Why are push/pull sub builds not more popular? - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 14Likes
Reply
 
Thread Tools
post #1 of 39 Old 11-30-2018, 08:35 AM - Thread Starter
AVS Forum Special Member
 
legierk's Avatar
 
Join Date: Mar 2007
Location: Elysian Fields, TX
Posts: 1,068
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 169 Post(s)
Liked: 144
Why are push/pull sub builds not more popular?

I have an old sub (cabinet only now) that I built about 20-25 years ago mirroring an M&K design. (I wanted to add a photo of it, but I am at work). I had Kicker 12" drivers in it back then. The cabinet currently resides in the garage in a corner, empty.

I also have an old JBL Control SB5 sub, that has been sitting for many years unused. The last time I used it was maybe 10 years ago or more, and I do remember opening it up and bypassing the internal wiring and passive crossover.

My question is, why are these types of subs not more popular in the DIY market? Is it solely because of the build complexity, or is it more related to performance? Or is it that the sealed/ported/rectangular box is just so easy to build/provides a higher price to performance ratio?

I have wondered what one of these designs would sound like using modern 18" drivers. Would love to know what the sub gurus think. (Also, what about the Sonotube sub designs? They were really popular 2-5 years ago. Now I don't see any new builds. Have they fallen out of fashion?)
legierk is offline  
Sponsored Links
Advertisement
 
post #2 of 39 Old 11-30-2018, 09:36 AM
AVS Forum Special Member
 
michael hurd's Avatar
 
Join Date: Nov 2007
Posts: 3,408
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 635 Post(s)
Liked: 670
Quote:
Originally Posted by legierk View Post
I have an old sub (cabinet only now) that I built about 20-25 years ago mirroring an M&K design. (I wanted to add a photo of it, but I am at work). I had Kicker 12" drivers in it back then. The cabinet currently resides in the garage in a corner, empty.

I also have an old JBL Control SB5 sub, that has been sitting for many years unused. The last time I used it was maybe 10 years ago or more, and I do remember opening it up and bypassing the internal wiring and passive crossover.

My question is, why are these types of subs not more popular in the DIY market? Is it solely because of the build complexity, or is it more related to performance? Or is it that the sealed/ported/rectangular box is just so easy to build/provides a higher price to performance ratio?

I have wondered what one of these designs would sound like using modern 18" drivers. Would love to know what the sub gurus think. (Also, what about the Sonotube sub designs? They were really popular 2-5 years ago. Now I don't see any new builds. Have they fallen out of fashion?)

Modern transducers are many times more linear than historical counterparts which were empirically derived from rudimentary rules of thumb without the advanced finite element analysis, rapid prototyping ability and Klippel analysis before going into production with a design.



Cabinet types like the M&K push pull contain less enclosure volume than a regular rectangular or square enclosure of the same external measurements.
LTD02 and jeno like this.

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
michael hurd is offline  
post #3 of 39 Old 11-30-2018, 10:54 AM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,182
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 643 Post(s)
Liked: 324
Quote:
Originally Posted by michael hurd View Post
Modern transducers are many times more linear than historical counterparts which were empirically derived from rudimentary rules of thumb without the advanced finite element analysis, rapid prototyping ability and Klippel analysis before going into production with a design.


took the words right out of my mouth, and that doesnt happen often.

Theres a company that makes the push/pull cylinder subs that you can stack, crazy output, I cant think of it right now.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
trilkb is offline  
Sponsored Links
Advertisement
 
post #4 of 39 Old 11-30-2018, 12:07 PM
AVS Forum Special Member
 
mtg90's Avatar
 
Join Date: Aug 2011
Location: Millbrook, IL
Posts: 1,944
Mentioned: 581 Post(s)
Tagged: 0 Thread(s)
Quoted: 766 Post(s)
Liked: 1580
Quote:
Originally Posted by trilkb View Post
took the words right out of my mouth, and that doesnt happen often.

