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LAB 12 Direct Radiator

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Topic: LAB 12 Direct Radiator
Posted By: rbarone
Subject: LAB 12 Direct Radiator
Date Posted: 01 April 2018 at 2:16pm
I'm checking out the performance spec's from Eminence for a LAB 12 4ohm in a simple 2.874 square foot vented box - which can be built from half a sheet of plywood.

If these are accurate, is there enough to be gained by building a bigger/heavier folded horn?

looking forward to some experienced folks weighing in for advice.  thx

  uploads/3467/LAB12_DR.pdf" rel="nofollow - uploads/3467/LAB12_DR.pdf

http://www.eminence.com/pdf/LAB_12C_cab.pdf





Replies:
Posted By: Hemisphere
Date Posted: 01 April 2018 at 2:43pm
Depends what you're trying to achieve. Folded horn loading will give a huge boost in efficiency for the Lab 12, as it's direct radiator efficiency is quite low, but you can achieve excellent results if you want a smaller box that'll play low and be used in singles. There was a recent thread about Art Welter's design for 2x Lab 12's in reflex, but as it turned out there was a preferable option for the same enclosure using a BMS woofer, so I wouldn't say the Lab12 is optimal even for that sort of small box reflex sub design, but if you've got them laying around they will certainly do. 

If you're building Lab 12 horns you'll be looking at stacks of 6 cabinets to play low with a smooth response, but if you're doing large gigs with extreme SPL requirements, and you regularly use stacks of 6 (4 in a pinch if you mostly play indoors) then horn loading is the way to go. If not, probably reflex but you can also look at tapped horns or bandpass as a halfway house solution.


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Posted By: rbarone
Date Posted: 01 April 2018 at 3:30pm
thx hemisphere for shedding some light.

to add a bit more info, i'd use just a pair to hold up the bottom of a pub-sized p.a. <200 people.  

small footprints are always helpful; it's mobile, so light weight is good too... 

i've built a few different subs, but never a tapped horn, so i'm curious.  as a woodworker, i think i'd also enjoy the build.

I've read a lot about the tham family & some about jbell's similar design.  when i began reading up on the lab sub, i wondered if the gains over the vented box were justified.

i've got plenty of class d power for a pair, so i guess efficiency may not be the most important factor at this small scale.

once again, thanks for sharing your time & experience





Posted By: Hemisphere
Date Posted: 01 April 2018 at 4:20pm
No point in building two Lab subs (or it would be one actually, if you only have two drivers), but even with small gigs you'll still find your bass section lacking with a pair of 89dB reflex subs.

Some discussion on Lab12 suitable tapped horn designs here:  http://www.diyaudio.com/forums/subwoofers/264766-pair-lab12s-recommendations.html" rel="nofollow - http://www.diyaudio.com/forums/subwoofers/264766-pair-lab12s-recommendations.html

And the thread for the PAL12:  http://www.diyaudio.com/forums/subwoofers/232219-325-lab-12-based-pa-tapped-horn-35hz-extension.html" rel="nofollow - http://www.diyaudio.com/forums/subwoofers/232219-325-lab-12-based-pa-tapped-horn-35hz-extension.html

That'll really hit the low notes, and although it is excursion limited to about 120-124B peak SPL, you've got plenty of wiggle room in the 60-80Hz region to boost the bass a few dB in the regions where it's most prominent in music program.

Here's the thread on Art Welter's Dual Lab12 design: https://forum.speakerplans.com/arts-dual-lab-12_topic99080.html" rel="nofollow - https://forum.speakerplans.com/arts-dual-lab-12_topic99080.html

A single lab12 in an 80 litre enclosure is going to max out at just 113dB, so about half as loud as it would go in a PAL12 with similar frequency extension.

As I mentioned in that thread, the driver you really want for this sort of design is a BMS 12s305, that'll achieve 122dB, about as much as the PAL12 tapped horn with comparable frequency response in a considerably smaller box, provided you have enough Watts to drive it. Driver is about the same price in the UK but for you it'll be more.

User 'doller' on this forum has built a bunch of Art Welter's dual Lab12 reflex design so you should talk with him - maybe his applications are similar enough to yours that you can get precise advice on how many Lab 12 reflex bins you'd need to build.


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Posted By: rbarone
Date Posted: 01 April 2018 at 5:01pm
thank you very much - really intriguing stuff.


Posted By: JonB67
Date Posted: 01 April 2018 at 8:07pm
https://www.forum.speakerplans.com/the-beginning-of-bliss-soundsystem_topic92433&OB=DESC_page6.html" rel="nofollow - cookie dj's tham 12 rig

Read this too. I really like this setup and may copy it for a second room rig. It clearly punches above its compact size!

Could also build some compact 15s?

You need decide what your goal is. How low do you need to go, how loud and how small?

Striking this balance to meet your needs is the hard bit.


