley) and phase is different for all of them too.
It’s what works and measures best depending on sub location and design.
Best,
Anand.
All my subs are sealed. The only sub that has a high pass filter is my 21 inch to minimize excessive excursion below 20 Hz. All of the subs have low pass filters, all are at different frequencies and slopes vary between 2nd to 4th order (Linkwitz-Riley) and phase is different for all of them too.
It’s what works and measures best depending on sub location and design.
Best,
Anand.
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So if you came to my house and played recordings you knew on your own system that you hauled over using a collective grant from this forum, you could identify, "A peak of about X dB at 90 (give or take 5 Hz) and a dip at 45..." and so on?
Would it be advantageous to notify the Guiness Book of World Records ahead of time?
B.
That's swell Scott, but I am very glad you didn't say, "Just look at the FR curve."
The non-trivial question is whether you are claiming earlier that you can hear the room irregularities without resorting to special test sweeps, eh.
My point earlier point that I thought you were dismissing based on your elevated personal hearing skills is whether you can "hear" an FR or just hear tone colour. Now I realize that you are not claiming you can actually here the dips and peaks except using test tones.
Like with phase and other insignificant issues*, not important to lose sleep over every bump and dip since there is no mental baseline to "hear" them.
B.
* transient behaviour is a good example of something rarely fussed over on this forum yet is very important to the sound of your system.
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Ben
(Since you are so critical of others)
You should certainly understand that in a linear system if I know the FR then I also know the transient response. Meaning that since they are just different ways of looking at the same thing it doesn't matter which one you talk about. Of course, I am assuming that we also know the phase, because there are some audible effects of phase on an impulse response, but you have made clear that you don't think that phase is audible, hence FR and transient response must be the same things.