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New Push-Pull 15"

Printed From: Speakerplans.com
Category: Plans
Forum Name: Ported Enclosures
Forum Description: Post all your reflex and bandpass and 'other' boxes with holes in stuff here...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=57536
Printed Date: 23 January 2020 at 1:13pm
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Topic: New Push-Pull 15"
Posted By: Tony Wilkes
Subject: New Push-Pull 15"
Date Posted: 29 September 2011 at 4:59pm
First image of push pull box, B6 loading Fb =38hz  Size 750w x 500h x 550d. Drivers BMS 15S330

Drivers on order, will post full drawings when tested and proven.




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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)



Replies:
Posted By: GekoMusic94
Date Posted: 29 September 2011 at 6:14pm
uuuh! nice ;)

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Posted By: Edd Jordan
Date Posted: 29 September 2011 at 10:06pm
perspective is a bit weird but i draw all my boxes with a pencil. im sure it will sound mint cant wait for some pics. Thumbs Up

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I do a sideline in ply wood wheels.


Posted By: soundchippy
Date Posted: 30 September 2011 at 12:11am
looks really nice!
why the countersinks on the port panel?

what is sim'ed excursion saying on the b6? what are your real world opinions on the same? max input?  why that slot/manifold shape?





Posted By: soundchippy
Date Posted: 30 September 2011 at 12:16am
what vb?
looks about 100L


Posted By: Tony Wilkes
Date Posted: 30 September 2011 at 9:05am
A view showing port layout, port plate is bolted in to allow fine tuning. The CAD program (Varicad) does not do perspective which is why they look strange.

Vb = 95L   Xmax simms at 9mm (55hz) which is fine for that driver.




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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: kevin tyler
Date Posted: 30 September 2011 at 9:53am
looks goodSmile


Posted By: Edd Jordan
Date Posted: 30 September 2011 at 11:55am
Looking tasty Clap got to get hold of bass box pro.

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I do a sideline in ply wood wheels.


Posted By: SamV
Date Posted: 04 October 2011 at 12:50am
Nice :)


Posted By: Steve_B
Date Posted: 04 October 2011 at 9:45am
Tony,

Why the Push-Pull description? From the pics it looks like they should be push-push.


Posted By: Tony Wilkes
Date Posted: 04 October 2011 at 10:35am
Steve, The driver on the right will be magnet out, the reason for the offset configuration is to try to get the centre of mass better for lifting.

Tony

p.s. just realised that you may just be being pedantic Smile


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: mykey-
Date Posted: 04 October 2011 at 12:28pm
nice

similar to DJK's?


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Posted By: Tony Wilkes
Date Posted: 04 October 2011 at 12:34pm
Originally posted by mykey- mykey- wrote:

nice

similar to DJK's?


Exactly, he has convinced me to at least give it a go.


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: soundchippy
Date Posted: 04 October 2011 at 6:54pm
any thought on whether this driver arrangement would yield any benefit to a double bp6?


Posted By: Tony Wilkes
Date Posted: 04 October 2011 at 7:22pm
Different beast altogether, the sole purpose of a BP6 is to make use of the extra gain from the pass band loading. It results in a louder cab than a standard reflex but also comes with a downside.

The cab as shown is optimised for B6 loading which gives good extension in a compact enclosure but requires external processing to achieve this.

The so called Push-Pull loading gives the advantage of lower 2nd and 3rd harmonic distortion which results in very clean bass. Group delay is also very low in this design.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: soundchippy
Date Posted: 04 October 2011 at 7:37pm
i understand that. what i am curious about is whether the push/pull loading and a bp6 design could be married to create the best of both worlds. low distortion/group delay and higher output thanks to bp6 design.

think of it as having the slot area ported making it the front chamber.

i'm not talking about using a b6 alignment.


Posted By: Steve_B
Date Posted: 04 October 2011 at 11:19pm

Tony I just saw push pull and though of an isobaric type come movement rather than push push where the air in the cabinet and V slot is compressed even if one of the drive units is reversed.