Posted By: rbarone
Date Posted: 01 April 2018 at 8:50pm
wow..  that's a cool small rig.  i dig it.

the tham's are designed around speakers that are rare in the u.s.  i'd be inclined to experiment with a pair if i found a suitable replacement.

eminence speakers abound over here, & i also have a wholesale account that makes them very affordable.

i do have access to this sica - the spec's are close..  are they close enough?  i don't know.  

uploads/3467/p-a-s12k3_2018-04-01_20-45-59.pdf" rel="nofollow - uploads/3467/p-a-s12k3_2018-04-01_20-45-59.pdf






Posted By: JonB67
Date Posted: 02 April 2018 at 10:34am
https://forum.speakerplans.com/tham-12-a-compact-12-th_topic64833.html" rel="nofollow - tham 12 on sp

Info on it here.

Martinsson the designer has posted all the info on the cabinet so you can model it in the free software hornresp. Yes you'll have to do some legwork but its a free plan!

Mr martinsson also says in this thread there are some drivers simmed on his thread... link for that inn the first post of the thread I've linked to.

If this floats your boat you could also look at the tham 15, the jbell ss15 and mth30. Again, hit Google and see if they appeal.


Posted By: doller
Date Posted: 02 April 2018 at 11:02am
If you arn't putting labs in a lab horn the impedence is a pain in the arse. You will need a good solid amp to drive them. You can be hitting 2 to 3 ohms. I would go with the BMS if I could. Luckly I do have amps that will drive them. just a thought.


Posted By: rbarone
Date Posted: 02 April 2018 at 1:01pm
very true...  i haven't been able to find hornresp for a mac.  is it available?


Posted By: Hemisphere
Date Posted: 02 April 2018 at 2:38pm
No, but it's very lightweight so you can easily run it in a virtual machine (I mean, as easy as it is to run anything in a virtual machine!)

I should point out that my advice about the Labs and BMS driver only really applies if you're constrained to a particular box design or driver choice - the THAM12 is an excellent option for a compact, lightweight rig that will go loud, but you will sacrifice a little sound quality over a straight reflex system (subjectively speaking and genre dependent of course, but reflex is going to be the best all rounder for the widest variety of audience tastes and genres).

From Martinsson's page, the Tham12 can achieve around 132dB with some drivers, which for the box size is just nuts. Literally four times as loud as your original design idea (not the equivalent of four boxes - actually equivalent of about eight boxes), and although you won't get much below 50Hz at that level, you can still achieve 120dB at 40Hz.

That said, if true sub bass is something you and your audience will really appreciate, the BMS 12s305 in the Art Welter box can really excel. With enough amp power and a limiter, the dual 12" box can reach 128dB at 33Hz, or 122dB for a single 12". A THAM12 is only 105dB at the same frequency.


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Posted By: rbarone
Date Posted: 02 April 2018 at 2:52pm
thx hemi - i'm sure it's evident, that my sim & tech knowledge is not a strong suit...  so, all of this help is very much appreciated.  my "expertise" as it is, lies in the fabrication end of things - i'm a musician with a custom cabinet shop.

my apprentice is very savvy with his pc..  i'll put him on it.  i should've thought of that sooner.  thx!


Posted By: MarjanM
Date Posted: 02 April 2018 at 3:57pm
If you are using one Labsub inside for 200 people, and place it in a corner, it will probably be an overkill :-).
Use the  room acoustics to your advantage. One 2xLab12 reflex box will be beat by one Labsub for about 12db minimum. That is HUGE difference.
Not very mobile friendly dough.


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


Posted By: rbarone
Date Posted: 02 April 2018 at 5:22pm
thanks for that comparison... 


Posted By: Hemisphere
Date Posted: 02 April 2018 at 8:19pm
Yea, Marjan is right - I forgot the lab subs are actually reasonably flat and go low in small quantities compared with other horn subs (probably due to dual drivers, but it's also a very clever and effective design and the driver is tailored for it so no wonder).

Lots of practical reasons to go with a pair of smaller boxes though. Lightweight the Lab Sub is not!


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Posted By: rbarone
Date Posted: 02 April 2018 at 9:00pm
Many Thanks to all - 

 The Lab Sub wasn't high on my list because of it's size/weight - so, the original question of a Lab 12 in the Eminence-designed, small vented box. 

I've got a lot to learn..  

Cheers! 


Posted By: doller
Date Posted: 03 April 2018 at 4:24am
those dual lab reflex in a pair (so 4 drivers) would struggle I think to do 200 pax. You would have to drive them very hard. No headroom. The lab isn't actualy a great driver out of a lab horn I think. I have lab horns too. I would look at others. They don't sell any of them here and the labs are very cheap for me. 4x the reflex would fill a room ok. out side they are no good atall. They do sound very nice not woofy in my opinion. But it all comes down to amps. to get them going you need at least 1200w into 4r. 1600w is ideal. but danger. labs don't distort. much.


Posted By: Hemisphere
Date Posted: 03 April 2018 at 8:14am
Originally posted by rbarone rbarone wrote:

Many Thanks to all - 

 The Lab Sub wasn't high on my list because of it's size/weight - so, the original question of a Lab 12 in the Eminence-designed, small vented box. 