Theres a company that makes the push/pull cylinder subs that you can stack, crazy output, I cant think of it right now.
If you are thinking of Bossobass those are dual opposed subwoofers not push pull or isobaric.
mtg90 is offline  
post #5 of 39 Old 11-30-2018, 12:18 PM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,182
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 643 Post(s)
Liked: 324
YUP, Those were what I was thinking about, I think I really just wanted to reply so I could mess with micheal hurds response lol, I got lost at "empirically derived from rudimentary goals"! Plus its been a boring day.
legierk likes this.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
trilkb is offline  
post #6 of 39 Old 11-30-2018, 12:24 PM
AVS Forum Special Member
 
Samps's Avatar
 
Join Date: Feb 2014
Location: Pittsburgh, PA
Posts: 2,729
Mentioned: 50 Post(s)
Tagged: 0 Thread(s)
Quoted: 1220 Post(s)
Liked: 901
While not your typical push pull design, I am curious why we don't see dual sub boxes with one woofer inverted more often. From what I've read, inverting one driver does have some benefits.
Samps is offline  
post #7 of 39 Old 11-30-2018, 12:28 PM
AVS Forum Special Member
 
Join Date: Nov 2014
Location: College Station, Texas
Posts: 2,070
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 993 Post(s)
Liked: 540
Quote:
Originally Posted by trilkb View Post
took the words right out of my mouth, and that doesnt happen often.

Theres a company that makes the push/pull cylinder subs that you can stack, crazy output, I cant think of it right now.
Rythmik has their new G25 dual opposed sub. Released earlier this year.
liffie420 is offline  
post #8 of 39 Old 11-30-2018, 12:35 PM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,182
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 643 Post(s)
Liked: 324
Quote:
Originally Posted by Samps View Post
While not your typical push pull design, I am curious why we don't see dual sub boxes with one woofer inverted more often. From what I've read, inverting one driver does have some benefits.
From my car audio days, all that really does is give the driver more air space since the magnet is not taking up any cuft inside the box, basically no displacement. Dont think it does much for sound/output other then the 1/8 cubic foot or so you gain from box size. You basically just wire one out of phase so they are still "in phase".

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
trilkb is offline  
post #9 of 39 Old 11-30-2018, 12:39 PM
AVS Forum Special Member
 
Samps's Avatar
 
Join Date: Feb 2014
Location: Pittsburgh, PA
Posts: 2,729
Mentioned: 50 Post(s)
Tagged: 0 Thread(s)
Quoted: 1220 Post(s)
Liked: 901
I've read that is reduces nonlinearities between the two drivers and reduces distortion. If a particular motor design has some form of irregularity on its inward stroke, the inverted driver will help cancel that out, and vis versa.
legierk, Trimlock and bebb like this.
Samps is offline  
post #10 of 39 Old 11-30-2018, 02:01 PM - Thread Starter
AVS Forum Special Member
 
legierk's Avatar
 
Join Date: Mar 2007
Location: Elysian Fields, TX
Posts: 1,068
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 169 Post(s)
Liked: 144
From the M&K website:

"Push-Pull Deep Bass
Push-Pull Dual-Driver Configuration M&K’s innovative Push-Pull Dual Driver configuration delivers a major improvement in subwoofer detail and clarity by virtually eliminating even-order harmonic distortion, which produces a boomy and poorly defined bass sound.
In these subwoofers, one driver is mounted conventionally on the cabinet’s front baffle. The second driver, however, is mounted inverted. The front of its cone faces the inside of the cabinet, with the rear of the cone, magnet, and frame facing the outside.
Although both drivers fire into the room in pressure phase (one with the front side of its cone and the other with the rear), they operate mechanically out of phase relative to each other’s magnetic structure. (They are driven electrically out of phase). Therefore, regardless of position, each cone is always in the exact opposite position from the other in its travel, relative to its own magnet.
The even-order (second, fourth, etc.) harmonic distortion products of each driver cancel acoustically, because the even-order harmonics of each driver are both virtually equal and exactly opposite in time phase to each other. Even-order harmonic distortion is caused by different non-linearities in the cone’s motion when the voice coil is moving deep into its magnet compared with when it is moving away from its magnet.
As important as the distortion cancellation, push-pull also doubles efficiency in comparison to a single 12” driver subwoofer (the same as doubling the amplifier power), as well as allowing twice the amplifier power to be used because of the power dissipation of two drivers. The total output improvement is four times! (6 dB).
M&K Push-Pull Dual Driver designs deliver deep bass with very low musical distortion and tremendous articulation to produce a very natural and powerful bass reproduction."

