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Old 22nd March 2006, 05:59 PM   #1
inrank is offline inrank  United Kingdom
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Default Css FR125S Cabinet

hi, i am new to speaker building, i have previously built a pair for an A-Level project but they were rubbish.

i would love to make another pair but somthing that has the voice and imaging of my current Tannoy DC1000's.

so i have started looking at Full Range Drivers and the CSS FR125S in particular.

i would like to design an enclosure that is between 7 and 15 litres and is as efficient a possible and prefably rear ported. i am not too bothered about bass as i have a Tannoy TS8 sub.

my source is a NAD L53 amp/dvd/reciever and i maily listen to classic rock, easy listening, folk, blues.

can anyone help?
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Old 22nd March 2006, 06:12 PM   #2
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I would do a sealed enclosure if you have a sub. 9 Litre sealed will be close to the optimal.
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Old 22nd March 2006, 06:43 PM   #3
inrank is offline inrank  United Kingdom
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just found the RAW 1F at http://quicksitebuilder.cnet.com/wrnch2/rawseries.html
thats the sort of thing im looking for or even a bit bigger.
Click the image to open in full size.
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Old 22nd March 2006, 06:43 PM   #4
inrank is offline inrank  United Kingdom
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is there any reason to go for a sealed?

found these aswell-


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Old 22nd March 2006, 06:45 PM   #5
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inrank, there are many threads here concerning that driver. When you search you'll see what I mean.
planet10 needs your help:
Let's help Ruth and Dave
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Old 22nd March 2006, 06:54 PM   #6
inrank is offline inrank  United Kingdom
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hi thanks, what is a "aperiodic" or "BR" cabinet?

my speakers will be either side of my tv and around 1ft from a rear wall.
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Old 22nd March 2006, 08:29 PM   #7
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Originally posted by inrank
[B]is there any reason to go for a sealed?
Yes. Most people find the bass output of vented FR125S designs to be exaggerated. The simulations show a hump at ~100-150Hz. The FR125 has quite high Qts, so that would be one reason to avoid a vented enclosure. BR = bass reflex = vented.

Other reasons to go with sealed are the lower group delay (=better sound quality) and the higher power handling capacity at lower frequencies.

Aperiodic is basically something between sealed and vented designs. Here's an example:

Read the other threads, there's a lot of info about these.
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Old 22nd March 2006, 08:53 PM   #8
chrisb is offline chrisb  Canada
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FWIW, Dave P10 & I have built / heard more than a few of single driver or simple 2-ways with various combos of WR & FR125's

By far our choice of most musical single driver* cabinet has been the mini-Onken. Depending on system/room matching, this designs allows for damping of the slot ports from slightly aperiodic to almost completely sealed.

Unless you're installing in an existing shelving or display unit, the floor space required for stands for such a mini sized box is no less than a full height floor stander.

*If you've the floor space behind the speaker, a 25liter sealed bipole using a pair of the WR125ST (16ohm) & fill-in tweeter of your choice sounds great - approx dimensions would be 7"x9.75"x36"

Look for a revised drawing of the "bipolar bipoles" on the Planet10 box drawings page.
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Old 22nd March 2006, 09:01 PM   #9
inrank is offline inrank  United Kingdom
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hi, i have seen the Mini-Onken on here and on the web.

how is it easy to make?

ive seen that the bass might need to be toned down for some rooms, do you have any idea what the +-3dB point is?

i prefably want a bookshelf/standmount because i go back and forth between University so a floorstander would not be appropriate.

I currently have a NAD L53 Hifi, will this be ok for them? (2x50w)
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Old 23rd March 2006, 09:58 AM   #10
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Well I would not recommend an Onken, it's harder to build and you can not adjust the tunning frequency (fb) of the vents once you have build it.

With a simple BR design, you will be able to "play" with the vent length to adjust the bass to your room and taste and it can be stuffed too from vented to aperiodic, depending on stuffing amount and density.

I don't know if that's easy to get in the US, but here you can buy telescopic BR ports, so adjusting them is fairly easy, even in the finished box.

IMO the problem with this driver is, that the T/S parameters published are not very reliable. I believe that's why most BR designs are not tunned correctly. If the cabinet is to small and/or the BR port is tunned to higher frequency than the optimum, you will get a hump and a muddy bass.

I'm having the FR125s in a 12 Liter BR, and after weeks of changing the port length and listening, I finally tuned it to ca. 40-45 Hz - from the official TSPs that's way to low and should not work at all, but it does! There is still a slight hump in the upper bass, but placed on stands, well off the wall in my 25 m2 (270 sq-feet) room, the bass and overall sound is pretty good, in a smaller room, closer to the rear wall the ports need some damping though and the bafflestep correction needs some adjustment - but that's normal too.

If I had to do it again, I'd build a even bigger cabinet - say like 16-18 Liters, as this lowers the Q of the system, and use a telescopic port for easy adjustment.

best, LC
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