Posted By: Tony Wilkes
Date Posted: 05 October 2011 at 7:59am
It confused me at first but it does seem to have become a generic name for them.

Hope you are well mate,

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: geez
Date Posted: 08 January 2012 at 12:44pm
Tony, I've spent some time reading up on these and the B6 alignment for a potential experimental project of my own so this is a really interesting post for me.

How would you do the required processing using a DCX? from what i've read you need +6db of gain at Fb with Q=2. The DCX only gives a Q adjustment on it's bandpass filter. If a potential B6 cab had an Fb of say 35Hz how would you set the low crossover point and an additional filter to correct it to flat?

Cheers
Tom



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You don't always get what you pay for, but you always pay for what you get.


Posted By: neonogin
Date Posted: 05 March 2012 at 4:45am
Looks very similar to the Ohm Pukk 212 / 215 / 218 box if you look inside.

http://www.ohm.co.uk/download/DATASHEET/PUKK-218%20Datasheet.pdf

I wonder if that is B6 loaded too ???


Posted By: Tony Wilkes
Date Posted: 05 March 2012 at 7:24am
Originally posted by neonogin neonogin wrote:

Looks very similar to the Ohm Pukk 212 / 215 / 218 box if you look inside.

http://www.ohm.co.uk/download/DATASHEET/PUKK-218%20Datasheet.pdf

I wonder if that is B6 loaded too ???


Yes AFAIK the Ohms are B6 slot loaded like djk's, they use great drivers as well :)

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Disco Stu
Date Posted: 05 March 2012 at 9:05am
Tony did you say you managed to squeeze 2x15" into 95l? 

Stu


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Sensitivity + Power Handling - Power Compression = Max Output

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Posted By: Tony Wilkes
Date Posted: 05 March 2012 at 2:09pm
Originally posted by Disco Stu Disco Stu wrote:

Tony did you say you managed to squeeze 2x15" into 95l? 

Stu


Yes mate but that's net volume, the total volume of the box is larger because of the chamber. Actual box sizes are 750w x 500h x 550d.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Chaps
Date Posted: 16 April 2012 at 6:07pm
Did this box ever become reality? Smile


Posted By: Sheggy
Date Posted: 16 April 2012 at 7:58pm
+1 I've had my eye on this thread to see what happens


Posted By: overdrive
Date Posted: 16 April 2012 at 8:07pm
I happen to have 2 homeless 15S330 drivers dying for a new housing, will you publish the drawings?


Posted By: jeff generik
Date Posted: 16 April 2012 at 8:22pm
I have 4 fane 15 b 400's lying around do you think they would work in a design like this?


Posted By: Tony Wilkes
Date Posted: 17 April 2012 at 3:39am
Originally posted by overdrive overdrive wrote:

I happen to have 2 homeless 15S330 drivers dying for a new housing, will you publish the drawings?


p.m. me your Email and I will send you the drawing. It will be as a dxf so you will need to load it into a CAD programme like the free Draftsight* to get dimensions but all the info you need is on there. I don't have time at the moment to dimension it up.

Tony

*  http://www.3ds.com/products/draftsight/overview/


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Tony Wilkes
Date Posted: 17 April 2012 at 3:42am
Originally posted by Chaps Chaps wrote:

Did this box ever become reality? Smile



Did a 12" version, but that went commercial Embarrassed

Tony





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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Chaps
Date Posted: 17 April 2012 at 5:31am
Originally posted by Tony Wilkes Tony Wilkes wrote:

Originally posted by Chaps Chaps wrote:

Did this box ever become reality? Smile



Did a 12" version, but that went commercial Embarrassed

Tony




Oh, i see Smile

It's because I now have 4 KappaLite 3015LF in JBell SS15 tapped horns, but i'm not satisfied with the single-box output if you're doing a job with one on each side of the stage. I can centerstack two for a lot better performance, but it isn't that practical for all type og gigs.

