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Title: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Chris Grimshaw on August 31, 2019, 08:49:56 am
Thought I'd make a new thread. There was some interest in developing a compact but loud subwoofer for rock 'n' roll gigs, where low-end extension isn't particularly important.

So far, here are the goals I'd consider sensible. Happy to chop/change them by popular demand, though.

- 4ohm (maximises power with 1 sub per amp channel)
- Flat to 55Hz
- Can be lifted with one hand by Average Joe
- Loud as possible while keeping the above
- Sensible money
- Beat a KW181


In my experience, more expensive drivers are worth the money. They typically allow more output in a smaller box than a cheap driver, meaning output density (which is a priority here) is high.

So, my first simulation was with a https://www.bcspeakers.com/en/products/lf-driver/15-0/4/15sw115-4 - it's about as good as it gets for 15" subwoofers, and is conveniently available in 4ohm impedance. I simulated a simple ported box.

With 90v RMS input (about 2KW input) and a highpass filter to cut out-of-band excursion, we're at 128.5dB at 55Hz, 130dB at 60Hz, dropping slowly to 128dB at 100Hz.
Port velocity is a little high at the bottom end, but that will only be a problem if 55Hz comes along at full power - not likely to come up with the intended program material.

The cabinet volume is 62L net, which is nice and compact. Once built, it'll be a bit bigger - wood thickness and bracing all add to the overall external volume.

It's worth noting that a KW181 will manage 128dB at 70Hz, and dropping off to each side. In theory, then, this compact 15" ought to do quite well.


I do have some other ideas:
- 2x 12" mounted for force-cancellation could be interesting - stops the cabinet walking around
- Investigate bandpass and/or other designs - tapped horns etc.

Chris
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Tim McCulloch on August 31, 2019, 12:09:46 pm
Rock goes down to 44Hz (open E string on a conventional bass guitar, and the pants-ruffling kick drum hits; the chest cavity part is around 60-80.

I generally have disliked band pass designs although Nexo has gradually convinced me they can be done "more right" than I've previously experienced.

I don't care about 1-hand speaker management as I still have 2 hands attached to me.  What I want is balance, poise, and no awkward dimensions.

Truck/van pack-friendly dimensions.  Handles on at least 5 sides.  Optional pole cup for those who desire such things.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Chris Grimshaw on September 01, 2019, 03:30:53 am
Tim,

Open E is 41Hz. Low B (on a 5-string) is around 30Hz.

My current subwoofers (which I'm happy to share the designs for) are compact 15" boxes which are flat down to 40Hz. They beat a KW181 by around 6dB at 40Hz, but lose out at 70Hz.

They tick most of the boxes in the design spec. However, if we're willing to sacrifice some low-frequency extension then it would be possible to make a much louder box.

Tradeoffs, as always.

Chris
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: John Halliburton on September 01, 2019, 09:55:17 am
Thought I'd make a new thread. There was some interest in developing a compact but loud subwoofer for rock 'n' roll gigs, where low-end extension isn't particularly important.

So far, here are the goals I'd consider sensible. Happy to chop/change them by popular demand, though.

- 4ohm (maximises power with 1 sub per amp channel)
- Flat to 55Hz
- Can be lifted with one hand by Average Joe
- Loud as possible while keeping the above
- Sensible money
- Beat a KW181


In my experience, more expensive drivers are worth the money. They typically allow more output in a smaller box than a cheap driver, meaning output density (which is a priority here) is high.

So, my first simulation was with a https://www.bcspeakers.com/en/products/lf-driver/15-0/4/15sw115-4 - it's about as good as it gets for 15" subwoofers, and is conveniently available in 4ohm impedance. I simulated a simple ported box.

With 90v RMS input (about 2KW input) and a highpass filter to cut out-of-band excursion, we're at 128.5dB at 55Hz, 130dB at 60Hz, dropping slowly to 128dB at 100Hz.
Port velocity is a little high at the bottom end, but that will only be a problem if 55Hz comes along at full power - not likely to come up with the intended program material.

The cabinet volume is 62L net, which is nice and compact. Once built, it'll be a bit bigger - wood thickness and bracing all add to the overall external volume.

It's worth noting that a KW181 will manage 128dB at 70Hz, and dropping off to each side. In theory, then, this compact 15" ought to do quite well.


I do have some other ideas:
- 2x 12" mounted for force-cancellation could be interesting - stops the cabinet walking around
- Investigate bandpass and/or other designs - tapped horns etc.