Photo is inside the JBL Control SB5. Is this push/pull or dual opposed?
Attached Thumbnails
Click image for larger version

Name:	jbl.JPG
Views:	94
Size:	81.0 KB
ID:	2489456  
legierk is offline  
post #11 of 39 Old 11-30-2018, 02:31 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,197
Mentioned: 315 Post(s)
Tagged: 0 Thread(s)
Quoted: 3731 Post(s)
Liked: 3705
Quote:
Originally Posted by Samps View Post
While not your typical push pull design, I am curious why we don't see dual sub boxes with one woofer inverted more often. From what I've read, inverting one driver does have some benefits.
because now your wiring and sub are dangling outside of the box. It's just not clean
notnyt is offline  
post #12 of 39 Old 11-30-2018, 03:13 PM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,182
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 643 Post(s)
Liked: 324
That looks more like a band pass enclosure to me on the JBL picture.

Interesting to read the mk info. I didn't know about those benefits.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
trilkb is offline  
post #13 of 39 Old 11-30-2018, 05:19 PM
AVS Forum Special Member
 
Vince_B's Avatar
 
Join Date: Aug 2001
Location: Hummelstown PA USA
Posts: 1,440
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 316 Post(s)
Liked: 209
Quote:
Originally Posted by Samps View Post
While not your typical push pull design, I am curious why we don't see dual sub boxes with one woofer inverted more often. From what I've read, inverting one driver does have some benefits.

What notnyt said. I’ve tinkered with the idea but you either dangle the magnet out or build out the box walls to go past the magnet which then makes the box huge externally without any interior volume gain.



Sent from my iPhone using Tapatalk
Vince_B is offline  
post #14 of 39 Old 11-30-2018, 05:32 PM
AVS Forum Special Member
 
jpmst3's Avatar
 
Join Date: Dec 2005
Location: Davidsville, PA
Posts: 8,591
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 196 Post(s)
Liked: 314
Check out this derivative: https://www.powersoundaudio.com/products/S7201

______________________________________________
Joe = LFE Addict
Past Builds: 24" LMS-5400 cube, Anarchy 25Hz Tapped Horn, Danley DTS-10 kit, BFM AutoTuba, BFM THT, BFM THT-LP
Joe's LOWARHORN build, Dual LMS-5400 Ultra Endtables build
jpmst3 is offline  
post #15 of 39 Old 11-30-2018, 05:38 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,197
Mentioned: 315 Post(s)
Tagged: 0 Thread(s)
Quoted: 3731 Post(s)
Liked: 3705
Quote:
Originally Posted by jpmst3 View Post
same as the m&k's basically, you lose interior volume. As designed, the cabs will also cause a resonance.
notnyt is offline  
post #16 of 39 Old 11-30-2018, 06:56 PM
AVS Forum Special Member
 
Join Date: Jan 2015
Location: United States
Posts: 2,530
Mentioned: 48 Post(s)
Tagged: 0 Thread(s)
Quoted: 1258 Post(s)
Liked: 1973
Quote:
Originally Posted by Samps View Post
I've read that is reduces nonlinearities between the two drivers and reduces distortion. If a particular motor design has some form of irregularity on its inward stroke, the inverted driver will help cancel that out, and vis versa.
Correct,

Not very common but M&K, TAD and even Cerwin-Vega made them. The main issue is one of the drivers is inverted which demands that the drivers are very quiet with little vent noise. You also are limited in what drivers you can do depending on impedance you desire.

