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Multi-Way Conventional loudspeakers with crossovers

Notch filter at x'over freq. of woofer?
Notch filter at x'over freq. of woofer?
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Old 21st August 2006, 02:57 PM   #11
infinia is offline infinia  United States
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If you choose a simple first/second order crossover for this woofer (not too great LF response here) then a 3-way is better suited. I can garantee at least 20dB off axis response for this driver at 2.5 KHz, so a high order LPF only as high as 1.8KHz, maybe lower would be the sensible aproach for a 2-way. (Hint look at Jon Marsh's designs for a RS180, the one he uses a 3rd order eliptical/Cauer at 1.8KHz) The response of the RS180 (metal cone) is similar to your driver.
A 1st order crossover approach is known for use on well behaved wideband drivers ala Dynaudio and Morel, unlike this driver.
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Old 21st August 2006, 03:01 PM   #12
tinitus is offline tinitus  Europe
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resistor across coil, well you can say it looks like a series notch, with out the C - R should be around 15 to 35 ohm

Its ok to use in a "every day workhorse"
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Old 22nd August 2006, 01:28 PM   #13
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by infinia
...I can garantee at least 20dB off axis response for this driver at 2.5 KHz, so a high order LPF only as high as 1.8KHz, maybe lower would be the sensible aproach for a 2-way. (Hint look at Jon Marsh's designs for a RS180, the one he uses a 3rd order eliptical/Cauer at 1.8KHz) The response of the RS180 (metal cone) is similar to your driver.
A 1st order crossover approach is known for use on well behaved wideband drivers ala Dynaudio and Morel, unlike this driver.

Hmmm......

It would help if you actually knew what you are talking about.
This is not the first time that you given apparently sensible
advice based on a set of premises that are simply not correct.

I do wish you'd stop pretending you know more than you actually do.

/sreten.
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Old 22nd August 2006, 01:36 PM   #14
pinkmouse is offline pinkmouse  Europe
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Notch filter at x'over freq. of woofer?


Sreten, stop getting personal. Attack theories, not people.
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Old 22nd August 2006, 03:10 PM   #15
grantnsw is offline grantnsw  Australia
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Hi!
I'd like to thank ALL respondents for your very helpful replies!
Unfortunately, my knowledge, at this stage can not fully
comprehend all your replies. But I do thank ALL off you sincerely.

I have the '97 'cookbook' - can anyone recommend a more
comprehensive text or website, as I have spent eons searching
this wonderful resource for some basic definitions, like BSC,
which I presume is baffle step compensation.

I have dozens of questions, but I need to study before I could
make a sensible reply.
Thanks to all of you, most graciously, and respectfully, Grant
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Old 22nd August 2006, 03:44 PM   #16
grantnsw is offline grantnsw  Australia
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Hello again sreten and thank you kindly for your considered reply.

I am embarrassed to ask such a probably stupid question but,
(as I haven't found the definitive thread yet) is baffle step defined by
the horizontal displacement of drivers on the baffle, i.e. the tweeter
should be mounted several inches *behind* the woofer,(hence slanted baffles)
or does it mean the distance between the drivers 'frame' and the edge of the
enclosure? and...
Full/partial Zobelling? I would have assumed full was required to get a
flat impedance curve (after resonance)?
Diffraction ripple - will also have to put that on my 'study list' but I assume
similar to 'fluid (water) waves diffracting around an obstruction'!
Yes! I am planning to put these in a sealed box.(but MLTWQT? I'm lost, Lol!)
Thanks again, very best wishes, Grant
(sorry for delay in posting)
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Old 22nd August 2006, 04:40 PM   #17
infinia is offline infinia  United States
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Quote:
Originally posted by sreten



Hmmm......

It would help if you actually knew what you are talking about.
This is not the first time that you given apparently sensible
advice based on a set of premises that are simply not correct.

I do wish you'd stop pretending you know more than you actually do.

/sreten.

Hmmmm...Some weird dynamic going on here. Sreten why do I deserve a tirad like this? You should look to your own posts, and put in more quality of instead of quantity. I am prepared to defend myself from any technical argument you can muster. Sreten with a response like this, you have just proven you are not a gentleman by any means.
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Old 22nd August 2006, 06:08 PM   #18
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by grantnsw
Hello again sreten and thank you kindly for your considered reply.