So i was looking into trying another kind of box for them. Allways been a fan of simple reflex because of the sound quality and the fact that the cabs can be rather compact. And they work just fine on there own.

Was thinking about a compact cab with a V-baffle similar to this:  http://www.novacoustic.com/english/VS215SUB01.jpg" rel="nofollow - http://www.novacoustic.com/english/VS215SUB01.jpg

But I then started to read more about PPSL enclosures and the benefits from push-pull and thought it sounded interesting, as I just see it as a kind of improved reflex design.

If you are familiar with the 3015LF, do you think it is possible to do something like your design/PPSL with good results? I'm really not into hornsresp, akabak etc., but maybe i should take my time to learn it?


Posted By: overdrive
Date Posted: 17 April 2012 at 11:42am
DXF no problem, but the PM button...where is it?!


Posted By: Tony Wilkes
Date Posted: 17 April 2012 at 11:56am
You need 2 more post's, 10 needed to PM anyone



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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: overdrive
Date Posted: 17 April 2012 at 11:59am
Well that...


Posted By: overdrive
Date Posted: 17 April 2012 at 11:59am
..shouldn't be..


Posted By: overdrive
Date Posted: 17 April 2012 at 12:00pm
..(indeed Tony LOL)


Posted By: Tony Wilkes
Date Posted: 17 April 2012 at 12:00pm
a problem?

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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Timebomb
Date Posted: 17 April 2012 at 1:56pm
Looks good Tony, should have good output in a box not much bigger than a single HD15, i like the idea of keeping the weight in the middle too these things do make a difference. 
I was confused with the term "push pull" too, surely if one is pushing and the other is pulling they will cancel each other out, should really be push push,  or push push pull pull, or isobaric...

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Posted By: Tony Wilkes
Date Posted: 17 April 2012 at 2:18pm
Originally posted by Timebomb Timebomb wrote:

Looks good Tony, should have good output in a box not much bigger than a single HD15, i like the idea of keeping the weight in the middle too these things do make a difference. 
I was confused with the term "push pull" too, surely if one is pushing and the other is pulling they will cancel each other out, should really be push push,  or push push pull pull, or isobaric...


Cheers mate, I was hoping someone would pick up on the reason for the offset :)

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: eltron
Date Posted: 17 April 2012 at 2:19pm
Originally posted by Timebomb Timebomb wrote:

Looks good Tony, should have good output in a box not much bigger than a single HD15, i like the idea of keeping the weight in the middle too these things do make a difference. 
I was confused with the term "push pull" too, surely if one is pushing and the other is pulling they will cancel each other out, should really be push push,  or push push pull pull, or isobaric...


If you think about how the individual motors are working (when the pair is wired correctly i.e. technically out of phase) when the driver mounted with basket in the back chamber pushes the cone outward the other with basket out pulls its cone.

@ Tony
If these are plans you are otherwise willing to share I would happily help with drafting plans from your dxf-model for the good of SP's community. (No personal need for the plans as of yet)


Posted By: Tony Wilkes
Date Posted: 17 April 2012 at 4:40pm
Originally posted by eltron eltron wrote:



@ Tony
If these are plans you are otherwise willing to share I would happily help with drafting plans from your dxf-model for the good of SP's community. (No personal need for the plans as of yet)


Thank you for the offer but I do not want the plans published until they have been built and proven to meet their design targets.

At the moment I just do not have the time to commit to building a pair however I am happy to provide the plans that I have got to folks on the understanding that no plans get published until I am happy that the design performs well.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: eltron
Date Posted: 17 April 2012 at 7:26pm
Yes, that makes perfect sense. Didn't mean to put any pressure on this matter.


Posted By: Tony Wilkes
Date Posted: 03 June 2012 at 3:46am
Quick update, obtained drivers and hopefully should have a box completed in approx 2 weeks. More soon.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Sheggy
Date Posted: 05 June 2012 at 8:00pm
Originally posted by Tony Wilkes Tony Wilkes wrote:

Quick update, obtained drivers and hopefully should have a box completed in approx 2 weeks. More soon.