I have a variant called Push-Pull Slot Loaded or PPSL subs. They are used in my garage because the slot is just additional box size and coupled with two 15's--they are some big boxes! The main reason I built them was not distortion reduction but they don't vibrate which is important for my line arrays placed on top of them. The other point was the drivers are protected inside the slot from flying parts, people, drinks or freight moving around in my garage. I use two 15's in an 8.7 cubic foot enclosure tuned to 24Hz with the slot compression at 2.2:1. The battle continues over at DIY Audio about what compression ratio gains how many dB's in efficiency and so on.

I've been using mine for almost 6 years and like the protection of the drivers in the slot and they don't vibrate which is eerie when they shake the entire garage and house. The efficiency gain, distortion reduction and increased cooling is just frosting on the cake. Never mind the comments of "you mounted one of your subs wrong" or "Arrays and goofy backwards subs--don't you build anything normal?"

My inhouse subs are not push-pull or PPSL--just 15's in traditional ported end table boxes. Since you have to use two drivers and either build something to protect the inverted driver or go PPSL, they are just too large for inhouse use. There are over 800 posts at DIY Audio forum about PPSL, very interesting and spirited discussion concerning that alignment.

A major reason is they look weird--you can run regular ported or sealed speakers with inverted drivers also--not common to see that! As far as push-pull goes, I've seen many horn designs that use that alignment but you can't see the drivers in the first place. All part of the compromises one makes when building subs--pick your poison.

If you have subwoofers behind a screen and have the space--going push-pull is a nice option and easy to change back if it scares the children. Push-pull and PPSL are tradtionally commonly used in infinite baffle subwoofers so they don't shake the walls and inside the plenumn for protection reasons. Not a good idea to have an inverted sub around kids, they have the habit of playing with wires so not kid friendly.
legierk likes this.
18Hurts is offline  
post #17 of 39 Old 11-30-2018, 08:36 PM
AVS Forum Special Member
 
trilkb's Avatar
 
Join Date: Mar 2017
Location: Cincinnati, Oh
Posts: 1,182
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 643 Post(s)
Liked: 324
Quote:
Originally Posted by jpmst3 View Post
Wonder what a clone full of JBL 12s would do! Lol!
legierk likes this.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
trilkb is offline  
post #18 of 39 Old 11-30-2018, 10:02 PM
AVS Forum Special Member
 
Join Date: Sep 2016
Posts: 1,074
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 397 Post(s)
Liked: 342
Quote:
Originally Posted by trilkb View Post
That looks more like a band pass enclosure to me on the JBL picture.

Interesting to read the mk info. I didn't know about those benefits.


It says in the article it is. Shared middle chamber.
Trimlock is online now  
post #19 of 39 Old 11-30-2018, 10:45 PM
AVS Forum Special Member
 
Join Date: Aug 2016
Posts: 1,674
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 1012 Post(s)
Liked: 1261
I like the sealed inverted config with the um18s for the increased enclosure volume and free air voice coil cooling. If I was building dual opposed enclosures I'd prob do dual inverted. However it does make the 4 cuft flatpacks quite tip happy with the motor weight hanging out that far, and as mentioned absolutely a disaster waiting to happen if you have small hands wandering.

Sent from my SM-N920V using Tapatalk
18Hurts likes this.
Pradeep2 is offline  
post #20 of 39 Old 12-01-2018, 12:29 PM
Advanced Member
 
bebb's Avatar
 
Join Date: Sep 2017
Location: Middle Illinois
Posts: 578
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 221 Post(s)
Liked: 156
Quote:
Originally Posted by legierk View Post
From the M&K website:

"Push-Pull Deep Bass
Push-Pull Dual-Driver Configuration M&K’s innovative Push-Pull Dual Driver configuration delivers a major improvement in subwoofer detail and clarity by virtually eliminating even-order harmonic distortion, which produces a boomy and poorly defined bass sound.............
M&K Push-Pull Dual Driver designs deliver deep bass with very low musical distortion and tremendous articulation to produce a very natural and powerful bass reproduction."
In my jaded mind it sounds like a bunch of marketing malarkey you would hear from a salesperson. Having said that, for my main speakers I did build an isobaric woofer chamber from a design in Speaker Builder magazine (which later became glass audio). The reason I built it was for muchof the same reasons mentioned above.

