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What is the best 30-300hz bass cab solution?

178.148.230.176
Posted on April 6, 2012 at 17:54:20
ceriatone@gmail.com
Audiophile

Posts: 170
Joined: August 19, 2008
 I did some very encouraging measurements of Audax PR170M0 both in OS as well as tractrix horns and it's ruler flat from some 270-300hz to around 1.7k, where it peaks down -5db and comes back flat around 2k again (probably a horn dip). anyway it sounds very clean and fine without any nasal or honk attributes.

with this measurements it seems i've sorted out a 100+db driver for the voice region and with it I can use beyma TPL-150 with the top open.

both drivers have nearly similar efficiency which is a nice feature.

i'm now looking to get the best i can do bellow audax. i can't afford both money and real estate to split it into sub-bass and mid-bass so it has to be one solution from 300hz down, as low as possible. the main goals are to:
- match the efficiency of the mid/hi system, around 100-101db
- reach as low as possible, ideal would be -3 around 30hz or so
- not to compromise any performance in the midbass i.e. to be flat up to 270-300hz....
- if this doesn't sound too silly, to be as close in quality to a front horn sub bass as possible...:)

i don't have much experience with good bass cabs and have no idea if something like onken or VOTT would be a good solution. probably yes, but let's hear your ideas or thoughts....

 

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RE: What is the best 30-300hz bass cab solution?, posted on April 6, 2012 at 23:59:24
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 Try one of my my PPSL designs. This one is 100.5dB/2.83V/1M midband, and is usable to 400hz or so.

Driver Properties
Name: 295-120
Type: Standard one-way driver
Company: Dayton Loudspeaker Co.
Comment: Nov 2011 (New)
No. of Drivers = 2
Mounting = Standard
Wiring = Parallel
Fs = 29.6 Hz
Qms = 10.55
Vas = 128.1 liters
Cms = 0.351 mm/N
Mms = 82.29 g
Rms = 1.451 kg/s
Xmax = 8 mm
Xmech = 12 mm
P-Dia = 254 mm
Sd = 506.7 sq.cm
P-Vd = 0.405 liters
Qes = 0.36
Re = 6 ohms
Le = 3.07 mH
Z = 8 ohms
BL = 15.97 Tm
Pe = 275 watts
Qts = 0.348
no = 0.89 %
1-W SPL = 91.64 dB
2.83-V SPL = 92.89 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box w/ Active HP Filter
Shape: Prism, square
Vb = 4.502 cu.ft
Fb = 27 Hz
QL = 6.24
F3 = 27.1 Hz
Fill = minimal
No. of Vents = 2
Vent shape = rectangle
Vent ends = two flush
Hv = 10 in
Wv = 2 in
Lv = 29.49 in
-----------------------------------------
Active 12 dB/oct. HP Filter
Fx = 27 Hz
Qx = 2

Here is a picture of Asylum member Les Hudson's efforts:

This is roughly a 24" cube, and is -3dB at 27hz.

PPSL stands for push-pull slot-loaded and is done to reduce distortion. Art Welter did a test at DIYaudio and got a 30dB reduction in 2nd harmonic and a 20dB reduction in 4th harmonic in the bottom octave at full power. 20dB is a 100:1 reduction!

 

RE: What is the best 30-300hz bass cab solution?, posted on April 7, 2012 at 01:43:44
ceriatone@gmail.com
Audiophile

Posts: 170
Joined: August 19, 2008
 thanks, are there any drawings or detailed explanations elsewhere.

does it matter if the drivers are wired parallel or in series (i would prefer later to raise up the impedance....)?

what kind of criteria is applied to the drivers, would something like this work:

http://www.bd-design.nl/contents/en-us/d19.html

it's modified beyma. i have 4 of this and could knock a box fast...

 

RE: What is the best 30-300hz bass cab solution?, posted on April 7, 2012 at 05:53:07
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 The Qts on that driver is a bit too low to be optimum, it can go to about 35hz.

The PPSL is preferred to be 6th order vented for minimum box size, maximum bass extension, and maximum efficiency.

A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).

The optimum Qts for a 6th order would be 0.312, other values will work, but there will be trade-offs.

Here is a plan for a 35hz 15" PPSL (Eminence KappaPro 15LF), the size would need to be larger for the BD-design 15.

