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Push-Pull Double 15 Subwoofer Pic

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Posted on August 6, 2010 at 13:18:10
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005



Just completed a new experiment Push-Pull double 15" subwoofer. This is the best sounding subwoofer that I've ever heard after building sub cabinets for 33 yrs. Love it. Les Hudson

 

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I want one, posted on August 19, 2010 at 04:11:46
ssssly
Audiophile

Posts: 35
Joined: January 18, 2002
Are you planning on making plans available? I would be very interested in building this.

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 9, 2010 at 15:14:43
Retsel
Audiophile

Posts: 1060
Joined: April 17, 2000
Is it a transmission line design? What is the length of the vent for the backwave of the driver to where it vents at front-bottom?

Retsel

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 10, 2010 at 08:05:11
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
It may be close to a mass loaded TL but I didn't model it that way. I modeled it as simply a slot ported push-pull box. Les Hudson

 

It should be called a "Push-Push" subwoofer ..., posted on August 7, 2010 at 19:37:59
zobsky
Audiophile

Posts: 559
Location: dallas, tx
Joined: June 11, 2005
with respect to the simultaneous action of both the woofers upon the enclosed air mass.

Good job. Is this for PA , music or HT. What are the efficiency and frequency response specs ?

 

RE: It should be called a "Push-Push" subwoofer ..., posted on August 9, 2010 at 07:28:09
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
At the moment my friend is casting aside his $10,000.00 subwoofer in his theater room for this push-pull double 15. Frequency range 32hz - 400hz. I have to guess on sensitivity about 104db. Les Hudson

 

At that frequency range, posted on August 9, 2010 at 23:41:51
Brian Walsh
Dealer

Posts: 10543
Location: Barrington, Illinois
Joined: December 6, 1999
it should be called a woofer/lower midrange...true subwoofers go down to 20 Hz or lower and don't go above 50 to 80 Hz.

Brian

So much music, so little time!

 

RE: At that frequency range, posted on August 10, 2010 at 07:55:07
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
I'm sure that everyone has a different definition as to what a true subwoofer is. My definition is one that covers as low as all of the source material being played and up to just before it becomes directional. I usually actively cross this sub over at about 75 hz and I have maybe 10,000 songs with no information below 32hz. This subwoofer has the ability to play from 20hz. - 400 hz. but I don't require that. Les Hudson

 

RE: At that frequency range, posted on August 10, 2010 at 08:48:53
Brian Walsh
Dealer

Posts: 10543
Location: Barrington, Illinois
Joined: December 6, 1999
I disagree. Recorded music may not contain anything below 32 Hz except in rare cases, but low bass (below that) is present on many recordings in the form of venue information. An orchestra may not play a single note below 30 or 35 Hz, but the concert hall often conveys more.

One of my clients has electrostatic subwoofers that are flat to 20 Hz, I think 3 dB down at 14 Hz, with usable response to 8 Hz. Another client is considering a pair of Bruce Thigpen's unique rotary subwoofers (http://www.rotarywoofer.com) which are effectively flat to DC. Thigpen's product rolls off substantially above 30 Hz. That is a subwoofer, and for its performance is something of a bargain, in my opinion.

Brian

So much music, so little time!

 

Sealed, posted on August 11, 2010 at 00:30:33
djk
Manufacturer

Posts: 5688
Joined: June 17, 2000
If you want to reproduce hall rumble, just run the PPSL boxes sealed and EQ the low end (like BagEnd).
Not 2 Big 2 Jail

 

No..., posted on August 12, 2010 at 19:11:40
Brian Walsh
Dealer

Posts: 10543
Location: Barrington, Illinois
Joined: December 6, 1999
Why not:
- Much lower sensitivity due to EQ
- I'm a purist. The less stuff in the chain the better. EQ is a lot of stuff. Lots more to be said.
- It does not address LF response, or more correctly the lack thereof, at low volumes.

Brian

So much music, so little time!

 

Fallacy, posted on August 12, 2010 at 22:37:09
djk
Manufacturer

Posts: 5688
Joined: June 17, 2000

"Much lower sensitivity due to EQ"

EQ does not affect sensitivity, box size does.

It makes no sense to build a huge box to have high sensitivity at 8~10hz.

It makes sense to build a medium sized box with high sensitivity above 40hz and EQ it to have output at 8~10hz. Hall effects (room rumble), may be low in frequency, but they are not particularly loud.

"It does not address LF response, or more correctly the lack thereof, at low volumes."

So you want loudness compensation?

"I'm a purist"

OK, if you say so.

"EQ is a lot of stuff"

EQ may be designed into an existing circuit, frequently without needing extra active stages.


Not 2 Big 2 Jail

 

RE: It should be called a "Push-Push" subwoofer ..., posted on August 8, 2010 at 01:26:48
djk
Manufacturer

Posts: 5688
Joined: June 17, 2000
"It should be called a "Push-Push" subwoofer with respect to the simultaneous action of both the woofers upon the enclosed air mass."

But that would also describe a system where both driver faced into the plenum (Linear BassVent), or both drivers faced out of the plenum (EV MTL2).