Chris

If you go with the vented design, I'd still enlarge the port area(which of course also lengthens it) to reduce vent velocity, and lower that distortion which to me is more audible than one would think.

It is what would separate this project from typical commercial versions. 

Yes, likely larger overall, but IMO worth it if it still fits in the Yugo. ;>)

If more bang for the box is desired, I'd certainly consider going with a bandpass design. 

Best regards,

John
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Tim Weaver on September 01, 2019, 10:36:44 am
With today's megawatt-handling extra-excursion having super woofers, should we be revisiting linkwitz-transform type enclosures? Or Maybe the Carver Sunfire type?

If you aren't savvy, they are basically undersized sealed boxes that use power and lots of EQ to make up the extension. The benefits are that you can essentially "choose your Q" of the finished product. Also they are very well controlled having a massive air spring in the cabinet. The downside for PA use is it uses tons of power and your HP and limiting needs to be spot on or you'll be launching voice coils.

For a while Bag-End was using this method but that was before modern drivers and amps were common.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Mark Wilkinson on September 01, 2019, 01:15:24 pm
With today's megawatt-handling extra-excursion having super woofers, should we be revisiting linkwitz-transform type enclosures? Or Maybe the Carver Sunfire type?

If you aren't savvy, they are basically undersized sealed boxes that use power and lots of EQ to make up the extension. The benefits are that you can essentially "choose your Q" of the finished product. Also they are very well controlled having a massive air spring in the cabinet. The downside for PA use is it uses tons of power and your HP and limiting needs to be spot on or you'll be launching voice coils.

For a while Bag-End was using this method but that was before modern drivers and amps were common.

I tried that, using the same 18" driver in a sealed box, and in a larger vented box. bms 18n862 8ohm, 95dB 1 watt, 1500w AES, 19mm xmax.
The sealed is about a 21" cube, and probably could have been made an inch or so smaller.
The vented is 23"x 23"x 28" deep and is tuned to 31Hz.
The Linkwitz transform needed too much boost to make the sealed reasonable at 31Hz,
but i do believe it would work fine if restricted to say 40-45Hz, and at less than anger SPL.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Chris Grimshaw on September 02, 2019, 03:26:19 am
With today's megawatt-handling extra-excursion having super woofers, should we be revisiting linkwitz-transform type enclosures? Or Maybe the Carver Sunfire type?

I actually tried sealed subs before moving to ported. Over a useful frequency range, the ported box would keep up with 3x sealed boxes. Each box had 1KW on tap. So, you'd need 3x the drivers and 3x the power if you wanted to go sealed.

IMO, not worth it. I was slightly embarassed to find that my (ported) main speakers would happily out-run the sealed subwoofers down to 60Hz.

It's possible to use some clever multi-band limiting to get something that's flat to 20Hz at low SPLs, but cuts off higher as you push the fader. However, that's not how I like to run my PA systems - IMO they should respond linearly as you push the faders. No change in tonality, just louder and louder.
It would also restrict the user base to those that have access to high-end DSPs. Ideally I'd like to keep the filtering as simple as possible: lowpass, highpass, maybe a PEQ to tilt the overall response.



If you go with the vented design, I'd still enlarge the port area(which of course also lengthens it) to reduce vent velocity, and lower that distortion which to me is more audible than one would think.

It is what would separate this project from typical commercial versions. 

Yes, likely larger overall, but IMO worth it if it still fits in the Yugo. ;>)

If more bang for the box is desired, I'd certainly consider going with a bandpass design. 

Best regards,

John

Hi John,

Right now I'm simulating a port with 300cm^2 area, for a driver with 855cm^2 of cone area.
Should keep port compression to less than a couple of dB if you hammer it with worst-case sine waves.

A quick simulation for a 6th order bandpass looks pretty promising - 3-4dB more output above 70Hz. The internal box size goes to 82L, so the net volume would come to roughly 100L.
I'll try running a few other drivers through that cabinet to see how flexible it will be. I don't want to have a design that's nailed for exactly one driver, but terrible for all others.

Cheers, all.

Chris
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Steve M Smith on September 02, 2019, 11:06:37 am
My current subwoofers (which I'm happy to share the designs for)


I would like to see your design.




Steve.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Mark Wilkinson on September 02, 2019, 11:25:03 am
I actually tried sealed subs before moving to ported. Over a useful frequency range, the ported box would keep up with 3x sealed boxes. Each box had 1KW on tap. So, you'd need 3x the drivers and 3x the power if you wanted to go sealed.