35hz PPSL for Kappa Pro 15LF-2

A couple of different PPSL with Fc=31hz, 29hz, and 35hz:

http://i56.photobucket.com/albums/g196/dkleitsch/CoePA-2009.jpg

http://i56.photobucket.com/albums/g196/dkleitsch/COE08-3.jpg

http://i56.photobucket.com/albums/g196/dkleitsch/MilesAdamsBand3.jpg

A series of copies available in Europe from OHM using BMS drivers:

http://www.ohm.co.uk/images/ohm_pukk_sub_tower.jpg

General:

http://forum.speakerplans.com/topic45790_post464475.html#464475

 

RE: What is the best 30-300hz bass cab solution?, posted on April 7, 2012 at 06:53:36
ceriatone@gmail.com
Audiophile

Posts: 170
Joined: August 19, 2008
 thanks a lot, this is very interesting. plenty of reading for the weekend:)

this is very interesting looking cabs and quite along what i want to do at the moment (audax pr170m0 in tractrix or JMLC 200 horn for 200-2000, beyma tpl-150 for 2000-on)....:

http://gallery.audioasylum.com/cgi/view.mpl?u=33876&f=100_1485.JPG&v=f&UserImages=33876&session=&&moniker=Les%20Hudson&invite=&w=1288&h=966

however in comparison with the pics from your links, a shape of this cab is a bit different / taller / which nicely complements arranging a tweeter around an ear height. do you know what's the driver inside and are there published drawings of the cab?

also curious to know about the 12" dayton driver you recommend - what magic you use to push it from 92db/m sensitivy to 100db/m in your calc? 3db for PP, what else?

last but not least, as these are pretty stiff pro drivers, what amps the users reported to work the best. i come from the SET camp and i can smell trouble....


 

RE: What is the best 30-300hz bass cab solution?, posted on April 7, 2012 at 08:29:08
Inmate51
 Not to hijack Ceratonin's thread... I'm very interested in the PPSL design. My biggest concern is the need for two drivers per cabinet, which drives up the cost. What are your thoughts about driver quality, size, etc. in order to keep the cost down and still have high quality low bass?

I'm mostly thinking about the ability to use a smaller and therefore cheaper driver.

Thanks!

 

no problem:), posted on April 7, 2012 at 09:52:48
ceriatone@gmail.com
Audiophile

Posts: 170
Joined: August 19, 2008
 ... to hijack my thread as it's worth exploring it in full depth, especially if the design stands up to promise to be a good substitute for horn subs

the dayton 12" driver djk pointed at is around $100 - i find it perfectly affordable even for an experiment....

it would be good to find schematics somewhere for us who are a bit challenged with autoCAD and calcs... i would for starters prefer to go safe way and maybe experiment later, when at least get some clue on how design sounds.

 

RE: What is the best 30-300hz bass cab solution?, posted on April 7, 2012 at 10:04:26
weltersys
Industry Professional

Posts: 685
Location: FL
Joined: September 28, 2004
 "PPSL stands for push-pull slot-loaded and is done to reduce distortion. Art Welter did a test at DIYaudio and got a 30dB reduction in 2nd harmonic and a 20dB reduction in 4th harmonic in the bottom octave at full power. 20dB is a 100:1 reduction!"

For those interested in more detail:
http://www.diyaudio.com/forums/subwoofers/191833-push-pull-vs-normal-distortion-compared.html
Dennis,
Although 2nd, 4rth, sixth (even order) harmonics were greatly reduced by push pull loading, the third harmonic sometimes increased, resulting in the THD (total harmonic distortion) not always significantly changing, as can be seen in the 20 Hz 49 volt test results .
That said, distortion figures were reduced by 50% or more at some frequencies.

Since the frequency response and output of both the PP and standard cabinets were almost identical, an A/B listening test was simple, just swap the speaker cord and short out the unused cabinet.

At lower power levels, where the Lab12 is quite clean, no difference could be detected. When pushed at a power level where distortion could be noticed, the most distracting artifact was the audible vent noise from the reversed cone of the PP.
The lack of the second harmonic, an octave, made the now predominant third harmonic distortion more apparent in the PP cabinet. This is music related thing, the third harmonic , being a perfect fifth, may sound OK with some compositions, while sounding “wrong” with others.

Although the technical side of me says reduction of distortion of any sort is a good thing as far as a reproduction system is concerned, both my old ears, and a college freshman apprentice thought the push pull cabinet sounded less “musical” when pushed hard.




Doing another far more extensive test between six different HF drivers all on the same type of horn now, they sound quite different at different levels..

Art

 

RE: What is the best 30-300hz bass cab solution?, posted on April 7, 2012 at 11:04:58
Inmate51
 This is fascinating, although not entirely unexpected.

2nd and 4th harmonic distortion affects the tone quality of a sound, often making it sound "fuller" or "more defined", while not being objectionable. 3rd harmonic distortion certainly is objectionable.

I would never have thought that removing a large percentage of 2nd and 4th would "reveal" the 3rd so dramatically, but I suppose - psychoacoustic masking being what it is - that makes complete sense.

The exposure of the 3rd harmonic distortion affecting the sound of various musical works also makes perfect sense. Although we humans have decided to tune our bands and orchestras and pianos using the "equal temperament" approach, nature insists on producing overtones (harmonics) based on natural physics. This throws everything out of whack, and it's a constant battle to make things sound good when we and nature are fighting each other!

