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Old 8th August 2007, 09:10 AM   #21
DorinD is offline DorinD  Romania
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Tinitus,
Ascendo does some speakers with similar ideea design like yours (4th BP instead of 6th, 3way instead of 4-way), or vice-versa:

http://www.ascendo.de/english/frameH.htm
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Old 8th August 2007, 09:14 AM   #22
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by jamikl

Is there a difference in the performance of the two speakers laid out as shown?
jamikl
Hi,

With the ports only an octave apart there would be some interaction.

If they were say 2 octaves apart, say 25Hz and 100Hz then I would
say the two layouts would perform the same way, though porting
the main box into the high pass box would suppress harmonic
modes of the main box port.

At low frequencies bass response is determined by the main box,
essentially you can ignore the high pass box well below resonance,
but the nearer together the two port frequencies the more interaction
you get.

I do not have a modelling program for the arrangement shown
by Tinitus, but as I understand it 4th order BP and 6th order BP
cannot give better extreme low bass performance then sealed
or vented respectively for the same cabinet volume.

/sreten.
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Old 8th August 2007, 11:16 AM   #23
tinitus is offline tinitus  Europe
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DorinD, nice one !

Sreten explains it perfectly, but I am also pretty sure that although both different design work as 6th order they will sound different
About the low rolloff Sretens chart doesnt show port length
And true, the one showed by me has lower tuning with bigger bach champer and I guess longer port
Sreten points out that this will result in a boombox sound, but I think that it is because he looks at it like a normal BR

But I think it is very different in that, that there is no woofer cone to interfere, making phase problems which I think is the course of boom sound in a BR
In the bandpass you only listen to the port, and in "my" design only one port
With this design you will get the phase problems between the sub port and the midbass driver, like in any other 3way xo

The sub drivers I have selected are double 8ohm voicecoils, so they can be connected in different ways
Wit sub voicecoils in series the sub might be connected directly in paralel with the midbass driver, without any xo
Configured in paralel the sub may be connected in series with the midbass, and in this case I do wonder if the voice induction of the sub driver will result in a highend rolloff on the midbass driver

To make this work, I think it is important to select a sub driver with sensitivity that are a bit lower than the midbass

Yes I know, it may not work at all, but now I may have to try
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Old 8th August 2007, 12:37 PM   #24
tinitus is offline tinitus  Europe
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Oh yes, I still miss information of how much FR is down at calculated cutoff ... is -6db standard, or ....

Does anyone have information about this issue ?

According to Sretens chart it is -6db down at low cutoff, and linear up to upper tuning FR cutoff ?
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Old 8th August 2007, 02:19 PM   #25
sreten is offline sreten  United Kingdom
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Hi,

I'm still not sure what you are trying to do - low Qts BP in a very large
total box size does go deep it seems but port tuning frequencies are
incredibly critical for flat reponse.

With that 8", 6" and tweeter I'd probably go 2.5 way.

/sreten.
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Old 8th August 2007, 06:06 PM   #26
tinitus is offline tinitus  Europe
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Thanks Sreten, I think the purple and yellow graphs match quite nicely ... that could work

What I want to do ... hell, if only I knew

I have thought about which "design", and I reckon that my next speaker should be with highish SPL, with the Legend B102/Hivi RT8II and the 12" woofer, but it gets rather big and a bit exspencive

The small one in your latest sim would be a cheapie, as I have a nice XT19 tweeter which would be a perfect match ... but a bit too similar to the speaker I have now
I am sure it will play very nice at lower levels


Does anyone know how the Qts values change, whether you paralel or series connect the double voice coil of a woofer ?
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Old 8th August 2007, 08:50 PM   #27
tinitus is offline tinitus  Europe
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Ah yes, I see now ... by increasing front volume and maybe longer port, upper FR tuning will lower ... thats kind of slick, and makes better coherense with midbass more possible, right ?
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Old 9th August 2007, 11:58 AM   #28
tinitus is offline tinitus  Europe
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I have decided to make the 6th order sub with the 12", and see where it takes me

It will be made to lay down along the wall
Advantage is that the box "rock" less this way, and it dont it dont take up too much space

For the main speaker I now also consider PHY 8" in dipole or maybe even a line array, time will show
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Old 9th August 2007, 12:35 PM   #29
DorinD is offline DorinD  Romania
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Your focus to the sub and little to the main speakers doesn't look like putting the carriage in front of horses?!
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Old 9th August 2007, 03:01 PM   #30
tinitus is offline tinitus  Europe
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You are right, I think so too

But its to find out if this principle is working properly or not, and if not I wont go further with any of it ... so in some way the sub is the key to the rest
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