Tony



Watching carefully


Posted By: smallfishbigpond
Date Posted: 08 December 2012 at 4:10pm
Originally posted by Sheggy Sheggy wrote:

Originally posted by Tony Wilkes Tony Wilkes wrote:

Quick update, obtained drivers and hopefully should have a box completed in approx 2 weeks. More soon.

Tony



Watching carefully

indeed :)


Posted By: Tony Wilkes
Date Posted: 09 December 2012 at 9:44am
Due to the amount of work at present had to put this on the back burner, however after the performance of the Q15 which has a similar alignment and uses the same drivers I will make sure that this is the next box I finish.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Forward Motion SS
Date Posted: 11 December 2012 at 10:54pm
Originally posted by Tony Wilkes Tony Wilkes wrote:

Due to the amount of work at present had to put this on the back burner, however after the performance of the Q15 which has a similar alignment and uses the same drivers I will make sure that this is the next box I finish.

Tony

Thumbs Up


Posted By: unclejam
Date Posted: 22 March 2013 at 2:16am
bump for a beer?


Posted By: Tony Wilkes
Date Posted: 08 July 2013 at 9:20am
Quick update, these are being built by a fellow SP member who has kindly kept me up to date with the progress. Will post his images if he gives permission.

Tony

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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Sheggy
Date Posted: 08 July 2013 at 9:09pm


Posted By: t.geessounds
Date Posted: 09 July 2013 at 4:24pm
nice


Posted By: Oscar
Date Posted: 13 July 2013 at 3:43am
Sorry if I missed it, but why not place the drivers on axis to get the benefit from PPSL?


Posted By: Tony Wilkes
Date Posted: 21 July 2013 at 5:43pm
My thanks to Joost for sending me the images and allowing them to be shown on SP






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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: djeddie
Date Posted: 21 July 2013 at 7:16pm
That is a nice box Tony. And seems smaller in real life than the description!


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Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB


Posted By: Edd Jordan
Date Posted: 21 July 2013 at 8:46pm
That looks tiny bet it needs some welly to get it going. is that a couple of bms15" i spy? 
great work as all ways Tony and great build too Joost! any data yet for us?


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I do a sideline in ply wood wheels.


Posted By: overdrive
Date Posted: 21 July 2013 at 9:50pm
Hi Edd and others,

Indeed a pair of BMS 15S330, like Tony designed it for :) 
Sounds very clean and fast response, exactly like Tony intended.
Working on finding the right EQ for B6 type allignment now together with Tony.

Did some quick measurements with Smaart. Hope to do an impedance measurement soon to validate the Fb.
LPF LR48 150Hz, no EQ:

Best, Joost


Posted By: Edd Jordan
Date Posted: 21 July 2013 at 11:08pm
Man thats tidy for no eq Thumbs Up

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I do a sideline in ply wood wheels.


Posted By: ermita
Date Posted: 22 July 2013 at 12:09am
Originally posted by Edd Jordan Edd Jordan wrote:

Man thats tidy for no eq Thumbs Up

+1 Clap


Posted By: overdrive
Date Posted: 22 July 2013 at 9:30pm
Today I did an impedance measurement to check the Fb and its almost on target, need to tweak just a bit!

Also applied the B6 alignment correction. Unfortuneately Smaart crashed and lost that measurement...Ouch But can tell that with correction, it runs flat till 50Hz then droppes off.

Impedance + phase show Fb ~35Hz(phase=0):



Joost


Posted By: overdrive
Date Posted: 22 July 2013 at 9:47pm
Some pics from this afternoon, some subs can do a lot of damage measuring with pink noize Tongue



25meters away, other side of house: 



Posted By: MarjanM
Date Posted: 22 July 2013 at 11:07pm
Can you measure the boxes without any HPF? That way we can see how low it really goes. It does look to me that the back chamber can do a little bit better under 55Hz. Can you put the mic right on the round port exit so can see where the back chamber is tuned? Front one seems to be spot on where it suppose to be.