I am embarrassed to ask such a probably stupid question but,
(as I haven't found the definitive thread yet) is baffle step defined by
the horizontal displacement of drivers on the baffle, i.e. the tweeter
should be mounted several inches *behind* the woofer,(hence slanted baffles)
or does it mean the distance between the drivers 'frame' and the edge of the
enclosure? and...
Full/partial Zobelling? I would have assumed full was required to get a
flat impedance curve (after resonance)?
Diffraction ripple - will also have to put that on my 'study list' but I assume
similar to 'fluid (water) waves diffracting around an obstruction'!
Yes! I am planning to put these in a sealed box.(but MLTWQT? I'm lost, Lol!)
Thanks again, very best wishes, Grant
(sorry for delay in posting)

Hi,

BSC you'll have to search on - but its not horizontal alignment.
Related to BSC it has ripples it is not a smooth progression.
BSC is caused by diffraction, the difraction has ripples.
Start here : http://sound.westhost.com/bafflestep.htm

Many speaker designs do not zobel the bass driver. Full is required
for flat impedance, but partial can be used for flatter impedance
(but not flat) and to manipulate response, phase + impedance.
There is a whole range of possibilities for the series L and parallel
C (with / without an R in series with C) that can be manipulated
between 1st order with Zobel and a second order c/o.

MLTQWT (not mltwqt) is mass loaded tapered quarter wave tube,
a variation of TL's and TQWTs,
see : http://www.quarter-wave.com/
also see http://www.t-linespeakers.org/

Sealed box loading is fairly simple but as Fs is not particularly
low you would need to do something for genuine deep bass.

At this point I must say you cannot base a design on a published
response graph unless you can absolutely trust it. Basing the c/o
design on interacting with the response of the driver is asking
for trouble if the drivers response is not measured and confirmed.

You really should measure the driver, in fact, you need to.
If you can't you have to ask yourself what is the point of
what your trying to do ?

Perhaps you'd be better off simply defining what it is is you
ideally want and finding an existing design to suit, then at
least it wouild be worth all the building effort.

Checkout http://www.zaphaudio.com/ for the speaker
design process , deals with BSC and models diffraction.

/sreten.
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Old 23rd August 2006, 04:14 AM   #19
PeteMcK is offline PeteMcK
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Grant,

I've used a couple similar models to this (jaycar with Carbon fibre cone, Altronics Poly cone), They are at present working well as woofers in a 3 way system, in 30L vented enclosures.

I've used what's called an 'EBS' alignment, which is when you tune the box lower than recommended - this extends the response lower, but you lose a bit of level. I make this up by turning up the bass tone control a tad - works very well in my system.

You can see how this works by playing with one of the software progs that let you simulate a box design.

But I'm only using them up to around 160Hz.

I'd try the 'xover with a hole in it' approach to see how they sound as a 2 way system, then think about getting a couple of nice mid-woofers to make them 3 way (I'm using the old Peerless 850488s).

Cheers,
Pete McK
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Old 23rd August 2006, 01:36 PM   #20
grantnsw is offline grantnsw  Australia
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Thanks very much again sreten!
I'm reading your helpful links and taking it all in (but it will take a while, I guess).
Thank you for this (and I quote):

"At this point I must say you cannot base a design on a published
response graph unless you can absolutely trust it. Basing the c/o
design on interacting with the response of the driver is asking
for trouble if the drivers response is not measured and confirmed.

You really should measure the driver, in fact, you need to.
If you can't you have to ask yourself what is the point of
what your trying to do ?

Perhaps you'd be better off simply defining what it is is you
ideally want and finding an existing design to suit, then at
least it wouild be worth all the building effort."

I agree entirely! I was initially wondering if these woofers would be even remotely feasible in a 2-way, maybe I didn't state that specifically enough? And if so, asking for some general help which to now has well exceeded any expectations.
The off-axis response, impedance graph and Le for these
drivers is not shown, so it really does make me question the validity of the published data. I think I may have indeed wasted my money on them and that 'all the building effort' would certainly not be warranted especially considering my current scant knowledge and lack of test equipment. It seems that I should 'junk' them and cut my losses, and as you suggest find a suitable (and well received) 'existing design'. Many, many thanks, Grant

(to the other people who have replied in the last few days, also many thanks
I am trying to reply to your posts in turn)
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