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Old 21st November 2010, 06:51 PM   #21
Bigun is offline Bigun  Canada
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Hi,

Well the datasheet for the driver is here http://www.solen.ca/pdf/fountek/fr88ex.pdf and it seems on paper to have quite a range.
I modeled my enclosure (attached) using an on-line calculator from here Loudspeaker enclosure calculating with Thiele Small parameter and I use a box Q that is lower than usual to account for my port design. I use an alignment between a sealed box and ideal ported box, based on a recommendation from Dave at planet10 (I've seen others who also prefer this alignment).
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Old 21st November 2010, 06:53 PM   #22
Bigun is offline Bigun  Canada
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I've updated my drawings with some additional construction notes:
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Old 21st November 2010, 08:44 PM   #23
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Quote:
Originally Posted by Bigun View Post
... and I'm listening to them through my Cellini tube amp.
Crossed over, eh?
Oh my.

These are very nice little speakers and that colour is perfect. Well done Gareth!
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Old 21st November 2010, 09:45 PM   #24
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by MJL21193 View Post
Crossed over, eh?
I'm afraid so

you know what they say, "resistance is ...."
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Last edited by Bigun; 21st November 2010 at 09:48 PM.
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Old 24th November 2010, 09:11 AM   #25
superR is offline superR  Netherlands
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I am building a mini monitor with a FR88EX with allmost have the exact same inner cubic cm^3 (of ft^3 ) and would like to use a BR as well. I calculated that 2.6cm radius 10-11 cm would be "great" considering the size.

Click the image to open in full size.

I have two issues;

Will putting the BR port in the back create problems?
I would like the enclosure to be as "clean" as possible. If I would glue the front, implementing a filter would be hard. What filter have you tried?
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Old 24th November 2010, 10:01 AM   #26
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Hi SuperRRRRR !! By looking at the image seems that :1) the box is deep about 10 cm ,so how would a duct fit either way (front or back )
So putting it on the bottom would be the natural solution ,providing 3 spikes that lift the box at about 2cm.
2)a little sound deadening material inside should (could) be used
3) A filter is not what is needed with a single driver box . Some equalization is possible (usually a coil+Resistor paralleled,in series with the driver)
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Old 24th November 2010, 10:17 AM   #27
superR is offline superR  Netherlands
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You seem to have great "depth-estimation-from-a-photo"! The inner dimensions are 112 mm width* 224 mm height * 92 mm depth.
I might use an elbow for the port or just bend a piece of steel/aluminium pipe. The other option would be using a bit smaller pipe 1.8cm radius which would lead to +/-5 cm length, but would increase airspeed to +/-18m/s.
Damping"wool" is not on the photo, but I have some available.
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Old 24th November 2010, 10:57 AM   #28
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Yes I do ! Metric and eyesight have occupied most part of my life
Elbow duct ? No good ; it adds losses (whatever they might be )
I would not go ending with that little hole that we usually see in plastic-cast low class PC speakers .
A port on the bottom seems the best way ,far better than in the front ,when it is not well executed ,brings to the "mix" all the nasty inside-box medium -frequency resonances ....
BTW Gareth's speakers are nice !
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Old 24th November 2010, 02:05 PM   #29
Bigun is offline Bigun  Canada
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There's a lot of mystique around ports. I think a straight round pipe is going to let the most high freq out of the port - maybe lining the box with felt reduces the amount that reflects around and out of the pipe. A rear firing port should help reduce the amount of hf that finds its way back to the listening position but it could introduce placement issues (e.g. distance to wall). I think downward firing is the best option and it was the first option I considered - I abandoned it only to make construction easier.

The front slot port I've used doesn't seem to allow hf to escape, the bend at the throat of the port helps with this as does the restricted opening to the port (it's an expanding prism shape).
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Old 24th November 2010, 08:53 PM   #30
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Super, you mean diameter, not radius, or ?

A filter can be added later on in a seperate small box. That´s what I did with my Cyburgs Sticks....

Joe
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