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6th Order bandpass build

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deepss View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deepss Quote  Post ReplyReply Direct Link To This Post Posted: 09 December 2009 at 10:00pm
  The problem we were having at 37Hz before,did turn out to be the building we were in. luckily!
 
  The winisd plots have an input power of 1000w.
 
cone excursion
 
 
Rear port velocity
 
Front port velocity
 
Impedance
 
 
 
And this is what was recorded outside today:
 
 
 
 
As of yet,I dont have a total grasp of all the above plots,its still a learning curve,but, Kieran (doober) was with me today to help out,so any questions I cant answer,I'm going to shamefully shove his way!!
 
   I dont have heaps of experience when it come to listening to various types of cabs/designs etc,but,I was really happy with how this sounded........which is nice!
 
Cheers
 
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MarjanM View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2009 at 9:27am
Is this a true 1m sensitivity?
With a calibrated microphone?

If it is, then it is not much better than a simple double 18 BR box. Not better at all.
Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713
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doober View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doober Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2009 at 4:30pm
The measured frequency response plot is not calibrated and is not at 1m. The purpose of it was to check smoothness of response in an open space, as previous measurements indoors showed a huge dip around 37hz.

The plot may have looked even flatter if it had been done with a reasonable microphone. Unfortunately I didn't realise I had no phantom power for the measurement mic until we had dragged a huge speaker into the middle of a muddy field. We ended up using the output from my cheap spl meter to do the plot. This meter only has A or C weighting available. C weighting was used for that plot, which may explain why the line drops off at around 3db/octave as the frequency lowers.

We may well have another go at measuring it next time there is a dry day without too much wind, and I'll use a flatter mic next time. I can't do accurate 1w/1m measurements due to not having a decent spl meter to calibrate the software with, although I hope to be able to do some comparative plots with the same setup in the same location against some other cabs (punishers and various reflex boxes) to establish relative differences in efficiency.

The box certainly sounds good. Being a horn fan and not very experienced with bandpass I was amazed at the attack of this cab, It doesn't sound boomy or one note at all, very clean. And deep.

Kieran
Blahblahblah
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Strange Daze Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2009 at 4:39pm

Very well done.

:)

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james folkes View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote james folkes Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2009 at 10:58pm
fantastic plots, they really tie the project together. it's interesting that the impedance peaks, which were pretty evenly weighted in the model, are even more balanced in real life. the output plot is really, really smooth and demonstrates the cab's whopping great usable range, i too look forward to seeing one done with a flatter mic.

very interesting comments re attack kieran, very interesting. 8th order is supposed to be even better...

james.
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 14 December 2009 at 1:45am
That is a very nice response you have there. If you decide to add an equaliser, you can achieve a flat response from 40 – 100 Hz if you raise the 31.5 Hz slider by 3 dB.

Best Regards,
Elliot Thompson
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deepss View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deepss Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2009 at 10:28pm
Originally posted by Elliot Thompson Elliot Thompson wrote:

That is a very nice response you have there. If you decide to add an equaliser, you can achieve a flat response from 40 – 100 Hz if you raise the 31.5 Hz slider by 3 dB.

Best Regards,
 
OK,were starting to get somewhere with this.
This plot was taken today with a flat response mic.
 
 
We tested a few other cabs just to compare with.
K-bin hybred,
Punishers,
HD215, 
18" bass reflex
and a couple of 'off the shelf' cheepies,(berry 18" and peavey 15")  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 38HzQ2 Quote  Post ReplyReply Direct Link To This Post Posted: 07 September 2011 at 12:33pm
did this project get taken any further? more cabs built?
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deepss View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deepss Quote  Post ReplyReply Direct Link To This Post Posted: 14 September 2011 at 10:05pm
Yep! We just built the 1 (a second is still in flat pack) and its been out and about to back up our bass when we need it. Always a pleasure to listen to but its such a big cab. Really enjoyed going through the whole design process with lots of help from forum members. 
  Working on something new and different at the mo,have sworn Markie and Doober to secrecy but will post when its finishedSmile
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