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Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713


Posted By: Steve_B
Date Posted: 23 July 2013 at 12:51am
Originally posted by MarjanM MarjanM wrote:

Can you measure the boxes without any HPF? That way we can see how low it really goes. It does look to me that the back chamber can do a little bit better under 55Hz. Can you put the mic right on the round port exit so can see where the back chamber is tuned? Front one seems to be spot on where it suppose to be.

I thought that this was a reflex box with a B6 alignment??? I'm not sure what you mean by the tuning of the rear and front chamber.

If I remember correctly the box is tuned to the same frequency as the drive unit and the box is 4 times Qt^2 times Vas. The box then requires a boost of 6dB at 1 point a bit the resonant frequency, which is also the -3dB point; 38Hz I would presume from the OP.


Posted By: Tony Wilkes
Date Posted: 23 July 2013 at 7:41am
@Steve, correct, it was designed to have an Fb of 38hz.  

I know myself that the only way to get a good fix on this with this order of boxes is through the phase response thru zero which is why Joost has posted the image.

@Joost  The ECM8000 (apologies if I have identified it wrongly) can be quite a bit out at 100hz and below so don't take the results as gospel, assuming that you have not had it calibrated that is.

Tony

Edited for stupidity :)




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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: overdrive
Date Posted: 23 July 2013 at 8:46am
Zoost, thats a new one LOL

@Marjan: the graph shown before was without EQ and HPF, only a LPF @150Hz.

@Tony: Indeed a non-calibrated ECM8000, altough it can have a small offset, it works fine in finding the problem area's and giving an indication of the response. I think no bigger error than 1-2dB will be seen  30-100Hz.

What you suggest on tweaking the ports? 

Joost


 


Posted By: Tony Wilkes
Date Posted: 23 July 2013 at 9:03am
Originally posted by overdrive overdrive wrote:

Zoost, thats a new one LOL

Joost
 

Sorry about that , all corrected now :)

Take 25 mm off the port tubes, calc's show they should be around 300mm long BUT I would take it in stages.

Regards

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: MarjanM
Date Posted: 23 July 2013 at 11:52am
Originally posted by Steve_B Steve_B wrote:

Originally posted by MarjanM MarjanM wrote:

Can you measure the boxes without any HPF? That way we can see how low it really goes. It does look to me that the back chamber can do a little bit better under 55Hz. Can you put the mic right on the round port exit so can see where the back chamber is tuned? Front one seems to be spot on where it suppose to be.

I thought that this was a reflex box with a B6 alignment??? I'm not sure what you mean by the tuning of the rear and front chamber.

If I remember correctly the box is tuned to the same frequency as the drive unit and the box is 4 times Qt^2 times Vas. The box then requires a boost of 6dB at 1 point a bit the resonant frequency, which is also the -3dB point; 38Hz I would presume from the OP.

True, but the clam shelve baffle does act like sort of a chamber. As i suspected the box is probably tuned too low. That is why i asked to take measurements of the port. It will tell the real tuning frequency.


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Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713


Posted By: overdrive
Date Posted: 23 July 2013 at 12:06pm
Marjan, I posted the impedance and fase plots one page back. This tells you all you need to know about the tuning freqs. The port method I also tried but is unaccurate. 




Posted By: Tony Wilkes
Date Posted: 23 July 2013 at 12:09pm
Marjan,  The design is based on my Q15 box and all I have done is put 2 drivers in a PP arrangement to make use of the lower distortion that this gives.

The Q15 Fb is 41 hz and this one is tuned slightly lower at 38hz.

It looks like you can see the effect of the front chamber on the Imp graph at around 200hz.

Regards

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: MarjanM
Date Posted: 23 July 2013 at 1:04pm
Hmm, then why the response drops so rapidly below like 55Hz. I certainly dint expected to see that kind of drop. 

@Steve, you think that the driver will be ok with +6db at 38Hz?