The term Push-Pull Slot-Loaded (PPSL) was coined to describe the design and differentiate it from other designs that use some of the same ideas. One driver's cone 'pushes' out of its frame, while the other driver's cone 'pulls' into its frame, thus 'push-pull'. The slot loaded describes the mounting of the drivers, to differentiate from 'clam-shell' push pull, drivers on different sides of the box (M&K), or drivers on one side of the box (TAD, EAW, Peavey, etc).

"Good job. Is this for PA , music or HT. What are the efficiency and frequency response specs ? "

I have built PPSL for all the functions you list, and car stereo too. Efficiency and frequency response are a function of the drivers selected, and the box size. PPSL may also be used on sealed, 4th order vented (mine have all been 6th order vented), IB, or dipole (after Linkwitz). Recently, Danley has used some push pull driver mountings in some of his newer tapped horn designs, and Wayne Parham has built a push pull version of a LAB 12 type design.

LF response is controlled by the T/S parameters of the drivers used, and the box size chosen. Upper response is controlled by the plenum response, mainly the depth of the cavity.
Not 2 Big 2 Jail

 

RE: It should be called a "Push-Push" subwoofer ..., posted on August 9, 2010 at 11:59:35
kyle
Audiophile

Posts: 1193
Location: London Ontario
Joined: September 29, 1999
Is there an advantage to having the drivers opposed rather than both facing into the cavity?
Thanks, Kyle.

 

RE: It should be called a "Push-Push" subwoofer ..., posted on August 9, 2010 at 12:34:04
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
yes, big difference. with a push-pull config. the drivers eliminate each others harmonics. Les Hudson

 

Thanks. nt, posted on August 9, 2010 at 12:56:53
kyle
Audiophile

Posts: 1193
Location: London Ontario
Joined: September 29, 1999
.

 

Specs?, posted on August 7, 2010 at 13:23:21
WithTarragon
Audiophile

Posts: 222
Location: New England
Joined: June 29, 2007
Congratulations and I have a couple of questions.

I assume the upper freq range is limited by the plenum (I assume the plenum's volume) and not the drivers. How high up do they go (do you have a 3 or 6 dB down point measured)?

This next question would be speculation, but how high up in freq does the 2nd harmonic cancellation extend to? I assume this is also due to the geometry of the plenum (my guess is the width of the plenum, but that is only a guess).

Thanks

 

Ideal driver parameters for 15" PP and max bandwidth?, posted on August 7, 2010 at 01:08:17
PK
Audiophile

Posts: 524
Joined: April 6, 2001
Hi Les and djk,

Les: Your new subs look truly great - nice woodwork!

Les & djk:

1. What are the ideal driver parameters for PP system with 15" drivers? (specific candidates are welcome!)

2. What is the maximal bandwidth that can be obtained with a PP design without compromise based on two 15" woofers per side?

Thanks a lot!

Best regards
Peter

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 7, 2010 at 00:15:32
Frode
Audiophile

Posts: 146
Joined: March 17, 2002
Can you tell us more about the drivers, volume and tuning?

Frode

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 7, 2010 at 07:43:25
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
I designed the cabinet for the 15" Martin Sound woofers but I actually installed a couple of woofers that I engineered for "Crunch" called Fat Boys that have similar characteristics. 9 cubic ft. with a 1.4 cubic ft. plenum , tuned at 35hz Les Hudson

 

Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 6, 2010 at 19:18:19
eso
Manufacturer

Posts: 7784
Location: Long Beach, CA, USA
Joined: March 15, 2001
Berenek's law...



Have you ever heard a real bass horn?

eso
They were a carnival of American decay on parade, and they had no idea of the atrocity they had inflicted upon themselves. Henry Chinaski

 

The Best speaker I've even heard is the one I just built", posted on August 7, 2010 at 07:59:59
Bass horn do have there place. And its in my listening rooms. They sure are hard to design proper. I feel this is why some give up. Very easy to get them wrong. But when done right near the best in bass. I know large costly much easier to knock out designs like above. I see to many overly small bass horn attempts no wonder they where not enjoyable.

 

RE: The Best speaker I've even heard is the one I just built", posted on August 11, 2010 at 15:41:28
Retsel
Audiophile

Posts: 1060
Joined: April 17, 2000
Basshorns have a their compromises starting with the fact that the long path from the driver to the mouth means that the bass signal is usually delayed relative to the midbass in most systems. Unless if you are willing to live with the compromise, then this usually rules out bass horns. I cannot live with this compromise as the bass sounds confused.

The second drawback of basshorns is that, unless if the basshorns is VERY large/long, then they cannot be subwoofers because the frequency response drops off a cliff at a fairly high frequency (too high for many audiophiles) - they are just woofers.

The third drawback of basshorns is that while they are better than sealed subs and many ported subs, because they are simply high quality sealed subs with a megaphone in front of them, they suffer from some of the same drawbacks as sealed subs (compression and distortion caused by the "box" or compression chamber), although they do so at much higher levels than sealed subs.