I've got a lot to learn.. 
Me too! My post about the Lab Sub was terrible LOL

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Posted By: JonB67
Date Posted: 03 April 2018 at 8:23am
Rbarone what sort of music genres and events dance / wedding /parties/ rave is it you need them for?

For 200 people 12inch subs seem too small to me unless you plan on having a few... in which case why not go up to 15s or 18s in a compact format?


Posted By: rbarone
Date Posted: 03 April 2018 at 11:22am
jon - they're for a soul / funk band.. vocals, guitar, 4-string bass, bari & tenor sax, drums, conga/percussion.

there's some stage volume, & it's always indoors.  i'd like to go with 2 subs, if possible.  mainly for the lack of room on stage.

i do have a pair of kappalite 3015lf, that i thought to put into cubos or ss15's.  there's also the bf titan 48 that uses that speaker, but it's twice the size of a a cubo15 - don't know it's twice the cabinet, so i've held off.  

curiosity (& a lack of knowledge) about the Eminence spec'd cab for it's lab12 led me down this rabbit hole.  i guess you can't beat the system... it just hasn't stopped us from trying.  planning the build is half the joy... thx again to all.




Posted By: concept-10
Date Posted: 03 April 2018 at 11:56am
Labs in reflex cabs will sound very nice for a soul/funk band, you do not need to be killing people with bass like a dnb or dub step gig, a couple of well tuned reflex labs might just add the bass you are looking for, they will be small and discrete so the attention is where it should be, on the band, indoors i think you may be pleasantly surprised, Cubo's will not get the lows you are looking for imho, for the price of half a sheet of mdf to build a test box give it a go. 


Posted By: mobiele eenheid
Date Posted: 03 April 2018 at 12:57pm
A Cubo 15 will have more than enough low end for a soul/ funk band.

Considering the drivers you have I would suggest a Cubo 15, SS15 or T48. If you're going down the 2 x 12" route I would consider Cubo 12 or the THAM 12, if going the 4 x 12" route I would consider reflex cabinets. Imho, if you're looking at two small to medium sized bass cabinets, you should aim at SPL from 40 Hz and up, if you're looking to address audiences up to 200.

As much as I like the idea of a Lab 12 reflex, I would much rather have 2 x Cubo 15, SS15 or T48 than 4 x Lab 12 reflex cabinets for PA. For HT I have one Lab 12 in a tapped horn and it awesome (horses for courses).

Johan


Posted By: Hemisphere
Date Posted: 03 April 2018 at 1:58pm
113dB peak SPL for a Lab12 in reflex, 119dB for a pair minus long term power compression losses just isn't enough headroom even for this application. Think about 'those' tracks and instruments where the bass just never seems as loud (low harmonic content, uncompressed waveforms), even when the system is running full out, and if you've got a room packed with 200 people and a band doing an energetic closing number, an extra 10dB of headroom will save the show while an extra 15Hz of LF extension that you can hardly hear anyway at low levels (Fletcher-Munson effect) won't.

It'll help that it's always playing indoors, but some small venues are going to have unfortunate room modes that leave large areas of the dancefloor 10db down.


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Posted By: Meat
Date Posted: 04 April 2018 at 12:02am
Heard a single lab in a basement club in Bristol quite a number of years ago now. Crazy bass. Don't let anyone tell you that single horn subs can't work; when you have the right boundaries indoors silliness from a single box is fully possible. Free field then sure you really want 4 min but indoors all bets are off.

I quite liked my Ciare 12.00SW reflex. That had a higher max SPL capabliity than the double lab reflex under discussion and it was tiny. Didn't go as low (still did 35Hz though) but we didn't have any Shackleton records to play back then.

If you want a compact 12" reflex then maybe look at another driver, it's amazing what you can get out of a small high power driver or two when given suitable power and used inside. A pair of double 12" subs with proper drivers and proper power can really work well in the right space. They ain't gonna smash up stadiums but they will probably serve your purpose.


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Posted By: bass*en*mass
Date Posted: 04 April 2018 at 12:14am
faital rs series is another great option for compact, low tuned reflex imo..
2x10 is louder at lower power than a single 12 and easier to power (4ohm vs. 8), 2x12 wont require much more volume though, just twice+ the power..


Posted By: rbarone
Date Posted: 04 April 2018 at 12:42am
much appreciated - i'll look into those options..  


Posted By: mini-mad
Date Posted: 04 April 2018 at 3:12am
Originally posted by bass*en*mass bass*en*mass wrote:

faital rs series is another great option for compact, low tuned reflex imo..
2x10 is louder at lower power than a single 12 and easier to power (4ohm vs. 8), 2x12 wont require much more volume though, just twice+ the power..

..wouldn't mind seeing a plan of that double 10 you speak of... please

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If it sounds like a gorilla is trying to escape, turn it down.



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