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Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713


Posted By: Tony Wilkes
Date Posted: 23 July 2013 at 1:49pm
Marjan, Max X is at 55hz and is 9mm,  At Fb it is around 4mm at max power (600 per driver)

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: +/-3dB
Date Posted: 23 July 2013 at 2:04pm
Never heard PP or PPSL, but I'm tempted to try one. Can you tell us something about your impressions regarding lower harmonic distortion?

If measurements has been taken, which indicate lower distortion, what is your subjective impression? Do you think it sounds better than a BR with the same drivers?
Is the difference clearly audible at loud volume?




Posted By: Steve_B
Date Posted: 23 July 2013 at 11:28pm
The B6 alignment is supposed to have good control over cone excursion both in and out of the operating bandwidth. It was documented in Thiele’s Loudspeakers in Vented Boxes paper, and Keele wrote a paper on variations of this alignment.

With modern software I don’t see the point in sticking to specific alignments as the programs give full response plots for every possible combination of box volume and tuning.

With regards to using electronic eq to achive the desired response I am all for it. The easiest thing is to give an example.

The plots below are for an Eminence Delta 12LF. As a comparison the pink plot is a BMS 12.

The green plot is the default winisd box. This is 129 litres

Keeping the same tuning, but reducing the box volume to 36 litres gives the blue plot.

Using the above tuning but adding some electronic eq results in the red plot (+8dB at 40Hz and -4dB at 100Hz. Remember this is in a box 3.5 times smaller than the green plot. So what is the catch, because everyone knows you can’t get much bass out of a small box.

Well the next plots show the max SPL. Again the pink plot is the BMS 12” sub speaker in a 36 litre box.

Apart from some loss at the port resonance, the max output is exactly the same for the big and small boxes. If you are after a flat response both boxes will give 114dB down to 40Hz. The BMS puts out a couple of dB more.

Lots of eq probably means lots of phase shift. The next lot of graphs show the group delay. There is not much to choose between them above 40Hz. The red peak is caused by the fact I added a high pass filter to that design.



Posted By: Tony Wilkes
Date Posted: 24 July 2013 at 7:40am
Steve, That is why I usually refer to these boxes as "assisted alignment" as I do not stick exactly to the B6 rules.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: Steve_B
Date Posted: 24 July 2013 at 11:26am
Tony, I didn't think for a minute you did not understand - (well maybe for a couple of seconds Tongue ).

The response was to Marjan asking about the applied boost.

I previous threads some people people seem to have a hard time understanding that you can make a box that on its own is not flat and then correct it electronically. I thought that the example would explain it more clearly.

For PA work, the most useful graph in winisd is the maximum spl. This is the equivalent of the safe operating area familiar to the electronic guys. If your target response fits under the curve you are good to go. Getting a transfer function that is flat down to 30Hz is useless if excursion limitations restrict the output to 100dB between 50H and 85Hz. It is far better to tune the box higher and get the output up where it is generally more useful. If the resultant transfer function requires eq fine.


Posted By: Tony Wilkes
Date Posted: 24 July 2013 at 11:56am
Steve, I know it was not aimed at me, just reinforcing a point to anyone interested. 

In the Q15 design and this double version I played around with the parameters until I got a box with the extension I needed that also maximised the driver in the smallest practical volume.

I also reckon that the tiny boxes also help to cut down on what I term "Box Talk". Should be self explanatory. :)

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: MarjanM
Date Posted: 24 July 2013 at 2:07pm
Just simmed that driver. It is nothing like the 12S330. Asking for a 300+ lit for a double 15 box. Similar box with 12S330 will get you a better low end. 

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Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713


Posted By: Steve_B
Date Posted: 24 July 2013 at 4:47pm
If you are designing a box to be maximally flat with no eq then the BMS 15 does require a volume of 300 litres. The following graph shows such a box plotted in red.


The green plot is for a 150 litre box with a 4dB boost.

The smaller box does suffer slightly at the bottom end when you look at the max spl plots, but don't forget the green plot is in a box half the size of the red plot.


For the live type bands I do, the smaller box would win all the time. I usually run with a 40 - 45Hz HP filter anyway. I doubt you would hear much difference.