If bad sound were Faital, good sound would be almost impossible
Killed two Mach5 21s and three UM-18s (and counting?)
bebb is offline  
post #21 of 39 Old 12-01-2018, 03:20 PM
Advanced Member
 
Join Date: May 2016
Location: Chicago, IL
Posts: 741
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 347 Post(s)
Liked: 484
I'll offer some perspective.

Many here know a lot more than me and some are pro engineers.

But understanding history is important.

Ken Kriesel of the MK moniker is considered one of the foremost pioneers of home theater sound design. Look it up, learn about his subwoofer satellite ideas oh wait we all know we just dont always know where it came from.

Careful what you dismiss before you truly understand it! If Steely Dan or satellite sub systems or push pull interests you....

http://www.kreiselsound.com/timeline.php

A while back a friend gave me a set of old SVX4s and they are quite a design from 20+ years ago with adjustable crossovers! I looked for Ken Kriesel and he responded to some questions I had.

Hes an impressive person and the push pull design us one of his hallmarks.

#mtg90 if you ever have an interest let me know I would likely give you the mk pair as a token for your htm designs. Adjustable crossovers built into the bookshelves 20+ years ago
RoboAVS is offline  
post #22 of 39 Old 12-01-2018, 05:15 PM
AVS Forum Special Member
 
michael hurd's Avatar
 
Join Date: Nov 2007
Posts: 3,408
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 635 Post(s)
Liked: 670
Quote:
Originally Posted by legierk View Post
I have wondered what one of these designs would sound like using modern 18" drivers. Would love to know what the sub gurus think. (Also, what about the Sonotube sub designs? They were really popular 2-5 years ago. Now I don't see any new builds. Have they fallen out of fashion?)

https://www.avsforum.com/forum/155-d...x30ft-3-a.html


legierk and 18Hurts like this.

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
michael hurd is offline  
post #23 of 39 Old 12-01-2018, 06:54 PM
AVS Forum Special Member
 
Join Date: Jan 2015
Location: United States
Posts: 2,530
Mentioned: 48 Post(s)
Tagged: 0 Thread(s)
Quoted: 1258 Post(s)
Liked: 1973
Quote:
Originally Posted by michael hurd View Post
A picture says a thousand I'm not worthies.... sweet build!
18Hurts is offline  
post #24 of 39 Old 12-01-2018, 06:57 PM
AVS Forum Special Member
 
michael hurd's Avatar
 
Join Date: Nov 2007
Posts: 3,408
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 635 Post(s)
Liked: 670
Quote:
Originally Posted by 18Hurts View Post
A picture says a thousand I'm not worthies.... sweet build!

Yes, you will have to credit @aron7awol for taking the plunge and building those incredibly sweet subwoofers. Painted to match the decor, they look like they belong.

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
michael hurd is offline  
post #25 of 39 Old 12-01-2018, 07:25 PM
Senior Member
 
VegaMan's Avatar
 
Join Date: Nov 2015
Location: Chicagoland
Posts: 266
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 102 Post(s)
Liked: 78
the jbl system is a dual 4th order bandpass box using isobaric loading. while this is push pull in the sense, its not typically what is described in "standard" push pull alignments. however, since there are two ways to isobarically mount, its a necessity to mention. In any case, a standard push pull alignment, as described previously in the commentary re: the PPSL enclosure, is a reduction in even order harmonics. As well as a cancellation of non linearities, but does require relatively quiet motors or all that's negated.
The PPSL as popularized by DJK (rip) slot loads the drivers which gives an inherent gain or burp in the midbass region, which with some of todays higher inductance drivers could actually net a benefit, but with the larger diameter drivers popular around these parts, the boxes would be just retarded big, and of course the slot eats space. alternatively, just inverse mounting a driver kills aesthetics to a degree most couldn't live with....though some speakers just have a motor that begs to be seen.
VegaMan is offline  
post #26 of 39 Old 12-01-2018, 07:30 PM
AVS Forum Special Member
 
michael hurd's Avatar
 
Join Date: Nov 2007
Posts: 3,408
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 635 Post(s)
Liked: 670
Quote:
Originally Posted by Samps View Post
While not your typical push pull design, I am curious why we don't see dual sub boxes with one woofer inverted more often. From what I've read, inverting one driver does have some benefits.