Thanks for your very insightful and helpful post!!

 

Anything Bigger or Lower?, posted on April 7, 2012 at 14:36:45
thetubeguy1954
Audiophile

Posts: 6112
Location: Orlando, Fla
Joined: January 7, 2001
 HI Dennis!

Do you have anything that would go even lower? I need a subwoofer, that can match the speed of my FE208ES-R in Sachiko cabinets, with Fostex T900a tweeters covering from 10Khz and above. As the Sachiko/FE208ES-R combo is great to 80Hz and "usable" to 50Hz and I'm not concerned with the sub having much over 100Hz. I'm looking for a very fast sub that will cover from 100Hz to as low as it can get, that will also keep up with my Sachiko/FE208ES-R/T900a combo. Do you have a PPSL design that would fit my needs? Wouldn't mind one that's using two 15" or 18" woofers!


I'm listening to:





Thetubeguy1954 (Tom Scata)


Full-range/Wide-range Drivers --- Front & Back-Loaded Horns
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
=========================================================================
"The man that hath no music in himself, nor is not moved with the concord of sweet sounds, is fit for treasons, deceptions, and spoils; The motions of his spirit are dull as night and his affections dark as Hell. Let no such man be trusted."

William Shakespeare from The Merchant of Venice; Act V,i
Thetubeguy1954 (Tom)

Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers


 

RE: Anything Bigger or Lower?, posted on April 8, 2012 at 06:54:01
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 You should probably look at using a sealed box and using a huge amplifier, otherwise the size gets huge.

Going from 40hz to 20hz and keeping the efficiency fixed dictates the box size increase by a factor of EIGHT.

I picked the -3dB point at 27hz for the reason that it's the lowest note on a piano.

Doubling the size and going to 15s will only gain you 3dB of efficiency.

Pick two of three, efficiency, cut-off frequency, size. Once you pick two, the other is fixed.

 

What amp to drive the PPSL?, posted on April 8, 2012 at 06:54:02
Frank Mena
Audiophile

Posts: 279
Location: S Western Ontario
Joined: May 28, 2006
 Newb question(run for your lives!!), but am I correct in assuming that an SS plate amp would drive the PPSL (for Eminence KappaPro 15LF)? & crossover point would be in the ball park of 100-150?

Cheers and Happy Easter
Frank M

 

RE: What amp to drive the PPSL?, posted on April 8, 2012 at 08:21:42
Saturntube
Manufacturer

Posts: 331
Location: Austin
Joined: April 21, 2006
 I havent listened to a PPSL yet, but I tried a lot of SS plate amps and they are so bad, there is no way of knowing how a sub enclosure would sound based on it running from a Plate amp... JMHO

 

Efficiency vs Sensitivity, posted on April 9, 2012 at 05:43:20
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 The BassBox v6.0 has you enter either voltage or power. In this case I entered 2.83V, which would be 1W if the actual impedance was 8Ω.

One driver would be 91.64dB/W/1M, but since it is not quite 8Ω (Re=6Ω, actually a little high for what is considered an 8Ω driver) it is 92.93dB/2.83V/1M.

Two drivers would thus be 3dB higher efficiency, or 6dB higher sensitivity than one driver.

The particular alignment I used has a gain of about 1.5dB above 100hz. The minimum impedance is at Fb=27hz and is 3.71Ω, so it is a nominal 4Ω speaker system.

There may actually be some small increase due to the slot loading. Nelson Pass measured a 2.78dB gain in a slot-loaded model he made that had a 3:1 compression ratio, I usually only run 2:1 (roughly). He did have a 36" wide front panel (as my 29hz~31hz double 15 PPSL have) but this cabinet would probably be narrower, and have less gain (if any).

As to what Les was using in the speaker you linked to, I'm not sure. It looks like either 10s or 12s. Within reason, about any aspect ratio could be constructed. A while back I made a narrow double 15 system that was about 48" tall that had a small sealed sub-chamber with a 12 and an Altec 931-12 MantaRay horn in it.

 

RE: What amp to drive the PPSL?, posted on April 9, 2012 at 09:10:20
weltersys
Industry Professional

Posts: 685
Location: FL
Joined: September 28, 2004
 "I havent listened to a PPSL yet, but I tried a lot of SS plate amps and they are so bad, there is no way of knowing how a sub enclosure would sound based on it running from a Plate amp.."

I have only listened to one plate amp (other than the amp in Meyers 650P subs), the Torpedo SP1-4000 from SpeakerPower, and it sounds excellent on a variety of subs.
The amp is rated 4000W/2 ohm, 2400W/4, 1300W/8, it weighs only 7 lbs.
It has no problem driving four Lab 12 (nominally 6 ohm) in parallel, which at the impedance minimum points is only a 1.07 ohm load.
It also makes very little heat, other amps by comparison seemed like blow dryers when pushed to similar output levels.
Speakerpower also has less powerful and multi-way amps in their line up, which if the SP1-4000 is any indication, also would sound great.

