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Old 5th October 2019, 07:28 PM   #41
mart34 is offline mart34  England
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Photos correct way up
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Old 5th October 2019, 09:12 PM   #42
mart34 is offline mart34  England
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Ok, so looking closely at Bjornos modelling, clearly I should have used some stuffing to eliminate the spikes at around the port resonance. This was an oversight on my part, but lessons learnt! This was a trial for me, and I'm really happy with the results. My floorstanders have useable response down to approx 45Hz, so this design was intended mainly to fill from there down. My "as built" port length was 1.3meters.

Thanks
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Old 5th October 2019, 09:13 PM   #43
mart34 is offline mart34  England
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Ps - I'll look at getting some poly fill in the enclosure - further research to be done!
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Old 12th October 2019, 03:54 PM   #44
mart34 is offline mart34  England
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Put 4 coats of primer on, leaving the top coat for next summer, should give the enclosure time to climatize, possibility for seems to open up, so don't see point in finishing it yet anyway.

All sounding well, really happy with it. When I open it up next year, I'll consider putting acoustic lining on the panel behind the drivers, as I suspect this is contributing to a slightly muddy upper bass - reflections coming through the driver. It's barely noticeable, I'm just being quite picky

Any advice on what type of lining might be suitable? I've seen some eggbox self adhesive foam which might be ok - Eggbox Profile Foam Laminate Panel

Thanks
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Old 25th October 2019, 08:43 PM   #45
mart34 is offline mart34  England
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Measurements with UMIK. Pink Line is natural response with only the AV Amps 60Hz - 24dB/octave LPF. Blue Line is the same but with mild PEQ applied.

Each of the two lines are averages derived from 5 positions (across 3 seats on a sofa), with the mic in the exact same spot for each of the 5 x before and after PEQ measurements.

Martin
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Old 26th October 2019, 12:39 AM   #46
5th element is offline 5th element  United Kingdom
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These have turned out very nice!
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Old 26th October 2019, 03:05 PM   #47
mart34 is offline mart34  England
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Thanks. I'm really happy with it. Here's some more measurements. This time, I took 27 measurements from 9 points across the whole of my corner four seat sofa. These are averages of 9 measurements. I've included the raw measurements too.

Pink Line - 250Hz 24dB/oct LPF.

Blue Line - Above + PEQ

Green Line - Above + 16Hz BW 30dB/oct HPF + 100Hz BW 12dB/oct LPF

I also played a song with 30Hz content, and recorded 116.5dB on the REW meter with UMIK. Really should have done a sweep as well, but headache and neighbours inhibited me. I'll post that another weekend.

Thanks for everyone's help on this forum. Cheers, Martin
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Old 26th October 2019, 05:41 PM   #48
Jag768 is offline Jag768  Netherlands
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Nice looking sub, good work. And good looking in room response for a single sub!
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Old 27th October 2019, 12:11 AM   #49
mart34 is offline mart34  England
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Thanks Jag768, and many thanks for the inspiration along the way.

The reality is I would not have built this without the contributions from diyaudio. This was a learning experience for myself, and I can only hope the record of my design (including its faults), will help others in the future.

Cheers, Martin
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Old 30th October 2019, 10:37 AM   #50
mart34 is offline mart34  England
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Jag768. I forgot to mention - I bought the Minidsp 2x4 HD version. The graphs above show a subsonic filter applied, with what appears to be no peaking. I know this isn't the best method to test, should really be done with electrical measurements directly at the input and output of the minidsp, but I'm guessing any peaking would show up in the green response curve?

Cheers
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