I have read some on inverting a driver, the late Dennis Kleitsch ( DJK on various forums ) has many posts on slot loaded push pull subwoofers. The only test I have seen actual data from was from Art Welter, with a dual Eminence Lab-12 driver ported subwoofer.



If the drivers themselves have major non-linearities in Bl, suspension stiffness, cone offset or inductance, push pull will make this less noticeable. Using better drivers is also a possibility.

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
michael hurd is offline  
post #27 of 39 Old 12-02-2018, 09:04 AM
AVS Forum Addicted Member
 
BassThatHz's Avatar
 
Join Date: Apr 2008
Location: Northern Okan range (NW Cascades region)
Posts: 10,637
Mentioned: 221 Post(s)
Tagged: 0 Thread(s)
Quoted: 3679 Post(s)
Liked: 4170
1) It basically takes up the same external volume.
2) It turns the WAF from 2 out of 10 into 0 out of 10; and now you have this big ugly thing that is even harder to hide/place.
3) It's twice as expensive or can't be used for smoothing.
4) and now you need two of them at 4x the cost, to have smoothing.
5) Requires quiet motors
6) Because high-end motors are a lot better now.

That said:
I really want to see someone buy two push-pull RF-19 motors and put them in a push-pull mounting.
Never google for google: you'll break the universe! https://www.google.com/search?q=https://www.google.com
bebb likes this.
BassThatHz is offline  
post #28 of 39 Old 12-02-2018, 09:19 AM
AVS Forum Special Member
 
Vince_B's Avatar
 
Join Date: Aug 2001
Location: Hummelstown PA USA
Posts: 1,440
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 316 Post(s)
Liked: 209
Yeah I was gonna say #3 above as well. If you have to choose between two push pull cabs with two drivers each you’d end up better off with four cabs to even the response or to provide near field. Two up front and two near field for example would have much better impact.

I think the bottom line is that the benefits of push pull are probably outweighed by the benefits of more cabinets to spread around.



Sent from my iPhone using Tapatalk
Vince_B is offline  
post #29 of 39 Old 12-02-2018, 11:31 AM
AVS Forum Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 22,640
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1819 Post(s)
Liked: 631
[QUOTE=legierk;57193960]From the M&K website:

"...The even-order (second, fourth, etc.) harmonic distortion products of each driver cancel acoustically, because the even-order harmonics of each driver are both virtually equal and exactly opposite in time phase to each other. Even-order harmonic distortion is caused by different non-linearities in the cone’s motion when the voice coil is moving deep into its magnet compared with when it is moving away from its magnet."


I think the above is incorrect.

P-P would cancel the +/- excursion asymmetries in suspension stiffness and BL curve, but not the distortion due to increase in the former and decrease in the latter.

Noah
noah katz is offline  
post #30 of 39 Old 12-02-2018, 12:05 PM
AVS Forum Special Member
 
Join Date: Aug 2016
Posts: 1,674
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 1012 Post(s)
Liked: 1261
Quote:
Originally Posted by BassThatHz View Post
1) It basically takes up the same external volume.
2) It turns the WAF from 2 out of 10 into 0 out of 10; and now you have this big ugly thing that is even harder to hide/place.
3) It's twice as expensive or can't be used for smoothing.
4) and now you need two of them at 4x the cost, to have smoothing.
5) Requires quiet motors
6) Because high-end motors are a lot better now.

That said:
I really want to see someone buy two push-pull RF-19 motors and put them in a push-pull mounting.
Never google for google: you'll break the universe! https://www.google.com/search?q=https://www.google.com
I think we need to distinguish push pull isobaric where two drivers are needed to produce one drivers worth of output and the inverted driver with polarity reversed push push arrangement that the MKs etc are using, where you do get more output.
Pradeep2 is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off