Art

 

I have a good question..........., posted on April 10, 2012 at 11:45:10
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Hello Art,

As a SE low powered amp designer and DIY builder, I am wondering about how much weight I should put on your tests, at 400 watts and 800 watts input to these speakers?

Are there other reasons why Les and Dennis like this design ? Like speed, low distortion, etc, etc, ( I don't know) and how can one be aware of the design's other attributes, both positive or negative, and how this woofer approach sounds in a living room environment as I would possibly employ it ???

Comments welcomed.

Jeff Medwin

 

RE: What is the best 30-300hz bass cab solution?, posted on April 10, 2012 at 20:30:23
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 a Klipschorn

 

Sorry, , posted on April 10, 2012 at 23:55:16
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 Sorry, the dual 15 PPSL eats a Klipschorn woofer section.

 

RE: I have a good question..........., posted on April 11, 2012 at 07:29:39
weltersys
Industry Professional

Posts: 685
Location: FL
Joined: September 28, 2004
 Jeff,

I have not built or listened to a push pull plenum (slot) exit cabinet, but have built many plenum exit cabinets in both rectangular and "V" shapes. The plenum seems to reduce group delay slightly, giving a greater sense of impact than a front loaded bass reflex of the same net cabinet space, similar to a large horn.

The difference in sound between push pull and both cones forward is speaker dependent, a speaker with a high degree of suspension irregularity may benefit more from PP than a more linear speaker.

The Lab 12 is a very low distortion speaker to start with, at low drive levels, I could not tell the difference between PP or normal loading.

At high levels, the difference was fairly obvious, and we thought the PP sounded worse because of the obvious cooling port chuffing noise, and some odd order harmonics had increased, sounding somewhat "unmusical".

A plenum gets the speakers closer together, reducing even order harmonic distortion more than my side by side tests. A plenum would reduce the cooling port chuffing noise. Some speakers have no cooling ports, so don't have that issue when reverse mounted.

If one decides to use a plenum mount cabinet, one can try PP or normal, and decide which is more appropriate for the chosen speakers and your personal taste in distortion "flavor".

Art

 

RE: Sorry, , posted on April 11, 2012 at 11:57:57
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 Yes, indeed, that's the stuff I like to hear. Looks like this might be my next project since you are so adamant about their perfromance and they look easy to build.

What woofers can I use? LAB 12, LAB 15? or any other Eminence driver (buy American).

 

JBL 4719, posted on April 12, 2012 at 06:21:04
bassbinotoko
Audiophile

Posts: 469
Location: Vancouver Island
Joined: January 27, 2009
 A vented cabinet with an 18" can reach into the 30's and give you floor-shuddering bass with efficiency. The suggested JBL cabinet may be overkill, but it's something you should be able to rent from a music store or sound company to try out. An Eminence Omega Pro 18" in about 9 cubic feet might be "good enough" at a fraction of the cost.

I can't say if the quality is going to be what you're looking for, though. Sealed boxes and generous wattage seems like a more reliable route to good sound and deep bass.

 

RE: I have a good question..........., posted on April 12, 2012 at 09:18:46
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Hello Art,

Thanks a lot for sharing your thoughts. I need to speak with Les next.

Jeff Medwin

 

are there plans and build instructions available?, posted on April 12, 2012 at 17:48:10
sunnysal
Audiophile

Posts: 845
Location: Central America
Joined: May 27, 2000
 I also wonder how would one adjust the size, etc. to handle a 20hz sub? regards, T
Jean-Francois Lessard 2A3 PP amp
Marantz 7T Preamp
Klipschorns w/ALK xovers
Squeezebox Touch
Asus netbook running itunes and LMS feeding
MSB link DACIII w24/96k
MSB digital director
Technics M85 Cassette

 

RE: are there plans and build instructions available?, posted on April 13, 2012 at 00:12:19
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 Here is a cut plan for a dual 15 (KappaPro 15LF) 35hz PPSL.

35hz PPSL for Kappa Pro 15LF-2

It really depends on the T/S parameters of the driver.

Many of those super x-max drivers prefer a sealed box and a Linkwitz transform. You could make it look a bit like a Klipsch Belle.

Belle type cosmetics

 

Thanks D! (nt), posted on April 17, 2012 at 15:40:15
sunnysal
Audiophile

Posts: 845
Location: Central America
Joined: May 27, 2000
 NT!
Jean-Francois Lessard 2A3 PP amp
Marantz 7T Preamp
Klipschorns w/ALK xovers
Squeezebox Touch
Asus netbook running itunes and LMS feeding
MSB link DACIII w24/96k
MSB digital director
Technics M85 Cassette

 

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