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Old 26th November 2007, 06:04 PM   #1
DaveCan is offline DaveCan  Canada
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Smile High efficient subwoofer design

Hi all, I've been very intrigued with Zu Audio products and would like to make a sub like their Mini Method design. http://zuaudio.com/mini-method.asp

The other sub they have is called the Method and there is a good review of it here at 6moons http://6moons.com/audioreviews/zu3/method.html

If anyone has some suggestions on driver's, amp etc that would be great.

The criteria I'm looking for is;

#1 has to be a paper cone driver with high efficiency like the Zu
#2 has to be a sealed design like the Zu

It's not important for me to be able to break any spl records or crack the walls. I want to make a sub like the Zu that is the utmost in sound quality and natural to listen to.. Can it be done? Dave
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Old 26th November 2007, 06:58 PM   #2
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G'day Davecan

Good luck finding any driver that will perform as well as they claim.

Let's look at the numbers:

70L sealed

96dB efficiency @ 20Hz

Dual 15" drivers

Any driver you try in a sealed box of that size will have an efficiency of 74 or 75dB/W/M. That is a FAR CRY from the claimed 96dB figure. If they were right this would be the ONLY sub anyone would buy. It breaks Hoffman's Iron Law. It can even outgun the Danley DTS-20 Tapped horn, if you believe the marketing BS.

I smell fish.

Cheers

William Cowan
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Old 26th November 2007, 07:12 PM   #3
tinitus is offline tinitus  Europe
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A couple of drivers like this 12" SC-1250 will bring you as close as you need to be

http://www.madisound.com/catalog/PDF/SC12NRT.pdf

A similar looking driver like the SBAcoustics 12" - but I dont think its available yet

http://www.madisound.com/catalog/PDF/SC12NRT.pdf

This AurumCantus could be an alternative, but I am unsure of the rated Xmax, whether its 8mm p/p, or 8mm+/- (16mm p/p)

http://www.partsexpress.com/pe/showd...number=296-434


There is a handy trick you could use if you only want one driver pr side or if you need even higher sensitivity - use a subamp with adjustable exstra 6db gain, you may have to build it yourself, either the amp or filter - Anthony Holton has something going on but also SKA can deliver a filter to do this, or use a simple gain module from ESP
The exstra 6db gain means that you may not be able to play insanely loud
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Old 26th November 2007, 07:34 PM   #4
DaveCan is offline DaveCan  Canada
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Thanks William and tinitus. Did you get to read the 6moons review William? I know Zu has been gaining a lot of respect so I'm not sure about the marketing hype but then again I'm not a speaker designer and have little experience..

The only sub box I ever made was way back in the early 90's for two 10'' MTX Blue Thunder subs in a sealed enclosure for a girlfriends car...

I'd love to hear the Zu Definitions but at $11,000 I'd need a big Lotto win to even think about getting those.. Just hoping that I can try to build a sub keeping close to the idea of the Zu mini Method. Looking for a reasonable sized sealed enclosure, paper cone driver(s) and the highest SQ that can be had for reasonable $, and of course the help of good people in the know like you guys!! Dave
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Old 26th November 2007, 07:38 PM   #5
tinitus is offline tinitus  Europe
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So, why do you need this high sensitive sub

Yes, I also believe that ZU is a bit of clever "hype" - but I am sure they are ok, but nothng more - you know, grass doesnt grow on the moon ... yet
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Old 26th November 2007, 07:48 PM   #6
DaveCan is offline DaveCan  Canada
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Quote:
Originally posted by tinitus
So, why do you need this high sensitive sub

Just wanting to get close to the old school way where great sound came from natural paper cones, high efficiency etc ,and everything wasn't about massive x-max, big monster surrounds, giant magnets and mega watts, plus it goes against the norm which I like If I had the room I'd do a horn (a big one) or do a IB set up but for now this is what I'm wanting to try.. It doesn't have to play that loud as I listen at low to medium volumes Dave
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Old 26th November 2007, 08:01 PM   #7
DaveCan is offline DaveCan  Canada
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Could drivers like these be made to play lower than the fs? Eminence at Parts Express have many drivers but I just pulled this one as an example.. http://www.partsexpress.com/pe/pshow...Number=290-593

http://www.partsexpress.com/pe/pshow...number=294-480
Dave
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Old 26th November 2007, 08:26 PM   #8
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G'day again DaveCan

>Did you get to read the 6moons review William?

Any reviewer that doesn't at least question such ridiculous claims is not worth reading, IMHO. Who can the general public turn to for a critique of the technology involved and the engineering applied to a product if they can't turn to the reviewer? The claims made by the manufacturer are outrageous yet the reviewer doesn't even question them. For me, audio is all about the proper application of sound engineering practice. This product is just smoke and mirrors. The product CANNOT work as advertised.

"with 120dB SPLs of non-distorted output claimed possible before THD bares its yellow fangs while your ears have long since fried and your beloved wall art crashed to the floor, its glass covers shattered to smithereens."

Stuff like this makes me laugh. Anyone who has tried knows that it is far harder achieving 120dB at the listening position at any bass frequency than what 6moons would lead you to believe. I have 8 very high quality 12" drivers (Peerless 830847) in my system in around 500 liters of sealed enclosures driven with multi kilowatt amps that can only just achieve this remarkable feat. I wish it were as easy as dropping two 15's into a 70L sealed box and powering them with a 200W amp!

This stuff is a joke in a DIY Subwoofer forum where many of the readers do know better.

To Zu's credit the sensitivity of the subwoofer is not included on their website, or on the PDF spec sheet: http://www.zucable.com/pdf/MethodSpecs.pdf
There is only one obvious lie in that document. It states: "120 dB without distortion" I'd put my money on it that the subwoofer won't achieve this specification across it's specified bandwidth of 20-200Hz.

I'll hop down from my soap box now.....

Cheers

William Cowan
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Old 26th November 2007, 08:40 PM   #9
DaveCan is offline DaveCan  Canada
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Thanks William, I have no idea of what is and isn't correct( especially with complex math) as I said I'm not a speaker builder so your comments really help me..

I built myself a pair of BIB's a year or so ago for the Fostex fe108ez drivers and just love them. Been thinking on moving up to some BIB's for a 6'' driver as a compromise, but I'm afraid I may loose the beautiful mids of the 108's so hence the subwoofer idea... I'd love to do a BIB sub because the bass sounds so realistic and accurate through them but don't have the room etc.. Thanks for your time and help... Dave
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Old 26th November 2007, 08:45 PM   #10
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6moons reviews are POS. Willaim, read it if you want a laugh.

The only subs I've ever heard capable of doing 30Hz at 120dB, low distortion, were my corner loaded LABs.
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