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Reflex Design For Pd.186

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Adam_Iron_Horse View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam_Iron_Horse Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2013 at 7:05pm
Originally posted by rffrecords rffrecords wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:


The LE is not important unless someone is planning to play frequencies above 1 kHz through an 18-inch driver.

 


Sorry, but this isn't true Elliot. A simple A-B comparison in any simulator contradicts your point even for a woofer with a small Le like the 186.
Furthermore the rise of inductance with diminishing frequency is a very well known source of descrepancy between basic models and real life in numerous subwoofer prototypes. And this statement is no top secret. You can study beyma's manuals (only company to my knowedge which gives detailed inductance vs frequency plots) if you don't believe me.


But enough with the theoretical inductance debate.
On with the "my subwoofers lack punch, do I need kick bins?" debate.


Adam, your proposed design is fine. I agree with Elliot Thompson. It really is fine.
If fine is fine with you, then go ahead and build it as you say. 200Ltrs.
If you own kick bins or lower extension more important to you than efficiency/distortion and transient response this discussion should have already ended. If you lengthen the port it will take more volume in the cab and net volume will drop below 200Ltrs anyway. But not enough for my liking.


But I would definetely be tempted to gain 0.5dB by moving the -3 point to 36hz (with 160Ltrs) or even better gain 0.8dB and move it to 36.5Hz (with 154Ltrs) and let them kick hard.
Sure 0.5 or 0.8dB sound small to my ears, too when adjusting a level or EQ pot, but not when talking about true/real cabinet gain/efficiency which I can get for free and even save on some wood. All in all if my pocket or wallet had ears 0.8 dB wouldn't sound small to them at all.


Adam, don't forget to check port resonances in comparison to your crossover point if your port(s) are coming out longer than 12 inches.


To answer your question I don't own kick bins.

I should probably explain, we play DnB, Garage, Dubstep (old bass heavy stuff), House, (pretty much a real mix of music) with a pair of x12s on top.

But pretty much I want a good all round bin that kicks and gets decent low extension, at the moment with the g-sub it sounds okay but as Iv mentioned the size and the fact its a double is the problem. (Our regular venue has a lot of stairs). But its came to the time when we can afford another sub (or pair in this case) so were wanting to build 4 single 18s that would suit the pd.186

At the moment the high pass on our sub is set around 39Hz which seems to be more than enough low extension but more is always welcome but I think Id prefer a nice Kick.

Is the port resonance the port gain in WinISD?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2013 at 7:37pm
Originally posted by Adam_Iron_Horse Adam_Iron_Horse wrote:



Problem is I can't find the sub 18 plan no longer... should of taken a copy of it when it was still on the website..

Do you think thatd be the best option of reflex for 186?




Is a proven design that works for many drivers unmodified.

Some say 2x of these outperforms 1x Gsub.


Edited by levyte357- - 30 April 2013 at 7:42pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam_Iron_Horse Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2013 at 7:45pm
Much appreciated, I know of a local guy that has a pair of these may see if i can get hold of them to have a listen to them before I go and build anything...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam_Iron_Horse Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2013 at 7:48pm
Saying that though still welcome to other suggestions...

Just wanna get a design Ill be happy with all round and then can just continue expanding...
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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: 30 April 2013 at 7:51pm

Originally posted by rffrecords rffrecords wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:


The LE is not important unless someone is planning to play frequencies above 1 kHz through an 18-inch driver.

 


Sorry, but this isn't true Elliot. A simple A-B comparison in any simulator contradicts your point even for a woofer with a small Le like the 186.
Furthermore the rise of inductance with diminishing frequency is a very well known source of descrepancy between basic models and real life in numerous subwoofer prototypes. And this statement is no top secret. You can study beyma's manuals (only company to my knowedge which gives detailed inductance vs frequency plots) if you don't believe me.




The majority uses an electronic crossover on their 18-inch drivers. It is common to use a starting point on the crossover anywhere from 80 - 100 Hz for an 18-inch reflex cabinet. How is the Le going to play a factor when the electronic crossover determines the starting point of the frequency sent to the woofer considering the Le comes into play above the tuning frequency settings of the crossover?



Best Regards,






Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2013 at 8:06pm
http://www.speakerstore.nl/constructions

They have helpfully mirrored the Sub18 and the rest of the old B&C designs.  There is an 18Sound Kit18 design which is almost identical and probably also suitable.

Personally I prefer shelf ports rather than the round ports of the old Fane Design so I would go Sub18 or similar.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 30 April 2013 at 8:20pm
Originally posted by Elliot Thompson Elliot Thompson wrote:

The majority uses an electronic crossover on their 18-inch drivers. It is common to use a starting point on the crossover anywhere from 80 - 100 Hz for an 18-inch reflex cabinet. How is the Le going to play a factor when the electronic crossover determines the starting point of the frequency sent to the woofer considering the Le comes into play above the tuning frequency settings of the crossover?

Best Regards, 
 
Below are the curves for the PD186 in 200l tuned to 35Hz, the Yellow one with Le = 0 and the Blue with it set to match the impedance at 1000Hz to the value on the spec sheet, ie 16Ohms.
Although no-one's really going to use the driver up at 1kHz, there is still a difference of over 1dB @ 100Hz, not a disaster but we might as well model as accurately as we can when the tools are freely available. In particular, if you try to get a properly smooth crossover from subs to the next bandpass up that difference in level and the shape of the response in the low mid range will throw off the alignment to some extent.
I've used 750W to model this, and interestingly the peakier response above Fb also results in more excursion around 50Hz when modelled without accounting for Le as well.
 