IMO, not worth it. I was slightly embarassed to find that my (ported) main speakers would happily out-run the sealed subwoofers down to 60Hz.

It's possible to use some clever multi-band limiting to get something that's flat to 20Hz at low SPLs, but cuts off higher as you push the fader. However, that's not how I like to run my PA systems - IMO they should respond linearly as you push the faders. No change in tonality, just louder and louder.
It would also restrict the user base to those that have access to high-end DSPs. Ideally I'd like to keep the filtering as simple as possible: lowpass, highpass, maybe a PEQ to tilt the overall response.


Chris

Hi Chris, I can't imagine how 1 ported box could keep up with 3 sealed boxes (other than in the frequency range where the port is making the big bulk of the output).
Were you using the same driver? Was the sealed box already rolling off at 60Hz ?

My experiments using the same driver showed near identical response and sensitivity once above the sealed box's rolloff corner.
That may be because i chose a driver known to work well either sealed of ported, I dunno. 
(What is the spec for when a driver works better sealed vs ported?  EBP (fs/Qes) ?  That a value around 90 works for both, lower value for sealed, higher for ported? You know more about that stuff than I do............)

Anyway, below are traces for the sealed and ported boxes as described earlier, with a little processing in place.
The sealed processing was using a Linkwitz transform, but only to get to about 40-45 Hz.  I'm pretty sure the same results  could be done with normal parametric & shelving filters, too.

I played both sealed and ported boxes hard, alot. 1500W into 8ohms. 
Unless content got very strong below mid 40's, it could be hard to tell a difference.
blue=ported   green=sealed   rather obviously  :)
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Chris Grimshaw on September 02, 2019, 01:50:49 pm
Hi Chris, I can't imagine how 1 ported box could keep up with 3 sealed boxes (other than in the frequency range where the port is making the big bulk of the output).
Were you using the same driver? Was the sealed box already rolling off at 60Hz ?


Hey Mark,

Looks like I mis-wrote. 1:2 is about right when you consider a frequency range of 40-100Hz. At 40Hz (port tuning), the ported box would match 3x sealed boxes.

Same drivers each time. Ported box was around 70L net, sealed boxes were 35L net. 1KW per driver.

FWIW, the sealed boxes were rolling off (gently) at 80Hz, and required a lot of EQ to get flat down low. Even then, the mechanical demands on the drivers were considerable.

Chris

PS - Steve, I'll send them via PM in the interest of keeping this thread tidy.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: John Halliburton on September 03, 2019, 09:06:03 am
A quick simulation for a 6th order bandpass looks pretty promising - 3-4dB more output above 70Hz. The internal box size goes to 82L, so the net volume would come to roughly 100L.
I'll try running a few other drivers through that cabinet to see how flexible it will be. I don't want to have a design that's nailed for exactly one driver, but terrible for all others.

Although it's been 20 plus years since I designed and used one-and it was 4th order, a 6th order BP IMO would be less bang for the effort than a tapped horn.  I fully expect a good TH design would have more output, lower distortion, and better impulse response(especially this).

I think it's tougher to get a 6th BP design to have enough bandwidth to not sound like a one note wonder as well.

YMMV,

John
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Rory Buszka on September 04, 2019, 11:42:22 am
Although it's been 20 plus years since I designed and used one-and it was 4th order, a 6th order BP IMO would be less bang for the effort than a tapped horn.  I fully expect a good TH design would have more output, lower distortion, and better impulse response(especially this).

I think it's tougher to get a 6th BP design to have enough bandwidth to not sound like a one note wonder as well.

YMMV,

John

The original LAB Horn Subwoofer was designed for (and delivered) tremendous output, tremendous bass extension, and excellent efficiency, but the tradeoffs were large size, heavy weight, and difficult construction. It sounds like for the One Hand Subwoofer (OHS) the priorities are reversed: Small size, light weight, and easy construction, with the best possible output and efficiency available from such a design, and deliberately limiting bass extension to that required for most music.

Tapped horns are somewhere in the middle. They offer horn-like output from as few as one box, but they are still complex to construct, heavy, and relatively large. Don Keele did a survey during the earliest concept development for the JBL Vertec line array that compared various bass loading techniques and the amount of output that could be achieved from the smallest occupied volume. He found that the most output at low frequencies for a given volume could be achieved using a typical bass-reflex enclosure. I think his survey was limited and it probably deserves to be conducted again using today's designs, including 6th order bandpass and tapped horn configurations. But it does provide some guidance in the direction of a vented box.