Posted By: MarjanM
Date Posted: 24 July 2013 at 6:11pm
I get this all perfectly Steve. Just never really looked at the 15S330, and somehow was thinking it will be a biffed up 12S330, which clearly isnt. That was the confusing thing to me.

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Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713


Posted By: Tony Wilkes
Date Posted: 24 July 2013 at 6:17pm
Marjan, it uses the same motor assembly but obviously a standard surround, I find it a lovely sounding driver that is usable quite high.
 
Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: el_dj
Date Posted: 24 July 2013 at 7:02pm
been following this with interest... gentlemen... looks good..

im a bit of a noob, but can someone point me in the right direction to understand "the problem" with the impedance plot, and how that is related to the tuning. ? and on top of that, why this box does not go lower?

maybe a lot to ask. however i dont mind reading if you can point me to the correct links... whenever i search the subject i mainly get car audio subjects and it is not more ohm's low and what not to do.

thanks. :)


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Old twat, with an interest in light & sound



Posted By: MarjanM
Date Posted: 24 July 2013 at 7:50pm
Steve has already explained it quite well. Since English is not my native language i find it difficult for me to even begin explaining things like this over the forum.

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Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713


Posted By: Steve_B
Date Posted: 24 July 2013 at 8:44pm
With reflex cabinets there is an impedance minimum at the box resonant frequency. It is a useful way to check the tuning of the box. In the plots below I created a box and then changed the tuning from 30 to 40 and then 50Hz.



Posted By: overdrive
Date Posted: 25 July 2013 at 9:21am
Hi Steve, it's also good to post the impedance phase plot. Its the most accurate way to find you tuning freq point(s).


Posted By: overdrive
Date Posted: 28 July 2013 at 4:54pm
Today had some time to start tweaking the Fb. Eventually the 3 ports were shortened by 7cm.

Fb went from 35Hz to 38Hz :) And indeed the front chamber seems to act as a resonance chamber too around 160Hz.

(Green = 38.5cm ports / Pink = 31.5cm ports / Blue = no ports)

Next the freq plots: With assisted B6 alignment F3=~48Hz, F6=~44Hz:

(Pink=no filter/no EQ / Green = LPF LR48@151Hz / Blue = HPF BW12 + PEQ@40Hz-8.7dB-Q=1.8 and LPF LR48@151Hz)

Joost



Posted By: Tony Wilkes
Date Posted: 28 July 2013 at 7:47pm
Joost,  It is actually very close to my measurement of a THAM15 with the applied EQ  :)

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: stevie
Date Posted: 28 July 2013 at 8:15pm
What do you think is the usable upper frequency limit for this design (crossing over to a midrange driver, for example)?


Posted By: Tony Wilkes
Date Posted: 28 July 2013 at 8:24pm
In a normal box that driver sounds OK up to over 500hz but I suspect the front chamber and the angled drivers* will lower this, no idea what that Freq will be. Over to you Joost :) 

Looking at the graph I suspect at least 200 hz

* Causing a nice big phase cancellation dip.

Tony


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www.forteaudio.eu - BMS - db-Mark Processors - Lexon (SAE)


Posted By: overdrive
Date Posted: 28 July 2013 at 9:41pm
Well all i've done so far are measurements and low-level listening so I can't give a proper anwser on that one yet..

Hope to do some testing asap with diffenent kind of music with a more serious amplifier and higher SPL at a more suitable location :)


Posted By: Rojoh
Date Posted: 31 July 2013 at 11:33pm
Usable bandwidth is one thing. PP-coupling is another. Would be fun with impressions of PP vs. "normal". Personally I was convinced when flipping one driver in my JBL 4638-cabinet - 2226H loaded.


Posted By: _djk_
Date Posted: 01 August 2013 at 2:42am
Art Welter took a standard ported dual 12 enclosure (LAB 12 drivers) and ran it up to 400W.
 
Flipping one driver (and connecting it properly) reduced 2nd harmonic distortion by 30dB, 4th harmonic by 20dB.