Basshorns have a very important place and that is for very large venues where you need big and efficient output. But in audiophile listening rooms, there are better options which don't force you to live with these compromises.

If you have a basshorn and like it good for you. But others have found better options.

Retsel

 

So much wrong info to comment on so I just say happy listening, posted on August 12, 2010 at 06:42:24
nt

 

RE: The Best speaker I've even heard is the one I just built", posted on August 11, 2010 at 16:39:50
Bill Fitzmaurice
Industry Professional

Posts: 4425
Location: New England
Joined: October 20, 2002
"Basshorns have a very important place and that is for very large venues where you need big and efficient output. But in audiophile listening rooms, there are better options which don't force you to live with these compromises."

For an alternate point of view have a look about here:
http://www.avsforum.com/avs-vb/forumdisplay.php?f=155

Both my THT and Tom's DTS-10 have garnered a very loyal following amongst users who are not the least bit undemanding; some might even call them fanatical.

 

RE: Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 7, 2010 at 07:46:55
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
That's funny. I have and have built many bass horns. I will never build a bass horn again and I know others that agree. Les Hudson

 

RE: Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 6, 2010 at 22:38:50
djk
Manufacturer

Posts: 5688
Joined: June 17, 2000
"Have you ever heard a real bass horn?"

Yes, (quite) a few in my time.

The PPSL sounds cleaner, goes deeper, is more compact, and much easier to build.
Not 2 Big 2 Jail

 

RE: Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 7, 2010 at 07:49:47
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
I concure

 

RE: Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 7, 2010 at 00:12:26
Frode
Audiophile

Posts: 146
Joined: March 17, 2002
What would you suggest for the driver linked to below? I've got four of them lying around, and I'm really interested in trying out ppsl.

Frode

 

RE: Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 7, 2010 at 07:57:05
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
This driver might be a good candidate for a Karlson cabinet but not a subwoofer. Les Hudson

 

RE: Or, to paraphrase: " The Best speaker I've even heard is the one I just built", posted on August 7, 2010 at 09:48:23
Frode
Audiophile

Posts: 146
Joined: March 17, 2002
I was thinking more of a midbass solution, not a subwoofer. Cross at maybe 40-50Hz on the lower end and 300-500Hz on the upper. I guess 4 of these in Karlson boxes could work for this purpose.

Frode

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 6, 2010 at 13:39:11
Vinnie
Audiophile

Posts: 2074
Location: North Carolina
Joined: July 17, 2001
Installing the speakers has got to be tricky on that puppy, or does the back panel come off to do that?
Are plans available?

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 6, 2010 at 13:49:00
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
I use a ratcheting T shaped screwdriver. It's pretty easy if the screw holes are piloted before assembly. Sorry no plans yet. Les Hudson

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 6, 2010 at 13:29:37
freddyi
Audiophile

Posts: 2783
Joined: December 6, 2001
way cool Les - DJK must be right (is that guy ever wrong - lol) I've not room for anything that wide
Karlson Evangelist

 

18" ~ 24" ?, posted on August 6, 2010 at 16:04:51
djk
Manufacturer

Posts: 5688
Joined: June 17, 2000
These are 24" wide.

Photobucket

And the basic idea could be made 18" wide (as my original double 15 prototypes were).

PPSL2

Not 2 Big 2 Jail

 

RE: 18" ~ 24" ?, posted on August 6, 2010 at 17:11:03
freddyi
Audiophile

Posts: 2783
Joined: December 6, 2001
besides getting a physical fit of the 2nd woofer, are there any constraints on the cavity size with regards to working well? how much back chamber volume and good vent area is needed for a pair of 15269/1844?

ah I see

Karlson Evangelist

 

RE: 18" ~ 24" ?, posted on August 6, 2010 at 18:31:27
djk
Manufacturer

Posts: 5688
Joined: June 17, 2000
For the 15269/1844, about the smallest that will really work is the 29hz design of mine that you re-posted.

It would have to be about 24W x 30D x 36H, after all the plenum volume, port, and bracing are accounted for.

35hz OK?

The Eminence KappaPro 15LF-2 will work in 18W x 30D x 36H (or could be taller and shallower).
Not 2 Big 2 Jail

 

RE: 18" ~ 24" ?, posted on August 6, 2010 at 18:41:01
freddyi
Audiophile

Posts: 2783
Joined: December 6, 2001
35Hz is fine - I've enuff stuff for a warehouse packed into a little place. - I might have to look for a small but adequate tapped horn which will keep up with the midsize K's and XLS2000 as satellites - that amp sounds decent to my old ears on a Tonian test cd - the Transylvania tube is great
Karlson Evangelist

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 6, 2010 at 13:51:27
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
It's not so big, it's a little bigger that a 2' square. DLK will be proud. Les Hudson

 

RE: Push-Pull Double 15 Subwoofer Pic, posted on August 6, 2010 at 13:52:49
Les Hudson
Manufacturer

Posts: 698
Location: N. Chicago
Joined: June 8, 2005
sorry I meant to say that DJK will be proud. Les Hudson

 

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