I think it would be interesting to look at a Reflex/Horn Hybrid design (not the Martin one, as it would have some of the space-efficiency shortcomings of a horn). As you design a reflex enclosure with minimal chamber volume, you increase the port length necessary to achieve a certain tuning. You also increase the needed length of the port when the cross sectional area of the port is increased. What a few designers have done is designed an enclosure with a port that not only creates a bass-reflex resonance, but also has a quarter-wave pipe resonance in the frequency range of interest. Then when those two resonances are brought close together, they create a reflex enclosure that is very efficient over a narrow(ish) bandwidth. The RCF ESW 1018 subwoofer is an example of this. Then the famous Yorkville LS808 (or LS801p) applied a taper on the port section, turning it into a compromised rear-loaded horn. This doesn't enable the port to truly act like a horn (except for also possessing a quarter wave resonance), but it does add some damping to the port action. The benefit to a speaker like this is it would be easy to construct, and easy to make lightweight, while having more efficiency over a limited bandwidth than a classical bass-reflex enclosure.

To drive adoption, be careful of using a speaker that is either difficult to obtain outside of the EU, or very expensive.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: John Halliburton on September 04, 2019, 09:35:49 pm
The original LAB Horn Subwoofer was designed for (and delivered) tremendous output, tremendous bass extension, and excellent efficiency, but the tradeoffs were large size, heavy weight, and difficult construction. It sounds like for the One Hand Subwoofer (OHS) the priorities are reversed: Small size, light weight, and easy construction, with the best possible output and efficiency available from such a design, and deliberately limiting bass extension to that required for most music.

Tapped horns are somewhere in the middle. They offer horn-like output from as few as one box, but they are still complex to construct, heavy, and relatively large. Don Keele did a survey during the earliest concept development for the JBL Vertec line array that compared various bass loading techniques and the amount of output that could be achieved from the smallest occupied volume. He found that the most output at low frequencies for a given volume could be achieved using a typical bass-reflex enclosure. I think his survey was limited and it probably deserves to be conducted again using today's designs, including 6th order bandpass and tapped horn configurations. But it does provide some guidance in the direction of a vented box.

I think it would be interesting to look at a Reflex/Horn Hybrid design (not the Martin one, as it would have some of the space-efficiency shortcomings of a horn). As you design a reflex enclosure with minimal chamber volume, you increase the port length necessary to achieve a certain tuning. You also increase the needed length of the port when the cross sectional area of the port is increased. What a few designers have done is designed an enclosure with a port that not only creates a bass-reflex resonance, but also has a quarter-wave pipe resonance in the frequency range of interest. Then when those two resonances are brought close together, they create a reflex enclosure that is very efficient over a narrow(ish) bandwidth. The RCF ESW 1018 subwoofer is an example of this. Then the famous Yorkville LS808 (or LS801p) applied a taper on the port section, turning it into a compromised rear-loaded horn. This doesn't enable the port to truly act like a horn (except for also possessing a quarter wave resonance), but it does add some damping to the port action. The benefit to a speaker like this is it would be easy to construct, and easy to make lightweight, while having more efficiency over a limited bandwidth than a classical bass-reflex enclosure.

To drive adoption, be careful of using a speaker that is either difficult to obtain outside of the EU, or very expensive.

I find most tapped horns almost as easy to build as a vented cabinet.  When I first started working for Tom at Intersonics, my first day involved working on the SDL-4 Servodrive subwoofer prototype, which was the smaller brother of the SDL-5.  Both were horn loaded W designs with close to fifty pieces in each.  I may have slightly skewed take on what is an easy cabinet or hard cabinet to build.

That said, a vented cabinet is still likely to yield the lightest cabinet, and one can easily make high quality designs that are compact.

Best regards,

John
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Tim McCulloch on September 04, 2019, 09:56:24 pm
Tim,

Open E is 41Hz. Low B (on a 5-string) is around 30Hz.

My current subwoofers (which I'm happy to share the designs for) are compact 15" boxes which are flat down to 40Hz. They beat a KW181 by around 6dB at 40Hz, but lose out at 70Hz.

They tick most of the boxes in the design spec. However, if we're willing to sacrifice some low-frequency extension then it would be possible to make a much louder box.

