Heavily treated backwall can reduce the effect of the rear reflection, but even 2 feet thickness of OC703, it most probably can absorb only a few dB below 250Hz, I guess. The size of the room is almost everything in reality. The reason why some suggest 38% is it's would be possibly the ideal starting point to try to minimize the effect of the room mode. 38% is just a guideline, and it's all depends on the room anyway.
I personally think EQ usually just worsen the issue of the room, but some people seem to think it can improve it... I only use EQ for speaker correction, not for room correction.
I personally think EQ usually just worsen the issue of the room, but some people seem to think it can improve it... I only use EQ for speaker correction, not for room correction.
There's no need to guess
600mm Low Density Fibreglass, with an air gap which makes a big difference, not OC703 (which is quite high density). Not very practical but quite effective
A more practical size for a panel behind a couch, 150mm medium duty with a smaller air gap, example build attached below
EQ in the modal region is very effective and if combined with multiple sources a wide area can have a good response. Positioning is very important but not many people have the option to have their speakers 38% out into the room. If they can't be that far out moving them much closer to the walls is often better if there is EQ available to deal with the change in tonality.
Attachments
A good read on the subject of modal EQ
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.542.6328&rep=rep1&type=pdf
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.542.6328&rep=rep1&type=pdf
Pretty much, if there is a peak in the combined response introducing an opposite dip in the input will flatten out the combined response.
Nutshell: You can potentially improve FR and modal performance with EQ. The mode can only give out whats given, in terms of energy. So in the case where you have Fixed the FR in a mode that was peaking....without Room acoustic treatment you have Fixed FR and left a peak in group delay. Room acoustic treatment will improve GroupDelay and FR. FIR can improve GD as well, I have not heard of peoples experience using FIR to improve a GD peak in the response from room issues but theoretically it can be done I just wonder how effective it is...the point is to use EQ and room treatment together.
Do you have any source where I could find how to use hornresp in this case? What I've found is quite intimidating.
I'm a bit confused about the replies with diffraction mentioned. Diffraction is what happens at the outside box edges, right? I know diffraction from optics; my specialisation at university and work at ASML (in a distant past).
I tried to use VituixCAD's diffraction tool and it showed no problem. Is consistent with what I've read about diffraction not being an issue if the edges are close to the cone/mouth.
Plenty of information from Toole and Geddes amongst others. The modal region of a room is very different in how it responds to basic EQ. There is such wide consensus of research and opinion that there is nothing to be unsure of if you do some reading and experimenting. Try it.
This is not right, room modes are predominantly minimum phase, fixing the frequency response fixes the phase and associated group delay too. I thought you understood this from all the discussion on your thread.
This can't really be a one line answer. The same mechanism is at play but the effect is different due to the wavelength of the frequencies affected.
In a speaker the size you are making the baffle is wide which lowers the frequency of the baffle step. The woofer being large starts to beam as frequency rises which limits the amount of higher frequencies illuminating the edges just as a waveguide has the same effect by keeping the sound away from the edges. There is still diffraction but whether it causes an audible problem is more strongly debated, but there is good reason to support why it would be less of an issue in a speaker like the ones you are proposing.
Having dimensions that are multiples of each other cause an effect to be more pronounced just as a cube is a bad shape from a modal point of view.
Unless you make the cabinet resemble a pipe, the internal modes are easily controlled with absorbent material, you can put the absorbent halfway up the cabinet to have the same effect as having the driver halfway up the cabinet for the same reason.
As mark said above the modes in the room will be a real problem and you gain much more by dealing with those properly than you will from manipulating the cabinet shape.
After I took a good look at cost and availability, while trying to keep the look of the Calpamos baffle, I think I'll have to go with:
Faital pro 15pr400 (€125,- each)
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101060100Faital pro HF108R (€100,- each)
https://faitalpro.com/en/products/HF_Drivers/product_details/index.php?id=502010175Celestion H1 9040P (€16,- each)
https://celestion.com/product/h1-9040p/
Any obvious or not so obvious mismatches?
I've looked for some wood in my wood pile, although not as big as my cardboard pile, and found some MDF & plywood sheet of 18mm. I'm not not sure if it's representative stiffness-wise, but it at least gives me a chance to practice and decide on the bracing.
As one might have noticed, I'm not good at just copying design
Faital pro 15pr400 (€125,- each)
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101060100Faital pro HF108R (€100,- each)
https://faitalpro.com/en/products/HF_Drivers/product_details/index.php?id=502010175Celestion H1 9040P (€16,- each)
https://celestion.com/product/h1-9040p/
Any obvious or not so obvious mismatches?
I've looked for some wood in my wood pile, although not as big as my cardboard pile, and found some MDF & plywood sheet of 18mm. I'm not not sure if it's representative stiffness-wise, but it at least gives me a chance to practice and decide on the bracing.
