MARTELLO enclosure for FR88EX - Page 11 - diyAudio
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Old 19th May 2011, 04:12 AM   #101
Krystan is offline Krystan  Canada
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Hi,

I jumped in and built a pair. They are almost fully assembled with the baffle clamped and sealed with opencell foam for tune-up. So far, the sound is quite good (20h of break-in) when at hear level with a simple BSC filter (2.7ohms/0.39mH for 3dB at 1100Hz). I still have to find something not too ugly to raise them by about 8" because lowering my head as I do presently is not very confortable.

The only problem I have is a nasty resonance around 150Hz (WAG based on tests with Foobar equalizer) when installed on my desk. I tried to raise them a bit (about 2") on some polystyrene blocks I had laying around to lower the reflections on the desk but with no help. I also listened to my desk with a screwdriver and it's not a resonance from the desk.

So I was wondering if it could come from the lining I used since I had no flet:1" dense polyester batting, probably half the density of cotton felt, on all side except brace and baffle... or can it be simply the box liking at the baffle?
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Old 21st May 2011, 01:31 AM   #102
Bigun is offline Bigun  Canada
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I'd suggest the felt lining is most important for the treble (> 5kHz) - preventing sound bouncing around inside the box and back out through the driver. I can't see it affecting frequencies down at 150Hz.

I've no real ideas what could produce a resonance there unless something is off-base in terms of the construction or that clamping of the baffle isn't cutting it somehow. You said it occurs when installed on your desk - does it happen when it's not on your desk but, say, on a hard surface like the kitchen floor ?
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Old 21st May 2011, 01:40 AM   #103
ryuji is offline ryuji  United States
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why is the filter even needed, my speakers have great response at all frequencies as far as i can tell
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Old 22nd May 2011, 12:41 AM   #104
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what's with the new FR89EX? he has a paint coated Cone that calms the peaks?
bigger Xmax and big Magnet!
https://www.madisound.com/store/prod...oducts_id=8824
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Old 26th May 2011, 08:02 PM   #105
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Quote:
Originally Posted by DYNABLASTERTUNERS View Post
what's with the new FR89EX? he has a paint coated Cone that calms the peaks?
bigger Xmax and big Magnet!
https://www.madisound.com/store/prod...oducts_id=8824
It needs a tweet according to the DIYMA crowd, quite a few on there say the same thing after using them.. ie the cheap coating seems to reduce treble performance unlike the cheaper untreated version.
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Old 14th July 2011, 02:53 AM   #106
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My father-in-law built and stained a pair for me. Lined it with open cell foam. These really do sound great!
Click the image to open in full size.

Click the image to open in full size.
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Old 14th July 2011, 03:12 AM   #107
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bobsagat666,

Very nice. What amp are you using?
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Old 14th July 2011, 03:34 PM   #108
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Quote:
Originally Posted by malibujeff View Post
bobsagat666,

Very nice. What amp are you using?


LM1875 Chipamp kit

Completed LM1875 Stereo build
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Old 16th July 2011, 04:36 AM   #109
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I posted pics in another thread, but in case you did not see them here is a pic of my finished Martello's
Attached Images
File Type: jpg Martello speaker 26a.JPG (217.7 KB, 775 views)
File Type: jpg Martello speaker 31a.JPG (264.9 KB, 752 views)
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Old 24th July 2011, 06:25 PM   #110
pabbi1 is offline pabbi1  United States
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That is nice!

I added the notch filter, per an earlier post, and have really come around on it. Originally, it really took some of the sparkle out of acoustic steel string guitar, but has come back with about 100h of burn in. These are now being used with a small tube amp, which is making a great small apartment combo for a friend.
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