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Aperiodic boxes for Ciare CH250
Aperiodic boxes for Ciare CH250
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Old 25th September 2006, 10:51 AM   #11
Henkjan is offline Henkjan  Netherlands
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I should dig in my archive for that.... and am not certain on the effect of the variovent on the impedance... could have an impact as well
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Old 25th September 2006, 05:46 PM   #12
planet10 is online now planet10  Canada
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Aperiodic boxes for Ciare CH250
One of the few papers on aperiodic boxes (by Ted Jordan):

http://p10hifi.net/tlinespeakers/TLS...nAperiodic.pdf (4.6 MB)

dave
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Old 25th September 2006, 08:27 PM   #13
foniton is offline foniton  Spain
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Hi everybody.

Lovechild,
thanks for your post. Very interesting design for the Omnes Audio driver. Im also thinking on a much wider than deeper cabinet and I like the idea of holes, but I dont know if I must combine them with some form of foam or similar.

From past experiences with Ciares in open-baffle I know is not easy to get reasonable bass from this drivers. In open baffle (with same panel dimensions) they are a lot more bass-light than the 215 Supravox drivers, for example. So, Im convinced a big box is needed and Im thinking about 100-120 liters. It sounds a bit excessive but with this project I want a big and visceral sound for my Motown, Stax or Trojan albums. Detail and delicacy is needed too, of course, but with a big and cohesive presentation. After years of precise but bass-light monitor speakers I want to indulge myself with a more "high-calorie" speaker for modern music.
Ive seen the MJKs worksheets but I must confess they are too technical for me. Thanks anyway.

Dave,
thanks for the clarification about the impedance jig. Id like to thoroughly examine Ted Jordans article about aperiodic boxes. Its dense and quite technical but very promising.

Nanook,
very interesting articles from World Design. I like the dual chamber with aperiodic loading concept but its too complex for me. At my present home I have minimal wood-working possibilities. Thanks anyway.

Henkjan,
Please, could you explain more the series condensator to smoothen the bass frequency curve?. Im interested. And Im interested too in a passive correction circuit to put before the power amp. Many thanks.

Best Regards.
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Old 26th September 2006, 03:29 AM   #14
Nanook is offline Nanook  Canada
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Default foniton...

not complicated at all. Basically a brace in a larger enclosure with a DIY resistive vent covering it. So a Closed Box, 1 brace, some staples and some dacron or similar(or fibreglass)

Not sure if the CH250s would work though, more of a point to an aperiodic design that does.
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Old 26th September 2006, 09:36 PM   #15
Henkjan is offline Henkjan  Netherlands
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well, the principle of the series condensator is to both smooth out the bump caused by the high Q, and to extend the f3 downward to approx the same as if it were a Q=0.7. this effect is caused by a lowering of the system impedance due to a resonance with the voicecoil.

the general formula for the series condensator is:

Cs = (265000*Qts)/(Re*fs) [uF]

source: Hobby Hifi 1/2006 p.48

this is based on a Qtb=0.9 - 1.0, sa some adjustment might be required for the very high Q of the Ciare.


while digging for this, I came across a design (HH 5/2006) for the Ciare in a closed box, 20 liters with a variovent... and 4 (four) correction RCL's.... and without series C.....
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Old 26th September 2006, 10:57 PM   #16
Nanook is offline Nanook  Canada
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Default Henkjan..

so many ways to skin a cat..

The 20 litre 4 variovent design sounds interesting any links to it?
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Old 27th September 2006, 08:56 AM   #17
Henkjan is offline Henkjan  Netherlands
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http://www.hobbyhifi.de/Archiv/06/05_06/05_06.html

http://www.lautsprechershop.de/hifi/...o_tower_en.htm
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Old 27th September 2006, 02:55 PM   #18
felixx is offline felixx  Romania
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Thx. Henkjan.
I'm in the same situation...but with qts.=0,53---Fs.=52hz..Supravox 215rtf bicone.
In the end I choose a big enclosure with a little port help in MLTL design...still looking.
That's why I ask about series capacitor.
Look another design here and the performance of that enclosure ...maybe it work for my Supra and also for you....
The Manger driver have qts=0,88.
Any thoughts?
http://www.cooltune.ch/index.html
http://www.cooltune.ch/Projects/Menhir01.htm
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Old 27th September 2006, 05:45 PM   #19
foniton is offline foniton  Spain
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Hi everybody.
Nannok and Henkjan, I greatly appreciate your help.

The SEAS drivers employed by World Design (in their dual chamber aperiodic design) are electrically and mechanically quite different to my Ciares, so I presume that a minimal experience with this kind of loading is required to successfully translate the dual chamber concept from one design to another.

More info about multichamber aperiodic boxes...
http://www.northcreekmusic.com/MAPD1.htm

By the way, despite the aperiodic-box potential for bulk saving, in my case a compact box or slimline floorstander is not a priority. Great results can be achieved with compact monitors playing small scale acoustic music but, in my humble opinion, "bigger is better" for amplified music.
Im thinking about 100-120 liters (100hx50wx25d. aprox). I dont have any box calculation software, so this dimensions are purely intuitive. Please, any help on this matter is very welcome.

At this point, and Im just trying to put in order my ideas, some things are reasonably clear about the aperiodically damped loading technique...

- Aperiodic loading reduces the impedance peak and box resonances at Fs.
- Less internal stuffing is needed for aperiodic boxes than for sealed boxes. Bitumen pads can be used for panels resonances.
- Aperiodic ports ("acoustic resistors", "air springs", etc) can be made of many shapes and materials, being fiber-glass or any low-density high-porousity foam the most accesible. Commercial examples are FLOW RESISTANCE VENTS by ScanSpeak...
http://www.partsexpress.com/pe/pshow...number=296-546
and VARIOVENTS by Dynaudio.
Materials, shapes and quantity of aperiodic ports is a question open to experimentation. About location, in the back panel just behind the main or bass driver its a good starting point.

I wonder if could be beneficial using aperiodic ports (or just little
"holes") in other locations (like high pressurized places in the box) and their impact on bass performance.

Best regards.
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Old 27th September 2006, 06:15 PM   #20
Henkjan is offline Henkjan  Netherlands
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yes, I've seen designs where the aperiodic port was a bunch of smal holes in the back of the speaker and then covered with felt, feels like nicer way than 1 big hole that could act as resonator
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