As one might have noticed, I'm not good at just copying design
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After I took a good look at cost and availability, while trying to keep the look of the Calpamos baffle, I think I'll have to go with:
Faital pro 15pr400 (€125,- each)
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101060100Faital pro HF108R (€100,- each)
https://faitalpro.com/en/products/HF_Drivers/product_details/index.php?id=502010175Celestion H1 9040P (€16,- each)
https://celestion.com/product/h1-9040p/
Any obvious or not so obvious mismatches?
I've looked for some wood in my wood pile, although not as big as my cardboard pile, and found some MDF & plywood sheet of 18mm. I'm not not sure if it's representative stiffness-wise, but it at least gives me a chance to practice and decide on the bracing.
As one might have noticed, I'm not good at just copying design
Wow, crossing the atlantic really changes prices. If the euro is $1.30, in Ohio the 15PR400 is E209 and the HF108r is E142. (free freight over $100 order). By contrast the aluminum frame 500w Eminence kappa-pro15A is E130 and the horn driver Eminence ASD1001b 2 bolt is E30. With more watts the 2 bolt 1" Eminence PSD2013-8 is E69.
I imagine you can get a 15" + 1" horn driver +-3 db on axis, but I have my doubts about 45 degree angle -3b. 15" beam above the wavelength of the driver width. Whereas with a 1.4" horn driver 70 W you can cross at 1200 hz (300 watt rating) or 800 hz (175 w rating) and let the horn do the wide angle response in the voice range. Eminence PSD3006-8 2 bolt is E165 and Peavey RX22 screw on driver is E123. I own the Peaveys and am very happy with the sound even walking around the room. Downside, RX22 doesn't do 17.5-20 khz, but I can't hear that anyway. My hearing is tested okay to 14 khz.
I imagine you can get a 15" + 1" horn driver +-3 db on axis, but I have my doubts about 45 degree angle -3b. 15" beam above the wavelength of the driver width. Whereas with a 1.4" horn driver 70 W you can cross at 1200 hz (300 watt rating) or 800 hz (175 w rating) and let the horn do the wide angle response in the voice range. Eminence PSD3006-8 2 bolt is E165 and Peavey RX22 screw on driver is E123. I own the Peaveys and am very happy with the sound even walking around the room. Downside, RX22 doesn't do 17.5-20 khz, but I can't hear that anyway. My hearing is tested okay to 14 khz.
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Good evening Tom,
noted that you were looking for a 1.4" horn.
I have a (new) pair of Beyma TD365 (https://www.beyma.com/en/products/c/horns/1TD365/bocina-td-365/ ) doing nothing here as i use only the drivers and not these horns.
Maybe these can be of use to you ? Just let me know. These horns are metal (gegoten aluminium) and no funny plastic.
Looking at your name i guess you're from the Netherlands; this should make things easier as i'm from the same country (Elst; near Arnheim).
If interested just let me know.
I combined these with a 12" Supravox midbass in order to have a ridicilous efficiënt 2 way system.
Regards, Reinout
noted that you were looking for a 1.4" horn.
I have a (new) pair of Beyma TD365 (https://www.beyma.com/en/products/c/horns/1TD365/bocina-td-365/ ) doing nothing here as i use only the drivers and not these horns.
Maybe these can be of use to you ? Just let me know. These horns are metal (gegoten aluminium) and no funny plastic.
Looking at your name i guess you're from the Netherlands; this should make things easier as i'm from the same country (Elst; near Arnheim).
If interested just let me know.
I combined these with a 12" Supravox midbass in order to have a ridicilous efficiënt 2 way system.
Regards, Reinout
Attachments
Those prices are actually quite normal. The ones I mentioned are from a second hand site, although the drivers are new. I guess a batch (?) from an auction.
Yes, I'm from the Netherlands. It's not my real name though
. I'm from Den Ham. Arnhem is roughly an hour. I'm not a big fan of the looks of square horns. I'll try it out in freecad to see how it looks.
Is resone
Impedance peak of HF108R is at over 1 kHz. Would it be better to be at lower freq?
Horn is smaller than one in Calpamos.After I took a good look at cost and availability, while trying to keep the look of the Calpamos baffle, I think I'll have to go with:
Faital pro 15pr400 (€125,- each)
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=101060100Faital pro HF108R (€100,- each)
https://faitalpro.com/en/products/HF_Drivers/product_details/index.php?id=502010175Celestion H1 9040P (€16,- each)
https://celestion.com/product/h1-9040p/
Any obvious or not so obvious mismatches?
I've looked for some wood in my wood pile, although not as big as my cardboard pile, and found some MDF & plywood sheet of 18mm. I'm not not sure if it's representative stiffness-wise, but it at least gives me a chance to practice and decide on the bracing.
As one might have noticed, I'm not good at just copying design
Impedance peak of HF108R is at over 1 kHz. Would it be better to be at lower freq?
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Yes, indeed. I've changed my (cardboard) prototypes accordingly
. It is the same horn as in the Asathor though. So I thought it would be ok. The impedance peak indeed is above 1kHz. What is the impact of that impedance peak? The HF144, a 1.4" option, has a lower frequency main impedance peak, but also a smaller one at 2kHz. Would that be a problem? @indianajo mentions his concerns about the higher cross over point...