Regards,
David.
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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: 01 May 2013 at 2:09am

Originally posted by DMorison DMorison wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:

The majority uses an electronic crossover on their 18-inch drivers. It is common to use a starting point on the crossover anywhere from 80 - 100 Hz for an 18-inch reflex cabinet. How is the Le going to play a factor when the electronic crossover determines the starting point of the frequency sent to the woofer considering the Le comes into play above the tuning frequency settings of the crossover?

Best Regards, 

 
Below are the curves for the PD186 in 200l tuned to 35Hz, the Yellow one with Le = 0 and the Blue with it set to match the impedance at 1000Hz to the value on the spec sheet, ie 16Ohms.
Although no-one's really going to use the driver up at 1kHz, there is still a difference of over 1dB @ 100Hz, not a disaster but we might as well model as accurately as we can when the tools are freely available. In particular, if you try to get a properly smooth crossover from subs to the next bandpass up that difference in level and the shape of the response in the low mid range will throw off the alignment to some extent.
I've used 750W to model this, and interestingly the peakier response above Fb also results in more excursion around 50Hz when modelled without accounting for Le as well.
 
Regards,
David.


A +1 dB gain is not going to mean anything for bass. It takes +3 dB change for the average person to notice a difference. A 1 dB differential is like comparing a 100-watt amplifier to a 125-watt amplifier.

If you want something accurate it would be best to literally measure the frequency response of the cabinet using measuring software & a microphone. You will also need to measure the TS Parameters of the driver in question. WinISD, Bassbox Pro in addition to Horn Response are simulators.

Best Regards,
Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rffrecords Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2013 at 2:50pm
Originally posted by Adam_Iron_Horse Adam_Iron_Horse wrote:

To answer your question I don't own kick bins.

I should probably explain, we play DnB, Garage, Dubstep (old bass heavy stuff), House, (pretty much a real mix of music) with a pair of x12s on top.

But pretty much I want a good all round bin that kicks and gets decent low extension, at the moment with the g-sub it sounds okay but as Iv mentioned the size and the fact its a double is the problem. (Our regular venue has a lot of stairs). But its came to the time when we can afford another sub (or pair in this case) so were wanting to build 4 single 18s that would suit the pd.186

At the moment the high pass on our sub is set around 39Hz which seems to be more than enough low extension but more is always welcome but I think Id prefer a nice Kick.

Is the port resonance the port gain in WinISD?



No. You can find the port resonace in Winsd in the third tab of the project window which has the title "vents".
Actually what winsd calls the 1rst resonance is the second one. The first one sits one octave below the second one (half the frequency) and is usually the most severe.


I did some calculations on the Gsub plan. Total internal volume is 330 Ltrs. Subtraction of the port and the braces leaves it with 300.9 Ltrs. Still one has to subtract the volume occupied by the woofers to come down to the net internall volume. I don't know this volume because I am missing the info on the diameter and the depth of the magnet. Anybody that can measure them let me know. From experience with 18 inch woofers the net internall volume of the G Sub must be between 290-295 Ltrs.
So half a G sub uses 145-147.5 Ltrs.


Adam, if you find that the G Sub suits your ears and your program very well and if you changed a thing you'd trade a tad of subbass for kick, then stay away of 200 or 185 Ltr boxes and use no more than 147.5 Ltrs.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adam_Iron_Horse Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2013 at 4:10pm
Originally posted by rffrecords rffrecords wrote:


Originally posted by Adam_Iron_Horse Adam_Iron_Horse wrote:

To answer your question I don't own kick bins.

I
should probably explain, we play DnB, Garage, Dubstep (old bass heavy
stuff), House, (pretty much a real mix of music) with a pair of x12s on
top.

But pretty much I want a good all round bin that kicks and
gets decent low extension, at the moment with the g-sub it sounds okay
but as Iv mentioned the size and the fact its a double is the problem.
(Our regular venue has a lot of stairs). But its came to the time when
we can afford another sub (or pair in this case) so were wanting to
build 4 single 18s that would suit the pd.186

At the moment the
high pass on our sub is set around 39Hz which seems to be more than
enough low extension but more is always welcome but I think Id prefer a
nice Kick.

Is the port resonance the port gain in WinISD?






No. You can find the port resonace in Winsd in the third tab of the project window which has the title "vents".

Actually what winsd calls the 1rst resonance is the second one. The
first one sits one octave below the second one (half the frequency) and
is usually the most severe.





I did some calculations on the Gsub plan. Total internal volume is 330
Ltrs. Subtraction of the port and the braces leaves it with 300.9 Ltrs.
Still one has to subtract the volume occupied by the woofers to come
down to the net internall volume. I don't know this volume because I am
missing the info on the diameter and the depth of the magnet. Anybody
that can measure them let me know. From experience with 18 inch woofers
the net internall volume of the G Sub must be between 290-295 Ltrs.

So half a G sub uses 145-147.5 Ltrs.





Adam, if you find that the G Sub suits your ears and your program very
well and if you changed a thing you'd trade a tad of subbass for kick,
then stay away of 200 or 185 Ltr boxes and use no more than 147.5 Ltrs.



Okay thanks for that...

A Half G-sub kinda size would be nice for us to transport and store really as well.

The only thing is I do feel the g-sub a bit lacking in kick and low extension maybe a little bit.
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