Sonos approach to subwoofer

[Alfredo02]

I was enticed to build a dual opposed subwoofer, with two SB Acoustic 8" SB23MFCL45-8 , at a 150 eur each, and a Hypex Fusion plate 251, since it can take up to 2,2 ohm impedance output, at 350 eur.

Dual speakers I knew (Rhythmic G25HP, PSA S3010, S3611, Paradigm sub,...) have much higher prices, so it was an interesting project. But Sonos released last year their sub mini at 300 eur.

Does it make sense now to do a DIY dual subwoofer project? Or is it anyway to emulate Sonos design, to bring the DIY price down?

Best

Alfredo

 

[Timcognito]

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Theoretically best subwoofer enclosure

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[Alfredo02]

Thanks for your response

Point is that Sonos launching last yéar their mini Subwoofer for 350 euros, it makes almost impossible to do a competitive DIY project in dual opposed subwoofers, since they have risen significantly the bar, particularly in pricing.

Several issues should be addressed in order for a DIY project to become competitive:

- Firstly, it is obvious the size of the driver should be smaller, bringing them down from 8 in to 6 in or lower. Or using qualified brands like Tang Band with their 5.5 inch sub driver, to bring the cost even lower.

- Secondly, the use of high quality amplifiers it is obviously out of the question. Plate amplifiers from brands like Purify, Hipex, IcePower, .. , all are far away in pricing. Would be a solution to use boards based on the TPA 3255 ampllifier? Some are designed specifically for subwoofers , even including phase adjustments and Lin Rayleihgt variable low pass filters. Prices are constrained at 37 eur each, plus 36/48v power supply. But what about quality?

-Third question is more theoretical. Sonos positions their drivers opposed to each other, but a significant distance. This is not a traditional positioning for developing opposed dual subwoofers. Question is if traditional laws still apply. Should they still be at 180° opposed fase. Should them be located at a quarter of a length of their wavelength? Does any other traditional laws should apply? Any new ones?

Thanks for your support. Alfredo

 

[Timcognito]

Thanks for your response

Point is that Sonos launching last yéar their mini Subwoofer for 350 euros, it makes almost impossible to do a competitive DIY project in dual opposed subwoofers, since they have risen significantly the bar, particularly in pricing.

Several issues should be addressed in order for a DIY project to become competitive:

- Firstly, it is obvious the size of the driver should be smaller, bringing them down from 8 in to 6 in or lower. Or using qualified brands like Tang Band with their 5.5 inch sub driver, to bring the cost even lower.

- Secondly, the use of high quality amplifiers it is obviously out of the question. Plate amplifiers from brands like Purify, Hipex, IcePower, .. , all are far away in pricing. Would be a solution to use boards based on the TPA 3255 ampllifier? Some are designed specifically for subwoofers , even including phase adjustments and Lin Rayleihgt variable low pass filters. Prices are constrained at 37 eur each, plus 36/48v power supply. But what about quality?

-Third question is more theoretical. Sonos positions their drivers opposed to each other, but a significant distance. This is not a traditional positioning for developing opposed dual subwoofers. Question is if traditional laws still apply. Should they still be at 180° opposed fase. Should them be located at a quarter of a length of their wavelength? Does any other traditional laws should apply? Any new ones?

Thanks for your support. Alfredo

No doesn't for the money, for the experience, learning and pride, maybe, if like DIY and have the time.

 

[bigjacko]

Firstly, it is obvious the size of the driver should be smaller, bringing them down from 8 in to 6 in or lower. Or using qualified brands like Tang Band with their 5.5 inch sub driver, to bring the cost even lower.

Size not always match price. Grs subs on parts express are quite cheap. They claim to have klippel verified excursion. Although I guess only the motor is verified, not the surround.

- Secondly, the use of high quality amplifiers it is obviously out of the question. Plate amplifiers from brands like Purify, Hipex, IcePower, .. , all are far away in pricing. Would be a solution to use boards based on the TPA 3255 ampllifier? Some are designed specifically for subwoofers , even including phase adjustments and Lin Rayleihgt variable low pass filters. Prices are constrained at 37 eur each, plus 36/48v power supply. But what about quality?

Sonos probably use very low quality amp. It is not that bad since subwoofer driver will produce most of the distortion.

Big companies can make specific amp module for so cheap that we can't match, but tpa3255 nowadays are pretty good. With adau1701 modules for 20 to 30 USD we get DSP too.

Third question is more theoretical. Sonos positions their drivers opposed to each other, but a significant distance. This is not a traditional positioning for developing opposed dual subwoofers. Question is if traditional laws still apply. Should they still be at 180° opposed fase. Should them be located at a quarter of a length of their wavelength? Does any other traditional laws should apply? Any new ones?

Dual opposed means put two drivers in opposite wall and both drivers should face out at the same time. It only cancels out mechanical vibration on the box, it does not reduce distortion of the driver.

If you want to reduce distortion you need to reverse the facing of one driver. By doing that the surround of one driver will neutralize the other surround. The distortion from the surround will get lower. It is not as important as motor distortion because it only affect distortion below resonant frequency of driver.

Remember the GRS sub I talked up there? Take two of them, one driver face out one driver face in, you are probably 90 percent there for good subwoofer.