Tradeoffs, as always.

Chris

Okay, I'll take the -10 at 45Hz, reasonably peaky from 55ish to 80, useful to 100ish and combine those with size (transport friendly) and balance (ergonomics).  Oh, wait, that's almost what the JTR Growler does, it just weighs more than "one handed."

I'd take a weight penalty if it means preserving output and handling.  Like I said, I still have 2 hands.

Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Michael Thompson on September 05, 2019, 01:28:50 am
Thought I'd make a new thread. There was some interest in developing a compact but loud subwoofer for rock 'n' roll gigs, where low-end extension isn't particularly important.

So far, here are the goals I'd consider sensible. Happy to chop/change them by popular demand, though.

- 4ohm (maximises power with 1 sub per amp channel)
- Flat to 55Hz
- Can be lifted with one hand by Average Joe
- Loud as possible while keeping the above
- Sensible money
- Beat a KW181


In my experience, more expensive drivers are worth the money. They typically allow more output in a smaller box than a cheap driver, meaning output density (which is a priority here) is high.

So, my first simulation was with a https://www.bcspeakers.com/en/products/lf-driver/15-0/4/15sw115-4 - it's about as good as it gets for 15" subwoofers, and is conveniently available in 4ohm impedance. I simulated a simple ported box.

With 90v RMS input (about 2KW input) and a highpass filter to cut out-of-band excursion, we're at 128.5dB at 55Hz, 130dB at 60Hz, dropping slowly to 128dB at 100Hz.
Port velocity is a little high at the bottom end, but that will only be a problem if 55Hz comes along at full power - not likely to come up with the intended program material.

The cabinet volume is 62L net, which is nice and compact. Once built, it'll be a bit bigger - wood thickness and bracing all add to the overall external volume.

It's worth noting that a KW181 will manage 128dB at 70Hz, and dropping off to each side. In theory, then, this compact 15" ought to do quite well.


I do have some other ideas:
- 2x 12" mounted for force-cancellation could be interesting - stops the cabinet walking around
- Investigate bandpass and/or other designs - tapped horns etc.

Chris

As simple DIY goes, the Cubo designs from www.freespeakerdesigns.com already hit pretty much all of these marks and are forgiving enough that you can add handles, pole mounts, casters, etc...  I've built some and find them to be pretty handy boxes to have around.  You get an extra ~3 db in trade for some low end compared to ported box, but they are still plenty low for most things.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Nathan Riddle on September 05, 2019, 09:04:49 am
As simple DIY goes, the Cubo designs from www.freespeakerdesigns.com already hit pretty much all of these marks and are forgiving enough that you can add handles, pole mounts, casters, etc...  I've built some and find them to be pretty handy boxes to have around.  You get an extra ~3 db in trade for some low end compared to ported box, but they are still plenty low for most things.

https://freespeakerplans.com/plans/14-plans/basscab/44-cubo15

This seems rather interesting. Also pretty easy & cheap to build.

~130dB peak output...not bad.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Rich Riotto on September 06, 2019, 02:06:04 pm
Thought I'd make a new thread. There was some interest in developing a compact but loud subwoofer for rock 'n' roll gigs, where low-end extension isn't particularly important.

So far, here are the goals I'd consider sensible. Happy to chop/change them by popular demand, though.

- 4ohm (maximises power with 1 sub per amp channel)
- Flat to 55Hz
- Can be lifted with one hand by Average Joe
- Loud as possible while keeping the above
- Sensible money
- Beat a KW181


In my experience, more expensive drivers are worth the money. They typically allow more output in a smaller box than a cheap driver, meaning output density (which is a priority here) is high.

So, my first simulation was with a https://www.bcspeakers.com/en/products/lf-driver/15-0/4/15sw115-4 - it's about as good as it gets for 15" subwoofers, and is conveniently available in 4ohm impedance. I simulated a simple ported box.

With 90v RMS input (about 2KW input) and a highpass filter to cut out-of-band excursion, we're at 128.5dB at 55Hz, 130dB at 60Hz, dropping slowly to 128dB at 100Hz.
Port velocity is a little high at the bottom end, but that will only be a problem if 55Hz comes along at full power - not likely to come up with the intended program material.

The cabinet volume is 62L net, which is nice and compact. Once built, it'll be a bit bigger - wood thickness and bracing all add to the overall external volume.

