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Q100 speaker as surround in sealed small enclosure

Nwickliff

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Dec 3, 2020
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Hello Everyone,

I have two pair of KEF q100's I got for super cheap. They sound great for my surrounds but even better when I plugged the ports. I was wondering for home theater if I could make some pretty tiny sealed boxes to be able to place these tiny things just about anywhere.

Looking at WinISD I'm trying to figure out how small I can go without the speaker sounding enemic. I cross everything to subs around 80hz but can I cross to surrounds higher since I have dual subs, (one in the front and one in the back of the room).

I think the original box is about 8.5 liters and port I think is tuned to around 40hz.

I'm looking at 4.5 liters with no port. Slow roll off starting at around 200hz and 6db down at 90hz. Factoring some boundary gain do you think I'll be ok integrating with subs etc?
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alex-z

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Being 6dB down at 90Hz will make integration with subs tricky. I find using a crossover above 100Hz makes them too location sensitive.

Rather than going with a sealed cabinet, I would just redo the ported cabinet to achieve a flat response to 70Hz. With proper damping and bracing you should be able to heavily reduce the resonances of the stock Q100. You could even create speaker stands with a hollow cavity to contain a sizable port with resonance traps.

https://www.audiosciencereview.com/...-suppression-inspiration-from-technics.13202/

https://techtalk.parts-express.com/...e-plumber-s-delight-indiyana-nanotech-winners

Also, KEF uses a pretty mediocre crossover in the Q100 if my memory is correct. Using steeper filters should offer a minor to moderate improvement in distortion.
 
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Nwickliff

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Being 6dB down at 90Hz will make integration with subs tricky. I find using a crossover above 100Hz makes them too location sensitive.

Rather than going with a sealed cabinet, I would just redo the ported cabinet to achieve a flat response to 70Hz. With proper damping and bracing you should be able to heavily reduce the resonances of the stock Q100. You could even create speaker stands with a hollow cavity to contain a sizable port with resonance traps.

https://www.audiosciencereview.com/...-suppression-inspiration-from-technics.13202/

https://techtalk.parts-express.com/...e-plumber-s-delight-indiyana-nanotech-winners

Also, KEF uses a pretty mediocre crossover in the Q100 if my memory is correct. Using steeper filters should offer a minor to moderate improvement in distortion.

Thanks! Yeah, I was also thinking about going active with Ayima class d amp and not using their crossover at all. I have an extra mini dsp I won’t be using after the rearrangement.

I was just surprised since when looking at subs way back when, sealed needed almost only half the space of their ported brethren, but they too start to drop in frequency earlier but smoother. I’m wondering what room gain might give me as, the localization is something I’m definitely trying to avoid. Speakers will most likely be on shelves against the back wall.
I suppose even if I go ported I can still go smaller. Trying my best for WAF here. I feel lucky I’m able to have two 18” subs in 4cu ft boxes. Trying to add as little speaker as possible that will get the job done.
 

alex-z

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Thanks! Yeah, I was also thinking about going active with Ayima class d amp and not using their crossover at all. I have an extra mini dsp I won’t be using after the rearrangement.

I was just surprised since when looking at subs way back when, sealed needed almost only half the space of their ported brethren, but they too start to drop in frequency earlier but smoother. I’m wondering what room gain might give me as, the localization is something I’m definitely trying to avoid. Speakers will most likely be on shelves against the back wall.
I suppose even if I go ported I can still go smaller. Trying my best for WAF here. I feel lucky I’m able to have two 18” subs in 4cu ft boxes. Trying to add as little speaker as possible that will get the job done.

Going active crossover is definitely a great solution if your AV receiver has pre-out support you can hook up to the miniDSP.

The amount of room gain depends on the placement of the subs, your room dimensions, and even how the room is constructed. Generally you will still need EQ to achieve the same F3 point as a comparable ported design. As a quick example, sealed 12" models generally have a natural F3 around 35-40Hz, room gain can bring that down to around 25Hz.

Localization has nothing to do with room gain. Localization only happens when you use a subwoofer crossover set too high. Usually 80Hz is best, although 100Hz is an acceptable compromise to boost power handling in small woofer designs.

8.5 liters is already reasonably small for a bookshelf speaker. You might be able to achieve 7 liters, but I doubt you can get much smaller without compromising the ability to achieve an F3 point of 70-80Hz. To minimize the physical size you could do a passive radiator or two, takes up less internal volume than a port.
 
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Nwickliff

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Going active crossover is definitely a great solution if your AV receiver has pre-out support you can hook up to the miniDSP.

The amount of room gain depends on the placement of the subs, your room dimensions, and even how the room is constructed. Generally you will still need EQ to achieve the same F3 point as a comparable ported design. As a quick example, sealed 12" models generally have a natural F3 around 35-40Hz, room gain can bring that down to around 25Hz.

Localization has nothing to do with room gain. Localization only happens when you use a subwoofer crossover set too high. Usually 80Hz is best, although 100Hz is an acceptable compromise to boost power handling in small woofer designs.

8.5 liters is already reasonably small for a bookshelf speaker. You might be able to achieve 7 liters, but I doubt you can get much smaller without compromising the ability to achieve an F3 point of 70-80Hz. To minimize the physical size you could do a passive radiator or two, takes up less internal volume than a port.

Sorry I mean boundary gain for the small q100's to get below that 90hz threshold even though the box's anechoic would be only 90-100hz. Passive radiator sounds interesting but easy to screw up I'm sure. Port, I can start long and then shorten to tune if need be.

AVR has pre-outs which I use for the front mains and another mini DSP. I might upgrade both miniDSP to Dirac at some point. I'm super intrigued with fixing both time and frequency and not just my current frequency adjustments. Subs go to separate miniDSP that are time aligned with the mains and each other. Don't need to worry about room gain with those. They are in corners and supply a pretty decent response to abo9ut 18hz in the room.
 
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