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djk


Posted By: Art Welter
Date Posted: 08 August 2013 at 9:29pm
Originally posted by _djk_ _djk_ wrote:

Art Welter took a standard ported dual 12 enclosure (LAB 12 drivers) and ran it up to 400W.
 
Flipping one driver (and connecting it properly) reduced 2nd harmonic distortion by 30dB, 4th harmonic by 20dB.

The results of my PP to normal tests were interesting:

http://www.diyaudio.com/forums/subwoofers/191833-push-pull-vs-normal-distortion-compared.html" rel="nofollow - http://www.diyaudio.com/forums/subwoofers/191833-push-pull-vs-normal-distortion-compared.html
Although the second harmonic was reduced at some frequencies, at others it was not, and since the third harmonic sometimes rose higher with PP, overall distortion was not always reduced.

At high power, low frequency, where excursion is the largest contributing factor to distortion, the overall distortion was barely reduced at all in the front loaded Lab 12.
The reversed Lab 12 had a fair amount of noise from it's cooling vent, which was annoying.

Art


Posted By: djtuffer
Date Posted: 13 August 2013 at 9:55pm
I have been playing with a logic systems IS26 cab which is basically a small reflex box with the woofer slot loaded.  Only a single driver so not push pull.  There is output up to about 300hz but it doesn't sound nice to my ears over about 150hz.  That was tested with two different drivers with similar results.


Posted By: bob4
Date Posted: 31 October 2015 at 6:57pm
I found This thread searching for PPSL designs and General info. Sadly since Tony passed away This project seems to have been abandoned unfinished. In his posts Tony stated that he Wanted To Test and prove his design before publishing the Plan, but Never Got To that point. Tony Did share the cad file With a few People however.
 
Is There anyone Around that has the Plan, and Would be Kind enough To share it? If not, I'll do My own version, but it Would be nicee To Try tonys design and continue the discussion onhere.......
 
sry about weird capitalisation, im writing This on My Phone.....
 


Posted By: dlyxover
Date Posted: 31 October 2015 at 7:48pm
try contacting bee on this forum.

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In the Truth there is no news, and in the News there is no truth


Posted By: bob4
Date Posted: 01 November 2015 at 1:30pm
Originally posted by dlyxover dlyxover wrote:

try contacting bee on this forum.


will do that, thanks for the hint!




Posted By: bob4
Date Posted: 10 November 2015 at 11:21am
so no one can help me on this one?


Posted By: sn95
Date Posted: 10 November 2015 at 5:36pm
Look in diy audio forum i have seen some plans ther


Posted By: krazyneil
Date Posted: 10 November 2015 at 8:27pm
i think djk posted a few plans might be worth a pm

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GOD TOLD ME TO DO IT !!!!!


Posted By: pfly
Date Posted: 10 November 2015 at 8:33pm
http://forum.speakerplans.com/2x12-ppsl-anyone_topic55730.html" rel="nofollow - http://forum.speakerplans.com/2x12-ppsl-anyone_topic55730.html


Posted By: bob4
Date Posted: 11 November 2015 at 8:40am
Thank you guys, although I was asking  specifically  for Tony's design which was presented in this thread


Originally posted by pfly pfly wrote:

http://forum.speakerplans.com/2x12-ppsl-anyone_topic55730.html" rel="nofollow - http://forum.speakerplans.com/2x12-ppsl-anyone_topic55730.html


on the other hand, I like the symmetry in your design a lot pfly!


Posted By: kr1sounds
Date Posted: 19 July 2016 at 3:34am
Originally posted by Tony Wilkes Tony Wilkes wrote:

First image of push pull box, B6 loading Fb =38hz  Size 750w x 500h x 550d. Drivers BMS 15S330

Drivers on order, will post full drawings when tested and proven.



anyone got the plans?


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I MAN SERVE SELASSIE CONTINUALLY... NO MATTER WHAT THE WEAK HEART SAY

fostonshfs.webs.com



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