It's worth noting that a KW181 will manage 128dB at 70Hz, and dropping off to each side. In theory, then, this compact 15" ought to do quite well.


I do have some other ideas:
- 2x 12" mounted for force-cancellation could be interesting - stops the cabinet walking around
- Investigate bandpass and/or other designs - tapped horns etc.

Chris

If it were me, I'd prefer reasonable flatness down to 40Hz for the bass open E.  Like Tim, I'd be OK with two hands as long as it was under 75 lbs and not an awkward lift.  Also, high efficiency drivers so less power is required to get to full output.  Depending on the power requirements, I might also opt for 8 ohms so I could run two chained at (4 ohms) off of one amp channel.  With that said, definitely as loud as possible from low 40s to low 100s.  It seems like the JTR Cap212Pro checks a lot of the same boxes.  The design seems pretty simple...it's the custom drivers that might be key to making it work.

Full disclosure: Everything I think I MIGHT know about speaker cabinet design has been learned from reading these threads!  Please correct any false assumptions.

- Rich
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Caleb Dueck on September 07, 2019, 01:25:46 pm
If it were me, I'd prefer reasonable flatness down to 40Hz for the bass open E.  Like Tim, I'd be OK with two hands as long as it was under 75 lbs and not an awkward lift.  Also, high efficiency drivers so less power is required to get to full output.  Depending on the power requirements, I might also opt for 8 ohms so I could run two chained at (4 ohms) off of one amp channel.  With that said, definitely as loud as possible from low 40s to low 100s.  It seems like the JTR Cap212Pro checks a lot of the same boxes.  The design seems pretty simple...it's the custom drivers that might be key to making it work.

Full disclosure: Everything I think I MIGHT know about speaker cabinet design has been learned from reading these threads!  Please correct any false assumptions.

- Rich

I agree with flat to 40Hz at least.  Subs without good low end extension just feel a bit emasculated regardless of SPL. 

Another point that is important to me - quality, neodymium magnet drivers.  Non- neo drivers just sound a bit mushy.  I got to hear pretty much the entire Fulcrum subwoofer lineup side by side a couple times, and the muddy vs tight sound fit with neo vs non difference. 

If you assume 2 people, wheels, and a form factor that can be tilted easily - that keeps the performance from getting hosed.  If you assume carry by 1 person - SPL or extension, or both, are crippled.  Setting up a sound system is real work, that's why there are wheels, paid muscle, ramps, etc.  When I think tiny and light, what comes to mind is a Bose WaveRadio! 
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Bill Hornibrook on September 07, 2019, 04:33:45 pm
If it were me, I'd prefer reasonable flatness down to 40Hz for the bass open E.  Like Tim, I'd be OK with two hands as long as it was under 75 lbs and not an awkward lift. 

- Rich

Yeah my thinking too. B&C's own recommendation for that 15 is an enclosure size of 3.2 cubic feet tuned to 40hz. That gets me me there, and is still incredibly small and easy to transport.

If any of you guys (who are much better at this than I am) would care to design a simple bass reflex cab for that driver based on B&C's recommendations, I'd be very interested.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Rory Buszka on September 15, 2019, 08:41:17 pm
https://freespeakerplans.com/plans/14-plans/basscab/44-cubo15

This seems rather interesting. Also pretty easy & cheap to build.

~130dB peak output...not bad.

I wonder if that number was arrived at through measuring an actual box, or through simulation.

In terms of the physics involved, this seems more like an ElectroVoice Sb180 "SubScoop" style of design - that is, NOT a tapped horn. The horn path is much too short to resonate below about 80-90 Hz, and output below that is provided by a reflex mode of operation where the air in the narrow entrance of the horn starts acting like the air mass in a ported enclosure. Helmholtz resonance cannot be back-driven like a quarter wave resonator can to achieve a second tuning point at the half wavelength, as a tapped horn does.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Nathan Riddle on October 30, 2019, 09:02:05 am
Sooo, anyone with design chops way better than me (I can use HornResp to make pictures) come up with a design that fits our 'requirements'?

I mean, JTR's Captivator 212PRO is impressive  (https://forums.prosoundweb.com/index.php/topic,169764.msg1587950.html#new) but A DIY variant (NOT A COPY) of that or something like the DSL Mini seems exactly what we're all looking for?

Distilled requirements seem to me to be:
135dB peak SPL
Usable output 40hz-120hz
Strong output 50hz-110hz
70lbs or less
Truck pack
Handles
Wheels
Pole cup


(somewhat relevant)
My purposes are small subs to go under the SM100's I grabbed. DJ Monitors & small rig (weddings, etc).
DSL Mini is probably the natural choice, but I don't want to spend money and wood is easily accessible.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Chris Grimshaw on October 30, 2019, 09:22:23 am
135dB? Really?
If you want 135dB at 40Hz, you're looking at a couple of good double-18"s. If you use a sealed box, it's 10x 18" drivers each moving 24mm peak-to-peak to manage that sort of number.
FWIW, I can get 139dB "peak" out of a single 15". It's at the cone breakup peak (103dB@1w) at 1.2kHz, and the driver will stand 4KW short-term peaks at that frequency if you can find an amp big enough.


Seems to me like a ported 15" ticks most of the boxes. I suspect it'd be easy enough to come up with a couple of variations - one that's tuned to 50Hz, and another that's tuned to 40Hz. I must make it clear, though, that the 50Hz box will put out basically nothing at 40Hz.

If that'd be interesting, I'll get started.

Chris
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Taylor Hall on October 30, 2019, 09:47:19 am
You could try looking at Art's dual LAB12 box. I've built a couple and they're pretty potent for their size, albeit power hungry. They tick all the requirements apart from the one-handed transport.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Nathan Riddle on October 30, 2019, 10:03:40 am
135dB? Really?
If you want 135dB at 40Hz, you're looking at a couple of good double-18"s. If you use a sealed box, it's 10x 18" drivers each moving 24mm peak-to-peak to manage that sort of number.
FWIW, I can get 139dB "peak" out of a single 15". It's at the cone breakup peak (103dB@1w) at 1.2kHz, and the driver will stand 4KW short-term peaks at that frequency if you can find an amp big enough.

Seems to me like a ported 15" ticks most of the boxes. I suspect it'd be easy enough to come up with a couple of variations - one that's tuned to 50Hz, and another that's tuned to 40Hz. I must make it clear, though, that the 50Hz box will put out basically nothing at 40Hz.

If that'd be interesting, I'll get started.

Chris

Thanks Chris, note I'm not tasking you ;)
Just for funsies, and I'd love to have these under my Sm100's for DJ monitors come Nov 30th ;)
Trial run!

Note I didn't say 135dB @ 40Hz
I said 135dB peak.

To me, it seems the JTR 212Pro hits all the marks I stated prior (see image).

Image (JTR 212Pro): Add 9db for 1 meter, peak (measurement 2m/rms)
[stolen from JTR's FB page]
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Nathan Riddle on October 30, 2019, 10:10:50 am
You could try looking at Art's dual LAB12 box. I've built a couple and they're pretty potent for their size, albeit power hungry. They tick all the requirements apart from the one-handed transport.

https://soundforums.net/community/threads/free-sub-plan-dual-lab12-front-loaded-by-welter-systems.164/

I did not know about these. That's pretty awesome!
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Taylor Hall on October 30, 2019, 10:19:28 am
https://soundforums.net/community/threads/free-sub-plan-dual-lab12-front-loaded-by-welter-systems.164/ (https://soundforums.net/community/threads/free-sub-plan-dual-lab12-front-loaded-by-welter-systems.164/)

I did not know about these. That's pretty awesome!
Yeah, build took a couple weekends, super easy to throw together. Still need to make grilles for them but that project is way down the totem pole until our busy season winds down in a month or so.
Title: Re: LAB Sub 2 - Small 'n' Loud for Rock 'n' Roll
Post by: Art Welter on October 30, 2019, 01:40:42 pm
https://soundforums.net/community/threads/free-sub-plan-dual-lab12-front-loaded-by-welter-systems.164/

I did not know about these. That's pretty awesome!
Heavy little bricks, lotsa LF and little punch. For DJ use with droning LF, the LAB 12 are not going to handle the long term power dished out like modern drivers can, and for most genres, whomping hard 60-120 Hz will be "more impressive".
After side by side comparisons, I sold several pairs of small tapped and front loaded horns to DJs that had nearly an octave less low frequency, but more top- the WS LAB 2x12s ended up being sold to a great 5 string bass player that knew what he was looking for, and could notice the difference.

You might consider the Tham designs:

http://www.martinsson.cc/blog/index.php?m=03&y=12&entry=entry120331-124819

They will get you into TH-Mini territory, with Papa, Momma, and Baby Bear options.

Art